/exprtk.hpp

/*
 ******************************************************************
 *           C++ Mathematical Expression Toolkit Library          *
 *                                                                *
 * Author: Arash Partow (1999-2015)                               *
 * URL: http://www.partow.net/programming/exprtk/index.html       *
 *                                                                *
 * Copyright notice:                                              *
 * Free use of the C++ Mathematical Expression Toolkit Library is *
 * permitted under the guidelines and in accordance with the most *
 * current version of the Common Public License.                  *
 * http://www.opensource.org/licenses/cpl1.0.php                  *
 *                                                                *
 * Example expressions:                                           *
 * (00) (y + x / y) * (x - y / x)                                 *
 * (01) (x^2 / sin(2 * pi / y)) - x / 2                           *
 * (02) sqrt(1 - (x^2))                                           *
 * (03) 1 - sin(2 * x) + cos(pi / y)                              *
 * (04) a * exp(2 * t) + c                                        *
 * (05) if(((x + 2) == 3) and ((y + 5) <= 9),1 + w, 2 / z)        *
 * (06) (avg(x,y) <= x + y ? x - y : x * y) + 2 * pi / x          *
 * (07) z := x + sin(2 * pi / y)                                  *
 * (08) u := 2 * (pi * z) / (w := x + cos(y / pi))                *
 * (09) clamp(-1,sin(2 * pi * x) + cos(y / 2 * pi),+1)            *
 * (10) inrange(-2,m,+2) == if(({-2 <= m} and [m <= +2]),1,0)     *
 * (11) (2sin(x)cos(2y)7 + 1) == (2 * sin(x) * cos(2*y) * 7 + 1)  *
 * (12) (x ilike 's*ri?g') and [y < (3 z^7 + w)]                  *
 *                                                                *
 ******************************************************************
*/


#ifndef INCLUDE_EXPRTK_HPP
#define INCLUDE_EXPRTK_HPP


#include <algorithm>
#include <cctype>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <deque>
#include <exception>
#include <functional>
#include <iterator>
#include <limits>
#include <list>
#include <map>
#include <set>
#include <stack>
#include <stdexcept>
#include <string>
#include <utility>
#include <vector>


namespace exprtk
{
   #if exprtk_enable_debugging
     #define exprtk_debug(params) printf params
   #else
     #define exprtk_debug(params) (void)0
   #endif

   namespace details
   {
      inline bool is_whitespace(const char c)
      {
         return (' '  == c) || ('\n' == c) ||
                ('\r' == c) || ('\t' == c) ||
                ('\b' == c) || ('\v' == c) ||
                ('\f' == c) ;
      }

      inline bool is_operator_char(const char c)
      {
         return ('+' == c) || ('-' == c) ||
                ('*' == c) || ('/' == c) ||
                ('^' == c) || ('<' == c) ||
                ('>' == c) || ('=' == c) ||
                (',' == c) || ('!' == c) ||
                ('(' == c) || (')' == c) ||
                ('[' == c) || (']' == c) ||
                ('{' == c) || ('}' == c) ||
                ('%' == c) || (':' == c) ||
                ('?' == c) || ('&' == c) ||
                ('|' == c) || (';' == c) ;
      }

      inline bool is_letter(const char c)
      {
         return (('a' <= c) && (c <= 'z')) ||
                (('A' <= c) && (c <= 'Z')) ;
      }

      inline bool is_digit(const char c)
      {
         return ('0' <= c) && (c <= '9');
      }

      inline bool is_letter_or_digit(const char c)
      {
         return is_letter(c) || is_digit(c);
      }

      inline bool is_left_bracket(const char c)
      {
         return ('(' == c) || ('[' == c) || ('{' == c);
      }

      inline bool is_right_bracket(const char c)
      {
         return (')' == c) || (']' == c) || ('}' == c);
      }

      inline bool is_bracket(const char c)
      {
         return is_left_bracket(c) || is_right_bracket(c);
      }

      inline bool is_sign(const char c)
      {
         return ('+' == c) || ('-' == c);
      }

      inline bool is_invalid(const char c)
      {
         return !is_whitespace   (c) &&
                !is_operator_char(c) &&
                !is_letter       (c) &&
                !is_digit        (c) &&
                ('.'  != c)          &&
                ('_'  != c)          &&
                ('$'  != c)          &&
                ('~'  != c)          &&
                ('\'' != c);
      }

      inline bool imatch(const char c1, const char c2)
      {
         return std::tolower(c1) == std::tolower(c2);
      }

      inline bool imatch(const std::string& s1, const std::string& s2)
      {
         if (s1.size() == s2.size())
         {
            for (std::size_t i = 0; i < s1.size(); ++i)
            {
               if (std::tolower(s1[i]) != std::tolower(s2[i]))
               {
                  return false;
               }
            }

            return true;
         }

         return false;
      }

      inline bool is_valid_sf_symbol(const std::string& symbol)
      {
         // Special function: $f12 or $F34
         return (4 == symbol.size())  &&
                ('$' == symbol[0])    &&
                imatch('f',symbol[1]) &&
                is_digit(symbol[2])   &&
                is_digit(symbol[3]);
      }

      inline const char& front(const std::string& s)
      {
         return s[0];
      }

      inline const char& back(const std::string& s)
      {
         return s[s.size() - 1];
      }

      inline std::string to_str(int i)
      {
         if (0 == i)
            return std::string("0");

         std::string result;

         if (i < 0)
         {
            for ( ; i; i /= 10)
            {
               result += '0' + char(-(i % 10));
            }

            result += '-';
         }
         else
         {
            for ( ; i; i /= 10)
            {
               result += '0' + char(i % 10);
            }
         }

         std::reverse(result.begin(), result.end());

         return result;
      }

      inline bool is_hex_digit(const std::string::value_type digit)
      {
         return (('0' <= digit) && (digit <= '9')) ||
                (('A' <= digit) && (digit <= 'F')) ||
                (('a' <= digit) && (digit <= 'f')) ;
      }

      inline unsigned char hex_to_bin(unsigned char h)
      {
         if (('0' <= h) && (h <= '9'))
            return (h - '0');
         else
            return (std::toupper(h) - 'A');
      }

      template <typename Iterator>
      inline void parse_hex(Iterator& itr, Iterator end, std::string::value_type& result)
      {
         if (
              (end !=  (itr    )) &&
              (end !=  (itr + 1)) &&
              (end !=  (itr + 2)) &&
              (end !=  (itr + 3)) &&
              ('0' == *(itr    )) &&
              (
                ('x' == *(itr + 1)) ||
                ('X' == *(itr + 1))
              ) &&
              (is_hex_digit(*(itr + 2))) &&
              (is_hex_digit(*(itr + 3)))
            )
         {
            result = hex_to_bin(*(itr + 2)) << 4 | hex_to_bin(*(itr + 3));
            itr += 3;
         }
         else
            result = '\0';
      }

      inline void cleanup_escapes(std::string& s)
      {
         typedef std::string::iterator str_itr_t;

         str_itr_t itr1 = s.begin();
         str_itr_t itr2 = s.begin();
         str_itr_t end  = s.end  ();

         std::size_t removal_count  = 0;

         while (end != itr1)
         {
            if ('\\' == (*itr1))
            {
               ++removal_count;

               if (end == ++itr1)
                  break;
               else if ('\\' != (*itr1))
               {
                  switch (*itr1)
                  {
                     case 'n' : (*itr1) = '\n'; break;
                     case 'r' : (*itr1) = '\r'; break;
                     case 't' : (*itr1) = '\t'; break;
                     case '0' : parse_hex(itr1, end, (*itr1));
                                removal_count += 3;
                                break;
                  }

                  continue;
               }
            }

            if (itr1 != itr2)
            {
               (*itr2) = (*itr1);
            }

            ++itr1;
            ++itr2;
         }

         s.resize(s.size() - removal_count);
      }

      class build_string
      {
      public:

         build_string(const std::size_t& initial_size = 64)
         {
            data_.reserve(initial_size);
         }

         inline build_string& operator << (const std::string& s)
         {
            data_ += s;
            return (*this);
         }

         inline build_string& operator << (const char* s)
         {
            data_ += std::string(s);
            return (*this);
         }

         inline operator std::string () const
         {
            return data_;
         }

         inline std::string as_string() const
         {
            return data_;
         }

      private:

         std::string data_;
      };

      struct ilesscompare
      {
         inline bool operator()(const std::string& s1, const std::string& s2) const
         {
            const std::size_t length = std::min(s1.size(),s2.size());

            for (std::size_t i = 0; i < length;  ++i)
            {
               const char c1 = static_cast<char>(std::tolower(s1[i]));
               const char c2 = static_cast<char>(std::tolower(s2[i]));

               if (c1 > c2)
                  return false;
               else if (c1 < c2)
                  return true;
            }

            return s1.size() < s2.size();
         }
      };

      static const std::string reserved_words[] =
                                  {
                                    "break",  "case",  "continue",  "default",  "false",  "for",
                                    "if", "else", "ilike",  "in", "like", "and",  "nand", "nor",
                                    "not",  "null",  "or",   "repeat", "return",  "shl",  "shr",
                                    "swap", "switch", "true",  "until", "var",  "while", "xnor",
                                    "xor", "&", "|"
                                  };

      static const std::size_t reserved_words_size = sizeof(reserved_words) / sizeof(std::string);

      static const std::string reserved_symbols[] =
                                  {
                                    "abs",  "acos",  "acosh",  "and",  "asin",  "asinh", "atan",
                                    "atanh", "atan2", "avg",  "break", "case", "ceil",  "clamp",
                                    "continue",   "cos",   "cosh",   "cot",   "csc",  "default",
                                    "deg2grad",  "deg2rad",   "equal",  "erf",   "erfc",  "exp",
                                    "expm1",  "false",   "floor",  "for",   "frac",  "grad2deg",
                                    "hypot", "iclamp", "if",  "else", "ilike", "in",  "inrange",
                                    "like",  "log",  "log10", "log2",  "logn",  "log1p", "mand",
                                    "max", "min",  "mod", "mor",  "mul", "ncdf",  "nand", "nor",
                                    "not",   "not_equal",   "null",   "or",   "pow",  "rad2deg",
                                    "repeat", "return", "root", "round", "roundn", "sec", "sgn",
                                    "shl", "shr", "sin", "sinc", "sinh", "sqrt",  "sum", "swap",
                                    "switch", "tan",  "tanh", "true",  "trunc", "until",  "var",
                                    "while", "xnor", "xor", "&", "|"
                                  };

      static const std::size_t reserved_symbols_size = sizeof(reserved_symbols) / sizeof(std::string);

      static const std::string base_function_list[] =
                                  {
                                    "abs", "acos",  "acosh", "asin",  "asinh", "atan",  "atanh",
                                    "atan2",  "avg",  "ceil",  "clamp",  "cos",  "cosh",  "cot",
                                    "csc",  "equal",  "erf",  "erfc",  "exp",  "expm1", "floor",
                                    "frac", "hypot", "iclamp",  "like", "log", "log10",  "log2",
                                    "logn", "log1p", "mand", "max", "min", "mod", "mor",  "mul",
                                    "ncdf",  "pow",  "root",  "round",  "roundn",  "sec", "sgn",
                                    "sin", "sinc", "sinh", "sqrt", "sum", "swap", "tan", "tanh",
                                    "trunc",  "not_equal",  "inrange",  "deg2grad",   "deg2rad",
                                    "rad2deg", "grad2deg"
                                  };

      static const std::size_t base_function_list_size = sizeof(base_function_list) / sizeof(std::string);

      static const std::string logic_ops_list[] =
                                  {
                                    "and", "nand", "nor", "not", "or",  "xnor", "xor", "&", "|"
                                  };

      static const std::size_t logic_ops_list_size = sizeof(logic_ops_list) / sizeof(std::string);

      static const std::string cntrl_struct_list[] =
                                  {
                                    "for", "if", "repeat", "switch", "while"
                                  };

      static const std::size_t cntrl_struct_list_size = sizeof(cntrl_struct_list) / sizeof(std::string);

      inline bool is_reserved_word(const std::string& symbol)
      {
         for (std::size_t i = 0; i < reserved_words_size; ++i)
         {
            if (imatch(symbol,reserved_words[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_reserved_symbol(const std::string& symbol)
      {
         for (std::size_t i = 0; i < reserved_symbols_size; ++i)
         {
            if (imatch(symbol,reserved_symbols[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_base_function(const std::string& function_name)
      {
         for (std::size_t i = 0; i < base_function_list_size; ++i)
         {
            if (imatch(function_name,base_function_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_control_struct(const std::string& cntrl_strct)
      {
         for (std::size_t i = 0; i < cntrl_struct_list_size; ++i)
         {
            if (imatch(cntrl_strct,cntrl_struct_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      inline bool is_logic_opr(const std::string& lgc_opr)
      {
         for (std::size_t i = 0; i < cntrl_struct_list_size; ++i)
         {
            if (imatch(lgc_opr,logic_ops_list[i]))
            {
               return true;
            }
         }

         return false;
      }

      struct cs_match
      {
         static inline bool cmp(const char c0, const char c1)
         {
            return (c0 == c1);
         }
      };

      struct cis_match
      {
         static inline bool cmp(const char c0, const char c1)
         {
            return (std::tolower(c0) == std::tolower(c1));
         }
      };

      template <typename Iterator, typename Compare>
      inline bool match_impl(const Iterator pattern_begin,
                             const Iterator pattern_end,
                             const Iterator data_begin,
                             const Iterator data_end,
                             const typename std::iterator_traits<Iterator>::value_type& zero_or_more,
                             const typename std::iterator_traits<Iterator>::value_type& zero_or_one)
      {
         if (0 == std::distance(data_begin,data_end))
         {
            return false;
         }

         Iterator d_itr = data_begin;
         Iterator p_itr = pattern_begin;
         Iterator c_itr = data_begin;
         Iterator m_itr = data_begin;

         while ((data_end != d_itr) && (zero_or_more != (*p_itr)))
         {
            if ((!Compare::cmp((*p_itr),(*d_itr))) && (zero_or_one != (*p_itr)))
            {
               return false;
            }

            ++p_itr;
            ++d_itr;
         }

         while (data_end != d_itr)
         {
            if (zero_or_more == (*p_itr))
            {
               if (pattern_end == (++p_itr))
               {
                  return true;
               }

               m_itr = p_itr;
               c_itr = d_itr;
               ++c_itr;
            }
            else if ((Compare::cmp((*p_itr),(*d_itr))) || (zero_or_one == (*p_itr)))
            {
               ++p_itr;
               ++d_itr;
            }
            else
            {
               p_itr = m_itr;
               d_itr = c_itr++;
            }
         }

         while ((p_itr != pattern_end) && (zero_or_more == (*p_itr))) { ++p_itr; }

         return (p_itr == pattern_end);
      }

      inline bool wc_match(const std::string& wild_card,
                           const std::string& str)
      {
         return match_impl<const char*,cs_match>(wild_card.data(),
                                                 wild_card.data() + wild_card.size(),
                                                 str.data(),
                                                 str.data() + str.size(),
                                                 '*',
                                                 '?');
      }

      inline bool wc_imatch(const std::string& wild_card,
                            const std::string& str)
      {
         return match_impl<const char*,cis_match>(wild_card.data(),
                                                  wild_card.data() + wild_card.size(),
                                                  str.data(),
                                                  str.data() + str.size(),
                                                  '*',
                                                  '?');
      }

      inline bool sequence_match(const std::string& pattern,
                                 const std::string& str,
                                 std::size_t&       diff_index,
                                 char&              diff_value)
      {
         if (str.empty() || pattern.empty())
            return false;
         else if ('*' == pattern[0])
            return false;

         typedef std::string::const_iterator itr_t;

         itr_t p_itr = pattern.begin();
         itr_t s_itr = str    .begin();

         itr_t p_end = pattern.end();
         itr_t s_end = str    .end();

         while ((s_end != s_itr) && (p_end != p_itr))
         {
            if ('*' == (*p_itr))
            {
               const char target = std::toupper(*(p_itr - 1));

               if ('*' == target)
               {
                  diff_index = std::distance(str.begin(),s_itr);
                  diff_value = std::toupper(*p_itr);

                  return false;
               }
               else
                  ++p_itr;

               while (s_itr != s_end)
               {
                  if (target != std::toupper(*s_itr))
                     break;
                  else
                     ++s_itr;
               }

               continue;
            }
            else if (
                      ('?' != *p_itr) &&
                      std::toupper(*p_itr) != std::toupper(*s_itr)
                    )
            {
               diff_index = std::distance(str.begin(),s_itr);
               diff_value = std::toupper(*p_itr);

               return false;
            }

            ++p_itr;
            ++s_itr;
         }

         return (
                  (s_end == s_itr) &&
                  (
                    (p_end ==  p_itr) ||
                    ('*'   == *p_itr)
                  )
                );
      }

      static const double pow10[] = {
                                      1.0,
                                      1.0E+001, 1.0E+002, 1.0E+003, 1.0E+004,
                                      1.0E+005, 1.0E+006, 1.0E+007, 1.0E+008,
                                      1.0E+009, 1.0E+010, 1.0E+011, 1.0E+012,
                                      1.0E+013, 1.0E+014, 1.0E+015, 1.0E+016
                                    };

     static const std::size_t pow10_size = sizeof(pow10) / sizeof(double);

      namespace numeric
      {
         namespace constant
         {
            static const double e       =  2.718281828459045235360;
            static const double pi      =  3.141592653589793238462;
            static const double pi_2    =  1.570796326794896619231;
            static const double pi_4    =  0.785398163397448309616;
            static const double pi_180  =  0.017453292519943295769;
            static const double _1_pi   =  0.318309886183790671538;
            static const double _2_pi   =  0.636619772367581343076;
            static const double _180_pi = 57.295779513082320876798;
            static const double log2    =  0.693147180559945309417;
            static const double sqrt2   =  1.414213562373095048801;
         }

         namespace details
         {
            struct unknown_type_tag {};
            struct real_type_tag    {};
            struct complex_type_tag {};
            struct int_type_tag     {};

            template <typename T>
            struct number_type { typedef unknown_type_tag type; };

            #define exprtk_register_real_type_tag(T)                          \
            template<> struct number_type<T> { typedef real_type_tag type; }; \

            #define exprtk_register_complex_type_tag(T)     \
            template<> struct number_type<std::complex<T> > \
            { typedef complex_type_tag type; };             \

            #define exprtk_register_int_type_tag(T)                          \
            template<> struct number_type<T> { typedef int_type_tag type; }; \

            exprtk_register_real_type_tag(double     )
            exprtk_register_real_type_tag(long double)
            exprtk_register_real_type_tag(float      )

            exprtk_register_complex_type_tag(double     )
            exprtk_register_complex_type_tag(long double)
            exprtk_register_complex_type_tag(float      )

            exprtk_register_int_type_tag(short                 )
            exprtk_register_int_type_tag(int                   )
            exprtk_register_int_type_tag(long long int         )
            exprtk_register_int_type_tag(unsigned short        )
            exprtk_register_int_type_tag(unsigned int          )
            exprtk_register_int_type_tag(unsigned long long int)

            #undef exprtk_register_real_type_tag
            #undef exprtk_register_int_type_tag

            template <typename T>
            struct epsilon_type
            {
               static inline T value()
               {
                  const T epsilon = T(0.0000000001);
                  return epsilon;
               }
            };

            template <>
            struct epsilon_type <float>
            {
               static inline float value()
               {
                  const float epsilon = float(0.000001f);
                  return epsilon;
               }
            };

            template <>
            struct epsilon_type <long double>
            {
               static inline long double value()
               {
                  const long double epsilon = (long double)(0.000000000001);
                  return epsilon;
               }
            };

            template <typename T>
            inline bool is_nan_impl(const T v, real_type_tag)
            {
               return std::not_equal_to<T>()(v,v);
            }

            template <typename T>
            inline int to_int32_impl(const T v, real_type_tag)
            {
               return static_cast<int>(v);
            }

            template <typename T>
            inline long long int to_int64_impl(const T v, real_type_tag)
            {
               return static_cast<long long int>(v);
            }

            template <typename T>
            inline bool is_true_impl(const T v)
            {
               return std::not_equal_to<T>()(T(0),v);
            }

            template <typename T>
            inline bool is_false_impl(const T v)
            {
               return std::equal_to<T>()(T(0),v);
            }

            template <typename T>
            inline T abs_impl(const T v, real_type_tag)
            {
               return ((v >= T(0)) ? v : -v);
            }

            template <typename T>
            inline T min_impl(const T v0, const T v1, real_type_tag)
            {
               return std::min<T>(v0,v1);
            }

            template <typename T>
            inline T max_impl(const T v0, const T v1, real_type_tag)
            {
               return std::max<T>(v0,v1);
            }

            template <typename T>
            inline T equal_impl(const T v0, const T v1, real_type_tag)
            {
               const T epsilon = epsilon_type<T>::value();
               return (abs_impl(v0 - v1,real_type_tag()) <= (std::max(T(1),std::max(abs_impl(v0,real_type_tag()),abs_impl(v1,real_type_tag()))) * epsilon)) ? T(1) : T(0);
            }

            inline float equal_impl(const float v0, const float v1, real_type_tag)
            {
               const float epsilon = epsilon_type<float>::value();
               return (abs_impl(v0 - v1,real_type_tag()) <= (std::max(1.0f,std::max(abs_impl(v0,real_type_tag()),abs_impl(v1,real_type_tag()))) * epsilon)) ? 1.0f : 0.0f;
            }

            template <typename T>
            inline T equal_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 == v1) ? 1 : 0;
            }

            template <typename T>
            inline T expm1_impl(const T v, real_type_tag)
            {
               // return std::expm1<T>(v);
               if (abs_impl(v,real_type_tag()) < T(0.00001))
                  return v + (T(0.5) * v * v);
               else
                  return std::exp(v) - T(1);
            }

            template <typename T>
            inline T expm1_impl(const T v, int_type_tag)
            {
               return T(std::exp<double>(v)) - T(1);
            }

            template <typename T>
            inline T nequal_impl(const T v0, const T v1, real_type_tag)
            {
               typedef real_type_tag rtg;
               const T epsilon = epsilon_type<T>::value();
               return (abs_impl(v0 - v1,rtg()) > (std::max(T(1),std::max(abs_impl(v0,rtg()),abs_impl(v1,rtg()))) * epsilon)) ? T(1) : T(0);
            }

            inline float nequal_impl(const float v0, const float v1, real_type_tag)
            {
               typedef real_type_tag rtg;
               const float epsilon = epsilon_type<float>::value();
               return (abs_impl(v0 - v1,rtg()) > (std::max(1.0f,std::max(abs_impl(v0,rtg()),abs_impl(v1,rtg()))) * epsilon)) ? 1.0f : 0.0f;
            }

            template <typename T>
            inline T nequal_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 != v1) ? 1 : 0;
            }

            template <typename T>
            inline T modulus_impl(const T v0, const T v1, real_type_tag)
            {
               return std::fmod(v0,v1);
            }

            template <typename T>
            inline T modulus_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 % v1;
            }

            template <typename T>
            inline T pow_impl(const T v0, const T v1, real_type_tag)
            {
               return std::pow(v0,v1);
            }

            template <typename T>
            inline T pow_impl(const T v0, const T v1, int_type_tag)
            {
               return std::pow(static_cast<double>(v0),static_cast<double>(v1));
            }

            template <typename T>
            inline T logn_impl(const T v0, const T v1, real_type_tag)
            {
               return std::log(v0) / std::log(v1);
            }

            template <typename T>
            inline T logn_impl(const T v0, const T v1, int_type_tag)
            {
               return static_cast<T>(logn_impl<double>(static_cast<double>(v0),static_cast<double>(v1),real_type_tag()));
            }

            template <typename T>
            inline T log1p_impl(const T v, real_type_tag)
            {
               if (v > T(-1))
               {
                  if (abs_impl(v,real_type_tag()) > T(0.0001))
                  {
                     return std::log(T(1) + v);
                  }
                  else
                     return (T(-0.5) * v + T(1)) * v;
               }
               else
                  return std::numeric_limits<T>::quiet_NaN();
            }

            template <typename T>
            inline T log1p_impl(const T v, int_type_tag)
            {
               if (v > T(-1))
               {
                  return std::log(T(1) + v);
               }
               else
                  return std::numeric_limits<T>::quiet_NaN();
            }

            template <typename T>
            inline T root_impl(const T v0, const T v1, real_type_tag)
            {
               return std::pow(v0,T(1) / v1);
            }

            template <typename T>
            inline T root_impl(const T v0, const T v1, int_type_tag)
            {
               return root_impl<double>(static_cast<double>(v0),static_cast<double>(v1),real_type_tag());
            }

            template <typename T>
            inline T round_impl(const T v, real_type_tag)
            {
               return ((v < T(0)) ? std::ceil(v - T(0.5)) : std::floor(v + T(0.5)));
            }

            template <typename T>
            inline T roundn_impl(const T v0, const T v1, real_type_tag)
            {
               const int index = std::max<int>(0, std::min<int>(pow10_size - 1, (int)std::floor(v1)));
               const T p10 = T(pow10[index]);
               if (v0 < T(0))
                  return T(std::ceil ((v0 * p10) - T(0.5)) / p10);
               else
                  return T(std::floor((v0 * p10) + T(0.5)) / p10);
            }

            template <typename T>
            inline T roundn_impl(const T v0, const T, int_type_tag)
            {
               return v0;
            }

            template <typename T>
            inline T hypot_impl(const T v0, const T v1, real_type_tag)
            {
               return std::sqrt((v0 * v0) + (v1 * v1));
            }

            template <typename T>
            inline T hypot_impl(const T v0, const T v1, int_type_tag)
            {
               return static_cast<T>(std::sqrt(static_cast<double>((v0 * v0) + (v1 * v1))));
            }

            template <typename T>
            inline T atan2_impl(const T v0, const T v1, real_type_tag)
            {
               return std::atan2(v0,v1);
            }

            template <typename T>
            inline T atan2_impl(const T, const T, int_type_tag)
            {
               return 0;
            }

            template <typename T>
            inline T shr_impl(const T v0, const T v1, real_type_tag)
            {
               return v0 * (T(1) / std::pow(T(2),static_cast<T>(static_cast<int>(v1))));
            }

            template <typename T>
            inline T shr_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 >> v1;
            }

            template <typename T>
            inline T shl_impl(const T v0, const T v1, real_type_tag)
            {
               return v0 * std::pow(T(2),static_cast<T>(static_cast<int>(v1)));
            }

            template <typename T>
            inline T shl_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 << v1;
            }

            template <typename T>
            inline T sgn_impl(const T v, real_type_tag)
            {
                    if (v > T(0)) return T(+1);
               else if (v < T(0)) return T(-1);
               else               return T( 0);
            }

            template <typename T>
            inline T sgn_impl(const T v, int_type_tag)
            {
                    if (v > T(0)) return T(+1);
               else if (v < T(0)) return T(-1);
               else               return T( 0);
            }

            template <typename T>
            inline T and_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_true_impl(v0) && is_true_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T and_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 && v1;
            }

            template <typename T>
            inline T nand_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) || is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T nand_impl(const T v0, const T v1, int_type_tag)
            {
               return !(v0 && v1);
            }

            template <typename T>
            inline T or_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_true_impl(v0) || is_true_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T or_impl(const T v0, const T v1, int_type_tag)
            {
               return (v0 || v1);
            }

            template <typename T>
            inline T nor_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) && is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T nor_impl(const T v0, const T v1, int_type_tag)
            {
               return !(v0 || v1);
            }

            template <typename T>
            inline T xor_impl(const T v0, const T v1, real_type_tag)
            {
               return (is_false_impl(v0) != is_false_impl(v1)) ? T(1) : T(0);
            }

            template <typename T>
            inline T xor_impl(const T v0, const T v1, int_type_tag)
            {
               return v0 ^ v1;
            }

            template <typename T>
            inline T xnor_impl(const T v0, const T v1, real_type_tag)
            {
               const bool v0_true = is_true_impl(v0);
               const bool v1_true = is_true_impl(v1);
               if ((v0_true &&  v1_true) || (!v0_true && !v1_true))
                  return T(1);
               else
                  return T(0);
            }

            template <typename T>
            inline T xnor_impl(const T v0, const T v1, int_type_tag)
            {
               const bool v0_true = is_true_impl(v0);
               const bool v1_true = is_true_impl(v1);
               if ((v0_true &&  v1_true) || (!v0_true && !v1_true))
                  return T(1);
               else
                  return T(0);
            }

            template <typename T>
            inline T erf_impl(T v, real_type_tag)
            {
               #if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
               // Credits: Abramowitz & Stegun Equations 7.1.25-28
               const T t = T(1) / (T(1) + T(0.5) * abs_impl(v,real_type_tag()));
               static const T c[] = {
                                      T( 1.26551223), T(1.00002368),
                                      T( 0.37409196), T(0.09678418),
                                      T(-0.18628806), T(0.27886807),
                                      T(-1.13520398), T(1.48851587),
                                      T(-0.82215223), T(0.17087277)
                                    };
               T result = T(1) - t * std::exp((-v * v) -
                                      c[0] + t * (c[1] + t *
                                     (c[2] + t * (c[3] + t *
                                     (c[4] + t * (c[5] + t *
                                     (c[6] + t * (c[7] + t *
                                     (c[8] + t * (c[9]))))))))));
               return (v >= T(0)) ? result : -result;
               #else
               return ::erf(v);
               #endif
            }

            template <typename T>
            inline T erf_impl(T v, int_type_tag)
            {
               return erf_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T>
            inline T erfc_impl(T v, real_type_tag)
            {
               #if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
               return T(1) - erf_impl(v,real_type_tag());
               #else
               return ::erfc(v);
               #endif
            }

            template <typename T>
            inline T erfc_impl(T v, int_type_tag)
            {
               return erfc_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T>
            inline T ncdf_impl(T v, real_type_tag)
            {
               T cnd = T(0.5) * (T(1) + erf_impl(
                                           abs_impl(v,real_type_tag()) /
                                           T(numeric::constant::sqrt2),real_type_tag()));
               return  (v < T(0)) ? (T(1) - cnd) : cnd;
            }

            template <typename T>
            inline T ncdf_impl(T v, int_type_tag)
            {
               return ncdf_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T>
            inline T sinc_impl(T v, real_type_tag)
            {
               if (std::abs(v) >= std::numeric_limits<T>::epsilon())
                   return(std::sin(v) / v);
               else
                  return T(1);
            }

            template <typename T>
            inline T sinc_impl(T v, int_type_tag)
            {
               return sinc_impl(static_cast<double>(v),real_type_tag());
            }

            template <typename T> inline T  acos_impl(const T v, real_type_tag) { return std::acos (v); }
            template <typename T> inline T acosh_impl(const T v, real_type_tag) { return std::log(v + std::sqrt((v * v) - T(1))); }
            template <typename T> inline T  asin_impl(const T v, real_type_tag) { return std::asin (v); }
            template <typename T> inline T asinh_impl(const T v, real_type_tag) { return std::log(v + std::sqrt((v * v) + T(1))); }
            template <typename T> inline T  atan_impl(const T v, real_type_tag) { return std::atan (v); }
            template <typename T> inline T atanh_impl(const T v, real_type_tag) { return (std::log(T(1) + v) - log(T(1) - v)) / T(2); }
            template <typename T> inline T  ceil_impl(const T v, real_type_tag) { return std::ceil (v); }
            template <typename T> inline T   cos_impl(const T v, real_type_tag) { return std::cos  (v); }
            template <typename T> inline T  cosh_impl(const T v, real_type_tag) { return std::cosh (v); }
            template <typename T> inline T   exp_impl(const T v, real_type_tag) { return std::exp  (v); }
            template <typename T> inline T floor_impl(const T v, real_type_tag) { return std::floor(v); }
            template <typename T> inline T   log_impl(const T v, real_type_tag) { return std::log  (v); }
            template <typename T> inline T log10_impl(const T v, real_type_tag) { return std::log10(v); }
            template <typename T> inline T  log2_impl(const T v, real_type_tag) { return std::log(v)/T(numeric::constant::log2); }
            template <typename T> inline T   neg_impl(const T v, real_type_tag) { return -v;            }
            template <typename T> inline T   pos_impl(const T v, real_type_tag) { return +v;            }
            template <typename T> inline T   sin_impl(const T v, real_type_tag) { return std::sin  (v); }
            template <typename T> inline T  sinh_impl(const T v, real_type_tag) { return std::sinh (v); }
            template <typename T> inline T  sqrt_impl(const T v, real_type_tag) { return std::sqrt (v); }
            template <typename T> inline T   tan_impl(const T v, real_type_tag) { return std::tan  (v); }
            template <typename T> inline T  tanh_impl(const T v, real_type_tag) { return std::tanh (v); }
            template <typename T> inline T   cot_impl(const T v, real_type_tag) { return T(1) / std::tan(v); }
            template <typename T> inline T   sec_impl(const T v, real_type_tag) { return T(1) / std::cos(v); }
            template <typename T> inline T   csc_impl(const T v, real_type_tag) { return T(1) / std::sin(v); }
            template <typename T> inline T   r2d_impl(const T v, real_type_tag) { return (v * T(numeric::constant::_180_pi)); }
            template <typename T> inline T   d2r_impl(const T v, real_type_tag) { return (v * T(numeric::constant::pi_180));  }
            template <typename T> inline T   d2g_impl(const T v, real_type_tag) { return (v * T(20.0/9.0)); }
            template <typename T> inline T   g2d_impl(const T v, real_type_tag) { return (v * T(9.0/20.0)); }
            template <typename T> inline T  notl_impl(const T v, real_type_tag) { return (std::not_equal_to<T>()(T(0),v) ? T(0) : T(1)); }
            template <typename T> inline T  frac_impl(const T v, real_type_tag) { return (v - static_cast<long long>(v)); }
            template <typename T> inline T trunc_impl(const T v, real_type_tag) { return T(static_cast<long long>(v));    }

            template <typename T> inline T   abs_impl(const T v, int_type_tag) { return ((v >= T(0)) ? v : -v); }
            template <typename T> inline T   exp_impl(const T v, int_type_tag) { return std::exp  (v); }
            template <typename T> inline T   log_impl(const T v, int_type_tag) { return std::log  (v); }
            template <typename T> inline T log10_impl(const T v, int_type_tag) { return std::log10(v); }
            template <typename T> inline T  log2_impl(const T v, int_type_tag) { return std::log(v)/T(numeric::constant::log2); }
            template <typename T> inline T   neg_impl(const T v, int_type_tag) { return -v;            }
            template <typename T> inline T   pos_impl(const T v, int_type_tag) { return +v;            }
            template <typename T> inline T  ceil_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T floor_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T round_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T  notl_impl(const T v, int_type_tag) { return !v;            }
            template <typename T> inline T  sqrt_impl(const T v, int_type_tag) { return std::sqrt (v); }
            template <typename T> inline T  frac_impl(const T  , int_type_tag) { return T(0);          }
            template <typename T> inline T trunc_impl(const T v, int_type_tag) { return v;             }
            template <typename T> inline T  acos_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T acosh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  asin_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T asinh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  atan_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T atanh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   cos_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  cosh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   sin_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  sinh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   tan_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T  tanh_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   cot_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   sec_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }
            template <typename T> inline T   csc_impl(const T  , int_type_tag) { return std::numeric_limits<T>::quiet_NaN(); }

            template <typename T>
            inline bool is_integer_impl(const T& v, real_type_tag)
            {
               return std::equal_to<T>()(T(0),std::fmod(v,T(1)));
            }

            template <typename T>
            inline bool is_integer_impl(const T&, int_type_tag)
            {
               return true;
            }
         }

         template <typename Type>
         struct numeric_info { enum { length = 0, size = 32, bound_length = 0, min_exp = 0, max_exp = 0 }; };

         template<> struct numeric_info<int>         { enum { length = 10, size = 16, bound_length =  9}; };
         template<> struct numeric_info<float>       { enum { min_exp =  -38, max_exp =  +38}; };
         template<> struct numeric_info<double>      { enum { min_exp = -308, max_exp = +308}; };
         template<> struct numeric_info<long double> { enum { min_exp = -308, max_exp = +308}; };

         template <typename T>
         inline int to_int32(const T v)
         {
            typename details::number_type<T>::type num_type;
            return to_int32_impl(v,num_type);
         }

         template <typename T>
         inline long long int to_int64(const T v)
         {
            typename details::number_type<T>::type num_type;
            return to_int64_impl(v,num_type);
         }

         template <typename T>
         inline bool is_nan(const T v)
         {
            typename details::number_type<T>::type num_type;
            return is_nan_impl(v,num_type);
         }

         template <typename T>
         inline T min(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return min_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T max(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return max_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T equal(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return equal_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T nequal(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return nequal_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T modulus(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return modulus_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T pow(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return pow_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T logn(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return logn_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T root(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return root_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T roundn(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return roundn_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T hypot(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return hypot_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T atan2(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return atan2_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T shr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return shr_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T shl(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return shl_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T and_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return and_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T nand_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return nand_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T or_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return or_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T nor_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return nor_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T xor_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return xor_impl(v0,v1,num_type);
         }

         template <typename T>
         inline T xnor_opr(const T v0, const T v1)
         {
            typename details::number_type<T>::type num_type;
            return xnor_impl(v0,v1,num_type);
         }

         template <typename T>
         inline bool is_integer(const T v)
         {
            typename details::number_type<T>::type num_type;
            return is_integer_impl(v,num_type);
         }

         template <typename T, unsigned int N>
         struct fast_exp
         {
            static inline T result(T v)
            {
               unsigned int k = N;
               T l = T(1);

               while (k)
               {
                  if (k & 1)
                  {
                     l *= v;
                     --k;
                  }

                  v *= v;
                  k >>= 1;
               }

               return l;
            }
         };

         template <typename T> struct fast_exp<T,10> { static inline T result(T v) { T v_5 = fast_exp<T,5>::result(v); return v_5 * v_5; } };
         template <typename T> struct fast_exp<T, 9> { static inline T result(T v) { return fast_exp<T,8>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 8> { static inline T result(T v) { T v_4 = fast_exp<T,4>::result(v); return v_4 * v_4; } };
         template <typename T> struct fast_exp<T, 7> { static inline T result(T v) { return fast_exp<T,6>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 6> { static inline T result(T v) { T v_3 = fast_exp<T,3>::result(v); return v_3 * v_3; } };
         template <typename T> struct fast_exp<T, 5> { static inline T result(T v) { return fast_exp<T,4>::result(v) * v; } };
         template <typename T> struct fast_exp<T, 4> { static inline T result(T v) { T v_2 = v * v; return v_2 * v_2; } };
         template <typename T> struct fast_exp<T, 3> { static inline T result(T v) { return v * v * v; } };
         template <typename T> struct fast_exp<T, 2> { static inline T result(T v) { return v * v;     } };
         template <typename T> struct fast_exp<T, 1> { static inline T result(T v) { return v;         } };
         template <typename T> struct fast_exp<T, 0> { static inline T result(T  ) { return T(1);      } };

         #define exprtk_define_unary_function(FunctionName)   \
         template <typename T>                                \
         inline T FunctionName (const T v)                    \
         {                                                    \
            typename details::number_type<T>::type num_type;  \
            return  FunctionName##_impl(v,num_type);          \
         }                                                    \

         exprtk_define_unary_function(abs  )
         exprtk_define_unary_function(acos )
         exprtk_define_unary_function(acosh)
         exprtk_define_unary_function(asin )
         exprtk_define_unary_function(asinh)
         exprtk_define_unary_function(atan )
         exprtk_define_unary_function(atanh)
         exprtk_define_unary_function(ceil )
         exprtk_define_unary_function(cos  )
         exprtk_define_unary_function(cosh )
         exprtk_define_unary_function(exp  )
         exprtk_define_unary_function(expm1)
         exprtk_define_unary_function(floor)
         exprtk_define_unary_function(log  )
         exprtk_define_unary_function(log10)
         exprtk_define_unary_function(log2 )
         exprtk_define_unary_function(log1p)
         exprtk_define_unary_function(neg  )
         exprtk_define_unary_function(pos  )
         exprtk_define_unary_function(round)
         exprtk_define_unary_function(sin  )
         exprtk_define_unary_function(sinc )
         exprtk_define_unary_function(sinh )
         exprtk_define_unary_function(sqrt )
         exprtk_define_unary_function(tan  )
         exprtk_define_unary_function(tanh )
         exprtk_define_unary_function(cot  )
         exprtk_define_unary_function(sec  )
         exprtk_define_unary_function(csc  )
         exprtk_define_unary_function(r2d  )
         exprtk_define_unary_function(d2r  )
         exprtk_define_unary_function(d2g  )
         exprtk_define_unary_function(g2d  )
         exprtk_define_unary_function(notl )
         exprtk_define_unary_function(sgn  )
         exprtk_define_unary_function(erf  )
         exprtk_define_unary_function(erfc )
         exprtk_define_unary_function(ncdf )
         exprtk_define_unary_function(frac )
         exprtk_define_unary_function(trunc)
         #undef exprtk_define_unary_function
      }

      template <typename T>
      inline T compute_pow10(T d, const int exponent)
      {
         static const double fract10[] =
         {
           0.0,
           1.0E+001, 1.0E+002, 1.0E+003, 1.0E+004, 1.0E+005, 1.0E+006, 1.0E+007, 1.0E+008, 1.0E+009, 1.0E+010,
           1.0E+011, 1.0E+012, 1.0E+013, 1.0E+014, 1.0E+015, 1.0E+016, 1.0E+017, 1.0E+018, 1.0E+019, 1.0E+020,
           1.0E+021, 1.0E+022, 1.0E+023, 1.0E+024, 1.0E+025, 1.0E+026, 1.0E+027, 1.0E+028, 1.0E+029, 1.0E+030,
           1.0E+031, 1.0E+032, 1.0E+033, 1.0E+034, 1.0E+035, 1.0E+036, 1.0E+037, 1.0E+038, 1.0E+039, 1.0E+040,
           1.0E+041, 1.0E+042, 1.0E+043, 1.0E+044, 1.0E+045, 1.0E+046, 1.0E+047, 1.0E+048, 1.0E+049, 1.0E+050,
           1.0E+051, 1.0E+052, 1.0E+053, 1.0E+054, 1.0E+055, 1.0E+056, 1.0E+057, 1.0E+058, 1.0E+059, 1.0E+060,
           1.0E+061, 1.0E+062, 1.0E+063, 1.0E+064, 1.0E+065, 1.0E+066, 1.0E+067, 1.0E+068, 1.0E+069, 1.0E+070,
           1.0E+071, 1.0E+072, 1.0E+073, 1.0E+074, 1.0E+075, 1.0E+076, 1.0E+077, 1.0E+078, 1.0E+079, 1.0E+080,
           1.0E+081, 1.0E+082, 1.0E+083, 1.0E+084, 1.0E+085, 1.0E+086, 1.0E+087, 1.0E+088, 1.0E+089, 1.0E+090,
           1.0E+091, 1.0E+092, 1.0E+093, 1.0E+094, 1.0E+095, 1.0E+096, 1.0E+097, 1.0E+098, 1.0E+099, 1.0E+100,
           1.0E+101, 1.0E+102, 1.0E+103, 1.0E+104, 1.0E+105, 1.0E+106, 1.0E+107, 1.0E+108, 1.0E+109, 1.0E+110,
           1.0E+111, 1.0E+112, 1.0E+113, 1.0E+114, 1.0E+115, 1.0E+116, 1.0E+117, 1.0E+118, 1.0E+119, 1.0E+120,
           1.0E+121, 1.0E+122, 1.0E+123, 1.0E+124, 1.0E+125, 1.0E+126, 1.0E+127, 1.0E+128, 1.0E+129, 1.0E+130,
           1.0E+131, 1.0E+132, 1.0E+133, 1.0E+134, 1.0E+135, 1.0E+136, 1.0E+137, 1.0E+138, 1.0E+139, 1.0E+140,
           1.0E+141, 1.0E+142, 1.0E+143, 1.0E+144, 1.0E+145, 1.0E+146, 1.0E+147, 1.0E+148, 1.0E+149, 1.0E+150,
           1.0E+151, 1.0E+152, 1.0E+153, 1.0E+154, 1.0E+155, 1.0E+156, 1.0E+157, 1.0E+158, 1.0E+159, 1.0E+160,
           1.0E+161, 1.0E+162, 1.0E+163, 1.0E+164, 1.0E+165, 1.0E+166, 1.0E+167, 1.0E+168, 1.0E+169, 1.0E+170,
           1.0E+171, 1.0E+172, 1.0E+173, 1.0E+174, 1.0E+175, 1.0E+176, 1.0E+177, 1.0E+178, 1.0E+179, 1.0E+180,
           1.0E+181, 1.0E+182, 1.0E+183, 1.0E+184, 1.0E+185, 1.0E+186, 1.0E+187, 1.0E+188, 1.0E+189, 1.0E+190,
           1.0E+191, 1.0E+192, 1.0E+193, 1.0E+194, 1.0E+195, 1.0E+196, 1.0E+197, 1.0E+198, 1.0E+199, 1.0E+200,
           1.0E+201, 1.0E+202, 1.0E+203, 1.0E+204, 1.0E+205, 1.0E+206, 1.0E+207, 1.0E+208, 1.0E+209, 1.0E+210,
           1.0E+211, 1.0E+212, 1.0E+213, 1.0E+214, 1.0E+215, 1.0E+216, 1.0E+217, 1.0E+218, 1.0E+219, 1.0E+220,
           1.0E+221, 1.0E+222, 1.0E+223, 1.0E+224, 1.0E+225, 1.0E+226, 1.0E+227, 1.0E+228, 1.0E+229, 1.0E+230,
           1.0E+231, 1.0E+232, 1.0E+233, 1.0E+234, 1.0E+235, 1.0E+236, 1.0E+237, 1.0E+238, 1.0E+239, 1.0E+240,
           1.0E+241, 1.0E+242, 1.0E+243, 1.0E+244, 1.0E+245, 1.0E+246, 1.0E+247, 1.0E+248, 1.0E+249, 1.0E+250,
           1.0E+251, 1.0E+252, 1.0E+253, 1.0E+254, 1.0E+255, 1.0E+256, 1.0E+257, 1.0E+258, 1.0E+259, 1.0E+260,
           1.0E+261, 1.0E+262, 1.0E+263, 1.0E+264, 1.0E+265, 1.0E+266, 1.0E+267, 1.0E+268, 1.0E+269, 1.0E+270,
           1.0E+271, 1.0E+272, 1.0E+273, 1.0E+274, 1.0E+275, 1.0E+276, 1.0E+277, 1.0E+278, 1.0E+279, 1.0E+280,
           1.0E+281, 1.0E+282, 1.0E+283, 1.0E+284, 1.0E+285, 1.0E+286, 1.0E+287, 1.0E+288, 1.0E+289, 1.0E+290,
           1.0E+291, 1.0E+292, 1.0E+293, 1.0E+294, 1.0E+295, 1.0E+296, 1.0E+297, 1.0E+298, 1.0E+299, 1.0E+300,
           1.0E+301, 1.0E+302, 1.0E+303, 1.0E+304, 1.0E+305, 1.0E+306, 1.0E+307, 1.0E+308
         };

         static const int fract10_size = static_cast<int>(sizeof(fract10) / sizeof(double));

         const int e = std::abs(exponent);

         if (exponent >= std::numeric_limits<T>::min_exponent10)
         {
            if (e < fract10_size)
            {
               if (exponent > 0)
                  return T(d * fract10[e]);
               else
                  return T(d / fract10[e]);
            }
            else
               return T(d * std::pow(10.0, 10.0 * exponent));
         }
         else
         {
                     d /= T(fract10[           -std::numeric_limits<T>::min_exponent10]);
            return T(d /    fract10[-exponent + std::numeric_limits<T>::min_exponent10]);
         }
      }

      template <typename Iterator, typename T>
      inline bool string_to_type_converter_impl_ref(Iterator& itr, const Iterator end, T& result)
      {
         if (itr == end)
            return false;

         bool negative = ('-' == (*itr));

         if (negative || ('+' == (*itr)))
         {
            if (end == ++itr)
               return false;
         }

         while ((end != itr) && ('0' == (*itr))) ++itr;

         bool return_result = true;
         unsigned int digit = 0;
         const std::size_t length = std::distance(itr,end);

         if (length <= 4)
         {
            switch (length)
            {
               #ifdef exprtk_use_lut

               #define exprtk_process_digit \
               if ((digit = details::digit_table[(int)*itr++]) < 10) result = result * 10 + (digit); else { return_result = false; break; }

               #else
               #define exprtk_process_digit \
               if ((digit = (*itr++ - '0')) < 10) result = result * 10 + (digit); else { return_result = false; break; }

               #endif

               case  4 : exprtk_process_digit
               case  3 : exprtk_process_digit
               case  2 : exprtk_process_digit
               case  1 : if ((digit = (*itr - '0'))>= 10) { digit = 0; return_result = false; }

               #undef exprtk_process_digit
            }
         }
         else
            return_result = false;

         if (length && return_result)
         {
            result = result * 10 + static_cast<T>(digit);
            ++itr;
         }

         result = negative ? -result : result;
         return return_result;
      }

      template <typename Iterator, typename T>
      static inline bool parse_nan(Iterator& itr, const Iterator end, T& t)
      {
         typedef typename std::iterator_traits<Iterator>::value_type type;
         static const std::size_t nan_length = 3;
         if (std::distance(itr,end) != static_cast<int>(nan_length))
            return false;
         if (static_cast<type>('n') == (*itr))
         {
            if (
                 (static_cast<type>('a') != *(itr + 1)) ||
                 (static_cast<type>('n') != *(itr + 2))
               )
            {
               return false;
            }
         }
         else if (
                   (static_cast<type>('A') != *(itr + 1)) ||
                   (static_cast<type>('N') != *(itr + 2))
                 )
         {
            return false;
         }
         t = std::numeric_limits<T>::quiet_NaN();
         return true;
      }

      template <typename Iterator, typename T>
      static inline bool parse_inf(Iterator& itr, const Iterator end, T& t, bool negative)
      {
         static const char inf_uc[] = "INFINITY";
         static const char inf_lc[] = "infinity";
         static const std::size_t inf_length = 8;
         const std::size_t length = std::distance(itr,end);
         if ((3 != length) && (inf_length != length))
            return false;
         const char* inf_itr = ('i' == (*itr)) ? inf_lc : inf_uc;
         while (end != itr)
         {
            if (*inf_itr == static_cast<char>(*itr))
            {
               ++itr;
               ++inf_itr;
               continue;
            }
            else
               return false;
         }
         if (negative)
            t = -std::numeric_limits<T>::infinity();
         else
            t =  std::numeric_limits<T>::infinity();
         return true;
      }

      template <typename Iterator, typename T>
      inline bool string_to_real(Iterator& itr_external, const Iterator end, T& t, numeric::details::real_type_tag)
      {
         if (end == itr_external) return false;

         Iterator itr = itr_external;

         T d = T(0);

         bool negative = ('-' == (*itr));

         if (negative || '+' == (*itr))
         {
            if (end == ++itr)
               return false;
         }

         bool instate = false;

         #define parse_digit_1(d) \
         if ((digit = (*itr - '0')) < 10) { d = d * T(10) + digit; } else break; if (end == ++itr) break; \

         #define parse_digit_2(d) \
         if ((digit = (*itr - '0')) < 10) { d = d * T(10) + digit; } else break; ++itr; \

         if ('.' != (*itr))
         {
            const Iterator curr = itr;
            while ((end != itr) && ('0' == (*itr))) ++itr;
            unsigned int digit;

            while (end != itr)
            {
               // Note: For 'physical' superscalar architectures it
               // is advised that the following loop be: 4xPD1 and 1xPD2
               #ifdef exprtk_enable_superscalar
               parse_digit_1(d)
               parse_digit_1(d)
               #endif
               parse_digit_1(d)
               parse_digit_1(d)
               parse_digit_2(d)
            }

            if (curr != itr) instate = true;
         }

         int exponent = 0;

         if (end != itr)
         {
            if ('.' == (*itr))
            {
               const Iterator curr = ++itr;
               unsigned int digit;
               T tmp_d = T(0);

               while (end != itr)
               {
                  #ifdef exprtk_enable_superscalar
                  parse_digit_1(tmp_d)
                  parse_digit_1(tmp_d)
                  parse_digit_1(tmp_d)
                  #endif
                  parse_digit_1(tmp_d)
                  parse_digit_1(tmp_d)
                  parse_digit_2(tmp_d)
               }

               if (curr != itr)
               {
                  instate = true;
                  d += compute_pow10(tmp_d,-std::distance(curr,itr));
               }

               #undef parse_digit_1
               #undef parse_digit_2
            }

            if (end != itr)
            {
               typename std::iterator_traits<Iterator>::value_type c = (*itr);

               if (('e' == c) || ('E' == c))
               {
                  int exp = 0;

                  if (!details::string_to_type_converter_impl_ref(++itr,end,exp))
                  {
                     if (end == itr)
                        return false;
                     else
                        c = (*itr);
                  }

                  exponent += exp;
               }

               if (end != itr)
               {
                  if (('f' == c) || ('F' == c) || ('l' == c) || ('L' == c))
                     ++itr;
                  else if ('#' == c)
                  {
                     if (end == ++itr)
                        return false;
                     else if (('I' <= (*itr)) && ((*itr) <= 'n'))
                     {
                        if (('i' == (*itr)) || ('I' == (*itr)))
                        {
                           return parse_inf(itr,end,t,negative);
                        }
                        else if (('n' == (*itr)) || ('N' == (*itr)))
                        {
                           return parse_nan(itr,end,t);
                        }
                        else
                           return false;
                     }
                     else
                        return false;
                  }
                  else if (('I' <= (*itr)) && ((*itr) <= 'n'))
                  {
                     if (('i' == (*itr)) || ('I' == (*itr)))
                     {
                        return parse_inf(itr,end,t,negative);
                     }
                     else if (('n' == (*itr)) || ('N' == (*itr)))
                     {
                        return parse_nan(itr,end,t);
                     }
                     else
                        return false;
                  }
                  else
                     return false;
               }
            }
         }

         if ((end != itr) || (!instate))
            return false;
         else if (exponent)
            d = compute_pow10(d,exponent);

         t = static_cast<T>((negative) ? -d : d);
         return true;
      }

      template <typename T>
      inline bool string_to_real(const std::string& s, T& t)
      {
         const char* begin = s.data();
         const char* end   = s.data() + s.size();
         typename numeric::details::number_type<T>::type num_type;
         return string_to_real(begin,end,t,num_type);
      }

      template <typename T>
      struct functor_t
      {
         /*
            Note: The following definitions for Type, may require tweaking
                  based on the compiler and target architecture. The benchmark
                  should provide enough information to make the right choice.
         */
         //typedef T Type;
         //typedef const T Type;
         typedef const T& Type;
         typedef T (*qfunc_t)(Type t0, Type t1, Type t2, Type t3);
         typedef T (*tfunc_t)(Type t0, Type t1, Type t2);
         typedef T (*bfunc_t)(Type t0, Type t1);
         typedef T (*ufunc_t)(Type t0);
      };

   } // namespace details

   namespace lexer
   {
      struct token
      {
         enum token_type
         {
            e_none        =   0, e_error       =   1, e_err_symbol  =   2,
            e_err_number  =   3, e_err_string  =   4, e_err_sfunc   =   5,
            e_eof         =   6, e_number      =   7, e_symbol      =   8,
            e_string      =   9, e_assign      =  10, e_addass      =  11,
            e_subass      =  12, e_mulass      =  13, e_divass      =  14,
            e_modass      =  15, e_shr         =  16, e_shl         =  17,
            e_lte         =  18, e_ne          =  19, e_gte         =  20,
            e_swap        =  21, e_lt          = '<', e_gt          = '>',
            e_eq          = '=', e_rbracket    = ')', e_lbracket    = '(',
            e_rsqrbracket = ']', e_lsqrbracket = '[', e_rcrlbracket = '}',
            e_lcrlbracket = '{', e_comma       = ',', e_add         = '+',
            e_sub         = '-', e_div         = '/', e_mul         = '*',
            e_mod         = '%', e_pow         = '^', e_colon       = ':',
            e_ternary     = '?'
         };

         token()
         : type(e_none),
           value(""),
           position(std::numeric_limits<std::size_t>::max())
         {}

         void clear()
         {
            type     = e_none;
            value    = "";
            position = std::numeric_limits<std::size_t>::max();
         }

         template <typename Iterator>
         inline token& set_operator(const token_type tt, const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = tt;
            value.assign(begin,end);
            if (base_begin)
               position = std::distance(base_begin,begin);
            return *this;
         }

         template <typename Iterator>
         inline token& set_symbol(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_symbol;
            value.assign(begin,end);
            if (base_begin)
               position = std::distance(base_begin,begin);
            return *this;
         }

         template <typename Iterator>
         inline token& set_numeric(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_number;
            value.assign(begin,end);
            if (base_begin)
               position = std::distance(base_begin,begin);
            return *this;
         }

         template <typename Iterator>
         inline token& set_string(const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            type = e_string;
            value.assign(begin,end);
            if (base_begin)
               position = std::distance(base_begin,begin);
            return *this;
         }

         inline token& set_string(const std::string& s, const std::size_t p)
         {
            type     = e_string;
            value    = s;
            position = p;
            return *this;
         }

         template <typename Iterator>
         inline token& set_error(const token_type et, const Iterator begin, const Iterator end, const Iterator base_begin = Iterator(0))
         {
            if (
                 (e_error      == et) ||
                 (e_err_symbol == et) ||
                 (e_err_number == et) ||
                 (e_err_string == et) ||
                 (e_err_sfunc  == et)
               )
            {
               type = et;
            }
            else
               type = e_error;

            value.assign(begin,end);

            if (base_begin)
               position = std::distance(base_begin,begin);

            return *this;
         }

         static inline std::string to_str(token_type t)
         {
            switch (t)
            {
               case e_none        : return "NONE";
               case e_error       : return "ERROR";
               case e_err_symbol  : return "ERROR_SYMBOL";
               case e_err_number  : return "ERROR_NUMBER";
               case e_err_string  : return "ERROR_STRING";
               case e_eof         : return "EOF";
               case e_number      : return "NUMBER";
               case e_symbol      : return "SYMBOL";
               case e_string      : return "STRING";
               case e_assign      : return ":=";
               case e_addass      : return "+=";
               case e_subass      : return "-=";
               case e_mulass      : return "*=";
               case e_divass      : return "/=";
               case e_modass      : return "%=";
               case e_shr         : return ">>";
               case e_shl         : return "<<";
               case e_lte         : return "<=";
               case e_ne          : return "!=";
               case e_gte         : return ">=";
               case e_lt          : return "<";
               case e_gt          : return ">";
               case e_eq          : return "=";
               case e_rbracket    : return ")";
               case e_lbracket    : return "(";
               case e_rsqrbracket : return "]";
               case e_lsqrbracket : return "[";
               case e_rcrlbracket : return "}";
               case e_lcrlbracket : return "{";
               case e_comma       : return ",";
               case e_add         : return "+";
               case e_sub         : return "-";
               case e_div         : return "/";
               case e_mul         : return "*";
               case e_mod         : return "%";
               case e_pow         : return "^";
               case e_colon       : return ":";
               case e_ternary     : return "?";
               case e_swap        : return "<=>";
               default            : return "UNKNOWN";
            }
         }

         inline bool is_error() const
         {
            return (
                     (e_error      == type) ||
                     (e_err_symbol == type) ||
                     (e_err_number == type) ||
                     (e_err_string == type) ||
                     (e_err_sfunc  == type)
                   );
         }

         token_type type;
         std::string value;
         std::size_t position;
      };

      class generator
      {
      public:

         typedef token token_t;
         typedef std::vector<token_t> token_list_t;
         typedef std::vector<token_t>::iterator token_list_itr_t;

         generator()
         : base_itr_(0),
           s_itr_   (0),
           s_end_   (0)
         {
            clear();
         }

         inline void clear()
         {
            base_itr_ = 0;
            s_itr_    = 0;
            s_end_    = 0;
            token_list_.clear();
            token_itr_ = token_list_.end();
            store_token_itr_ = token_list_.end();
         }

         inline bool process(const std::string& str)
         {
            base_itr_ = str.data();
            s_itr_    = str.data();
            s_end_    = str.data() + str.size();

            eof_token_.set_operator(token_t::e_eof,s_end_,s_end_,base_itr_);
            token_list_.clear();

            while (!is_end(s_itr_))
            {
               scan_token();

               if (token_list_.empty())
                  return true;
               else if (token_list_.back().is_error())
               {
                  return false;
               }
            }

            return true;
         }

         inline bool empty() const
         {
            return token_list_.empty();
         }

         inline std::size_t size() const
         {
            return token_list_.size();
         }

         inline void begin()
         {
            token_itr_ = token_list_.begin();
            store_token_itr_ = token_list_.begin();
         }

         inline void store()
         {
            store_token_itr_ = token_itr_;
         }

         inline void restore()
         {
            token_itr_ = store_token_itr_;
         }

         inline token_t& next_token()
         {
            if (token_list_.end() != token_itr_)
            {
               return *token_itr_++;
            }
            else
               return eof_token_;
         }

         inline token_t& peek_next_token()
         {
            if (token_list_.end() != token_itr_)
            {
               return *token_itr_;
            }
            else
               return eof_token_;
         }

         inline token_t& operator[](const std::size_t& index)
         {
            if (index < token_list_.size())
               return token_list_[index];
            else
               return eof_token_;
         }

         inline token_t operator[](const std::size_t& index) const
         {
            if (index < token_list_.size())
               return token_list_[index];
            else
               return eof_token_;
         }

         inline bool finished() const
         {
            return (token_list_.end() == token_itr_);
         }

         inline void insert_front(token_t::token_type tk_type)
         {
            if (
                 !token_list_.empty() &&
                 (token_list_.end() != token_itr_)
               )
            {
               token_t t = *token_itr_;

               t.type     = tk_type;
               token_itr_ = token_list_.insert(token_itr_,t);
            }
         }

         inline std::string substr(const std::size_t& begin, const std::size_t& end)
         {
            const char* begin_itr = ((base_itr_ + begin) < s_end_) ? (base_itr_ + begin) : s_end_;
            const char* end_itr   = ((base_itr_ +   end) < s_end_) ? (base_itr_ +   end) : s_end_;
            return std::string(begin_itr,end_itr);
         }

         inline std::string remaining() const
         {
            if (finished())
               return "";
            else if (token_list_.begin() != token_itr_)
               return std::string(base_itr_ + (token_itr_ - 1)->position,s_end_);
            else
               return std::string(base_itr_ + token_itr_->position,s_end_);
         }

      private:

         inline bool is_end(const char* itr)
         {
            return (s_end_ == itr);
         }

         inline void skip_whitespace()
         {
            while (!is_end(s_itr_) && details::is_whitespace(*s_itr_))
            {
               ++s_itr_;
            }
         }

         inline void skip_comments()
         {
            #ifndef exprtk_disable_comments
            // The following comment styles are supported:
            // 1. // .... \n
            // 2. #  .... \n
            // 3. /* .... */
            struct test
            {
               static inline bool comment_start(const char c0, const char c1, int& mode, int& incr)
               {
                  mode = 0;
                       if ('#' == c0)    { mode = 1; incr = 1; }
                  else if ('/' == c0)
                  {
                          if ('/' == c1) { mode = 1; incr = 2; }
                     else if ('*' == c1) { mode = 2; incr = 2; }
                  }
                  return (0 != mode);
               }

               static inline bool comment_end(const char c0, const char c1, const int mode)
               {
                  return (
                           ((1 == mode) && ('\n' == c0)) ||
                           ((2 == mode) && ( '*' == c0) && ('/' == c1))
                         );
               }
            };

            int mode = 0;
            int increment = 0;

            if (is_end(s_itr_) || is_end((s_itr_ + 1)))
               return;
            else if (!test::comment_start(*s_itr_,*(s_itr_ + 1),mode,increment))
               return;

            s_itr_ += increment;

            while (!is_end(s_itr_) && !test::comment_end(*s_itr_,*(s_itr_ + 1),mode))
            {
               ++s_itr_;
            }

            if (!is_end(s_itr_))
            {
               s_itr_ += mode;
               skip_whitespace();
               skip_comments();
            }
            #endif
         }

         inline void scan_token()
         {
            skip_whitespace();
            skip_comments();
            if (is_end(s_itr_))
            {
               return;
            }
            else if (details::is_operator_char(*s_itr_))
            {
               scan_operator();
               return;
            }
            else if (details::is_letter(*s_itr_))
            {
               scan_symbol();
               return;
            }
            else if (details::is_digit((*s_itr_)) || ('.' == (*s_itr_)))
            {
               scan_number();
               return;
            }
            else if ('$' == (*s_itr_))
            {
               scan_special_function();
               return;
            }
            #ifndef exprtk_disable_string_capabilities
            else if ('\'' == (*s_itr_))
            {
               scan_string();
               return;
            }
            #endif
            else if ('~' == (*s_itr_))
            {
               token_t t;
               t.set_symbol(s_itr_,s_itr_ + 1,base_itr_);
               token_list_.push_back(t);
               ++s_itr_;
               return;
            }
            else
            {
               token_t t;
               t.set_error(token::e_error,s_itr_,s_itr_ + 2,base_itr_);
               token_list_.push_back(t);
               ++s_itr_;
            }
         }

         inline void scan_operator()
         {
            token_t t;

            const char c0 = s_itr_[0];

            if (!is_end(s_itr_ + 1))
            {
               const char c1 = s_itr_[1];

               if (!is_end(s_itr_ + 2))
               {
                  const char c2 = s_itr_[2];

                  if ((c0 == '<') && (c1 == '=') && (c2 == '>'))
                  {
                     t.set_operator(token_t::e_swap,s_itr_,s_itr_ + 3,base_itr_);
                     token_list_.push_back(t);
                     s_itr_ += 3;
                     return;
                  }
               }

               token_t::token_type ttype = token_t::e_none;

                    if ((c0 == '<') && (c1 == '=')) ttype = token_t::e_lte;
               else if ((c0 == '>') && (c1 == '=')) ttype = token_t::e_gte;
               else if ((c0 == '<') && (c1 == '>')) ttype = token_t::e_ne;
               else if ((c0 == '!') && (c1 == '=')) ttype = token_t::e_ne;
               else if ((c0 == '=') && (c1 == '=')) ttype = token_t::e_eq;
               else if ((c0 == ':') && (c1 == '=')) ttype = token_t::e_assign;
               else if ((c0 == '<') && (c1 == '<')) ttype = token_t::e_shl;
               else if ((c0 == '>') && (c1 == '>')) ttype = token_t::e_shr;
               else if ((c0 == '+') && (c1 == '=')) ttype = token_t::e_addass;
               else if ((c0 == '-') && (c1 == '=')) ttype = token_t::e_subass;
               else if ((c0 == '*') && (c1 == '=')) ttype = token_t::e_mulass;
               else if ((c0 == '/') && (c1 == '=')) ttype = token_t::e_divass;
               else if ((c0 == '%') && (c1 == '=')) ttype = token_t::e_modass;

               if (token_t::e_none != ttype)
               {
                  t.set_operator(ttype,s_itr_,s_itr_ + 2,base_itr_);
                  token_list_.push_back(t);
                  s_itr_ += 2;
                  return;
               }
            }

            if ('<' == c0)
               t.set_operator(token_t::e_lt ,s_itr_,s_itr_ + 1,base_itr_);
            else if ('>' == c0)
               t.set_operator(token_t::e_gt ,s_itr_,s_itr_ + 1,base_itr_);
            else if (';' == c0)
               t.set_operator(token_t::e_eof,s_itr_,s_itr_ + 1,base_itr_);
            else if ('&' == c0)
               t.set_symbol(s_itr_,s_itr_ + 1,base_itr_);
            else if ('|' == c0)
               t.set_symbol(s_itr_,s_itr_ + 1,base_itr_);
            else
               t.set_operator(token_t::token_type(c0),s_itr_,s_itr_ + 1,base_itr_);

            token_list_.push_back(t);
            ++s_itr_;
         }

         inline void scan_symbol()
         {
            const char* initial_itr = s_itr_;

            while (
                    (!is_end(s_itr_)) &&
                    (details::is_letter_or_digit(*s_itr_) || ((*s_itr_) == '_'))
                  )
            {
               ++s_itr_;
            }

            token_t t;
            t.set_symbol(initial_itr,s_itr_,base_itr_);
            token_list_.push_back(t);
         }

         inline void scan_number()
         {
            /*
               Attempt to match a valid numeric value in one of the following formats:
               1. 123456
               2. 123.456
               3. 123.456e3
               4. 123.456E3
               5. 123.456e+3
               6. 123.456E+3
               7. 123.456e-3
               8. 123.456E-3
            */
            const char* initial_itr = s_itr_;
            bool dot_found         = false;
            bool e_found           = false;
            bool post_e_sign_found = false;
            token_t t;

            while (!is_end(s_itr_))
            {
               if ('.' == (*s_itr_))
               {
                  if (dot_found)
                  {
                     t.set_error(token::e_err_number,initial_itr,s_itr_,base_itr_);
                     token_list_.push_back(t);
                     return;
                  }

                  dot_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (details::imatch('e',(*s_itr_)))
               {
                  const char& c = *(s_itr_ + 1);

                  if (is_end(s_itr_ + 1))
                  {
                     t.set_error(token::e_err_number,initial_itr,s_itr_,base_itr_);
                     token_list_.push_back(t);

                     return;
                  }
                  else if (
                            ('+' != c) &&
                            ('-' != c) &&
                            !details::is_digit(c)
                          )
                  {
                     t.set_error(token::e_err_number,initial_itr,s_itr_,base_itr_);
                     token_list_.push_back(t);

                     return;
                  }

                  e_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (e_found && details::is_sign(*s_itr_))
               {
                  if (post_e_sign_found)
                  {
                     t.set_error(token::e_err_number,initial_itr,s_itr_,base_itr_);
                     token_list_.push_back(t);

                     return;
                  }

                  post_e_sign_found = true;
                  ++s_itr_;

                  continue;
               }
               else if (('.' != (*s_itr_)) && !details::is_digit(*s_itr_))
                  break;
               else
                  ++s_itr_;
            }

            t.set_numeric(initial_itr,s_itr_,base_itr_);
            token_list_.push_back(t);

            return;
         }

         inline void scan_special_function()
         {
            const char* initial_itr = s_itr_;
            token_t t;

            // $fdd(x,x,x) = at least 11 chars
            if (std::distance(s_itr_,s_end_) < 11)
            {
               t.set_error(token::e_err_sfunc,initial_itr,s_itr_,base_itr_);
               token_list_.push_back(t);

               return;
            }

            if (
                 !(('$' == *s_itr_)                       &&
                   (details::imatch  ('f',*(s_itr_ + 1))) &&
                   (details::is_digit(*(s_itr_ + 2)))     &&
                   (details::is_digit(*(s_itr_ + 3))))
               )
            {
               t.set_error(token::e_err_sfunc,initial_itr,s_itr_,base_itr_);
               token_list_.push_back(t);

               return;
            }

            s_itr_ += 4; // $fdd = 4chars

            t.set_symbol(initial_itr,s_itr_,base_itr_);
            token_list_.push_back(t);

            return;
         }

         #ifndef exprtk_disable_string_capabilities
         inline void scan_string()
         {
            const char* initial_itr = s_itr_ + 1;
            token_t t;

            if (std::distance(s_itr_,s_end_) < 2)
            {
               t.set_error(token::e_err_string,s_itr_,s_end_,base_itr_);
               token_list_.push_back(t);
               return;
            }

            ++s_itr_;

            bool escaped_found = false;
            bool escaped = false;

            while (!is_end(s_itr_))
            {
               if (!escaped && ('\\' == *s_itr_))
               {
                  escaped_found = true;
                  escaped = true;
                  ++s_itr_;

                  continue;
               }
               else if (!escaped)
               {
                  if ('\'' == *s_itr_)
                     break;
               }
               else if (escaped)
               {
                  if (!is_end(s_itr_) && ('0' == *(s_itr_)))
                  {
                     /*
                        Note: The following 'awkward' conditional is
                              due to various broken msvc compilers.
                     */
                     #if _MSC_VER == 1600
                     const bool within_range = !is_end(s_itr_ + 2) &&
                                               !is_end(s_itr_ + 3) ;
                     #else
                     const bool within_range = !is_end(s_itr_ + 1) &&
                                               !is_end(s_itr_ + 2) &&
                                               !is_end(s_itr_ + 3) ;
                     #endif

                     const bool x_seperator  = ('x' == *(s_itr_ + 1)) ||
                                               ('X' == *(s_itr_ + 1)) ;

                     const bool both_digits  = details::is_hex_digit(*(s_itr_ + 2)) &&
                                               details::is_hex_digit(*(s_itr_ + 3)) ;

                     if (!within_range || !x_seperator || !both_digits)
                     {
                        t.set_error(token::e_err_string,initial_itr,s_itr_,base_itr_);
                        token_list_.push_back(t);

                        return;
                     }
                     else
                        s_itr_ += 3;
                  }

                  escaped = false;
               }

               ++s_itr_;
            }

            if (is_end(s_itr_))
            {
               t.set_error(token::e_err_string,initial_itr,s_itr_,base_itr_);
               token_list_.push_back(t);

               return;
            }

            if (!escaped_found)
               t.set_string(initial_itr,s_itr_,base_itr_);
            else
            {
               std::string parsed_string(initial_itr,s_itr_);
               details::cleanup_escapes(parsed_string);
               t.set_string(parsed_string, std::distance(base_itr_,initial_itr));
            }

            token_list_.push_back(t);
            ++s_itr_;

            return;
         }
         #endif

      private:

         token_list_t     token_list_;
         token_list_itr_t token_itr_;
         token_list_itr_t store_token_itr_;
         token_t eof_token_;
         const char* base_itr_;
         const char* s_itr_;
         const char* s_end_;

         friend class token_scanner;
         friend class token_modifier;
         friend class token_inserter;
         friend class token_joiner;
      };

      class helper_interface
      {
      public:

         virtual void init()                     {              }
         virtual void reset()                    {              }
         virtual bool result()                   { return true; }
         virtual std::size_t process(generator&) { return 0;    }
         virtual ~helper_interface()             {              }
      };

      class token_scanner : public helper_interface
      {
      public:

         virtual ~token_scanner()
         {}

         explicit token_scanner(const std::size_t& stride)
         : stride_(stride)
         {
            if (stride > 4)
            {
               throw std::invalid_argument("token_scanner() - Invalid stride value");
            }
         }

         inline std::size_t process(generator& g)
         {
            if (g.token_list_.size() >= stride_)
            {
               for (std::size_t i = 0; i < (g.token_list_.size() - stride_ + 1); ++i)
               {
                  token t;

                  switch (stride_)
                  {
                     case 1 :
                              {
                                 const token& t0 = g.token_list_[i];

                                 if (!operator()(t0))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 2 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];

                                 if (!operator()(t0,t1))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 3 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];
                                 const token& t2 = g.token_list_[i + 2];

                                 if (!operator()(t0,t1,t2))
                                 {
                                    return i;
                                 }
                              }
                              break;

                     case 4 :
                              {
                                 const token& t0 = g.token_list_[i    ];
                                 const token& t1 = g.token_list_[i + 1];
                                 const token& t2 = g.token_list_[i + 2];
                                 const token& t3 = g.token_list_[i + 3];

                                 if (!operator()(t0,t1,t2,t3))
                                 {
                                    return i;
                                 }
                              }
                              break;
                  }
               }
            }

            return (g.token_list_.size() - stride_ + 1);
         }

         virtual bool operator()(const token&)
         {
            return false;
         }

         virtual bool operator()(const token&, const token&)
         {
            return false;
         }

         virtual bool operator()(const token&, const token&, const token&)
         {
            return false;
         }

         virtual bool operator()(const token&, const token&, const token&, const token&)
         {
            return false;
         }

      private:

         std::size_t stride_;
      };

      class token_modifier : public helper_interface
      {
      public:

         inline std::size_t process(generator& g)
         {
            std::size_t changes = 0;

            for (std::size_t i = 0; i < g.token_list_.size(); ++i)
            {
               if (modify(g.token_list_[i])) changes++;
            }

            return changes;
         }

         virtual bool modify(token& t) = 0;
      };

      class token_inserter : public helper_interface
      {
      public:

         explicit token_inserter(const std::size_t& stride)
         : stride_(stride)
         {
            if (stride > 5)
            {
               throw std::invalid_argument("token_inserter() - Invalid stride value");
            }
         }

         inline std::size_t process(generator& g)
         {
            if (g.token_list_.empty())
               return 0;
            else if (g.token_list_.size() < stride_)
               return 0;

            std::size_t changes = 0;

            for (std::size_t i = 0; i < (g.token_list_.size() - stride_ + 1); ++i)
            {
               int insert_index = -1;
               token t;

               switch (stride_)
               {
                  case 1 : insert_index = insert(g.token_list_[i],t);
                           break;

                  case 2 : insert_index = insert(g.token_list_[i],g.token_list_[i + 1],t);
                           break;

                  case 3 : insert_index = insert(g.token_list_[i],g.token_list_[i + 1],g.token_list_[i + 2],t);
                           break;

                  case 4 : insert_index = insert(g.token_list_[i],g.token_list_[i + 1],g.token_list_[i + 2],g.token_list_[i + 3],t);
                           break;

                  case 5 : insert_index = insert(g.token_list_[i],g.token_list_[i + 1],g.token_list_[i + 2],g.token_list_[i + 3],g.token_list_[i + 4],t);
                           break;
               }

               if ((insert_index >= 0) && (insert_index <= (static_cast<int>(stride_) + 1)))
               {
                  g.token_list_.insert(g.token_list_.begin() + (i + insert_index),t);
                  changes++;
               }
            }

            return changes;
         }

         inline virtual int insert(const token&, token& )
         {
            return -1;
         }

         inline virtual int insert(const token&, const token&, token&)
         {
            return -1;
         }

         inline virtual int insert(const token&, const token&, const token&, token&)
         {
            return -1;
         }

         inline virtual int insert(const token&, const token&, const token&, const token&, token&)
         {
            return -1;
         }

         inline virtual int insert(const token&, const token&, const token&, const token&, const token&, token&)
         {
            return -1;
         }

      private:

         std::size_t stride_;
      };

      class token_joiner : public helper_interface
      {
      public:

         token_joiner(const std::size_t& stride)
         : stride_(stride)
         {}

         inline std::size_t process(generator& g)
         {
            if (g.token_list_.empty())
               return 0;

            switch (stride_)
            {
               case 2  : return process_stride_2(g);
               case 3  : return process_stride_3(g);
               default : return 0;
            }
         }

         virtual bool join(const token&, const token&, token&) { return false; }
         virtual bool join(const token&, const token&, const token&, token&) { return false; }

      private:

         inline std::size_t process_stride_2(generator& g)
         {
            if (g.token_list_.size() < 2)
               return 0;

            std::size_t changes = 0;

            for (std::size_t i = 0; i < g.token_list_.size() - 1; ++i)
            {
               token t;

               while (join(g.token_list_[i],g.token_list_[i + 1],t))
               {
                  g.token_list_[i] = t;
                  g.token_list_.erase(g.token_list_.begin() + (i + 1));
                  ++changes;
               }
            }

            return changes;
         }

         inline std::size_t process_stride_3(generator& g)
         {
            if (g.token_list_.size() < 3)
               return 0;

            std::size_t changes = 0;

            for (std::size_t i = 0; i < g.token_list_.size() - 2; ++i)
            {
               token t;

               while (join(g.token_list_[i],g.token_list_[i + 1],g.token_list_[i + 2],t))
               {
                  g.token_list_[i] = t;
                  g.token_list_.erase(g.token_list_.begin() + (i + 1),
                                      g.token_list_.begin() + (i + 3));
                  ++changes;
               }
            }

            return changes;
         }

         std::size_t stride_;
      };

      namespace helper
      {

         inline void dump(lexer::generator& generator)
         {
            for (std::size_t i = 0; i < generator.size(); ++i)
            {
               lexer::token t = generator[i];
               printf("Token[%02d] @ %03d  %6s  -->  '%s'\n",
                      static_cast<int>(i),
                      static_cast<int>(t.position),
                      t.to_str(t.type).c_str(),
                      t.value.c_str());
            }
         }

         class commutative_inserter : public lexer::token_inserter
         {
         public:

            commutative_inserter()
            : lexer::token_inserter(2)
            {}

            inline void ignore_symbol(const std::string& symbol)
            {
               ignore_set_.insert(symbol);
            }

            inline int insert(const lexer::token& t0, const lexer::token& t1, lexer::token& new_token)
            {
               bool match         = false;
               new_token.type     = lexer::token::e_mul;
               new_token.value    = "*";
               new_token.position = t1.position;

               if (t0.type == lexer::token::e_symbol)
               {
                  if (ignore_set_.end() != ignore_set_.find(t0.value))
                  {
                     return -1;
                  }
                  else if (!t0.value.empty() && ('$' == t0.value[0]))
                  {
                     return -1;
                  }
               }

               if (t1.type == lexer::token::e_symbol)
               {
                  if (ignore_set_.end() != ignore_set_.find(t1.value))
                  {
                     return -1;
                  }
               }
                    if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lbracket   )) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lcrlbracket)) match = true;
               else if ((t0.type == lexer::token::e_number     ) && (t1.type == lexer::token::e_lsqrbracket)) match = true;
               else if ((t0.type == lexer::token::e_symbol     ) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rbracket   ) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rcrlbracket) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rsqrbracket) && (t1.type == lexer::token::e_number     )) match = true;
               else if ((t0.type == lexer::token::e_rbracket   ) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_rcrlbracket) && (t1.type == lexer::token::e_symbol     )) match = true;
               else if ((t0.type == lexer::token::e_rsqrbracket) && (t1.type == lexer::token::e_symbol     )) match = true;

               return (match) ? 1 : -1;
            }

         private:

            std::set<std::string,details::ilesscompare> ignore_set_;
         };

         class operator_joiner : public token_joiner
         {
         public:

            operator_joiner(const std::size_t& stride)
            : token_joiner(stride)
            {}

            inline bool join(const lexer::token& t0, const lexer::token& t1, lexer::token& t)
            {
               // ': =' --> ':='
               if ((t0.type == lexer::token::e_colon) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_assign;
                  t.value    = ":=";
                  t.position = t0.position;
                  return true;
               }
               // '+ =' --> '+='
               else if ((t0.type == lexer::token::e_add) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_addass;
                  t.value    = "+=";
                  t.position = t0.position;
                  return true;
               }
               // '- =' --> '-='
               else if ((t0.type == lexer::token::e_sub) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_subass;
                  t.value    = "-=";
                  t.position = t0.position;
                  return true;
               }
               // '* =' --> '*='
               else if ((t0.type == lexer::token::e_mul) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_mulass;
                  t.value    = "*=";
                  t.position = t0.position;
                  return true;
               }
               // '/ =' --> '/='
               else if ((t0.type == lexer::token::e_div) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_divass;
                  t.value    = "/=";
                  t.position = t0.position;
                  return true;
               }
               // '% =' --> '%='
               else if ((t0.type == lexer::token::e_mod) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_modass;
                  t.value    = "%=";
                  t.position = t0.position;
                  return true;
               }
               // '> =' --> '>='
               else if ((t0.type == lexer::token::e_gt) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_gte;
                  t.value    = ">=";
                  t.position = t0.position;
                  return true;
               }
               // '< =' --> '<='
               else if ((t0.type == lexer::token::e_lt) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_lte;
                  t.value    = "<=";
                  t.position = t0.position;
                  return true;
               }
               // '= =' --> '=='
               else if ((t0.type == lexer::token::e_eq) && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_eq;
                  t.value    = "==";
                  t.position = t0.position;
                  return true;
               }
               // '! =' --> '!='
               else if ((static_cast<char>(t0.type) == '!') && (t1.type == lexer::token::e_eq))
               {
                  t.type     = lexer::token::e_ne;
                  t.value    = "!=";
                  t.position = t0.position;
                  return true;
               }
               // '< >' --> '<>'
               else if ((t0.type == lexer::token::e_lt) && (t1.type == lexer::token::e_gt))
               {
                  t.type     = lexer::token::e_ne;
                  t.value    = "<>";
                  t.position = t0.position;
                  return true;
               }
               // '<= >' --> '<=>'
               else if ((t0.type == lexer::token::e_lte) && (t1.type == lexer::token::e_gt))
               {
                  t.type     = lexer::token::e_swap;
                  t.value    = "<=>";
                  t.position = t0.position;
                  return true;
               }
               else
                  return false;
            }

            inline bool join(const lexer::token& t0, const lexer::token& t1, const lexer::token& t2, lexer::token& t)
            {
               // '[ * ]' --> '[*]'
               if (
                    (t0.type == lexer::token::e_lsqrbracket) &&
                    (t1.type == lexer::token::e_mul        ) &&
                    (t2.type == lexer::token::e_rsqrbracket)
                  )
               {
                  t.type     = lexer::token::e_symbol;
                  t.value    = "[*]";
                  t.position = t0.position;

                  return true;
               }
               else
                  return false;
            }
         };

         class bracket_checker : public lexer::token_scanner
         {
         public:

            bracket_checker()
            : token_scanner(1),
              state_(true)
            {}

            bool result()
            {
               if (!stack_.empty())
               {
                  lexer::token t;
                  t.value      = stack_.top().first;
                  t.position   = stack_.top().second;
                  error_token_ = t;
                  state_       = false;

                  return false;
               }
               else
                  return state_;
            }

            lexer::token error_token()
            {
               return error_token_;
            }

            void reset()
            {
               // Why? because msvc doesn't support swap properly.
               stack_ = std::stack<std::pair<char,std::size_t> >();
               state_ = true;
               error_token_.clear();
            }

            bool operator()(const lexer::token& t)
            {
               if (
                    !t.value.empty()                       &&
                    (lexer::token::e_string != t.type)     &&
                    (lexer::token::e_symbol != t.type)     &&
                    exprtk::details::is_bracket(t.value[0])
                  )
               {
                  char c = t.value[0];

                       if (t.type == lexer::token::e_lbracket)    stack_.push(std::make_pair(')',t.position));
                  else if (t.type == lexer::token::e_lcrlbracket) stack_.push(std::make_pair('}',t.position));
                  else if (t.type == lexer::token::e_lsqrbracket) stack_.push(std::make_pair(']',t.position));
                  else if (exprtk::details::is_right_bracket(c))
                  {
                     if (stack_.empty())
                     {
                        state_ = false;
                        error_token_ = t;

                        return false;
                     }
                     else if (c != stack_.top().first)
                     {
                        state_ = false;
                        error_token_ = t;

                        return false;
                     }
                     else
                        stack_.pop();
                  }
               }

               return true;
            }

         private:

            bool state_;
            std::stack<std::pair<char,std::size_t> > stack_;
            lexer::token error_token_;
         };

         class numeric_checker : public lexer::token_scanner
         {
         public:

            numeric_checker()
            : token_scanner (1),
              current_index_(0)
            {}

            bool result()
            {
               return error_list_.empty();
            }

            void reset()
            {
               error_list_.clear();
               current_index_ = 0;
            }

            bool operator()(const lexer::token& t)
            {
               if (token::e_number == t.type)
               {
                  double v;

                  if (!exprtk::details::string_to_real(t.value,v))
                  {
                     error_list_.push_back(current_index_);
                  }
               }

               ++current_index_;

               return true;
            }

            std::size_t error_count() const
            {
               return error_list_.size();
            }

            std::size_t error_index(const std::size_t& i)
            {
               if (i < error_list_.size())
                  return error_list_[i];
               else
                  return std::numeric_limits<std::size_t>::max();
            }

            void clear_errors()
            {
               error_list_.clear();
            }

         private:

            std::size_t current_index_;
            std::vector<std::size_t> error_list_;
         };

         class symbol_replacer : public lexer::token_modifier
         {
         private:

            typedef std::map<std::string,std::pair<std::string,token::token_type>,details::ilesscompare> replace_map_t;

         public:

            bool remove(const std::string& target_symbol)
            {
               replace_map_t::iterator itr = replace_map_.find(target_symbol);

               if (replace_map_.end() == itr)
                  return false;

               replace_map_.erase(itr);

               return true;
            }

            bool add_replace(const std::string& target_symbol,
                             const std::string& replace_symbol,
                             const lexer::token::token_type token_type = lexer::token::e_symbol)
            {
               replace_map_t::iterator itr = replace_map_.find(target_symbol);

               if (replace_map_.end() != itr)
               {
                  return false;
               }

               replace_map_[target_symbol] = std::make_pair(replace_symbol,token_type);

               return true;
            }

            void clear()
            {
               replace_map_.clear();
            }

         private:

            bool modify(lexer::token& t)
            {
               if (lexer::token::e_symbol == t.type)
               {
                  if (replace_map_.empty())
                     return false;

                  replace_map_t::iterator itr = replace_map_.find(t.value);

                  if (replace_map_.end() != itr)
                  {
                     t.value = itr->second.first;
                     t.type  = itr->second.second;

                     return true;
                  }
               }

               return false;
            }

            replace_map_t replace_map_;
         };

         class sequence_validator : public lexer::token_scanner
         {
         private:

            typedef std::pair<lexer::token::token_type,lexer::token::token_type> token_pair_t;
            typedef std::set<token_pair_t> set_t;

         public:

            sequence_validator()
            : lexer::token_scanner(2)
            {
               add_invalid(lexer::token::e_number ,lexer::token::e_number );
               add_invalid(lexer::token::e_string ,lexer::token::e_string );
               add_invalid(lexer::token::e_number ,lexer::token::e_string );
               add_invalid(lexer::token::e_string ,lexer::token::e_number );
               add_invalid(lexer::token::e_string ,lexer::token::e_ternary);
               add_invalid_set1(lexer::token::e_assign );
               add_invalid_set1(lexer::token::e_shr    );
               add_invalid_set1(lexer::token::e_shl    );
               add_invalid_set1(lexer::token::e_lte    );
               add_invalid_set1(lexer::token::e_ne     );
               add_invalid_set1(lexer::token::e_gte    );
               add_invalid_set1(lexer::token::e_lt     );
               add_invalid_set1(lexer::token::e_gt     );
               add_invalid_set1(lexer::token::e_eq     );
               add_invalid_set1(lexer::token::e_comma  );
               add_invalid_set1(lexer::token::e_add    );
               add_invalid_set1(lexer::token::e_sub    );
               add_invalid_set1(lexer::token::e_div    );
               add_invalid_set1(lexer::token::e_mul    );
               add_invalid_set1(lexer::token::e_mod    );
               add_invalid_set1(lexer::token::e_pow    );
               add_invalid_set1(lexer::token::e_colon  );
               add_invalid_set1(lexer::token::e_ternary);
            }

            bool result()
            {
               return error_list_.empty();
            }

            bool operator()(const lexer::token& t0, const lexer::token& t1)
            {
               set_t::value_type p = std::make_pair(t0.type,t1.type);

               if (invalid_bracket_check(t0.type,t1.type))
               {
                  error_list_.push_back(std::make_pair(t0,t1));
               }
               else if (invalid_comb_.find(p) != invalid_comb_.end())
               {
                  error_list_.push_back(std::make_pair(t0,t1));
               }

               return true;
            }

            std::size_t error_count()
            {
               return error_list_.size();
            }

            std::pair<lexer::token,lexer::token> error(const std::size_t index)
            {
               if (index < error_list_.size())
               {
                  return error_list_[index];
               }
               else
               {
                  static const lexer::token error_token;
                  return std::make_pair(error_token,error_token);
               }
            }

            void clear_errors()
            {
               error_list_.clear();
            }

         private:

            void add_invalid(lexer::token::token_type base, lexer::token::token_type t)
            {
               invalid_comb_.insert(std::make_pair(base,t));
            }

            void add_invalid_set1(lexer::token::token_type t)
            {
               add_invalid(t,lexer::token::e_assign);
               add_invalid(t,lexer::token::e_shr   );
               add_invalid(t,lexer::token::e_shl   );
               add_invalid(t,lexer::token::e_lte   );
               add_invalid(t,lexer::token::e_ne    );
               add_invalid(t,lexer::token::e_gte   );
               add_invalid(t,lexer::token::e_lt    );
               add_invalid(t,lexer::token::e_gt    );
               add_invalid(t,lexer::token::e_eq    );
               add_invalid(t,lexer::token::e_comma );
               add_invalid(t,lexer::token::e_div   );
               add_invalid(t,lexer::token::e_mul   );
               add_invalid(t,lexer::token::e_mod   );
               add_invalid(t,lexer::token::e_pow   );
               add_invalid(t,lexer::token::e_colon );
            }

            bool invalid_bracket_check(lexer::token::token_type base, lexer::token::token_type t)
            {
               if (details::is_right_bracket(static_cast<char>(base)))
               {
                  switch (t)
                  {
                     case lexer::token::e_assign : return (']' != base);
                     case lexer::token::e_string : return true;
                     default                     : return false;
                  }
               }
               else if (details::is_left_bracket(static_cast<char>(base)))
               {
                  if (details::is_right_bracket(static_cast<char>(t)))
                     return false;
                  else if (details::is_left_bracket(static_cast<char>(t)))
                     return false;
                  else
                  {
                     switch (t)
                     {
                        case lexer::token::e_number  : return false;
                        case lexer::token::e_symbol  : return false;
                        case lexer::token::e_string  : return false;
                        case lexer::token::e_add     : return false;
                        case lexer::token::e_sub     : return false;
                        case lexer::token::e_colon   : return false;
                        case lexer::token::e_ternary : return false;
                        default                      : return true;
                     }
                  }
               }
               else if (details::is_right_bracket(static_cast<char>(t)))
               {
                  switch (base)
                  {
                     case lexer::token::e_number  : return false;
                     case lexer::token::e_symbol  : return false;
                     case lexer::token::e_string  : return false;
                     case lexer::token::e_eof     : return false;
                     case lexer::token::e_colon   : return false;
                     case lexer::token::e_ternary : return false;
                     default                      : return true;
                  }
               }
               else if (details::is_left_bracket(static_cast<char>(t)))
               {
                  switch (base)
                  {
                     case lexer::token::e_rbracket    : return true;
                     case lexer::token::e_rsqrbracket : return true;
                     case lexer::token::e_rcrlbracket : return true;
                     default                          : return false;
                  }
               }

               return false;
            }

            set_t invalid_comb_;
            std::vector<std::pair<lexer::token,lexer::token> > error_list_;
         };

         struct helper_assembly
         {
            inline bool register_scanner(lexer::token_scanner* scanner)
            {
               if (token_scanner_list.end() != std::find(token_scanner_list.begin(),
                                                         token_scanner_list.end(),
                                                         scanner))
               {
                  return false;
               }

               token_scanner_list.push_back(scanner);
               return true;
            }

            inline bool register_modifier(lexer::token_modifier* modifier)
            {
               if (token_modifier_list.end() != std::find(token_modifier_list.begin(),
                                                          token_modifier_list.end(),
                                                          modifier))
               {
                  return false;
               }

               token_modifier_list.push_back(modifier);
               return true;
            }

            inline bool register_joiner(lexer::token_joiner* joiner)
            {
               if (token_joiner_list.end() != std::find(token_joiner_list.begin(),
                                                        token_joiner_list.end(),
                                                        joiner))
               {
                  return false;
               }

               token_joiner_list.push_back(joiner);
               return true;
            }

            inline bool register_inserter(lexer::token_inserter* inserter)
            {
               if (token_inserter_list.end() != std::find(token_inserter_list.begin(),
                                                          token_inserter_list.end(),
                                                          inserter))
               {
                  return false;
               }

               token_inserter_list.push_back(inserter);
               return true;
            }

            inline bool run_modifiers(lexer::generator& g)
            {
               error_token_modifier = reinterpret_cast<lexer::token_modifier*>(0);
               bool result = true;

               for (std::size_t i = 0; i < token_modifier_list.size(); ++i)
               {
                  lexer::token_modifier& modifier = (*token_modifier_list[i]);

                  modifier.reset();
                  modifier.process(g);

                  if (!modifier.result())
                  {
                     error_token_modifier = token_modifier_list[i];
                     return false;
                  }
               }

               return result;
            }

            inline bool run_joiners(lexer::generator& g)
            {
               error_token_joiner = reinterpret_cast<lexer::token_joiner*>(0);
               bool result = true;

               for (std::size_t i = 0; i < token_joiner_list.size(); ++i)
               {
                  lexer::token_joiner& joiner = (*token_joiner_list[i]);

                  joiner.reset();
                  joiner.process(g);

                  if (!joiner.result())
                  {
                     error_token_joiner = token_joiner_list[i];
                     return false;
                  }
               }

               return result;
            }

            inline bool run_inserters(lexer::generator& g)
            {
               error_token_inserter = reinterpret_cast<lexer::token_inserter*>(0);
               bool result = true;

               for (std::size_t i = 0; i < token_inserter_list.size(); ++i)
               {
                  lexer::token_inserter& inserter = (*token_inserter_list[i]);

                  inserter.reset();
                  inserter.process(g);

                  if (!inserter.result())
                  {
                     error_token_inserter = token_inserter_list[i];
                     return false;
                  }
               }

               return result;
            }

            inline bool run_scanners(lexer::generator& g)
            {
               error_token_scanner = reinterpret_cast<lexer::token_scanner*>(0);
               bool result = true;

               for (std::size_t i = 0; i < token_scanner_list.size(); ++i)
               {
                  lexer::token_scanner& scanner = (*token_scanner_list[i]);

                  scanner.reset();
                  scanner.process(g);

                  if (!scanner.result())
                  {
                     error_token_scanner = token_scanner_list[i];
                     return false;
                  }
               }

               return result;
            }

            std::vector<lexer::token_scanner*>  token_scanner_list;
            std::vector<lexer::token_modifier*> token_modifier_list;
            std::vector<lexer::token_joiner*>   token_joiner_list;
            std::vector<lexer::token_inserter*> token_inserter_list;

            lexer::token_scanner*  error_token_scanner;
            lexer::token_modifier* error_token_modifier;
            lexer::token_joiner*   error_token_joiner;
            lexer::token_inserter* error_token_inserter;
         };
      }

      class parser_helper
      {
      public:

         typedef token         token_t;
         typedef generator generator_t;

         inline bool init(const std::string& str)
         {
            if (!lexer_.process(str))
            {
               return false;
            }

            lexer_.begin();

            next_token();

            return true;
         }

         inline generator_t& lexer()
         {
            return lexer_;
         }

         inline const generator_t& lexer() const
         {
            return lexer_;
         }

         inline void store_token()
         {
            lexer_.store();
            store_current_token_ = current_token_;
         }

         inline void restore_token()
         {
            lexer_.restore();
            current_token_ = store_current_token_;
         }

         inline void next_token()
         {
            current_token_ = lexer_.next_token();
         }

         inline const token_t& current_token() const
         {
            return current_token_;
         }

         inline bool token_is(const token_t::token_type& ttype, const bool advance_token = true)
         {
            if (current_token().type != ttype)
            {
               return false;
            }

            if (advance_token)
            {
               next_token();
            }

            return true;
         }

         inline bool token_is(const token_t::token_type& ttype,
                              const std::string& value,
                              const bool advance_token = true)
         {
            if (
                 (current_token().type != ttype) ||
                 !exprtk::details::imatch(value,current_token().value)
               )
            {
               return false;
            }

            if (advance_token)
            {
               next_token();
            }

            return true;
         }

         inline bool token_is_then_assign(const token_t::token_type& ttype,
                                          std::string& token,
                                          const bool advance_token = true)
         {
            if (current_token_.type != ttype)
            {
               return false;
            }

            token = current_token_.value;

            if (advance_token)
            {
               next_token();
            }

            return true;
         }

         template <typename Allocator,
                   template <typename,typename> class Container>
         inline bool token_is_then_assign(const token_t::token_type& ttype,
                                          Container<std::string,Allocator>& token_list,
                                          const bool advance_token = true)
         {
            if (current_token_.type != ttype)
            {
               return false;
            }

            token_list.push_back(current_token_.value);

            if (advance_token)
            {
               next_token();
            }

            return true;
         }

         inline bool peek_token_is(const token_t::token_type& ttype)
         {
            return (lexer_.peek_next_token().type == ttype);
         }

         inline bool peek_token_is(const std::string& s)
         {
            return (exprtk::details::imatch(lexer_.peek_next_token().value,s));
         }

      private:

         generator_t lexer_;
         token_t     current_token_;
         token_t     store_current_token_;
      };
   }

   template <typename T> class results_context;

   template <typename T>
   struct type_store
   {
      enum store_type
      {
         e_unknown,
         e_scalar,
         e_vector,
         e_string
      };

      type_store()
      : size(0),
        data(0),
        type(e_unknown)
      {}

      std::size_t size;
      void*       data;
      store_type  type;

      class parameter_list
      {
      public:

         parameter_list(std::vector<type_store>& pl)
         : parameter_list_(pl)
         {}

         inline bool empty() const
         {
            return parameter_list_.empty();
         }

         inline std::size_t size() const
         {
            return parameter_list_.size();
         }

         inline type_store& operator[](const std::size_t& index)
         {
            return parameter_list_[index];
         }

         inline const type_store& operator[](const std::size_t& index) const
         {
            return parameter_list_[index];
         }

         inline type_store& front()
         {
            return parameter_list_[0];
         }

         inline const type_store& front() const
         {
            return parameter_list_[0];
         }

         inline type_store& back()
         {
            return parameter_list_.back();
         }

         inline const type_store& back() const
         {
            return parameter_list_.back();
         }

      private:

         std::vector<type_store>& parameter_list_;

         friend class results_context<T>;
      };

      template <typename ViewType>
      struct type_view
      {
         typedef type_store<T> type_store_t;
         typedef ViewType      value_t;

         type_view(type_store_t& ts)
         : ts_(ts),
           data_(reinterpret_cast<value_t*>(ts_.data))
         {}

         inline std::size_t size() const
         {
            return ts_.size;
         }

         inline value_t& operator[](const std::size_t& i)
         {
            return data_[i];
         }

         inline const value_t& operator[](const std::size_t& i) const
         {
            return data_[i];
         }

         inline const value_t* begin() const { return data_; }
         inline       value_t* begin()       { return data_; }

         inline const value_t* end() const
         {
            return static_cast<value_t*>(data_ + ts_.size);
         }

         inline value_t* end()
         {
            return static_cast<value_t*>(data_ + ts_.size);
         }

         type_store_t& ts_;
         value_t* data_;
      };

      typedef type_view<T>    vector_view;
      typedef type_view<char> string_view;

      struct scalar_view
      {
         typedef type_store<T> type_store_t;
         typedef T value_t;

         scalar_view(type_store_t& ts)
         : v_(*reinterpret_cast<value_t*>(ts.data))
         {}

         scalar_view(const type_store_t& ts)
         : v_(*reinterpret_cast<value_t*>(const_cast<type_store_t&>(ts).data))
         {}

         value_t& operator()()
         {
            return v_;
         }

         const value_t& operator()() const
         {
            return v_;
         }

         T& v_;
      };
   };

   template <typename StringView>
   inline std::string to_str(const StringView& view)
   {
      return std::string(view.begin(),view.size());
   }

   namespace details
   {
      template <typename T> class return_node;
      template <typename T> class return_envelope_node;
   }

   template <typename T>
   class results_context
   {
   public:

      typedef type_store<T> type_store_t;

      results_context()
      : results_available_(false)
      {}

      inline std::size_t count() const
      {
         if (results_available_)
            return parameter_list_.size();
         else
            return 0;
      }

      inline type_store_t& operator[](const std::size_t& index)
      {
         return parameter_list_[index];
      }

      inline const type_store_t& operator[](const std::size_t& index) const
      {
         return parameter_list_[index];
      }

   private:

      inline void clear()
      {
         results_available_ = false;
      }

      typedef std::vector<type_store_t> ts_list_t;
      typedef typename type_store_t::parameter_list parameter_list_t;

      inline void assign(const parameter_list_t& pl)
      {
         parameter_list_    = pl.parameter_list_;
         results_available_ = true;
      }

      bool results_available_;
      ts_list_t parameter_list_;

      friend class details::return_node<T>;
      friend class details::return_envelope_node<T>;
   };

   namespace details
   {
      enum operator_type
      {
         e_default , e_null    , e_add     , e_sub     ,
         e_mul     , e_div     , e_mod     , e_pow     ,
         e_atan2   , e_min     , e_max     , e_avg     ,
         e_sum     , e_prod    , e_lt      , e_lte     ,
         e_eq      , e_equal   , e_ne      , e_nequal  ,
         e_gte     , e_gt      , e_and     , e_nand    ,
         e_or      , e_nor     , e_xor     , e_xnor    ,
         e_mand    , e_mor     , e_scand   , e_scor    ,
         e_shr     , e_shl     , e_abs     , e_acos    ,
         e_acosh   , e_asin    , e_asinh   , e_atan    ,
         e_atanh   , e_ceil    , e_cos     , e_cosh    ,
         e_exp     , e_expm1   , e_floor   , e_log     ,
         e_log10   , e_log2    , e_log1p   , e_logn    ,
         e_neg     , e_pos     , e_round   , e_roundn  ,
         e_root    , e_sqrt    , e_sin     , e_sinc    ,
         e_sinh    , e_sec     , e_csc     , e_tan     ,
         e_tanh    , e_cot     , e_clamp   , e_iclamp  ,
         e_inrange , e_sgn     , e_r2d     , e_d2r     ,
         e_d2g     , e_g2d     , e_hypot   , e_notl    ,
         e_erf     , e_erfc    , e_ncdf    , e_frac    ,
         e_trunc   , e_assign  , e_addass  , e_subass  ,
         e_mulass  , e_divass  , e_modass  , e_in      ,
         e_like    , e_ilike   , e_multi   , e_swap    ,

         // Do not add new functions/operators after this point.
         e_sf00 = 1000, e_sf01 = 1001, e_sf02 = 1002, e_sf03 = 1003,
         e_sf04 = 1004, e_sf05 = 1005, e_sf06 = 1006, e_sf07 = 1007,
         e_sf08 = 1008, e_sf09 = 1009, e_sf10 = 1010, e_sf11 = 1011,
         e_sf12 = 1012, e_sf13 = 1013, e_sf14 = 1014, e_sf15 = 1015,
         e_sf16 = 1016, e_sf17 = 1017, e_sf18 = 1018, e_sf19 = 1019,
         e_sf20 = 1020, e_sf21 = 1021, e_sf22 = 1022, e_sf23 = 1023,
         e_sf24 = 1024, e_sf25 = 1025, e_sf26 = 1026, e_sf27 = 1027,
         e_sf28 = 1028, e_sf29 = 1029, e_sf30 = 1030, e_sf31 = 1031,
         e_sf32 = 1032, e_sf33 = 1033, e_sf34 = 1034, e_sf35 = 1035,
         e_sf36 = 1036, e_sf37 = 1037, e_sf38 = 1038, e_sf39 = 1039,
         e_sf40 = 1040, e_sf41 = 1041, e_sf42 = 1042, e_sf43 = 1043,
         e_sf44 = 1044, e_sf45 = 1045, e_sf46 = 1046, e_sf47 = 1047,
         e_sf48 = 1048, e_sf49 = 1049, e_sf50 = 1050, e_sf51 = 1051,
         e_sf52 = 1052, e_sf53 = 1053, e_sf54 = 1054, e_sf55 = 1055,
         e_sf56 = 1056, e_sf57 = 1057, e_sf58 = 1058, e_sf59 = 1059,
         e_sf60 = 1060, e_sf61 = 1061, e_sf62 = 1062, e_sf63 = 1063,
         e_sf64 = 1064, e_sf65 = 1065, e_sf66 = 1066, e_sf67 = 1067,
         e_sf68 = 1068, e_sf69 = 1069, e_sf70 = 1070, e_sf71 = 1071,
         e_sf72 = 1072, e_sf73 = 1073, e_sf74 = 1074, e_sf75 = 1075,
         e_sf76 = 1076, e_sf77 = 1077, e_sf78 = 1078, e_sf79 = 1079,
         e_sf80 = 1080, e_sf81 = 1081, e_sf82 = 1082, e_sf83 = 1083,
         e_sf84 = 1084, e_sf85 = 1085, e_sf86 = 1086, e_sf87 = 1087,
         e_sf88 = 1088, e_sf89 = 1089, e_sf90 = 1090, e_sf91 = 1091,
         e_sf92 = 1092, e_sf93 = 1093, e_sf94 = 1094, e_sf95 = 1095,
         e_sf96 = 1096, e_sf97 = 1097, e_sf98 = 1098, e_sf99 = 1099,
         e_sffinal  = 1100,
         e_sf4ext00 = 2000, e_sf4ext01 = 2001, e_sf4ext02 = 2002, e_sf4ext03 = 2003,
         e_sf4ext04 = 2004, e_sf4ext05 = 2005, e_sf4ext06 = 2006, e_sf4ext07 = 2007,
         e_sf4ext08 = 2008, e_sf4ext09 = 2009, e_sf4ext10 = 2010, e_sf4ext11 = 2011,
         e_sf4ext12 = 2012, e_sf4ext13 = 2013, e_sf4ext14 = 2014, e_sf4ext15 = 2015,
         e_sf4ext16 = 2016, e_sf4ext17 = 2017, e_sf4ext18 = 2018, e_sf4ext19 = 2019,
         e_sf4ext20 = 2020, e_sf4ext21 = 2021, e_sf4ext22 = 2022, e_sf4ext23 = 2023,
         e_sf4ext24 = 2024, e_sf4ext25 = 2025, e_sf4ext26 = 2026, e_sf4ext27 = 2027,
         e_sf4ext28 = 2028, e_sf4ext29 = 2029, e_sf4ext30 = 2030, e_sf4ext31 = 2031,
         e_sf4ext32 = 2032, e_sf4ext33 = 2033, e_sf4ext34 = 2034, e_sf4ext35 = 2035,
         e_sf4ext36 = 2036, e_sf4ext37 = 2037, e_sf4ext38 = 2038, e_sf4ext39 = 2039,
         e_sf4ext40 = 2040, e_sf4ext41 = 2041, e_sf4ext42 = 2042, e_sf4ext43 = 2043,
         e_sf4ext44 = 2044, e_sf4ext45 = 2045, e_sf4ext46 = 2046, e_sf4ext47 = 2047,
         e_sf4ext48 = 2048, e_sf4ext49 = 2049, e_sf4ext50 = 2050, e_sf4ext51 = 2051,
         e_sf4ext52 = 2052, e_sf4ext53 = 2053, e_sf4ext54 = 2054, e_sf4ext55 = 2055,
         e_sf4ext56 = 2056, e_sf4ext57 = 2057, e_sf4ext58 = 2058, e_sf4ext59 = 2059
      };

      struct base_operation_t
      {
         base_operation_t(const operator_type t, const unsigned int& np)
         : type(t),
           num_params(np)
         {}

         operator_type type;
         unsigned int num_params;
      };

      namespace numeric
      {
         namespace details
         {
            template <typename T>
            inline T process_impl(const operator_type operation, const T arg)
            {
               switch (operation)
               {
                  case e_abs   : return numeric::abs  (arg);
                  case e_acos  : return numeric::acos (arg);
                  case e_acosh : return numeric::acosh(arg);
                  case e_asin  : return numeric::asin (arg);
                  case e_asinh : return numeric::asinh(arg);
                  case e_atan  : return numeric::atan (arg);
                  case e_atanh : return numeric::atanh(arg);
                  case e_ceil  : return numeric::ceil (arg);
                  case e_cos   : return numeric::cos  (arg);
                  case e_cosh  : return numeric::cosh (arg);
                  case e_exp   : return numeric::exp  (arg);
                  case e_expm1 : return numeric::expm1(arg);
                  case e_floor : return numeric::floor(arg);
                  case e_log   : return numeric::log  (arg);
                  case e_log10 : return numeric::log10(arg);
                  case e_log2  : return numeric::log2 (arg);
                  case e_log1p : return numeric::log1p(arg);
                  case e_neg   : return numeric::neg  (arg);
                  case e_pos   : return numeric::pos  (arg);
                  case e_round : return numeric::round(arg);
                  case e_sin   : return numeric::sin  (arg);
                  case e_sinc  : return numeric::sinc (arg);
                  case e_sinh  : return numeric::sinh (arg);
                  case e_sqrt  : return numeric::sqrt (arg);
                  case e_tan   : return numeric::tan  (arg);
                  case e_tanh  : return numeric::tanh (arg);
                  case e_cot   : return numeric::cot  (arg);
                  case e_sec   : return numeric::sec  (arg);
                  case e_csc   : return numeric::csc  (arg);
                  case e_r2d   : return numeric::r2d  (arg);
                  case e_d2r   : return numeric::d2r  (arg);
                  case e_d2g   : return numeric::d2g  (arg);
                  case e_g2d   : return numeric::g2d  (arg);
                  case e_notl  : return numeric::notl (arg);
                  case e_sgn   : return numeric::sgn  (arg);
                  case e_erf   : return numeric::erf  (arg);
                  case e_erfc  : return numeric::erfc (arg);
                  case e_ncdf  : return numeric::ncdf (arg);
                  case e_frac  : return numeric::frac (arg);
                  case e_trunc : return numeric::trunc(arg);
                  default      : return std::numeric_limits<T>::quiet_NaN();
               }
            }

            template <typename T>
            inline T process_impl(const operator_type operation, const T arg0, const T arg1)
            {
               switch (operation)
               {
                  case e_add    : return (arg0 + arg1);
                  case e_sub    : return (arg0 - arg1);
                  case e_mul    : return (arg0 * arg1);
                  case e_div    : return (arg0 / arg1);
                  case e_mod    : return modulus<T>(arg0,arg1);
                  case e_pow    : return pow<T>(arg0,arg1);
                  case e_atan2  : return atan2<T>(arg0,arg1);
                  case e_min    : return std::min<T>(arg0,arg1);
                  case e_max    : return std::max<T>(arg0,arg1);
                  case e_logn   : return logn<T>(arg0,arg1);
                  case e_lt     : return (arg0 <  arg1) ? T(1) : T(0);
                  case e_lte    : return (arg0 <= arg1) ? T(1) : T(0);
                  case e_eq     : return std::equal_to<T>()(arg0,arg1) ? T(1) : T(0);
                  case e_ne     : return std::not_equal_to<T>()(arg0,arg1) ? T(1) : T(0);
                  case e_gte    : return (arg0 >= arg1) ? T(1) : T(0);
                  case e_gt     : return (arg0 >  arg1) ? T(1) : T(0);
                  case e_and    : return and_opr<T> (arg0,arg1);
                  case e_nand   : return nand_opr<T>(arg0,arg1);
                  case e_or     : return or_opr<T>  (arg0,arg1);
                  case e_nor    : return nor_opr<T> (arg0,arg1);
                  case e_xor    : return xor_opr<T> (arg0,arg1);
                  case e_xnor   : return xnor_opr<T>(arg0,arg1);
                  case e_root   : return root<T>    (arg0,arg1);
                  case e_roundn : return roundn<T>  (arg0,arg1);
                  case e_equal  : return equal<T>   (arg0,arg1);
                  case e_nequal : return nequal<T>  (arg0,arg1);
                  case e_hypot  : return hypot<T>   (arg0,arg1);
                  case e_shr    : return shr<T>     (arg0,arg1);
                  case e_shl    : return shl<T>     (arg0,arg1);
                  default       : return std::numeric_limits<T>::quiet_NaN();
               }
            }

            template <typename T>
            inline T process_impl(const operator_type operation, const T arg0, const T arg1, int_type_tag)
            {
               switch (operation)
               {
                  case e_add    : return (arg0 + arg1);
                  case e_sub    : return (arg0 - arg1);
                  case e_mul    : return (arg0 * arg1);
                  case e_div    : return (arg0 / arg1);
                  case e_mod    : return arg0 % arg1;
                  case e_pow    : return pow<T>(arg0,arg1);
                  case e_min    : return std::min<T>(arg0,arg1);
                  case e_max    : return std::max<T>(arg0,arg1);
                  case e_logn   : return logn<T>(arg0,arg1);
                  case e_lt     : return (arg0 <  arg1) ? T(1) : T(0);
                  case e_lte    : return (arg0 <= arg1) ? T(1) : T(0);
                  case e_eq     : return (arg0 == arg1) ? T(1) : T(0);
                  case e_ne     : return (arg0 != arg1) ? T(1) : T(0);
                  case e_gte    : return (arg0 >= arg1) ? T(1) : T(0);
                  case e_gt     : return (arg0 >  arg1) ? T(1) : T(0);
                  case e_and    : return ((arg0 != T(0)) && (arg1 != T(0))) ? T(1) : T(0);
                  case e_nand   : return ((arg0 != T(0)) && (arg1 != T(0))) ? T(0) : T(1);
                  case e_or     : return ((arg0 != T(0)) || (arg1 != T(0))) ? T(1) : T(0);
                  case e_nor    : return ((arg0 != T(0)) || (arg1 != T(0))) ? T(0) : T(1);
                  case e_xor    : return arg0 ^ arg1;
                  case e_xnor   : return !(arg0 ^ arg1);
                  case e_root   : return root<T>(arg0,arg1);
                  case e_equal  : return arg0 == arg1;
                  case e_nequal : return arg0 != arg1;
                  case e_hypot  : return hypot<T>(arg0,arg1);
                  case e_shr    : return arg0 >> arg1;
                  case e_shl    : return arg0 << arg1;
                  default       : return std::numeric_limits<T>::quiet_NaN();
               }
            }
         }

         template <typename T>
         inline T process(const operator_type operation, const T arg)
         {
            return exprtk::details::numeric::details::process_impl(operation,arg);
         }

         template <typename T>
         inline T process(const operator_type operation, const T arg0, const T arg1)
         {
            return exprtk::details::numeric::details::process_impl(operation,arg0,arg1);
         }
      }

      template <typename T>
      class expression_node
      {
      public:

         enum node_type
         {
            e_none         , e_null         , e_constant     , e_unary        ,
            e_binary       , e_binary_ext   , e_trinary      , e_quaternary   ,
            e_vararg       , e_conditional  , e_while        , e_repeat       ,
            e_for          , e_switch       , e_mswitch      , e_return       ,
            e_retenv       , e_variable     , e_stringvar    , e_stringconst  ,
            e_stringvarrng , e_cstringvarrng, e_strgenrange  , e_strconcat    ,
            e_stringvarsize, e_strswap      , e_stringsize   , e_function     ,
            e_vafunction   , e_genfunction  , e_strfunction  , e_strcondition ,
            e_strccondition, e_add          , e_sub          , e_mul          ,
            e_div          , e_mod          , e_pow          , e_lt           ,
            e_lte          , e_gt           , e_gte          , e_eq           ,
            e_ne           , e_and          , e_nand         , e_or           ,
            e_nor          , e_xor          , e_xnor         , e_in           ,
            e_like         , e_ilike        , e_inranges     , e_ipow         ,
            e_ipowinv      , e_abs          , e_acos         , e_acosh        ,
            e_asin         , e_asinh        , e_atan         , e_atanh        ,
            e_ceil         , e_cos          , e_cosh         , e_exp          ,
            e_expm1        , e_floor        , e_log          , e_log10        ,
            e_log2         , e_log1p        , e_neg          , e_pos          ,
            e_round        , e_sin          , e_sinc         , e_sinh         ,
            e_sqrt         , e_tan          , e_tanh         , e_cot          ,
            e_sec          , e_csc          , e_r2d          , e_d2r          ,
            e_d2g          , e_g2d          , e_notl         , e_sgn          ,
            e_erf          , e_erfc         , e_ncdf         , e_frac         ,
            e_trunc        , e_uvouv        , e_vov          , e_cov          ,
            e_voc          , e_vob          , e_bov          , e_cob          ,
            e_boc          , e_vovov        , e_vovoc        , e_vocov        ,
            e_covov        , e_covoc        , e_vovovov      , e_vovovoc      ,
            e_vovocov      , e_vocovov      , e_covovov      , e_covocov      ,
            e_vocovoc      , e_covovoc      , e_vococov      , e_sf3ext       ,
            e_sf4ext       , e_nulleq       , e_strass       , e_vector       ,
            e_vecelem      , e_vecdefass    , e_vecvalass    , e_vecvecass    ,
            e_vecopvalass  , e_vecopvecass  , e_vecfunc      , e_vecvecswap   ,
            e_vecvecineq   , e_vecvalineq   , e_valvecineq   , e_vecvecarith  ,
            e_vecvalarith  , e_valvecarith  , e_vecunaryop   , e_break        ,
            e_continue     , e_swap
         };

         typedef T value_type;
         typedef expression_node<T>* expression_ptr;

         virtual ~expression_node()
         {}

         inline virtual T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline virtual expression_node<T>* branch(const std::size_t& index = 0) const
         {
            return reinterpret_cast<expression_ptr>(index * 0);
         }

         inline virtual node_type type() const
         {
            return e_none;
         }
      };

      template <typename T>
      inline bool is_generally_string_node(const expression_node<T>* node);

      inline bool is_true(const double v)
      {
         return std::not_equal_to<double>()(0.0,v);
      }

      inline bool is_true(const long double v)
      {
         return std::not_equal_to<long double>()(0.0L,v);
      }

      inline bool is_true(const float v)
      {
         return std::not_equal_to<float>()(0.0f,v);
      }

      template <typename T>
      inline bool is_true(const std::complex<T>& v)
      {
         return std::not_equal_to<std::complex<T> >()(std::complex<T>(0),v);
      }

      template <typename T>
      inline bool is_true(const expression_node<T>* node)
      {
         return std::not_equal_to<T>()(T(0),node->value());
      }

      template <typename T>
      inline bool is_false(const expression_node<T>* node)
      {
         return std::equal_to<T>()(T(0),node->value());
      }

      template <typename T>
      inline bool is_unary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_unary == node->type());
      }

      template <typename T>
      inline bool is_neg_unary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_neg == node->type());
      }

      template <typename T>
      inline bool is_binary_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_binary == node->type());
      }

      template <typename T>
      inline bool is_variable_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_variable == node->type());
      }

      template <typename T>
      inline bool is_ivariable_node(const expression_node<T>* node)
      {
         return node &&
                (
                  details::expression_node<T>::e_variable == node->type() ||
                  details::expression_node<T>::e_vecelem  == node->type()
                );
      }

      template <typename T>
      inline bool is_vector_elem_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vecelem == node->type());
      }

      template <typename T>
      inline bool is_vector_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_vector == node->type());
      }

      template <typename T>
      inline bool is_ivector_node(const expression_node<T>* node)
      {
         if (node)
         {
            switch (node->type())
            {
               case details::expression_node<T>::e_vector      :
               case details::expression_node<T>::e_vecvalass   :
               case details::expression_node<T>::e_vecvecass   :
               case details::expression_node<T>::e_vecopvalass :
               case details::expression_node<T>::e_vecopvecass :
               case details::expression_node<T>::e_vecvecswap  :
               case details::expression_node<T>::e_vecvecarith :
               case details::expression_node<T>::e_vecvalarith :
               case details::expression_node<T>::e_valvecarith :
               case details::expression_node<T>::e_vecunaryop  : return true;
               default                                         : return false;
            }
         }
         else
            return false;
      }

      template <typename T>
      inline bool is_constant_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_constant == node->type());
      }

      template <typename T>
      inline bool is_null_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_null == node->type());
      }

      template <typename T>
      inline bool is_break_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_break == node->type());
      }

      template <typename T>
      inline bool is_continue_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_continue == node->type());
      }

      template <typename T>
      inline bool is_swap_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_swap == node->type());
      }

      template <typename T>
      inline bool is_function(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_function == node->type());
      }

      template <typename T>
      inline bool is_return_node(const expression_node<T>* node)
      {
         return node && (details::expression_node<T>::e_return == node->type());
      }

      template <typename T> class unary_node;

      template <typename T>
      inline bool is_negate_node(const expression_node<T>* node)
      {
         if (node && is_unary_node(node))
         {
            return (details::e_neg == static_cast<const unary_node<T>*>(node)->operation());
         }
         else
            return false;
      }

      template <typename T>
      inline bool branch_deletable(expression_node<T>* node)
      {
         return !is_variable_node(node) &&
                !is_string_node  (node) ;
      }

      template <std::size_t N, typename T>
      inline bool all_nodes_valid(expression_node<T>* (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            if (0 == b[i]) return false;
         }

         return true;
      }

      template <typename T,
                typename Allocator,
                template <typename,typename> class Sequence>
      inline bool all_nodes_valid(const Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            if (0 == b[i]) return false;
         }

         return true;
      }

      template <std::size_t N, typename T>
      inline bool all_nodes_variables(expression_node<T>* (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            if (0 == b[i])
               return false;
            else if (!is_variable_node(b[i]))
               return false;
         }

         return true;
      }

      template <typename T,
                typename Allocator,
                template <typename,typename> class Sequence>
      inline bool all_nodes_variables(Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            if (0 == b[i])
               return false;
            else if (!is_variable_node(b[i]))
               return false;
         }

         return true;
      }

      template <typename NodeAllocator, typename T, std::size_t N>
      inline void free_all_nodes(NodeAllocator& node_allocator, expression_node<T>* (&b)[N])
      {
         for (std::size_t i = 0; i < N; ++i)
         {
            free_node(node_allocator,b[i]);
         }
      }

      template <typename NodeAllocator,
                typename T,
                typename Allocator,
                template <typename,typename> class Sequence>
      inline void free_all_nodes(NodeAllocator& node_allocator, Sequence<expression_node<T>*,Allocator>& b)
      {
         for (std::size_t i = 0; i < b.size(); ++i)
         {
            free_node(node_allocator,b[i]);
         }

         b.clear();
      }

      template <typename NodeAllocator, typename T>
      inline void free_node(NodeAllocator& node_allocator, expression_node<T>*& node, const bool force_delete = false)
      {
         if (0 != node)
         {
            if (
                 (is_variable_node(node) || is_string_node(node)) ||
                 force_delete
               )
               return;

            node_allocator.free(node);
            node = 0;
         }
      }

      template <typename Type>
      class vector_holder
      {
      private:

         typedef Type value_type;
         typedef value_type* value_ptr;
         typedef const value_ptr const_value_ptr;

         class vector_holder_base
         {
         public:

            virtual ~vector_holder_base(){}

            inline value_ptr operator[](const std::size_t& index) const
            {
               return value_at(index);
            }

            inline std::size_t size() const
            {
               return vector_size();
            }

         protected:

            virtual value_ptr value_at(const std::size_t&) const = 0;
            virtual std::size_t vector_size()              const = 0;
         };

         class array_vector_impl : public vector_holder_base
         {
         public:

            array_vector_impl(const Type* vec, const std::size_t& vec_size)
            : vec_(vec),
              size_(vec_size)
            {}

         protected:

            value_ptr value_at(const std::size_t& index) const
            {
               if (index < size_)
                  return const_cast<const_value_ptr>(vec_ + index);
               else
                  return const_value_ptr(0);
            }

            std::size_t vector_size() const
            {
               return size_;
            }

         private:

            array_vector_impl operator=(const array_vector_impl&);

            const Type* vec_;
            const std::size_t size_;
         };

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         class sequence_vector_impl : public vector_holder_base
         {
         public:

            typedef Sequence<Type,Allocator> sequence_t;

            sequence_vector_impl(sequence_t& seq)
            : sequence_(seq)
            {}

         protected:

            value_ptr value_at(const std::size_t& index) const
            {
               return (index < sequence_.size()) ? (&sequence_[index]) : const_value_ptr(0);
            }

            std::size_t vector_size() const
            {
               return sequence_.size();
            }

         private:

            sequence_vector_impl operator=(const sequence_vector_impl&);

            sequence_t& sequence_;
         };

      public:

         vector_holder(Type* vec, const std::size_t& vec_size)
         : vector_holder_base_(new(buffer)array_vector_impl(vec,vec_size))
         {}

         template <typename Allocator>
         vector_holder(std::vector<Type,Allocator>& vec)
         : vector_holder_base_(new(buffer)sequence_vector_impl<Allocator,std::vector>(vec))
         {}

         template <typename Allocator>
         vector_holder(std::deque<Type,Allocator>& deq)
         : vector_holder_base_(new(buffer)sequence_vector_impl<Allocator,std::deque>(deq))
         {}

         inline value_ptr operator[](const std::size_t& index) const
         {
            return (*vector_holder_base_)[index];
         }

         inline std::size_t size() const
         {
            return vector_holder_base_->size();
         }

      private:

         mutable vector_holder_base* vector_holder_base_;
         unsigned char buffer[64];
      };

      template <typename T>
      class null_node : public expression_node<T>
      {
      public:

         inline T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_null;
         }
      };

      template <typename T>
      class null_eq_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         null_eq_node(expression_ptr brnch, const bool equality = true)
         : branch_(brnch),
           branch_deletable_(branch_deletable(branch_)),
           equality_(equality)
         {}

        ~null_eq_node()
         {
            if (branch_ && branch_deletable_)
            {
               delete branch_;
               branch_ = 0;
            }
         }

         inline T value() const
         {
            const T v = branch_->value();
            const bool result = details::numeric::is_nan(v);

            if (result)
               return (equality_) ? T(1) : T(0);
            else
               return (equality_) ? T(0) : T(1);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_nulleq;
         }

         inline operator_type operation() const
         {
            return details::e_eq;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_;
         }

      private:

         expression_ptr branch_;
         bool branch_deletable_;
         bool equality_;
      };

      template <typename T>
      class literal_node : public expression_node<T>
      {
      public:

         explicit literal_node(const T& v)
         : value_(v)
         {}

         inline T value() const
         {
            return value_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_constant;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return reinterpret_cast<expression_node<T>*>(0);
         }

      private:

         literal_node(literal_node<T>&) {}
         literal_node<T>& operator=(literal_node<T>&) { return *this; }

         const T value_;
      };

      template <typename T>
      struct range_pack;

      template <typename T>
      struct range_data_type;

      template <typename T>
      class range_interface
      {
      public:

         typedef range_pack<T> range_t;

         virtual range_t& range_ref() = 0;

         virtual const range_t& range_ref() const = 0;
      };

      template <typename T>
      class string_base_node
      {
      public:

         typedef range_data_type<T> range_data_type_t;

         virtual std::string str () const = 0;

         virtual const char* base() const = 0;

         virtual std::size_t size() const = 0;
      };

      template <typename T>
      class string_literal_node : public expression_node <T>,
                                  public string_base_node<T>,
                                  public range_interface <T>
      {
      public:

         typedef range_pack<T> range_t;

         explicit string_literal_node(const std::string& v)
         : value_(v)
         {
            rp_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            rp_.n1_c = std::make_pair<bool,std::size_t>(true,v.size() - 1);
            rp_.cache.first  = rp_.n0_c.second;
            rp_.cache.second = rp_.n1_c.second;
         }

         inline T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_stringconst;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return reinterpret_cast<expression_node<T>*>(0);
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return rp_;
         }

         const range_t& range_ref() const
         {
            return rp_;
         }

      private:

         string_literal_node(const string_literal_node<T>&);
         string_literal_node<T>& operator=(const string_literal_node<T>&);

         const std::string value_;
         range_t rp_;
      };

      template <typename T>
      class unary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         unary_node(const operator_type& opr,
                    expression_ptr brnch)
         : operation_(opr),
           branch_(brnch),
           branch_deletable_(branch_deletable(branch_))
         {}

        ~unary_node()
         {
            if (branch_ && branch_deletable_)
            {
               delete branch_;
               branch_ = 0;
            }
         }

         inline T value() const
         {
            const T arg = branch_->value();
            return numeric::process<T>(operation_,arg);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_unary;
         }

         inline operator_type operation() const
         {
            return operation_;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_;
         }

         inline void release()
         {
            branch_deletable_ = false;
         }

      protected:

         operator_type operation_;
         expression_ptr branch_;
         bool branch_deletable_;
      };

      template <typename T, std::size_t D, bool B>
      struct construct_branch_pair
      {
         template <std::size_t N>
         static inline void process(std::pair<expression_node<T>*,bool> (&)[N], expression_node<T>*)
         {}
      };

      template <typename T, std::size_t D>
      struct construct_branch_pair<T,D,true>
      {
         template <std::size_t N>
         static inline void process(std::pair<expression_node<T>*,bool> (&branch)[N], expression_node<T>* b)
         {
            if (b)
            {
               branch[D] = std::make_pair(b,branch_deletable(b));
            }
         }
      };

      template <std::size_t N, typename T>
      inline void init_branches(std::pair<expression_node<T>*,bool> (&branch)[N],
                                expression_node<T>* b0,
                                expression_node<T>* b1 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b2 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b3 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b4 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b5 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b6 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b7 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b8 = reinterpret_cast<expression_node<T>*>(0),
                                expression_node<T>* b9 = reinterpret_cast<expression_node<T>*>(0))
      {
         construct_branch_pair<T,0,(N > 0)>::process(branch,b0);
         construct_branch_pair<T,1,(N > 1)>::process(branch,b1);
         construct_branch_pair<T,2,(N > 2)>::process(branch,b2);
         construct_branch_pair<T,3,(N > 3)>::process(branch,b3);
         construct_branch_pair<T,4,(N > 4)>::process(branch,b4);
         construct_branch_pair<T,5,(N > 5)>::process(branch,b5);
         construct_branch_pair<T,6,(N > 6)>::process(branch,b6);
         construct_branch_pair<T,7,(N > 7)>::process(branch,b7);
         construct_branch_pair<T,8,(N > 8)>::process(branch,b8);
         construct_branch_pair<T,9,(N > 9)>::process(branch,b9);
      }

      struct cleanup_branches
      {
         template <typename T, std::size_t N>
         static inline void execute(std::pair<expression_node<T>*,bool> (&branch)[N])
         {
            for (std::size_t i = 0; i < N; ++i)
            {
               if (branch[i].first && branch[i].second)
               {
                  delete branch[i].first;
                  branch[i].first = 0;
               }
            }
         }

         template <typename T,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline void execute(Sequence<std::pair<expression_node<T>*,bool>,Allocator>& branch)
         {
            for (std::size_t i = 0; i < branch.size(); ++i)
            {
               if (branch[i].first && branch[i].second)
               {
                  delete branch[i].first;
                  branch[i].first = 0;
               }
            }
         }
      };

      template <typename T>
      class binary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         binary_node(const operator_type& opr,
                     expression_ptr branch0,
                     expression_ptr branch1)
         : operation_(opr)
         {
            init_branches<2>(branch_,branch0,branch1);
         }

        ~binary_node()
         {
            cleanup_branches::execute<T,2>(branch_);
         }

         inline T value() const
         {
            const T arg0 = branch_[0].first->value();
            const T arg1 = branch_[1].first->value();
            return numeric::process<T>(operation_,arg0,arg1);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_binary;
         }

         inline operator_type operation()
         {
            return operation_;
         }

         inline expression_node<T>* branch(const std::size_t& index = 0) const
         {
            if (0 == index)
               return branch_[0].first;
            else if (1 == index)
               return branch_[1].first;
            else
               return reinterpret_cast<expression_ptr>(0);
         }

      protected:

         operator_type operation_;
         branch_t branch_[2];
      };

      template <typename T, typename Operation>
      class binary_ext_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         binary_ext_node(expression_ptr branch0, expression_ptr branch1)
         {
            init_branches<2>(branch_,branch0,branch1);
         }

        ~binary_ext_node()
         {
            cleanup_branches::execute<T,2>(branch_);
         }

         inline T value() const
         {
            const T arg0 = branch_[0].first->value();
            const T arg1 = branch_[1].first->value();
            return Operation::process(arg0,arg1);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_binary_ext;
         }

         inline operator_type operation()
         {
            return Operation::operation();
         }

         inline expression_node<T>* branch(const std::size_t& index = 0) const
         {
            if (0 == index)
               return branch_[0].first;
            else if (1 == index)
               return branch_[1].first;
            else
               return reinterpret_cast<expression_ptr>(0);
         }

      protected:

         branch_t branch_[2];
      };

      template <typename T>
      class trinary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         trinary_node(const operator_type& opr,
                      expression_ptr branch0,
                      expression_ptr branch1,
                      expression_ptr branch2)
         : operation_(opr)
         {
            init_branches<3>(branch_,branch0,branch1,branch2);
         }

        ~trinary_node()
         {
            cleanup_branches::execute<T,3>(branch_);
         }

         inline T value() const
         {
            const T arg0 = branch_[0].first->value();
            const T arg1 = branch_[1].first->value();
            const T arg2 = branch_[2].first->value();

            switch (operation_)
            {
               case e_inrange : return (arg1 < arg0) ? T(0) : ((arg1 > arg2) ? T(0) : T(1));
               case e_clamp   : return (arg1 < arg0) ? arg0 : (arg1 > arg2 ? arg2 : arg1);
               case e_iclamp  : if ((arg1 <= arg0) || (arg1 >= arg2))
                                   return arg1;
                                else
                                   return ((T(2) * arg1  <= (arg2 + arg0)) ? arg0 : arg2);
               default        : return std::numeric_limits<T>::quiet_NaN();
            }
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_trinary;
         }

      protected:

         operator_type operation_;
         branch_t branch_[3];
      };

      template <typename T>
      class quaternary_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;

         quaternary_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1,
                         expression_ptr branch2,
                         expression_ptr branch3)
         : operation_(opr)
         {
            init_branches<4>(branch_,branch0,branch1,branch2,branch3);
         }

        ~quaternary_node()
         {
            cleanup_branches::execute<T,4>(branch_);
         }

         inline T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_quaternary;
         }

      protected:

         operator_type operation_;
         branch_t branch_[4];
      };

      template <typename T>
      class conditional_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         conditional_node(expression_ptr test,
                          expression_ptr consequent,
                          expression_ptr alternative)
         : test_(test),
           consequent_(consequent),
           alternative_(alternative),
           test_deletable_(branch_deletable(test_)),
           consequent_deletable_(branch_deletable(consequent_)),
           alternative_deletable_(branch_deletable(alternative_))
         {}

        ~conditional_node()
         {
            if (test_        && test_deletable_       ) delete test_;
            if (consequent_  && consequent_deletable_ ) delete consequent_;
            if (alternative_ && alternative_deletable_) delete alternative_;
         }

         inline T value() const
         {
            if (is_true(test_))
               return consequent_->value();
            else
               return alternative_->value();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_conditional;
         }

      private:

         expression_ptr test_;
         expression_ptr consequent_;
         expression_ptr alternative_;
         bool test_deletable_;
         bool consequent_deletable_;
         bool alternative_deletable_;
      };

      template <typename T>
      class cons_conditional_node : public expression_node<T>
      {
      public:

         // Consequent only conditional statement node
         typedef expression_node<T>* expression_ptr;

         cons_conditional_node(expression_ptr test,
                               expression_ptr consequent)
         : test_(test),
           consequent_(consequent),
           test_deletable_(branch_deletable(test_)),
           consequent_deletable_(branch_deletable(consequent_))
         {}

        ~cons_conditional_node()
         {
            if (test_       && test_deletable_      ) delete test_;
            if (consequent_ && consequent_deletable_) delete consequent_;
         }

         inline T value() const
         {
            if (is_true(test_))
               return consequent_->value();
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_conditional;
         }

      private:

         expression_ptr test_;
         expression_ptr consequent_;
         bool test_deletable_;
         bool consequent_deletable_;
      };

      #ifndef exprtk_disable_break_continue
      template <typename T>
      class break_exception
      {
      public:

         break_exception(const T& v)
         : value(v)
         {}

         T value;
      };

      class continue_exception
      {};

      template <typename T>
      class break_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         break_node(expression_ptr ret = expression_ptr(0))
         : return_(ret),
           return_deletable_(branch_deletable(return_))
         {}

        ~break_node()
         {
            if (return_deletable_)
            {
               delete return_;
            }
         }

         inline T value() const
         {
            throw break_exception<T>(return_ ? return_->value() : std::numeric_limits<T>::quiet_NaN());
            #ifndef _MSC_VER
            return std::numeric_limits<T>::quiet_NaN();
            #endif
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_break;
         }

      private:

         expression_ptr return_;
         bool return_deletable_;
      };

      template <typename T>
      class continue_node : public expression_node<T>
      {
      public:

         inline T value() const
         {
            throw continue_exception();
            #ifndef _MSC_VER
            return std::numeric_limits<T>::quiet_NaN();
            #endif
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_break;
         }
      };
      #endif

      template <typename T>
      class while_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         while_loop_node(expression_ptr condition, expression_ptr loop_body)
         : condition_(condition),
           loop_body_(loop_body),
           condition_deletable_(branch_deletable(condition_)),
           loop_body_deletable_(branch_deletable(loop_body_))
         {}

        ~while_loop_node()
         {
            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);

            while (is_true(condition_))
            {
               result = loop_body_->value();
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_while;
         }

      private:

         expression_ptr condition_;
         expression_ptr loop_body_;
         bool condition_deletable_;
         bool loop_body_deletable_;
      };

      template <typename T>
      class repeat_until_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         repeat_until_loop_node(expression_ptr condition, expression_ptr loop_body)
         : condition_(condition),
           loop_body_(loop_body),
           condition_deletable_(branch_deletable(condition_)),
           loop_body_deletable_(branch_deletable(loop_body_))
         {}

        ~repeat_until_loop_node()
         {
            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);

            do
            {
               result = loop_body_->value();
            }
            while (is_false(condition_));

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_repeat;
         }

      private:

         expression_ptr condition_;
         expression_ptr loop_body_;
         bool condition_deletable_;
         bool loop_body_deletable_;
      };

      template <typename T>
      class for_loop_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         for_loop_node(expression_ptr initialiser,
                       expression_ptr condition,
                       expression_ptr incrementor,
                       expression_ptr loop_body)
         : initialiser_(initialiser),
           condition_  (condition),
           incrementor_(incrementor),
           loop_body_  (loop_body),
           initialiser_deletable_(branch_deletable(initialiser_)),
           condition_deletable_  (branch_deletable(condition_  )),
           incrementor_deletable_(branch_deletable(incrementor_)),
           loop_body_deletable_  (branch_deletable(loop_body_  ))
         {}

        ~for_loop_node()
         {
            if (initialiser_ && initialiser_deletable_)
            {
               delete initialiser_;
            }

            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (incrementor_ && incrementor_deletable_)
            {
               delete incrementor_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);

            if (initialiser_)
               initialiser_->value();

            if (incrementor_)
            {
               while (is_true(condition_))
               {
                  result = loop_body_->value();
                  incrementor_->value();
               }
            }
            else
            {
               while (is_true(condition_))
               {
                  result = loop_body_->value();
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_for;
         }

      private:

         expression_ptr initialiser_;
         expression_ptr condition_  ;
         expression_ptr incrementor_;
         expression_ptr loop_body_  ;
         bool initialiser_deletable_;
         bool condition_deletable_  ;
         bool incrementor_deletable_;
         bool loop_body_deletable_  ;
      };

      #ifndef exprtk_disable_break_continue
      template <typename T>
      class while_loop_bc_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         while_loop_bc_node(expression_ptr condition, expression_ptr loop_body)
         : condition_(condition),
           loop_body_(loop_body),
           condition_deletable_(branch_deletable(condition_)),
           loop_body_deletable_(branch_deletable(loop_body_))
         {}

        ~while_loop_bc_node()
         {
            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);
            while (is_true(condition_))
            {
               try
               {
                  result = loop_body_->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }
            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_while;
         }

      private:

         expression_ptr condition_;
         expression_ptr loop_body_;
         bool condition_deletable_;
         bool loop_body_deletable_;
      };

      template <typename T>
      class repeat_until_loop_bc_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         repeat_until_loop_bc_node(expression_ptr condition, expression_ptr loop_body)
         : condition_(condition),
           loop_body_(loop_body),
           condition_deletable_(branch_deletable(condition_)),
           loop_body_deletable_(branch_deletable(loop_body_))
         {}

        ~repeat_until_loop_bc_node()
         {
            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);

            do
            {
               try
               {
                  result = loop_body_->value();
               }
               catch(const break_exception<T>& e)
               {
                  return e.value;
               }
               catch(const continue_exception&)
               {}
            }
            while (is_false(condition_));

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_repeat;
         }

      private:

         expression_ptr condition_;
         expression_ptr loop_body_;
         bool condition_deletable_;
         bool loop_body_deletable_;
      };

      template <typename T>
      class for_loop_bc_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         for_loop_bc_node(expression_ptr initialiser,
                       expression_ptr condition,
                       expression_ptr incrementor,
                       expression_ptr loop_body)
         : initialiser_(initialiser),
           condition_  (condition  ),
           incrementor_(incrementor),
           loop_body_  (loop_body  ),
           initialiser_deletable_(branch_deletable(initialiser_)),
           condition_deletable_  (branch_deletable(condition_  )),
           incrementor_deletable_(branch_deletable(incrementor_)),
           loop_body_deletable_  (branch_deletable(loop_body_  ))
         {}

        ~for_loop_bc_node()
         {
            if (initialiser_ && initialiser_deletable_)
            {
               delete initialiser_;
            }

            if (condition_ && condition_deletable_)
            {
               delete condition_;
            }

            if (incrementor_ && incrementor_deletable_)
            {
               delete incrementor_;
            }

            if (loop_body_ && loop_body_deletable_)
            {
               delete loop_body_;
            }
         }

         inline T value() const
         {
            T result = T(0);

            if (initialiser_)
               initialiser_->value();

            if (incrementor_)
            {
               while (is_true(condition_))
               {
                  try
                  {
                     result = loop_body_->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}

                  incrementor_->value();
               }
            }
            else
            {
               while (is_true(condition_))
               {
                  try
                  {
                     result = loop_body_->value();
                  }
                  catch(const break_exception<T>& e)
                  {
                     return e.value;
                  }
                  catch(const continue_exception&)
                  {}
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_for;
         }

      private:

         expression_ptr initialiser_;
         expression_ptr condition_  ;
         expression_ptr incrementor_;
         expression_ptr loop_body_  ;
         bool initialiser_deletable_;
         bool condition_deletable_  ;
         bool incrementor_deletable_;
         bool loop_body_deletable_  ;
      };
      #endif

      template <typename T>
      class switch_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         switch_node(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            if (1 != (arg_list.size() & 1))
               return;

            arg_list_.resize(arg_list.size());
            delete_branch_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i])
               {
                       arg_list_[i] = arg_list[i];
                  delete_branch_[i] = static_cast<unsigned char>(branch_deletable(arg_list_[i]) ? 1 : 0);
               }
               else
               {
                  arg_list_.clear();
                  delete_branch_.clear();
                  return;
               }
            }
         }

        ~switch_node()
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               if (arg_list_[i] && delete_branch_[i])
               {
                  delete arg_list_[i];
                  arg_list_[i] = 0;
               }
            }
         }

         inline T value() const
         {
            if (!arg_list_.empty())
            {
               const std::size_t upper_bound = (arg_list_.size() - 1);

               for (std::size_t i = 0; i < upper_bound; i += 2)
               {
                  expression_ptr condition  = arg_list_[i    ];
                  expression_ptr consequent = arg_list_[i + 1];

                  if (is_true(condition))
                  {
                     return consequent->value();
                  }
               }

               return arg_list_[upper_bound]->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_switch;
         }

      protected:

         std::vector<expression_ptr> arg_list_;
         std::vector<unsigned char> delete_branch_;
      };

      template <typename T, typename Switch_N>
      class switch_n_node : public switch_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         switch_n_node(const Sequence<expression_ptr,Allocator>& arg_list)
         : switch_node<T>(arg_list)
         {}

         inline T value() const
         {
            return Switch_N::process(switch_node<T>::arg_list_);
         }
      };

      template <typename T>
      class multi_switch_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         multi_switch_node(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            if (0 != (arg_list.size() & 1))
               return;

            arg_list_.resize(arg_list.size());
            delete_branch_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i])
               {
                       arg_list_[i] = arg_list[i];
                  delete_branch_[i] = static_cast<unsigned char>(branch_deletable(arg_list_[i]) ? 1 : 0);
               }
               else
               {
                  arg_list_.clear();
                  delete_branch_.clear();
                  return;
               }
            }
         }

        ~multi_switch_node()
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               if (arg_list_[i] && delete_branch_[i])
               {
                  delete arg_list_[i];
                  arg_list_[i] = 0;
               }
            }
         }

         inline T value() const
         {
            T result = T(0);

            if (arg_list_.empty())
            {
               return std::numeric_limits<T>::quiet_NaN();
            }

            const std::size_t upper_bound = (arg_list_.size() - 1);

            for (std::size_t i = 0; i < upper_bound; i += 2)
            {
               expression_ptr condition  = arg_list_[i    ];
               expression_ptr consequent = arg_list_[i + 1];

               if (is_true(condition))
               {
                  result = consequent->value();
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_mswitch;
         }

      private:

         std::vector<expression_ptr> arg_list_;
         std::vector<unsigned char> delete_branch_;
      };

      template <typename T>
      class ivariable
      {
      public:

         virtual T& ref() = 0;
         virtual const T& ref() const = 0;
      };

      template <typename T>
      class variable_node : public expression_node<T>,
                            public ivariable      <T>
      {
      public:

         static T null_value;

         explicit variable_node()
         : value_(&null_value),
           delete_value_(false)
         {}

         variable_node(T& v)
         : value_(&v),
           delete_value_(false)
         {}

        ~variable_node()
         {
            if (delete_value_)
            {
               delete value_;
            }
         }

         inline bool operator <(const variable_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const
         {
            return (*value_);
         }

         inline T& ref()
         {
            return (*value_);
         }

         inline const T& ref() const
         {
            return (*value_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_variable;
         }

         inline bool& delete_value()
         {
            return delete_value_;
         }

      private:

         T* value_;
         bool delete_value_;
      };

      template <typename T>
      T variable_node<T>::null_value = T(std::numeric_limits<T>::quiet_NaN());

      template <typename T>
      struct range_pack
      {
         typedef expression_node<T>*           expression_node_ptr;
         typedef std::pair<std::size_t,std::size_t> cached_range_t;

         range_pack()
         : n0_e (std::make_pair(false,expression_node_ptr(0))),
           n1_e (std::make_pair(false,expression_node_ptr(0))),
           n0_c (std::make_pair(false,0)),
           n1_c (std::make_pair(false,0)),
           cache(std::make_pair(0,0))
         {}

         void clear()
         {
            n0_e  = std::make_pair(false,expression_node_ptr(0));
            n1_e  = std::make_pair(false,expression_node_ptr(0));
            n0_c  = std::make_pair(false,0);
            n1_c  = std::make_pair(false,0);
            cache = std::make_pair(0,0);
         }

         void free()
         {
            if (n0_e.first && n0_e.second)
            {
               n0_e.first = false;

               if (
                    !is_variable_node(n0_e.second) &&
                    !is_string_node  (n0_e.second)
                  )
               {
                  delete n0_e.second;
                  n0_e.second = expression_node_ptr(0);
               }
            }

            if (n1_e.first && n1_e.second)
            {
               n1_e.first = false;

               if (
                    !is_variable_node(n1_e.second) &&
                    !is_string_node  (n1_e.second)
                  )
               {
                  delete n1_e.second;
                  n1_e.second = expression_node_ptr(0);
               }
            }
         }

         bool const_range()
         {
           return ( n0_c.first &&  n1_c.first) &&
                  (!n0_e.first && !n1_e.first);
         }

         bool var_range()
         {
           return ( n0_e.first &&  n1_e.first) &&
                  (!n0_c.first && !n1_c.first);
         }

         bool operator()(std::size_t& r0, std::size_t& r1, const std::size_t& size = std::numeric_limits<std::size_t>::max()) const
         {
            if (n0_c.first)
               r0 = n0_c.second;
            else if (n0_e.first)
            {
               T r0_value = n0_e.second->value();

               if (r0_value < 0)
                  return false;
               else
                  r0 = static_cast<std::size_t>(details::numeric::to_int64(r0_value));
            }
            else
               return false;

            if (n1_c.first)
               r1 = n1_c.second;
            else if (n1_e.first)
            {
               T r1_value = n1_e.second->value();

               if (r1_value < 0)
                  return false;
               else
                  r1 = static_cast<std::size_t>(details::numeric::to_int64(r1_value));
            }
            else
               return false;

            if (
                 (std::numeric_limits<std::size_t>::max() != size) &&
                 (std::numeric_limits<std::size_t>::max() == r1  )
               )
            {
               r1 = size - 1;
            }

            cache.first  = r0;
            cache.second = r1;

            return (r0 <= r1);
         }

         inline std::size_t const_size() const
         {
            return (n1_c.second - n0_c.second + 1);
         }

         inline std::size_t cache_size() const
         {
            return (cache.second - cache.first + 1);
         }

         std::pair<bool,expression_node_ptr> n0_e;
         std::pair<bool,expression_node_ptr> n1_e;
         std::pair<bool,std::size_t        > n0_c;
         std::pair<bool,std::size_t        > n1_c;
         mutable cached_range_t             cache;
      };

      template <typename T>
      class string_base_node;

      template <typename T>
      struct range_data_type
      {
         typedef range_pack<T> range_t;
         typedef string_base_node<T>* strbase_ptr_t;

         range_data_type()
         : range(0),
           data (0),
           size (0),
           type_size(0),
           str_node (0)
         {}

         range_t*      range;
         void*         data;
         std::size_t   size;
         std::size_t   type_size;
         strbase_ptr_t str_node;
      };

      template <typename T> class vector_node;

      template <typename T>
      class vector_interface
      {
      public:

         typedef vector_node<T>* vector_node_ptr;

         virtual ~vector_interface()
         {}

         virtual vector_node_ptr vec() const = 0;

         virtual vector_node_ptr vec() = 0;

         virtual std::size_t size() const = 0;
      };

      template <typename T>
      class vector_node : public expression_node <T>,
                          public vector_interface<T>
      {
      public:

         typedef expression_node<T>*  expression_ptr;
         typedef vector_holder<T>    vector_holder_t;
         typedef vector_node<T>*     vector_node_ptr;

         vector_node(vector_holder_t* vh)
         : vector_holder_(vh)
         {}

         inline T value() const
         {
            return *(ref()[0]);
         }

         inline const vector_holder_t& ref() const
         {
            return (*vector_holder_);
         }

         inline vector_holder_t& ref()
         {
            return (*vector_holder_);
         }

         vector_node_ptr vec() const
         {
            return const_cast<vector_node_ptr>(this);
         }

         vector_node_ptr vec()
         {
            return this;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vector;
         }

         std::size_t size() const
         {
            return ref().size();
         }

      private:

         vector_holder_t* vector_holder_;
      };

      template <typename T>
      class vector_elem_node : public expression_node<T>,
                               public ivariable      <T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_elem_node(expression_ptr index, T* vector_base)
         : index_(index),
           vector_base_(vector_base),
           index_deletable_(branch_deletable(index_))
         {}

        ~vector_elem_node()
         {
            if (index_ && index_deletable_)
            {
               delete index_;
            }
         }

         inline T value() const
         {
           return *(vector_base_ + static_cast<std::size_t>(details::numeric::to_int64(index_->value())));
         }

         inline T& ref()
         {
            return *(vector_base_ + static_cast<std::size_t>(details::numeric::to_int64(index_->value())));
         }

         inline const T& ref() const
         {
            return *(vector_base_ + static_cast<std::size_t>(details::numeric::to_int64(index_->value())));
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecelem;
         }

      private:

         expression_ptr index_;
         T* vector_base_;
         bool index_deletable_;
      };

      template <typename T>
      class vector_assignment_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vector_assignment_node(T* vector_base,
                                const std::size_t& size,
                                const std::vector<expression_ptr>& initialiser_list,
                                const bool single_value_initialse)
         : vector_base_(vector_base),
           initialiser_list_(initialiser_list),
           size_(size),
           single_value_initialse_(single_value_initialse)
         {}

        ~vector_assignment_node()
         {
            for (std::size_t i = 0; i < initialiser_list_.size(); ++i)
            {
               if (branch_deletable(initialiser_list_[i]))
               {
                  delete initialiser_list_[i];
               }
            }
         }

         inline T value() const
         {
            if (single_value_initialse_)
            {
               for (std::size_t i = 0; i < size_; ++i)
               {
                  *(vector_base_ + i) = initialiser_list_[0]->value();
               }
            }
            else
            {
               std::size_t il_size = initialiser_list_.size();

               for (std::size_t i = 0; i < il_size; ++i)
               {
                  *(vector_base_ + i) = initialiser_list_[i]->value();
               }

               if (il_size < size_)
               {
                  for (std::size_t i = il_size; i < size_; ++i)
                  {
                     *(vector_base_ + i) = T(0);
                  }
               }
            }

            return *(vector_base_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecdefass;
         }

      private:

         vector_assignment_node<T>& operator=(const vector_assignment_node<T>&);

         mutable T* vector_base_;
         std::vector<expression_ptr> initialiser_list_;
         const std::size_t size_;
         const bool single_value_initialse_;
      };

      template <typename T>
      class swap_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef variable_node<T>*   variable_node_ptr;

         swap_node(variable_node_ptr var0, variable_node_ptr var1)
         : var0_(var0),
           var1_(var1)
         {}

         inline T value() const
         {
            std::swap(var0_->ref(),var1_->ref());
            return var1_->ref();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_swap;
         }

      private:

         variable_node_ptr var0_;
         variable_node_ptr var1_;
      };

      template <typename T>
      class swap_generic_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef ivariable<T>* ivariable_ptr;

         swap_generic_node(expression_ptr var0, expression_ptr var1)
         : binary_node<T>(details::e_swap,var0,var1),
           var0_(dynamic_cast<ivariable_ptr>(var0)),
           var1_(dynamic_cast<ivariable_ptr>(var1))
         {}

         inline T value() const
         {
            std::swap(var0_->ref(),var1_->ref());
            return var1_->ref();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_swap;
         }

      private:

         ivariable_ptr var0_;
         ivariable_ptr var1_;
      };

      template <typename T>
      class swap_vecvec_node : public binary_node     <T>,
                               public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         swap_vecvec_node(expression_ptr branch0,
                          expression_ptr branch1)
         : binary_node<T>(details::e_swap,branch0,branch1),
           vec0_node_ptr_(0),
           vec1_node_ptr_(0),
           vec_size_     (0),
           initialised_(false)
         {
            if (is_ivector_node(binary_node<T>::branch_[0].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[0].first)))
               {
                  vec0_node_ptr_ = vi->vec();
               }
            }

            if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vec_size_ = std::min(vec0_node_ptr_->ref().size(),
                                    vec1_node_ptr_->ref().size());
               initialised_ = true;
            }
         }

         inline T value() const
         {
            if (initialised_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  std::swap((*vec0[i]),(*vec1[i]));
               }

               return vec1_node_ptr_->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvecswap;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         std::size_t     vec_size_;
         bool            initialised_;
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T>
      class stringvar_node : public expression_node <T>,
                             public string_base_node<T>,
                             public range_interface <T>
      {
      public:

         typedef range_pack<T> range_t;

         static std::string null_value;

         explicit stringvar_node()
         : value_(&null_value)
         {}

         explicit stringvar_node(std::string& v)
         : value_(&v)
         {
            rp_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            rp_.n1_c = std::make_pair<bool,std::size_t>(true,v.size() - 1);
            rp_.cache.first  = rp_.n0_c.second;
            rp_.cache.second = rp_.n1_c.second;
         }

         inline bool operator <(const stringvar_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const
         {
            rp_.n1_c.second  = (*value_).size() - 1;
            rp_.cache.second = rp_.n1_c.second;
            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return ref();
         }

         const char* base() const
         {
           return (*value_).data();
         }

         std::size_t size() const
         {
            return ref().size();
         }

         std::string& ref()
         {
            return (*value_);
         }

         const std::string& ref() const
         {
            return (*value_);
         }

         range_t& range_ref()
         {
            return rp_;
         }

         const range_t& range_ref() const
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_stringvar;
         }

      private:

         std::string* value_;
         mutable range_t rp_;
      };

      template <typename T>
      std::string stringvar_node<T>::null_value = std::string("");

      template <typename T>
      class string_range_node :  public expression_node <T>,
                                 public string_base_node<T>,
                                 public range_interface <T>
      {
      public:

         typedef range_pack<T> range_t;

         static std::string null_value;

         explicit string_range_node(std::string& v, range_t rp)
         : value_(&v),
           rp_(rp)
         {}

        ~string_range_node()
         {
            rp_.free();
         }

         inline bool operator <(const string_range_node<T>& v) const
         {
            return this < (&v);
         }

         inline T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         inline std::string str() const
         {
            return (*value_);
         }

         const char* base() const
         {
           return (*value_).data();
         }

         std::size_t size() const
         {
            return ref().size();
         }

         inline range_t range() const
         {
            return rp_;
         }

         inline virtual std::string& ref()
         {
            return (*value_);
         }

         inline virtual const std::string& ref() const
         {
            return (*value_);
         }

         inline range_t& range_ref()
         {
            return rp_;
         }

         inline const range_t& range_ref() const
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_stringvarrng;
         }

      private:

         std::string* value_;
         range_t      rp_;
      };

      template <typename T>
      std::string string_range_node<T>::null_value = std::string("");

      template <typename T>
      class const_string_range_node : public expression_node <T>,
                                      public string_base_node<T>,
                                      public range_interface <T>
      {
      public:

         typedef range_pack<T> range_t;

         explicit const_string_range_node(const std::string& v, range_t rp)
         : value_(v),
           rp_(rp)
         {}

        ~const_string_range_node()
         {
            rp_.free();
         }

         inline T value() const
         {
            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t range() const
         {
            return rp_;
         }

         range_t& range_ref()
         {
            return rp_;
         }

         const range_t& range_ref() const
         {
            return rp_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_cstringvarrng;
         }

      private:

         const_string_range_node<T>& operator=(const const_string_range_node<T>&);

         const std::string value_;
         range_t rp_;
      };

      template <typename T>
      class generic_string_range_node : public expression_node <T>,
                                        public string_base_node<T>,
                                        public range_interface <T>
      {
      public:

         typedef expression_node <T>*  expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>*    str_base_ptr;
         typedef range_pack      <T>          range_t;
         typedef range_t*                   range_ptr;
         typedef range_interface<T>          irange_t;
         typedef irange_t*                 irange_ptr;

         generic_string_range_node(expression_ptr str_branch, range_t brange)
         : initialised_(false),
           branch_(str_branch),
           branch_deletable_(branch_deletable(branch_)),
           str_base_ptr_ (0),
           str_range_ptr_(0),
           base_range_(brange)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);
            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(branch_))
            {
               str_base_ptr_ = dynamic_cast<str_base_ptr>(branch_);

               if (0 == str_base_ptr_)
                  return;

               str_range_ptr_ = dynamic_cast<irange_ptr>(branch_);

               if (0 == str_range_ptr_)
                  return;
            }

            initialised_ = (str_base_ptr_ && str_range_ptr_);
         }

        ~generic_string_range_node()
         {
            base_range_.free();

            if (branch_ && branch_deletable_)
            {
               delete branch_;
               branch_ = 0;
            }
         }

         inline T value() const
         {
            if (initialised_)
            {
               branch_->value();

               std::size_t str_r0 = 0;
               std::size_t str_r1 = 0;

               std::size_t r0 = 0;
               std::size_t r1 = 0;

               range_t& range = str_range_ptr_->range_ref();

               const std::size_t base_str_size = str_base_ptr_->size();

               if (
                    range      (str_r0,str_r1,base_str_size) &&
                    base_range_(    r0,    r1,base_str_size)
                  )
               {
                  const std::size_t size = (r1 - r0) + 1;

                  range_.n1_c.second  = size - 1;
                  range_.cache.second = range_.n1_c.second;

                  value_.assign(str_base_ptr_->base() + str_r0 + r0, size);
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strgenrange;
         }

      private:

         bool               initialised_;
         expression_ptr          branch_;
         bool          branch_deletable_;
         str_base_ptr      str_base_ptr_;
         irange_ptr       str_range_ptr_;
         mutable range_t     base_range_;
         mutable range_t          range_;
         mutable std::string      value_;
      };

      template <typename T>
      class string_concat_node : public binary_node     <T>,
                                 public string_base_node<T>,
                                 public range_interface <T>
      {
      public:

         typedef expression_node <T>*  expression_ptr;
         typedef string_base_node<T>*    str_base_ptr;
         typedef range_pack      <T>          range_t;
         typedef range_t*                   range_ptr;
         typedef range_interface<T>          irange_t;
         typedef irange_t*                 irange_ptr;

         string_concat_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           initialised_(false),
           str0_base_ptr_ (0),
           str1_base_ptr_ (0),
           str0_range_ptr_(0),
           str1_range_ptr_(0)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(binary_node<T>::branch_[0].first))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[0].first);

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(binary_node<T>::branch_[0].first);

               if (0 == str0_range_ptr_)
                  return;
            }

            if (is_generally_string_node(binary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               str1_range_ptr_ = dynamic_cast<irange_ptr>(binary_node<T>::branch_[1].first);

               if (0 == str1_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;
         }

         inline T value() const
         {
            if (initialised_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               std::size_t str0_r0 = 0;
               std::size_t str0_r1 = 0;

               std::size_t str1_r0 = 0;
               std::size_t str1_r1 = 0;

               range_t& range0 = str0_range_ptr_->range_ref();
               range_t& range1 = str1_range_ptr_->range_ref();

               if (
                    range0(str0_r0,str0_r1,str0_base_ptr_->size()) &&
                    range1(str1_r0,str1_r1,str1_base_ptr_->size())
                  )
               {
                  const std::size_t size0 = (str0_r1 - str0_r0) + 1;
                  const std::size_t size1 = (str1_r1 - str1_r0) + 1;

                  value_.assign(str0_base_ptr_->base() + str0_r0, size0);
                  value_.append(str1_base_ptr_->base() + str1_r0, size1);

                  range_.n1_c.second  = value_.size() - 1;
                  range_.cache.second = range_.n1_c.second;
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strconcat;
         }

      private:

         bool initialised_;
         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         irange_ptr   str0_range_ptr_;
         irange_ptr   str1_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;
      };

      template <typename T>
      class swap_string_node : public binary_node     <T>,
                               public string_base_node<T>,
                               public range_interface <T>
      {
      public:

         typedef expression_node <T>*  expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>*    str_base_ptr;
         typedef range_pack      <T>          range_t;
         typedef range_t*                   range_ptr;
         typedef range_interface<T>          irange_t;
         typedef irange_t*                 irange_ptr;

         swap_string_node(expression_ptr branch0, expression_ptr branch1)
         : binary_node<T>(details::e_swap,branch0,branch1),
           initialised_(false),
           str0_node_ptr_(0),
           str1_node_ptr_(0)
         {
            if (is_string_node(binary_node<T>::branch_[0].first))
            {
               str0_node_ptr_ = static_cast<strvar_node_ptr>(binary_node<T>::branch_[0].first);
            }

            if (is_string_node(binary_node<T>::branch_[1].first))
            {
               str1_node_ptr_ = static_cast<strvar_node_ptr>(binary_node<T>::branch_[1].first);
            }

            initialised_ = (str0_node_ptr_ && str1_node_ptr_);
         }

         inline T value() const
         {
            if (initialised_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               std::swap(str0_node_ptr_->ref(),str1_node_ptr_->ref());
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return str0_node_ptr_->str();
         }

         const char* base() const
         {
           return str0_node_ptr_->base();
         }

         std::size_t size() const
         {
            return str0_node_ptr_->size();
         }

         range_t& range_ref()
         {
            return str0_node_ptr_->range_ref();
         }

         const range_t& range_ref() const
         {
            return str0_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strswap;
         }

      private:

         bool initialised_;
         strvar_node_ptr str0_node_ptr_;
         strvar_node_ptr str1_node_ptr_;
      };

      template <typename T>
      class stringvar_size_node : public expression_node<T>
      {
      public:

         static std::string null_value;

         explicit stringvar_size_node()
         : value_(&null_value)
         {}

         explicit stringvar_size_node(std::string& v)
         : value_(&v)
         {}

         inline T value() const
         {
            return T((*value_).size());
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_stringvarsize;
         }

      private:

         std::string* value_;
      };

      template <typename T>
      std::string stringvar_size_node<T>::null_value = std::string("");

      template <typename T>
      class string_size_node : public expression_node<T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>*   str_base_ptr;

         string_size_node(expression_ptr brnch)
         : branch_(brnch),
           branch_deletable_(branch_deletable(branch_)),
           str_base_ptr_(0)
         {
            if (is_generally_string_node(branch_))
            {
               str_base_ptr_ = dynamic_cast<str_base_ptr>(branch_);

               if (0 == str_base_ptr_)
                  return;
            }
         }

        ~string_size_node()
         {
            if (branch_ && branch_deletable_)
            {
               delete branch_;
               branch_ = 0;
            }
         }

         inline T value() const
         {
            T result = std::numeric_limits<T>::quiet_NaN();

            if (str_base_ptr_)
            {
               branch_->value();
               result = T(str_base_ptr_->size());
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_stringsize;
         }

      private:

         expression_ptr branch_;
         bool branch_deletable_;
         str_base_ptr str_base_ptr_;
      };

      struct asn_assignment
      {
         static inline void execute(std::string& s, const char* data, const std::size_t size)
         { s.assign(data,size); }
      };

      struct asn_addassignment
      {
         static inline void execute(std::string& s, const char* data, const std::size_t size)
         { s.append(data,size); }
      };

      template <typename T, typename AssignmentProcess = asn_assignment>
      class assignment_string_node : public binary_node     <T>,
                                     public string_base_node<T>,
                                     public range_interface <T>
      {
      public:

         typedef expression_node <T>*  expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>*    str_base_ptr;
         typedef range_pack      <T>          range_t;
         typedef range_t*                   range_ptr;
         typedef range_interface<T>          irange_t;
         typedef irange_t*                 irange_ptr;

         assignment_string_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           initialised_(false),
           str0_base_ptr_ (0),
           str1_base_ptr_ (0),
           str0_node_ptr_ (0),
           str1_range_ptr_(0)
         {
            if (is_string_node(binary_node<T>::branch_[0].first))
            {
               str0_node_ptr_ = static_cast<strvar_node_ptr>(binary_node<T>::branch_[0].first);

               str0_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[0].first);
            }

            if (is_generally_string_node(binary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range_ptr = dynamic_cast<irange_ptr>(binary_node<T>::branch_[1].first);

               if (0 == range_ptr)
                  return;

               str1_range_ptr_ = &(range_ptr->range_ref());
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_node_ptr_  &&
                           str1_range_ptr_ ;
         }

         inline T value() const
         {
            if (initialised_)
            {
               binary_node<T>::branch_[1].first->value();

               std::size_t r0 = 0;
               std::size_t r1 = 0;

               range_t& range = (*str1_range_ptr_);

               if (range(r0,r1,str1_base_ptr_->size()))
               {
                  AssignmentProcess::execute(str0_node_ptr_->ref(),
                                             str1_base_ptr_->base() + r0,
                                             (r1 - r0) + 1);

                  binary_node<T>::branch_[0].first->value();
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return str0_node_ptr_->str();
         }

         const char* base() const
         {
           return str0_node_ptr_->base();
         }

         std::size_t size() const
         {
            return str0_node_ptr_->size();
         }

         range_t& range_ref()
         {
            return str0_node_ptr_->range_ref();
         }

         const range_t& range_ref() const
         {
            return str0_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strass;
         }

      private:

         bool            initialised_;
         str_base_ptr    str0_base_ptr_;
         str_base_ptr    str1_base_ptr_;
         strvar_node_ptr str0_node_ptr_;
         range_ptr       str1_range_ptr_;
      };

      template <typename T, typename AssignmentProcess = asn_assignment>
      class assignment_string_range_node : public binary_node     <T>,
                                           public string_base_node<T>,
                                           public range_interface <T>
      {
      public:

         typedef expression_node <T>*  expression_ptr;
         typedef stringvar_node  <T>* strvar_node_ptr;
         typedef string_base_node<T>*    str_base_ptr;
         typedef range_pack      <T>          range_t;
         typedef range_t*                   range_ptr;
         typedef range_interface<T>          irange_t;
         typedef irange_t*                 irange_ptr;

         assignment_string_range_node(const operator_type& opr,
                                      expression_ptr branch0,
                                      expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           initialised_(false),
           str0_base_ptr_ (0),
           str1_base_ptr_ (0),
           str0_node_ptr_ (0),
           str0_range_ptr_(0),
           str1_range_ptr_(0)
         {
            if (is_string_range_node(binary_node<T>::branch_[0].first))
            {
               str0_node_ptr_ = static_cast<strvar_node_ptr>(binary_node<T>::branch_[0].first);

               str0_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[0].first);

               irange_ptr range_ptr = dynamic_cast<irange_ptr>(binary_node<T>::branch_[0].first);

               if (0 == range_ptr)
                  return;

               str0_range_ptr_ = &(range_ptr->range_ref());
            }

            if (is_generally_string_node(binary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range_ptr = dynamic_cast<irange_ptr>(binary_node<T>::branch_[1].first);

               if (0 == range_ptr)
                  return;

               str1_range_ptr_ = &(range_ptr->range_ref());
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_node_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;
         }

         inline T value() const
         {
            if (initialised_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               std::size_t s0_r0 = 0;
               std::size_t s0_r1 = 0;

               std::size_t s1_r0 = 0;
               std::size_t s1_r1 = 0;

               range_t& range0 = (*str0_range_ptr_);
               range_t& range1 = (*str1_range_ptr_);

               if (
                    range0(s0_r0,s0_r1,str0_base_ptr_->size()) &&
                    range1(s1_r0,s1_r1,str1_base_ptr_->size())
                  )
               {
                  std::size_t size = std::min((s0_r1 - s0_r0),(s1_r1 - s1_r0)) + 1;

                  std::copy(str1_base_ptr_->base() + s1_r0,
                            str1_base_ptr_->base() + s1_r0 + size,
                            const_cast<char*>(base() + s0_r0));
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return str0_node_ptr_->str();
         }

         const char* base() const
         {
           return str0_node_ptr_->base();
         }

         std::size_t size() const
         {
            return str0_node_ptr_->size();
         }

         range_t& range_ref()
         {
            return str0_node_ptr_->range_ref();
         }

         const range_t& range_ref() const
         {
            return str0_node_ptr_->range_ref();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strass;
         }

      private:

         bool            initialised_;
         str_base_ptr    str0_base_ptr_;
         str_base_ptr    str1_base_ptr_;
         strvar_node_ptr str0_node_ptr_;
         range_ptr       str0_range_ptr_;
         range_ptr       str1_range_ptr_;
      };

      template <typename T>
      class conditional_string_node : public trinary_node    <T>,
                                      public string_base_node<T>,
                                      public range_interface <T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>*   str_base_ptr;
         typedef range_pack      <T>         range_t;
         typedef range_t*                  range_ptr;
         typedef range_interface<T>         irange_t;
         typedef irange_t*                irange_ptr;

         conditional_string_node(expression_ptr test,
                                 expression_ptr consequent,
                                 expression_ptr alternative)
         : trinary_node<T>(details::e_default,consequent,alternative,test),
           initialised_(false),
           str0_base_ptr_ (0),
           str1_base_ptr_ (0),
           str0_range_ptr_(0),
           str1_range_ptr_(0),
           test_              (test),
           consequent_  (consequent),
           alternative_(alternative)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(trinary_node<T>::branch_[0].first))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(trinary_node<T>::branch_[0].first);

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(trinary_node<T>::branch_[0].first);

               if (0 == str0_range_ptr_)
                  return;
            }

            if (is_generally_string_node(trinary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(trinary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               str1_range_ptr_ = dynamic_cast<irange_ptr>(trinary_node<T>::branch_[1].first);

               if (0 == str1_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_  &&
                           str1_base_ptr_  &&
                           str0_range_ptr_ &&
                           str1_range_ptr_ ;

         }

         inline T value() const
         {
            if (initialised_)
            {
               std::size_t r0 = 0;
               std::size_t r1 = 0;

               if (is_true(test_))
               {
                  consequent_->value();

                  range_t& range = str0_range_ptr_->range_ref();

                  if (range(r0,r1,str0_base_ptr_->size()))
                  {
                     const std::size_t size = (r1 - r0) + 1;

                     value_.assign(str0_base_ptr_->base() + r0, size);

                     range_.n1_c.second  = value_.size() - 1;
                     range_.cache.second = range_.n1_c.second;

                     return T(1);
                  }
               }
               else
               {
                  alternative_->value();

                  range_t& range = str1_range_ptr_->range_ref();

                  if (range(r0,r1,str1_base_ptr_->size()))
                  {
                     const std::size_t size = (r1 - r0) + 1;

                     value_.assign(str1_base_ptr_->base() + r0, size);

                     range_.n1_c.second  = value_.size() - 1;
                     range_.cache.second = range_.n1_c.second;

                     return T(0);
                  }
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strcondition;
         }

      private:

         bool initialised_;
         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         irange_ptr   str0_range_ptr_;
         irange_ptr   str1_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;

         expression_ptr test_;
         expression_ptr consequent_;
         expression_ptr alternative_;
      };

      template <typename T>
      class cons_conditional_str_node : public binary_node     <T>,
                                        public string_base_node<T>,
                                        public range_interface <T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>*   str_base_ptr;
         typedef range_pack      <T>         range_t;
         typedef range_t*                  range_ptr;
         typedef range_interface<T>         irange_t;
         typedef irange_t*                irange_ptr;

         cons_conditional_str_node(expression_ptr test,
                                   expression_ptr consequent)
         : binary_node<T>(details::e_default,consequent,test),
           initialised_(false),
           str0_base_ptr_ (0),
           str0_range_ptr_(0),
           test_      (test),
           consequent_(consequent)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);

            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;

            if (is_generally_string_node(binary_node<T>::branch_[0].first))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[0].first);

               if (0 == str0_base_ptr_)
                  return;

               str0_range_ptr_ = dynamic_cast<irange_ptr>(binary_node<T>::branch_[0].first);

               if (0 == str0_range_ptr_)
                  return;
            }

            initialised_ = str0_base_ptr_ && str0_range_ptr_ ;
         }

         inline T value() const
         {
            if (initialised_)
            {
               std::size_t r0 = 0;
               std::size_t r1 = 0;

               if (is_true(test_))
               {
                  consequent_->value();

                  range_t& range = str0_range_ptr_->range_ref();

                  if (range(r0,r1,str0_base_ptr_->size()))
                  {
                     const std::size_t size = (r1 - r0) + 1;

                     value_.assign(str0_base_ptr_->base() + r0, size);

                     range_.n1_c.second  = value_.size() - 1;
                     range_.cache.second = range_.n1_c.second;

                     return T(1);
                  }
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         std::string str() const
         {
            return value_;
         }

         const char* base() const
         {
           return value_.data();
         }

         std::size_t size() const
         {
            return value_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strccondition;
         }

      private:

         bool initialised_;
         str_base_ptr str0_base_ptr_;
         irange_ptr   str0_range_ptr_;
         mutable range_t     range_;
         mutable std::string value_;

         expression_ptr test_;
         expression_ptr consequent_;
      };
      #endif

      template <typename T, std::size_t N>
      inline T axn(T a, T x)
      {
         // a*x^n
         return a * exprtk::details::numeric::fast_exp<T,N>::result(x);
      }

      template <typename T, std::size_t N>
      inline T axnb(T a, T x, T b)
      {
         // a*x^n+b
         return a * exprtk::details::numeric::fast_exp<T,N>::result(x) + b;
      }

      template <typename T>
      struct sf_base
      {
         typedef typename details::functor_t<T>::Type Type;
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t quaternary_functor_t;
         typedef typename functor_t::tfunc_t    trinary_functor_t;
         typedef typename functor_t::bfunc_t     binary_functor_t;
         typedef typename functor_t::ufunc_t      unary_functor_t;
      };

      #define define_sfop3(NN,OP0,OP1)                   \
      template <typename T>                              \
      struct sf##NN##_op : public sf_base<T>             \
      {                                                  \
         typedef typename sf_base<T>::Type Type;         \
         static inline T process(Type x, Type y, Type z) \
         {                                               \
            return (OP0);                                \
         }                                               \
         static inline std::string id()                  \
         {                                               \
            return OP1;                                  \
         }                                               \
      };                                                 \

      define_sfop3(00,(x + y) / z       ,"(t+t)/t")
      define_sfop3(01,(x + y) * z       ,"(t+t)*t")
      define_sfop3(02,(x + y) - z       ,"(t+t)-t")
      define_sfop3(03,(x + y) + z       ,"(t+t)+t")
      define_sfop3(04,(x - y) + z       ,"(t-t)+t")
      define_sfop3(05,(x - y) / z       ,"(t-t)/t")
      define_sfop3(06,(x - y) * z       ,"(t-t)*t")
      define_sfop3(07,(x * y) + z       ,"(t*t)+t")
      define_sfop3(08,(x * y) - z       ,"(t*t)-t")
      define_sfop3(09,(x * y) / z       ,"(t*t)/t")
      define_sfop3(10,(x * y) * z       ,"(t*t)*t")
      define_sfop3(11,(x / y) + z       ,"(t/t)+t")
      define_sfop3(12,(x / y) - z       ,"(t/t)-t")
      define_sfop3(13,(x / y) / z       ,"(t/t)/t")
      define_sfop3(14,(x / y) * z       ,"(t/t)*t")
      define_sfop3(15,x / (y + z)       ,"t/(t+t)")
      define_sfop3(16,x / (y - z)       ,"t/(t-t)")
      define_sfop3(17,x / (y * z)       ,"t/(t*t)")
      define_sfop3(18,x / (y / z)       ,"t/(t/t)")
      define_sfop3(19,x * (y + z)       ,"t*(t+t)")
      define_sfop3(20,x * (y - z)       ,"t*(t-t)")
      define_sfop3(21,x * (y * z)       ,"t*(t*t)")
      define_sfop3(22,x * (y / z)       ,"t*(t/t)")
      define_sfop3(23,x - (y + z)       ,"t-(t+t)")
      define_sfop3(24,x - (y - z)       ,"t-(t-t)")
      define_sfop3(25,x - (y / z)       ,"t-(t/t)")
      define_sfop3(26,x - (y * z)       ,"t-(t*t)")
      define_sfop3(27,x + (y * z)       ,"t+(t*t)")
      define_sfop3(28,x + (y / z)       ,"t+(t/t)")
      define_sfop3(29,x + (y + z)       ,"t+(t+t)")
      define_sfop3(30,x + (y - z)       ,"t+(t-t)")
      define_sfop3(31,(axnb<T,2>(x,y,z)),"       ")
      define_sfop3(32,(axnb<T,3>(x,y,z)),"       ")
      define_sfop3(33,(axnb<T,4>(x,y,z)),"       ")
      define_sfop3(34,(axnb<T,5>(x,y,z)),"       ")
      define_sfop3(35,(axnb<T,6>(x,y,z)),"       ")
      define_sfop3(36,(axnb<T,7>(x,y,z)),"       ")
      define_sfop3(37,(axnb<T,8>(x,y,z)),"       ")
      define_sfop3(38,(axnb<T,9>(x,y,z)),"       ")
      define_sfop3(39,x * numeric::log(y)   + z,"")
      define_sfop3(40,x * numeric::log(y)   - z,"")
      define_sfop3(41,x * numeric::log10(y) + z,"")
      define_sfop3(42,x * numeric::log10(y) - z,"")
      define_sfop3(43,x * numeric::sin(y) + z  ,"")
      define_sfop3(44,x * numeric::sin(y) - z  ,"")
      define_sfop3(45,x * numeric::cos(y) + z  ,"")
      define_sfop3(46,x * numeric::cos(y) - z  ,"")
      define_sfop3(47,details::is_true(x) ? y : z,"")

      #define define_sfop4(NN,OP0,OP1)                           \
      template <typename T>                                      \
      struct sf##NN##_op : public sf_base<T>                     \
      {                                                          \
         typedef typename sf_base<T>::Type Type;                 \
         static inline T process(Type x, Type y, Type z, Type w) \
         {                                                       \
            return (OP0);                                        \
         }                                                       \
         static inline std::string id() { return OP1; }          \
      };                                                         \

      define_sfop4(48,(x + ((y + z) / w)),"t+((t+t)/t)")
      define_sfop4(49,(x + ((y + z) * w)),"t+((t+t)*t)")
      define_sfop4(50,(x + ((y - z) / w)),"t+((t-t)/t)")
      define_sfop4(51,(x + ((y - z) * w)),"t+((t-t)*t)")
      define_sfop4(52,(x + ((y * z) / w)),"t+((t*t)/t)")
      define_sfop4(53,(x + ((y * z) * w)),"t+((t*t)*t)")
      define_sfop4(54,(x + ((y / z) + w)),"t+((t/t)+t)")
      define_sfop4(55,(x + ((y / z) / w)),"t+((t/t)/t)")
      define_sfop4(56,(x + ((y / z) * w)),"t+((t/t)*t)")
      define_sfop4(57,(x - ((y + z) / w)),"t-((t+t)/t)")
      define_sfop4(58,(x - ((y + z) * w)),"t-((t+t)*t)")
      define_sfop4(59,(x - ((y - z) / w)),"t-((t-t)/t)")
      define_sfop4(60,(x - ((y - z) * w)),"t-((t-t)*t)")
      define_sfop4(61,(x - ((y * z) / w)),"t-((t*t)/t)")
      define_sfop4(62,(x - ((y * z) * w)),"t-((t*t)*t)")
      define_sfop4(63,(x - ((y / z) / w)),"t-((t/t)/t)")
      define_sfop4(64,(x - ((y / z) * w)),"t-((t/t)*t)")
      define_sfop4(65,(((x + y) * z) - w),"((t+t)*t)-t")
      define_sfop4(66,(((x - y) * z) - w),"((t-t)*t)-t")
      define_sfop4(67,(((x * y) * z) - w),"((t*t)*t)-t")
      define_sfop4(68,(((x / y) * z) - w),"((t/t)*t)-t")
      define_sfop4(69,(((x + y) / z) - w),"((t+t)/t)-t")
      define_sfop4(70,(((x - y) / z) - w),"((t-t)/t)-t")
      define_sfop4(71,(((x * y) / z) - w),"((t*t)/t)-t")
      define_sfop4(72,(((x / y) / z) - w),"((t/t)/t)-t")
      define_sfop4(73,((x * y) + (z * w)),"(t*t)+(t*t)")
      define_sfop4(74,((x * y) - (z * w)),"(t*t)-(t*t)")
      define_sfop4(75,((x * y) + (z / w)),"(t*t)+(t/t)")
      define_sfop4(76,((x * y) - (z / w)),"(t*t)-(t/t)")
      define_sfop4(77,((x / y) + (z / w)),"(t/t)+(t/t)")
      define_sfop4(78,((x / y) - (z / w)),"(t/t)-(t/t)")
      define_sfop4(79,((x / y) - (z * w)),"(t/t)-(t*t)")
      define_sfop4(80,(x / (y + (z * w))),"t/(t+(t*t))")
      define_sfop4(81,(x / (y - (z * w))),"t/(t-(t*t))")
      define_sfop4(82,(x * (y + (z * w))),"t*(t+(t*t))")
      define_sfop4(83,(x * (y - (z * w))),"t*(t-(t*t))")

      define_sfop4(84,(axn<T,2>(x,y) + axn<T,2>(z,w)),"")
      define_sfop4(85,(axn<T,3>(x,y) + axn<T,3>(z,w)),"")
      define_sfop4(86,(axn<T,4>(x,y) + axn<T,4>(z,w)),"")
      define_sfop4(87,(axn<T,5>(x,y) + axn<T,5>(z,w)),"")
      define_sfop4(88,(axn<T,6>(x,y) + axn<T,6>(z,w)),"")
      define_sfop4(89,(axn<T,7>(x,y) + axn<T,7>(z,w)),"")
      define_sfop4(90,(axn<T,8>(x,y) + axn<T,8>(z,w)),"")
      define_sfop4(91,(axn<T,9>(x,y) + axn<T,9>(z,w)),"")
      define_sfop4(92,((details::is_true(x) && details::is_true(y)) ? z : w),"")
      define_sfop4(93,((details::is_true(x) || details::is_true(y)) ? z : w),"")
      define_sfop4(94,((x <  y) ? z : w),"")
      define_sfop4(95,((x <= y) ? z : w),"")
      define_sfop4(96,((x >  y) ? z : w),"")
      define_sfop4(97,((x >= y) ? z : w),"")
      define_sfop4(98,(details::is_true(numeric::equal(x,y)) ? z : w),"")
      define_sfop4(99,(x * numeric::sin(y) + z * numeric::cos(w)),"")

      define_sfop4(ext00,((x + y) - (z * w)),"(t+t)-(t*t)")
      define_sfop4(ext01,((x + y) - (z / w)),"(t+t)-(t/t)")
      define_sfop4(ext02,((x + y) + (z * w)),"(t+t)+(t*t)")
      define_sfop4(ext03,((x + y) + (z / w)),"(t+t)+(t/t)")
      define_sfop4(ext04,((x - y) + (z * w)),"(t-t)+(t*t)")
      define_sfop4(ext05,((x - y) + (z / w)),"(t-t)+(t/t)")
      define_sfop4(ext06,((x - y) - (z * w)),"(t-t)-(t*t)")
      define_sfop4(ext07,((x - y) - (z / w)),"(t-t)-(t/t)")
      define_sfop4(ext08,((x + y) - (z - w)),"(t+t)-(t-t)")
      define_sfop4(ext09,((x + y) + (z - w)),"(t+t)+(t-t)")
      define_sfop4(ext10,((x + y) * (z - w)),"(t+t)*(t-t)")
      define_sfop4(ext11,((x + y) / (z - w)),"(t+t)/(t-t)")
      define_sfop4(ext12,((x - y) - (z + w)),"(t-t)-(t+t)")
      define_sfop4(ext13,((x - y) + (z + w)),"(t-t)+(t+t)")
      define_sfop4(ext14,((x - y) * (z + w)),"(t-t)*(t+t)")
      define_sfop4(ext15,((x - y) / (z + w)),"(t-t)/(t+t)")
      define_sfop4(ext16,((x * y) - (z + w)),"(t*t)-(t+t)")
      define_sfop4(ext17,((x / y) - (z + w)),"(t/t)-(t+t)")
      define_sfop4(ext18,((x * y) + (z + w)),"(t*t)+(t+t)")
      define_sfop4(ext19,((x / y) + (z + w)),"(t/t)+(t+t)")
      define_sfop4(ext20,((x * y) + (z - w)),"(t*t)+(t-t)")
      define_sfop4(ext21,((x / y) + (z - w)),"(t/t)+(t-t)")
      define_sfop4(ext22,((x * y) - (z - w)),"(t*t)-(t-t)")
      define_sfop4(ext23,((x / y) - (z - w)),"(t/t)-(t-t)")
      define_sfop4(ext24,((x + y) * (z * w)),"(t+t)*(t*t)")
      define_sfop4(ext25,((x + y) * (z / w)),"(t+t)*(t/t)")
      define_sfop4(ext26,((x + y) / (z * w)),"(t+t)/(t*t)")
      define_sfop4(ext27,((x + y) / (z / w)),"(t+t)/(t/t)")
      define_sfop4(ext28,((x - y) / (z * w)),"(t-t)/(t*t)")
      define_sfop4(ext29,((x - y) / (z / w)),"(t-t)/(t/t)")
      define_sfop4(ext30,((x - y) * (z * w)),"(t-t)*(t*t)")
      define_sfop4(ext31,((x - y) * (z / w)),"(t-t)*(t/t)")
      define_sfop4(ext32,((x * y) * (z + w)),"(t*t)*(t+t)")
      define_sfop4(ext33,((x / y) * (z + w)),"(t/t)*(t+t)")
      define_sfop4(ext34,((x * y) / (z + w)),"(t*t)/(t+t)")
      define_sfop4(ext35,((x / y) / (z + w)),"(t/t)/(t+t)")
      define_sfop4(ext36,((x * y) / (z - w)),"(t*t)/(t-t)")
      define_sfop4(ext37,((x / y) / (z - w)),"(t/t)/(t-t)")
      define_sfop4(ext38,((x * y) * (z - w)),"(t*t)*(t-t)")
      define_sfop4(ext39,((x * y) / (z * w)),"(t*t)/(t*t)")
      define_sfop4(ext40,((x / y) * (z / w)),"(t/t)*(t/t)")
      define_sfop4(ext41,((x / y) * (z - w)),"(t/t)*(t-t)")
      define_sfop4(ext42,((x * y) * (z * w)),"(t*t)*(t*t)")
      define_sfop4(ext43,(x + (y * (z / w))),"t+(t*(t/t))")
      define_sfop4(ext44,(x - (y * (z / w))),"t-(t*(t/t))")
      define_sfop4(ext45,(x + (y / (z * w))),"t+(t/(t*t))")
      define_sfop4(ext46,(x - (y / (z * w))),"t-(t/(t*t))")
      define_sfop4(ext47,(((x - y) - z) * w),"((t-t)-t)*t")
      define_sfop4(ext48,(((x - y) - z) / w),"((t-t)-t)/t")
      define_sfop4(ext49,(((x - y) + z) * w),"((t-t)+t)*t")
      define_sfop4(ext50,(((x - y) + z) / w),"((t-t)+t)/t")
      define_sfop4(ext51,((x + (y - z)) * w),"(t+(t-t))*t")
      define_sfop4(ext52,((x + (y - z)) / w),"(t+(t-t))/t")
      define_sfop4(ext53,((x + y) / (z + w)),"(t+t)/(t+t)")
      define_sfop4(ext54,((x - y) / (z - w)),"(t-t)/(t-t)")
      define_sfop4(ext55,((x + y) * (z + w)),"(t+t)*(t+t)")
      define_sfop4(ext56,((x - y) * (z - w)),"(t-t)*(t-t)")
      define_sfop4(ext57,((x - y) + (z - w)),"(t-t)+(t-t)")
      define_sfop4(ext58,((x - y) - (z - w)),"(t-t)-(t-t)")
      define_sfop4(ext59,((x / y) + (z * w)),"(t/t)+(t*t)")

      #undef define_sfop3
      #undef define_sfop4

      template <typename T, typename SpecialFunction>
      class sf3_node : public trinary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf3_node(const operator_type& opr,
                  expression_ptr branch0,
                  expression_ptr branch1,
                  expression_ptr branch2)
         : trinary_node<T>(opr,branch0,branch1,branch2)
         {}

         inline T value() const
         {
            const T x = trinary_node<T>::branch_[0].first->value();
            const T y = trinary_node<T>::branch_[1].first->value();
            const T z = trinary_node<T>::branch_[2].first->value();

            return SpecialFunction::process(x,y,z);
         }
      };

      template <typename T, typename SpecialFunction>
      class sf4_node : public quaternary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf4_node(const operator_type& opr,
                  expression_ptr branch0,
                  expression_ptr branch1,
                  expression_ptr branch2,
                  expression_ptr branch3)
         : quaternary_node<T>(opr,branch0,branch1,branch2,branch3)
         {}

         inline T value() const
         {
            const T x = quaternary_node<T>::branch_[0].first->value();
            const T y = quaternary_node<T>::branch_[1].first->value();
            const T z = quaternary_node<T>::branch_[2].first->value();
            const T w = quaternary_node<T>::branch_[3].first->value();

            return SpecialFunction::process(x,y,z,w);
         }
      };

      template <typename T, typename SpecialFunction>
      class sf3_var_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf3_var_node(const T& v0, const T& v1, const T& v2)
         : v0_(v0),
           v1_(v1),
           v2_(v2)
         {}

         inline T value() const
         {
            return SpecialFunction::process(v0_,v1_,v2_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_trinary;
         }

      private:

         sf3_var_node(sf3_var_node<T,SpecialFunction>&);
         sf3_var_node<T,SpecialFunction>& operator=(sf3_var_node<T,SpecialFunction>&);

         const T& v0_;
         const T& v1_;
         const T& v2_;
      };

      template <typename T, typename SpecialFunction>
      class sf4_var_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         sf4_var_node(const T& v0, const T& v1, const T& v2, const T& v3)
         : v0_(v0),
           v1_(v1),
           v2_(v2),
           v3_(v3)
         {}

         inline T value() const
         {
            return SpecialFunction::process(v0_,v1_,v2_,v3_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_trinary;
         }

      private:

         sf4_var_node(sf4_var_node<T,SpecialFunction>&);
         sf4_var_node<T,SpecialFunction>& operator=(sf4_var_node<T,SpecialFunction>&);

         const T& v0_;
         const T& v1_;
         const T& v2_;
         const T& v3_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         vararg_node(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            arg_list_.resize(arg_list.size());
            delete_branch_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i])
               {
                       arg_list_[i] = arg_list[i];
                  delete_branch_[i] = static_cast<unsigned char>(branch_deletable(arg_list_[i]) ? 1 : 0);
               }
               else
               {
                  arg_list_.clear();
                  delete_branch_.clear();
                  return;
               }
            }
         }

        ~vararg_node()
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               if (arg_list_[i] && delete_branch_[i])
               {
                  delete arg_list_[i];
                  arg_list_[i] = 0;
               }
            }
         }

         inline T value() const
         {
            if (!arg_list_.empty())
               return VarArgFunction::process(arg_list_);
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vararg;
         }

      private:

         std::vector<expression_ptr> arg_list_;
         std::vector<unsigned char> delete_branch_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_varnode : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         template <typename Allocator,
                   template <typename,typename> class Sequence>
         vararg_varnode(const Sequence<expression_ptr,Allocator>& arg_list)
         {
            arg_list_.resize(arg_list.size());

            for (std::size_t i = 0; i < arg_list.size(); ++i)
            {
               if (arg_list[i] && is_variable_node(arg_list[i]))
               {
                  variable_node<T>* var_node_ptr = static_cast<variable_node<T>*>(arg_list[i]);
                  arg_list_[i] = (&var_node_ptr->ref());
               }
               else
               {
                  arg_list_.clear();
                  return;
               }
            }
         }

         inline T value() const
         {
            if (!arg_list_.empty())
               return VarArgFunction::process(arg_list_);
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vararg;
         }

      private:

         std::vector<const T*> arg_list_;
      };

      template <typename T, typename VecFunction>
      class vectorize_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vectorize_node(const expression_ptr v)
         : ivec_ptr_(0),
           v_(v),
           v_deletable_(branch_deletable(v_))
         {
            if (is_ivector_node(v))
            {
               ivec_ptr_ = dynamic_cast<vector_interface<T>*>(v);
            }
            else
               ivec_ptr_ = 0;
         }

        ~vectorize_node()
         {
            if (v_ && v_deletable_)
            {
               delete v_;
            }
         }

         inline T value() const
         {
            if (ivec_ptr_)
            {
               v_->value();
               return VecFunction::process(ivec_ptr_);
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecfunc;
         }

      private:

         vector_interface<T>* ivec_ptr_;
         expression_ptr v_;
         bool v_deletable_;
      };

      template <typename T>
      class assignment_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         assignment_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           var_node_ptr_(0)
         {
            if (is_variable_node(binary_node<T>::branch_[0].first))
            {
               var_node_ptr_ = static_cast<variable_node<T>*>(binary_node<T>::branch_[0].first);
            }
         }

         inline T value() const
         {
            if (var_node_ptr_)
            {
               T& result = var_node_ptr_->ref();
               result = binary_node<T>::branch_[1].first->value();

               return result;
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

      private:

         variable_node<T>* var_node_ptr_;
      };

      template <typename T>
      class assignment_vec_elem_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         assignment_vec_elem_node(const operator_type& opr,
                                  expression_ptr branch0,
                                  expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0)
         {
            if (is_vector_elem_node(binary_node<T>::branch_[0].first))
            {
               vec_node_ptr_ = static_cast<vector_elem_node<T>*>(binary_node<T>::branch_[0].first);
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
               T& result = vec_node_ptr_->ref();
               result = binary_node<T>::branch_[1].first->value();

               return result;
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

      private:

         vector_elem_node<T>* vec_node_ptr_;
      };

      template <typename T>
      class assignment_vec_node : public binary_node     <T>,
                                  public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*    vector_node_ptr;

         assignment_vec_node(const operator_type& opr,
                             expression_ptr branch0,
                             expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0),
           vec_size_    (0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[0].first);
               vec_size_     = vec_node_ptr_->ref().size();
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
               vector_holder<T>& vec_hldr = vec_node_ptr_->ref();
               const T v = binary_node<T>::branch_[1].first->value();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  (*vec_hldr[i]) = v;
               }

               return vec_node_ptr_->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvalass;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T>
      class assignment_vecvec_node : public binary_node     <T>,
                                     public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         assignment_vecvec_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec0_node_ptr_(0),
           vec1_node_ptr_(0),
           vec_size_     (0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec0_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[0].first);
            }

            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec1_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vec_size_ = std::min(vec0_node_ptr_->ref().size(),
                                    vec1_node_ptr_->ref().size());
            }
         }

         inline T value() const
         {
            binary_node<T>::branch_[1].first->value();

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  (*vec0[i]) = (*vec1[i]);
               }

               return vec0_node_ptr_->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvecass;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class assignment_op_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         assignment_op_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           var_node_ptr_(0)
         {
            if (is_variable_node(binary_node<T>::branch_[0].first))
            {
               var_node_ptr_ = static_cast<variable_node<T>*>(binary_node<T>::branch_[0].first);
            }
         }

         inline T value() const
         {
            if (var_node_ptr_)
            {
               T& v = var_node_ptr_->ref();
               v = Operation::process(v,binary_node<T>::branch_[1].first->value());

               return v;
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

      private:

         variable_node<T>* var_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_elem_op_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         assignment_vec_elem_op_node(const operator_type& opr,
                                     expression_ptr branch0,
                                     expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0)
         {
            if (is_vector_elem_node(binary_node<T>::branch_[0].first))
            {
               vec_node_ptr_ = static_cast<vector_elem_node<T>*>(binary_node<T>::branch_[0].first);
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
               T& v = vec_node_ptr_->ref();
                  v = Operation::process(v,binary_node<T>::branch_[1].first->value());

               return v;
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

      private:

         vector_elem_node<T>* vec_node_ptr_;
      };

      template <typename T, typename Operation>
      class assignment_vec_op_node : public binary_node     <T>,
                                     public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         assignment_vec_op_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0),
           vec_size_    (0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[0].first);
               vec_size_     = vec_node_ptr_->ref().size();
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
               vector_holder<T>& vec_hldr = vec_node_ptr_->ref();
               const T v = binary_node<T>::branch_[1].first->value();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  T& vec_i = *vec_hldr[i];
                     vec_i = Operation::process(vec_i,v);
               }

               return vec_node_ptr_->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecopvalass;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class assignment_vecvec_op_node : public binary_node     <T>,
                                        public vector_interface<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         assignment_vecvec_op_node(const operator_type& opr,
                                expression_ptr branch0,
                                expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec0_node_ptr_(0),
           vec1_node_ptr_(0),
           vec_size_     (0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec0_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[0].first);
            }

            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec1_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vec_size_ = std::min(vec0_node_ptr_->ref().size(),
                                    vec1_node_ptr_->ref().size());
            }
         }

         inline T value() const
         {
            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  T& vec0_i = *vec0[i];
                  T& vec1_i = *vec1[i];
                  vec0_i = Operation::process(vec0_i,vec1_i);
               }

               return vec0_node_ptr_->value();
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecopvecass;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class eqineq_vecvec_node : public binary_node     <T>,
                                 public vector_interface<T>
      {
      public:

         typedef expression_node<T>*  expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         eqineq_vecvec_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec0_node_ptr_(0),
           vec1_node_ptr_(0),
           vec_size_     (0)
         {

            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec0_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[0].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[0].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[0].first)))
               {
                  vec0_node_ptr_ = vi->vec();
               }
            }

            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec1_node_ptr_ = static_cast<vector_node<T>*>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vec_size_ = std::min(vec0_node_ptr_->ref().size(),
                                    vec1_node_ptr_->ref().size());
            }
         }

         inline T value() const
         {
            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  if (std::equal_to<T>()(T(0),Operation::process(*vec0[i],*vec1[i])))
                  {
                     return T(0);
                  }
               }

               return T(1);
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec0_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec0_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvecineq;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec0_node_ptr_;
         vector_node<T>* vec1_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class eqineq_vecval_node : public binary_node     <T>,
                                 public vector_interface<T>
      {
      public:

         typedef expression_node<T>*  expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         eqineq_vecval_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0),
           vec_size_    (0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[0].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[0].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[0].first)))
               {
                  vec_node_ptr_ = vi->vec();
               }
            }

            if (vec_node_ptr_)
            {
               vec_size_ = vec_node_ptr_->ref().size();
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
                     binary_node<T>::branch_[0].first->value();
               T v = binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec_hldr = vec_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  if (std::equal_to<T>()(T(0),Operation::process(*vec_hldr[i],v)))
                  {
                     return T(0);
                  }
               }

               return T(1);
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvalineq;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class eqineq_valvec_node : public binary_node     <T>,
                                 public vector_interface<T>
      {
      public:

         typedef expression_node<T>*  expression_ptr;
         typedef vector_node<T>*     vector_node_ptr;

         eqineq_valvec_node(const operator_type& opr,
                            expression_ptr branch0,
                            expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec_node_ptr_(0),
           vec_size_    (0)
         {
            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec_node_ptr_ = vi->vec();
               }
            }

            if (vec_node_ptr_)
            {
               vec_size_ = vec_node_ptr_->ref().size();
            }
         }

         inline T value() const
         {
            if (vec_node_ptr_)
            {
               T v = binary_node<T>::branch_[0].first->value();
                     binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec_hldr = vec_node_ptr_->ref();

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  if (std::equal_to<T>()(T(0),Operation::process(v,*vec_hldr[i])))
                  {
                     return T(0);
                  }
               }

               return T(1);
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return vec_node_ptr_;
         }

         vector_node_ptr vec()
         {
            return vec_node_ptr_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_valvecineq;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node<T>* vec_node_ptr_;
         std::size_t     vec_size_;
      };

      template <typename T, typename Operation>
      class vecarith_vecvec_node : public binary_node     <T>,
                                   public vector_interface<T>
      {
      public:

         typedef expression_node<T>*    expression_ptr;
         typedef vector_node<T>*       vector_node_ptr;
         typedef vector_holder<T>*   vector_holder_ptr;

         vecarith_vecvec_node(const operator_type& opr,
                              expression_ptr branch0,
                              expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec0_node_ptr_(0),
           vec1_node_ptr_(0),
           vec_size_     (0),
           data_         (0),
           temp_         (0),
           temp_vec_node_(0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[0].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[0].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[0].first)))
               {
                  vec0_node_ptr_ = vi->vec();
               }
            }

            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec1_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();

               vec_size_      = std::min(vec0.size(),vec1.size());
               data_          = new T[vec_size_];
               temp_          = new vector_holder<T>(data_,vec_size_);
               temp_vec_node_ = new vector_node<T>  (temp_);
            }
         }

        ~vecarith_vecvec_node()
         {
            delete[] data_;
            delete   temp_;
            delete   temp_vec_node_;
         }

         inline T value() const
         {
            if (vec0_node_ptr_ && vec1_node_ptr_)
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = vec1_node_ptr_->ref();
               vector_holder<T>& vec2 = *temp_;

               for (std::size_t i = 0; i < vec_size_; ++i)
               {

                  T& vec0_i = *vec0[i];
                  T& vec1_i = *vec1[i];
                  T& vec2_i = *vec2[i];

                  vec2_i = Operation::process(vec0_i,vec1_i);
               }

               return *vec2[0];
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return temp_vec_node_;
         }

         vector_node_ptr vec()
         {
            return temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvecarith;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node_ptr   vec0_node_ptr_;
         vector_node_ptr   vec1_node_ptr_;
         std::size_t       vec_size_;
         T*                data_;
         vector_holder_ptr temp_;
         vector_node_ptr   temp_vec_node_;
      };

      template <typename T, typename Operation>
      class vecarith_vecval_node : public binary_node     <T>,
                                   public vector_interface<T>
      {
      public:

         typedef expression_node<T>*    expression_ptr;
         typedef vector_node<T>*       vector_node_ptr;
         typedef vector_holder<T>*   vector_holder_ptr;

         vecarith_vecval_node(const operator_type& opr,
                              expression_ptr branch0,
                              expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec0_node_ptr_(0),
           vec_size_     (0),
           data_         (0),
           temp_         (0),
           temp_vec_node_(0)
         {
            if (is_vector_node(binary_node<T>::branch_[0].first))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[0].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[0].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[0].first)))
               {
                  vec0_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->ref();

               vec_size_      = vec0.size();
               data_          = new T[vec_size_];
               temp_          = new vector_holder<T>(data_,vec_size_);
               temp_vec_node_ = new vector_node<T>  (temp_);
            }
         }

        ~vecarith_vecval_node()
         {
            delete[] data_;
            delete   temp_;
            delete   temp_vec_node_;
         }

         inline T value() const
         {
            if (vec0_node_ptr_)
            {
                           binary_node<T>::branch_[0].first->value();
               const T v = binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = *temp_;

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  T& vec0_i = *vec0[i];
                  T& vec1_i = *vec1[i];

                  vec1_i = Operation::process(vec0_i,v);
               }

               return *vec1[0];
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return temp_vec_node_;
         }

         vector_node_ptr vec()
         {
            return temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvalarith;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node_ptr   vec0_node_ptr_;
         std::size_t       vec_size_;
         T*                data_;
         vector_holder_ptr temp_;
         vector_node_ptr   temp_vec_node_;
      };

      template <typename T, typename Operation>
      class vecarith_valvec_node : public binary_node     <T>,
                                   public vector_interface<T>
      {
      public:

         typedef expression_node<T>*    expression_ptr;
         typedef vector_node<T>*       vector_node_ptr;
         typedef vector_holder<T>*   vector_holder_ptr;

         vecarith_valvec_node(const operator_type& opr,
                              expression_ptr branch0,
                              expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           vec1_node_ptr_(0),
           vec_size_     (0),
           data_         (0),
           temp_         (0),
           temp_vec_node_(0)
         {
            if (is_vector_node(binary_node<T>::branch_[1].first))
            {
               vec1_node_ptr_ = static_cast<vector_node_ptr>(binary_node<T>::branch_[1].first);
            }
            else if (is_ivector_node(binary_node<T>::branch_[1].first))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(binary_node<T>::branch_[1].first)))
               {
                  vec1_node_ptr_ = vi->vec();
               }
            }

            if (vec1_node_ptr_)
            {
               vector_holder<T>& vec0 = vec1_node_ptr_->ref();

               vec_size_      = vec0.size();
               data_          = new T[vec_size_];
               temp_          = new vector_holder<T>(data_,vec_size_);
               temp_vec_node_ = new vector_node<T>  (temp_);
            }
         }

        ~vecarith_valvec_node()
         {
            delete[] data_;
            delete   temp_;
            delete   temp_vec_node_;
         }

         inline T value() const
         {
            if (vec1_node_ptr_)
            {
               const T v = binary_node<T>::branch_[0].first->value();
                           binary_node<T>::branch_[1].first->value();

               vector_holder<T>& vec1 = vec1_node_ptr_->ref();
               vector_holder<T>& vec2 = *temp_;

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  T& vec1_i = *vec1[i];
                  T& vec2_i = *vec2[i];

                  vec2_i = Operation::process(v,vec1_i);
               }

               return *vec2[0];
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return temp_vec_node_;
         }

         vector_node_ptr vec()
         {
            return temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecvalarith;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node_ptr   vec1_node_ptr_;
         std::size_t       vec_size_;
         T*                data_;
         vector_holder_ptr temp_;
         vector_node_ptr   temp_vec_node_;
      };

      template <typename T, typename Operation>
      class unary_vector_node : public unary_node      <T>,
                                public vector_interface<T>
      {
      public:

         typedef expression_node<T>*    expression_ptr;
         typedef vector_node<T>*       vector_node_ptr;
         typedef vector_holder<T>*   vector_holder_ptr;

         unary_vector_node(const operator_type& opr, expression_ptr branch0)
         : unary_node<T>(opr,branch0),
           vec0_node_ptr_(0),
           vec_size_     (0),
           data_         (0),
           temp_         (0),
           temp_vec_node_(0)
         {
            if (is_vector_node(unary_node<T>::branch_))
            {
               vec0_node_ptr_ = static_cast<vector_node_ptr>(unary_node<T>::branch_);
            }
            else if (is_ivector_node(unary_node<T>::branch_))
            {
               vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

               if ((vi = dynamic_cast<vector_interface<T>*>(unary_node<T>::branch_)))
               {
                  vec0_node_ptr_ = vi->vec();
               }
            }

            if (vec0_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->ref();

               vec_size_      = vec0.size();
               data_          = new T[vec_size_];
               temp_          = new vector_holder<T>(data_,vec_size_);
               temp_vec_node_ = new vector_node<T>  (temp_);
            }
         }

        ~unary_vector_node()
         {
            delete[] data_;
            delete   temp_;
            delete   temp_vec_node_;
         }

         inline T value() const
         {
            unary_node<T>::branch_->value();

            if (vec0_node_ptr_)
            {
               vector_holder<T>& vec0 = vec0_node_ptr_->ref();
               vector_holder<T>& vec1 = *temp_;

               for (std::size_t i = 0; i < vec_size_; ++i)
               {
                  T& vec0_i = *vec0[i];
                  T& vec1_i = *vec1[i];

                  vec1_i = Operation::process(vec0_i);
               }

               return *vec1[0];
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         vector_node_ptr vec() const
         {
            return temp_vec_node_;
         }

         vector_node_ptr vec()
         {
            return temp_vec_node_;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vecunaryop;
         }

         std::size_t size() const
         {
            return vec_size_;
         }

      private:

         vector_node_ptr   vec0_node_ptr_;
         std::size_t       vec_size_;
         T*                data_;
         vector_holder_ptr temp_;
         vector_node_ptr   temp_vec_node_;
      };

      template <typename T>
      class scand_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         scand_node(const operator_type& opr,
                    expression_ptr branch0,
                    expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1)
         {}

         inline T value() const
         {
            return (
                     std::not_equal_to<T>()
                        (T(0),binary_node<T>::branch_[0].first->value()) &&
                     std::not_equal_to<T>()
                        (T(0),binary_node<T>::branch_[1].first->value())
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      class scor_node : public binary_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         scor_node(const operator_type& opr,
                   expression_ptr branch0,
                   expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1)
         {}

         inline T value() const
         {
            return (
                     std::not_equal_to<T>()
                        (T(0),binary_node<T>::branch_[0].first->value()) ||
                     std::not_equal_to<T>()
                        (T(0),binary_node<T>::branch_[1].first->value())
                   ) ? T(1) : T(0);
         }
      };

      template <typename T, typename IFunction, std::size_t N>
      class function_N_node : public expression_node<T>
      {
      public:

         // Function of N paramters.
         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef IFunction ifunction;

         function_N_node(ifunction* func)
         : function_((N == func->param_count) ? func : reinterpret_cast<ifunction*>(0)),
           parameter_count_(func->param_count)
         {}

        ~function_N_node()
         {
            cleanup_branches::execute<T,N>(branch_);
         }

         template <std::size_t NumBranches>
         bool init_branches(expression_ptr (&b)[NumBranches])
         {
            // Needed for incompetent and broken msvc compiler versions
            #ifdef _MSC_VER
             #pragma warning(push)
             #pragma warning(disable: 4127)
            #endif
            if (N != NumBranches)
               return false;
            else
            {
               for (std::size_t i = 0; i < NumBranches; ++i)
               {
                  if (b[i])
                     branch_[i] = std::make_pair(b[i],branch_deletable(b[i]));
                  else
                     return false;
               }
               return true;
            }
            #ifdef _MSC_VER
             #pragma warning(pop)
            #endif
         }

         inline bool operator <(const function_N_node<T,IFunction,N>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const
         {
            // Needed for incompetent and broken msvc compiler versions
            #ifdef _MSC_VER
             #pragma warning(push)
             #pragma warning(disable: 4127)
            #endif
            if ((0 == function_) || (0 == N))
               return std::numeric_limits<T>::quiet_NaN();
            else
            {
               T v[N];
               evaluate_branches<T,N>::execute(v,branch_);
               return invoke<T,N>::execute(*function_,v);
            }
            #ifdef _MSC_VER
             #pragma warning(pop)
            #endif
         }

         template <typename T_, std::size_t BranchCount>
         struct evaluate_branches
         {
            static inline void execute(T_ (&v)[BranchCount], const branch_t (&b)[BranchCount])
            {
               for (std::size_t i = 0; i < BranchCount; ++i)
               {
                  v[i] = b[i].first->value();
               }
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,5>
         {
            static inline void execute(T_ (&v)[5], const branch_t (&b)[5])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
               v[3] = b[3].first->value();
               v[4] = b[4].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,4>
         {
            static inline void execute(T_ (&v)[4], const branch_t (&b)[4])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
               v[3] = b[3].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,3>
         {
            static inline void execute(T_ (&v)[3], const branch_t (&b)[3])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
               v[2] = b[2].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,2>
         {
            static inline void execute(T_ (&v)[2], const branch_t (&b)[2])
            {
               v[0] = b[0].first->value();
               v[1] = b[1].first->value();
            }
         };

         template <typename T_>
         struct evaluate_branches <T_,1>
         {
            static inline void execute(T_ (&v)[1], const branch_t (&b)[1])
            {
               v[0] = b[0].first->value();
            }
         };

         template <typename T_, std::size_t ParamCount>
         struct invoke { static inline T execute(ifunction&, branch_t (&)[ParamCount]) { return std::numeric_limits<T_>::quiet_NaN(); } };

         template <typename T_>
         struct invoke<T_,20>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[20])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16],v[17],v[18],v[19]); }
         };

         template <typename T_>
         struct invoke<T_,19>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[19])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16],v[17],v[18]); }
         };

         template <typename T_>
         struct invoke<T_,18>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[18])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16],v[17]); }
         };

         template <typename T_>
         struct invoke<T_,17>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[17])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15],v[16]); }
         };

         template <typename T_>
         struct invoke<T_,16>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[16])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14],v[15]); }
         };

         template <typename T_>
         struct invoke<T_,15>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[15])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13],v[14]); }
         };

         template <typename T_>
         struct invoke<T_,14>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[14])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12],v[13]); }
         };

         template <typename T_>
         struct invoke<T_,13>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[13])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11],v[12]); }
         };

         template <typename T_>
         struct invoke<T_,12>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[12])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10],v[11]); }
         };

         template <typename T_>
         struct invoke<T_,11>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[11])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9],v[10]); }
         };

         template <typename T_>
         struct invoke<T_,10>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[10])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8],v[9]); }
         };

         template <typename T_>
         struct invoke<T_,9>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[9])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7],v[8]); }
         };

         template <typename T_>
         struct invoke<T_,8>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[8])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6],v[7]); }
         };

         template <typename T_>
         struct invoke<T_,7>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[7])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5],v[6]); }
         };

         template <typename T_>
         struct invoke<T_,6>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[6])
            { return f(v[0],v[1],v[2],v[3],v[4],v[5]); }
         };

         template <typename T_>
         struct invoke<T_,5>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[5])
            { return f(v[0],v[1],v[2],v[3],v[4]); }
         };

         template <typename T_>
         struct invoke<T_,4>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[4])
            { return f(v[0],v[1],v[2],v[3]); }
         };

         template <typename T_>
         struct invoke<T_,3>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[3])
            { return f(v[0],v[1],v[2]); }
         };

         template <typename T_>
         struct invoke<T_,2>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[2])
            { return f(v[0],v[1]); }
         };

         template <typename T_>
         struct invoke<T_,1>
         {
            static inline T_ execute(ifunction& f, T_ (&v)[1])
            { return f(v[0]); }
         };

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_function;
         }

      private:

         ifunction* function_;
         std::size_t parameter_count_;
         branch_t branch_[N];
      };

      template <typename T, typename IFunction>
      class function_N_node<T,IFunction,0> : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef IFunction ifunction;

         function_N_node(ifunction* func)
         : function_((0 == func->param_count) ? func : reinterpret_cast<ifunction*>(0))
         {}

         inline bool operator <(const function_N_node<T,IFunction,0>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const
         {
            if (function_)
               return (*function_)();
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_function;
         }

      private:

         ifunction* function_;
      };

      template <typename T, typename VarArgFunction>
      class vararg_function_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;

         vararg_function_node(VarArgFunction*  func,
                              const std::vector<expression_ptr>& arg_list)
         : function_(func),
           arg_list_(arg_list)
         {
            value_list_.resize(arg_list.size(),std::numeric_limits<T>::quiet_NaN());
         }

        ~vararg_function_node()
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               if (arg_list_[i] && !details::is_variable_node(arg_list_[i]))
               {
                  delete arg_list_[i];
                  arg_list_[i] = 0;
               }
            }
         }

         inline bool operator <(const vararg_function_node<T,VarArgFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const
         {
            if (function_)
            {
               populate_value_list();
               return (*function_)(value_list_);
            }
            else
               return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_vafunction;
         }

      private:

         inline void populate_value_list() const
         {
            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               value_list_[i] = arg_list_[i]->value();
            }
         }

         VarArgFunction* function_;
         std::vector<expression_ptr> arg_list_;
         mutable std::vector<T> value_list_;
      };

      template <typename T, typename GenericFunction>
      class generic_function_node : public expression_node<T>
      {
      public:

         typedef type_store<T>                      type_store_t;
         typedef expression_node<T>*              expression_ptr;
         typedef variable_node<T>                variable_node_t;
         typedef vector_elem_node<T>          vector_elem_node_t;
         typedef vector_node<T>                    vector_node_t;
         typedef variable_node_t*            variable_node_ptr_t;
         typedef vector_elem_node_t*      vector_elem_node_ptr_t;
         typedef vector_node_t*                vector_node_ptr_t;
         typedef range_interface<T>            range_interface_t;
         typedef range_data_type<T>            range_data_type_t;
         typedef range_pack<T>                           range_t;
         typedef std::pair<expression_ptr,bool>         branch_t;
         typedef std::pair<void*,std::size_t>             void_t;
         typedef std::vector<T>                         tmp_vs_t;
         typedef std::vector<type_store_t>      typestore_list_t;
         typedef std::vector<range_data_type_t>     range_list_t;

         generic_function_node(const std::vector<expression_ptr>& arg_list,
                               GenericFunction* func = (GenericFunction*)(0))
         : function_(func),
           arg_list_(arg_list)
         {}

        ~generic_function_node()
         {
            cleanup_branches::execute(branch_);
         }

         virtual bool init_branches()
         {
            expr_as_vec1_store_.resize(arg_list_.size(),T(0)               );
            typestore_list_    .resize(arg_list_.size(),type_store_t()     );
            range_list_        .resize(arg_list_.size(),range_data_type_t());
            branch_            .resize(arg_list_.size(),branch_t((expression_ptr)0,false));

            for (std::size_t i = 0; i < arg_list_.size(); ++i)
            {
               type_store_t& ts = typestore_list_[i];

               if (0 == arg_list_[i])
                  return false;
               else if (is_ivector_node(arg_list_[i]))
               {
                  vector_interface<T>* vi = reinterpret_cast<vector_interface<T>*>(0);

                  if (0 == (vi = dynamic_cast<vector_interface<T>*>(arg_list_[i])))
                     return false;

                  ts.size = vi->size();
                  ts.data = vi->vec()->ref()[0];
                  ts.type = type_store_t::e_vector;
               }
               else if (is_generally_string_node(arg_list_[i]))
               {
                  string_base_node<T>* sbn = reinterpret_cast<string_base_node<T>*>(0);

                  if (0 == (sbn = dynamic_cast<string_base_node<T>*>(arg_list_[i])))
                     return false;

                  ts.size = sbn->size();
                  ts.data = reinterpret_cast<void*>(const_cast<char*>(sbn->base()));
                  ts.type = type_store_t::e_string;

                  range_list_[i].data      = ts.data;
                  range_list_[i].size      = ts.size;
                  range_list_[i].type_size = sizeof(char);
                  range_list_[i].str_node  = sbn;

                  range_interface_t* ri = reinterpret_cast<range_interface_t*>(0);

                  if (0 == (ri = dynamic_cast<range_interface_t*>(arg_list_[i])))
                     return false;

                  range_t& rp = ri->range_ref();

                  if (
                       rp.const_range() &&
                       is_const_string_range_node(arg_list_[i])
                     )
                  {
                     ts.size = rp.const_size();
                     ts.data = static_cast<char*>(ts.data) + rp.n0_c.second;
                     range_list_[i].range = reinterpret_cast<range_t*>(0);
                  }
                  else
                     range_list_[i].range = &(ri->range_ref());
               }
               else if (is_variable_node(arg_list_[i]))
               {
                  variable_node_ptr_t var = variable_node_ptr_t(0);

                  if (0 == (var = dynamic_cast<variable_node_ptr_t>(arg_list_[i])))
                     return false;

                  ts.size = 1;
                  ts.data = &var->ref();
                  ts.type = type_store_t::e_scalar;
               }
               else if (is_vector_elem_node(arg_list_[i]))
               {
                  vector_elem_node_ptr_t var = vector_elem_node_ptr_t(0);

                  if (0 == (var = dynamic_cast<vector_elem_node_ptr_t>(arg_list_[i])))
                     return false;

                  ts.size = 1;
                  ts.data = reinterpret_cast<void*>(&var->ref());
                  ts.type = type_store_t::e_scalar;
               }
               else
               {
                  ts.size = 1;
                  ts.data = reinterpret_cast<void*>(&expr_as_vec1_store_[i]);
                  ts.type = type_store_t::e_scalar;
               }

               branch_[i] = std::make_pair(arg_list_[i],branch_deletable(arg_list_[i]));
            }

            return true;
         }

         inline bool operator <(const generic_function_node<T,GenericFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const
         {
            if (function_)
            {
               if (populate_value_list())
               {
                  typedef typename GenericFunction::parameter_list_t parameter_list_t;

                  return (*function_)(parameter_list_t(typestore_list_));
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_genfunction;
         }

      protected:

         inline virtual bool populate_value_list() const
         {
            for (std::size_t i = 0; i < branch_.size(); ++i)
            {
               expr_as_vec1_store_[i] = branch_[i].first->value();
            }

            for (std::size_t i = 0; i < branch_.size(); ++i)
            {
               range_data_type_t& rdt = range_list_[i];

               if (rdt.range)
               {
                  range_t&    rp = (*rdt.range);
                  std::size_t r0 = 0;
                  std::size_t r1 = 0;

                  if (rp(r0,r1,rdt.size))
                  {
                     type_store_t& ts = typestore_list_[i];

                     ts.size = rp.cache_size();

                     if (ts.type == type_store_t::e_string)
                        ts.data = const_cast<char*>(rdt.str_node->base()) + rp.cache.first;
                     else
                        ts.data = static_cast<char*>(rdt.data) + (rp.cache.first * rdt.type_size);
                  }
                  else
                     return false;
               }
            }

            return true;
         }

         GenericFunction* function_;
         mutable typestore_list_t typestore_list_;

      private:

         std::vector<expression_ptr> arg_list_;
         std::vector<branch_t> branch_;
         mutable tmp_vs_t expr_as_vec1_store_;
         mutable range_list_t range_list_;
      };

      template <typename T, typename StringFunction>
      class string_function_node : public generic_function_node<T,StringFunction>,
                                   public string_base_node<T>,
                                   public range_interface <T>
      {
      public:

         typedef generic_function_node<T,StringFunction> gen_function_t;
         typedef range_pack<T> range_t;

         string_function_node(StringFunction* func,
                              const std::vector<typename gen_function_t::expression_ptr>& arg_list)
         : gen_function_t(arg_list,func)
         {
            range_.n0_c = std::make_pair<bool,std::size_t>(true,0);
            range_.n1_c = std::make_pair<bool,std::size_t>(true,0);
            range_.cache.first  = range_.n0_c.second;
            range_.cache.second = range_.n1_c.second;
         }

         inline bool operator <(const string_function_node<T,StringFunction>& fn) const
         {
            return this < (&fn);
         }

         inline T value() const
         {
            T result = std::numeric_limits<T>::quiet_NaN();

            if (gen_function_t::function_)
            {
               if (gen_function_t::populate_value_list())
               {
                  typedef typename StringFunction::parameter_list_t parameter_list_t;

                  result = (*gen_function_t::function_)(ret_string_,
                                                        parameter_list_t(gen_function_t::typestore_list_));

                  range_.n1_c.second  = ret_string_.size() - 1;
                  range_.cache.second = range_.n1_c.second;

                  return result;
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strfunction;
         }

         std::string str() const
         {
            return ret_string_;
         }

         const char* base() const
         {
           return ret_string_.data();
         }

         std::size_t size() const
         {
            return ret_string_.size();
         }

         range_t& range_ref()
         {
            return range_;
         }

         const range_t& range_ref() const
         {
            return range_;
         }

      protected:

         mutable range_t     range_;
         mutable std::string ret_string_;
      };

      template <typename T, typename GenericFunction>
      class multimode_genfunction_node : public generic_function_node<T,GenericFunction>
      {
      public:

         typedef generic_function_node<T,GenericFunction> gen_function_t;
         typedef range_pack<T> range_t;

         multimode_genfunction_node(GenericFunction* func,
                                    const std::size_t& param_seq_index,
                                    const std::vector<typename gen_function_t::expression_ptr>& arg_list)
         : gen_function_t(arg_list,func),
           param_seq_index_(param_seq_index)
         {}

         inline T value() const
         {
            T result = std::numeric_limits<T>::quiet_NaN();

            if (gen_function_t::function_)
            {
               if (gen_function_t::populate_value_list())
               {
                  typedef typename GenericFunction::parameter_list_t parameter_list_t;

                  return (*gen_function_t::function_)(param_seq_index_,
                                                      parameter_list_t(gen_function_t::typestore_list_));
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_genfunction;
         }

      private:

         std::size_t param_seq_index_;
      };

      template <typename T, typename StringFunction>
      class multimode_strfunction_node : public string_function_node<T,StringFunction>
      {
      public:

         typedef string_function_node<T,StringFunction> str_function_t;
         typedef range_pack<T> range_t;

         multimode_strfunction_node(StringFunction* func,
                                    const std::size_t& param_seq_index,
                                    const std::vector<typename str_function_t::expression_ptr>& arg_list)
         : str_function_t(func,arg_list),
           param_seq_index_(param_seq_index)
         {}

         inline T value() const
         {
            T result = std::numeric_limits<T>::quiet_NaN();

            if (str_function_t::function_)
            {
               if (str_function_t::populate_value_list())
               {
                  typedef typename StringFunction::parameter_list_t parameter_list_t;

                  result = (*str_function_t::function_)(param_seq_index_,
                                                        str_function_t::ret_string_,
                                                        parameter_list_t(str_function_t::typestore_list_));

                  str_function_t::range_.n1_c.second  = str_function_t::ret_string_.size() - 1;
                  str_function_t::range_.cache.second = str_function_t::range_.n1_c.second;

                  return result;
               }
            }

            return result;
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_strfunction;
         }

      private:

         std::size_t param_seq_index_;
      };

      class return_exception
      {};

      template <typename T>
      class null_igenfunc
      {
      public:

         typedef type_store<T> generic_type;
         typedef typename generic_type::parameter_list parameter_list_t;

         inline virtual T operator()(parameter_list_t)
         {
            return std::numeric_limits<T>::quiet_NaN();
         }
      };

      template <typename T>
      class return_node : public generic_function_node<T,null_igenfunc<T> >
      {
      public:

         typedef null_igenfunc<T> igeneric_function_t;
         typedef igeneric_function_t* igeneric_function_ptr;
         typedef generic_function_node<T,igeneric_function_t> gen_function_t;
         typedef results_context<T> results_context_t;

         return_node(const std::vector<typename gen_function_t::expression_ptr>& arg_list,
                     results_context_t& rc)
         : gen_function_t  (arg_list),
           results_context_(&rc)
         {}

         inline T value() const
         {
            if (
                 (0 != results_context_) &&
                 gen_function_t::populate_value_list()
               )
            {
               typedef typename type_store<T>::parameter_list parameter_list_t;

               results_context_->
                  assign(parameter_list_t(gen_function_t::typestore_list_));

               throw return_exception();
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_return;
         }

      private:

         results_context_t* results_context_;
      };

      template <typename T>
      class return_envelope_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef results_context<T>  results_context_t;

         return_envelope_node(expression_ptr body, results_context_t& rc)
         : results_context_(&rc),
           return_invoked_ (false),
           body_           (body),
           body_deletable_ (branch_deletable(body_))
         {}

        ~return_envelope_node()
         {
            if (body_ && body_deletable_)
            {
               delete body_;
            }
         }

         inline T value() const
         {
            try
            {
               return_invoked_ = false;
               results_context_->clear();

               return body_->value();
            }
            catch(const return_exception&)
            {
               return_invoked_ = true;
               return std::numeric_limits<T>::quiet_NaN();
            }
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_retenv;
         }

         inline bool* retinvk_ptr()
         {
            return &return_invoked_;
         }

      private:

         results_context_t* results_context_;
         mutable bool       return_invoked_;
         expression_ptr     body_;
         bool               body_deletable_;
      };

      #define exprtk_define_unary_op(OpName)                         \
      template <typename T>                                          \
      struct OpName##_op                                             \
      {                                                              \
         typedef typename functor_t<T>::Type Type;                   \
                                                                     \
         static inline T process(Type v)                             \
         {                                                           \
            return numeric:: OpName (v);                             \
         }                                                           \
                                                                     \
         static inline typename expression_node<T>::node_type type() \
         {                                                           \
            return expression_node<T>::e_##OpName;                   \
         }                                                           \
                                                                     \
         static inline details::operator_type operation()            \
         {                                                           \
            return details::e_##OpName;                              \
         }                                                           \
      };                                                             \

      exprtk_define_unary_op(abs  )
      exprtk_define_unary_op(acos )
      exprtk_define_unary_op(acosh)
      exprtk_define_unary_op(asin )
      exprtk_define_unary_op(asinh)
      exprtk_define_unary_op(atan )
      exprtk_define_unary_op(atanh)
      exprtk_define_unary_op(ceil )
      exprtk_define_unary_op(cos  )
      exprtk_define_unary_op(cosh )
      exprtk_define_unary_op(cot  )
      exprtk_define_unary_op(csc  )
      exprtk_define_unary_op(d2g  )
      exprtk_define_unary_op(d2r  )
      exprtk_define_unary_op(erf  )
      exprtk_define_unary_op(erfc )
      exprtk_define_unary_op(exp  )
      exprtk_define_unary_op(expm1)
      exprtk_define_unary_op(floor)
      exprtk_define_unary_op(frac )
      exprtk_define_unary_op(g2d  )
      exprtk_define_unary_op(log  )
      exprtk_define_unary_op(log10)
      exprtk_define_unary_op(log2 )
      exprtk_define_unary_op(log1p)
      exprtk_define_unary_op(ncdf )
      exprtk_define_unary_op(neg  )
      exprtk_define_unary_op(notl )
      exprtk_define_unary_op(pos  )
      exprtk_define_unary_op(r2d  )
      exprtk_define_unary_op(round)
      exprtk_define_unary_op(sec  )
      exprtk_define_unary_op(sgn  )
      exprtk_define_unary_op(sin  )
      exprtk_define_unary_op(sinc )
      exprtk_define_unary_op(sinh )
      exprtk_define_unary_op(sqrt )
      exprtk_define_unary_op(tan  )
      exprtk_define_unary_op(tanh )
      exprtk_define_unary_op(trunc)
      #undef exprtk_define_unary_op

      template <typename T>
      struct opr_base
      {
         typedef typename details::functor_t<T>::Type Type;
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t quaternary_functor_t;
         typedef typename functor_t::tfunc_t    trinary_functor_t;
         typedef typename functor_t::bfunc_t     binary_functor_t;
         typedef typename functor_t::ufunc_t      unary_functor_t;
      };

      template <typename T>
      struct add_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return t1 + t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 + t2 + t3; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_add; }
         static inline details::operator_type operation() { return details::e_add; }
      };

      template <typename T>
      struct mul_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return t1 * t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 * t2 * t3; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_mul; }
         static inline details::operator_type operation() { return details::e_mul; }
      };

      template <typename T>
      struct sub_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return t1 - t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 - t2 - t3; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_sub; }
         static inline details::operator_type operation() { return details::e_sub; }
      };

      template <typename T>
      struct div_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return t1 / t2; }
         static inline T process(Type t1, Type t2, Type t3) { return t1 / t2 / t3; }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_div; }
         static inline details::operator_type operation() { return details::e_div; }
      };

      template <typename T>
      struct mod_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return numeric::modulus<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_mod; }
         static inline details::operator_type operation() { return details::e_mod; }
      };

      template <typename T>
      struct pow_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return numeric::pow<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_pow; }
         static inline details::operator_type operation() { return details::e_pow; }
      };

      template <typename T>
      struct lt_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return ((t1 < t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 < t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_lt; }
         static inline details::operator_type operation() { return details::e_lt; }
      };

      template <typename T>
      struct lte_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return ((t1 <= t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 <= t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_lte; }
         static inline details::operator_type operation() { return details::e_lte; }
      };

      template <typename T>
      struct gt_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return ((t1 > t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 > t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_gt; }
         static inline details::operator_type operation() { return details::e_gt; }
      };

      template <typename T>
      struct gte_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return ((t1 >= t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 >= t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_gte; }
         static inline details::operator_type operation() { return details::e_gte; }
      };

      template <typename T>
      struct eq_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (std::equal_to<T>()(t1,t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 == t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_eq; }
         static inline details::operator_type operation() { return details::e_eq; }
      };

      template <typename T>
      struct ne_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (std::not_equal_to<T>()(t1,t2) ? T(1) : T(0)); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((t1 != t2) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_ne; }
         static inline details::operator_type operation() { return details::e_ne; }
      };

      template <typename T>
      struct and_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (details::is_true(t1) && details::is_true(t2)) ? T(1) : T(0); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_and; }
         static inline details::operator_type operation() { return details::e_and; }
      };

      template <typename T>
      struct nand_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (details::is_true(t1) && details::is_true(t2)) ? T(0) : T(1); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nand; }
         static inline details::operator_type operation() { return details::e_nand; }
      };

      template <typename T>
      struct or_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (details::is_true(t1) || details::is_true(t2)) ? T(1) : T(0); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_or; }
         static inline details::operator_type operation() { return details::e_or; }
      };

      template <typename T>
      struct nor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return (details::is_true(t1) || details::is_true(t2)) ? T(0) : T(1); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_nor; }
      };

      template <typename T>
      struct xor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return numeric::xor_opr<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_xor; }
      };

      template <typename T>
      struct xnor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(Type t1, Type t2) { return numeric::xnor_opr<T>(t1,t2); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_nor; }
         static inline details::operator_type operation() { return details::e_xnor; }
      };

      template <typename T>
      struct in_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return ((std::string::npos != t2.find(t1)) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_in; }
         static inline details::operator_type operation() { return details::e_in; }
      };

      template <typename T>
      struct like_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return (details::wc_match(t2,t1) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_like; }
         static inline details::operator_type operation() { return details::e_like; }
      };

      template <typename T>
      struct ilike_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(const T&, const T&) { return std::numeric_limits<T>::quiet_NaN(); }
         static inline T process(const std::string& t1, const std::string& t2) { return (details::wc_imatch(t2,t1) ? T(1) : T(0)); }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_ilike; }
         static inline details::operator_type operation() { return details::e_ilike; }
      };

      template <typename T>
      struct inrange_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;
         static inline T process(const T& t0, const T& t1, const T& t2) { return ((t0 <= t1) && (t1 <= t2)) ? T(1) : T(0); }
         static inline T process(const std::string& t0, const std::string& t1, const std::string& t2)
         {
            return ((t0 <= t1) && (t1 <= t2)) ? T(1) : T(0);
         }
         static inline typename expression_node<T>::node_type type() { return expression_node<T>::e_inranges; }
         static inline details::operator_type operation() { return details::e_inrange; }
      };

      template <typename T>
      inline T value(details::expression_node<T>* n)
      {
         return n->value();
      }

      template <typename T>
      inline T value(T* t)
      {
         return (*t);
      }

      template <typename T>
      struct vararg_add_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(0);

                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                              result += value(arg_list[i]);
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]) + value(arg_list[3]);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return value(arg_list[0]) + value(arg_list[1]) +
                   value(arg_list[2]) + value(arg_list[3]) +
                   value(arg_list[4]);
         }
      };

      template <typename T>
      struct vararg_mul_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               result *= value(arg_list[i]);
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]) * value(arg_list[3]);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return value(arg_list[0]) * value(arg_list[1]) *
                   value(arg_list[2]) * value(arg_list[3]) *
                   value(arg_list[4]);
         }
      };

      template <typename T>
      struct vararg_avg_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default : return vararg_add_op<T>::process(arg_list) / arg_list.size();
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1])) / T(2);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) + value(arg_list[2])) / T(3);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) +
                    value(arg_list[2]) + value(arg_list[3])) / T(4);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (value(arg_list[0]) + value(arg_list[1]) +
                    value(arg_list[2]) + value(arg_list[3]) +
                    value(arg_list[4])) / T(5);
         }
      };

      template <typename T>
      struct vararg_min_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               const T v = value(arg_list[i]);

                               if (v < result)
                                  result = v;
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return std::min<T>(value(arg_list[0]),value(arg_list[1]));
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return std::min<T>(std::min<T>(value(arg_list[0]),value(arg_list[1])),value(arg_list[2]));
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return std::min<T>(
                        std::min<T>(value(arg_list[0]),value(arg_list[1])),
                        std::min<T>(value(arg_list[2]),value(arg_list[3])));
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return std::min<T>(
                   std::min<T>(std::min<T>(value(arg_list[0]),value(arg_list[1])),
                               std::min<T>(value(arg_list[2]),value(arg_list[3]))),
                               value(arg_list[4]));
         }
      };

      template <typename T>
      struct vararg_max_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return T(0);
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            T result = T(value(arg_list[0]));

                            for (std::size_t i = 1; i < arg_list.size(); ++i)
                            {
                               const T v = value(arg_list[i]);
                               if (v > result)
                                  result = v;
                            }

                            return result;
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return std::max<T>(value(arg_list[0]),value(arg_list[1]));
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return std::max<T>(std::max<T>(value(arg_list[0]),value(arg_list[1])),value(arg_list[2]));
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return std::max<T>(
                        std::max<T>(value(arg_list[0]),value(arg_list[1])),
                        std::max<T>(value(arg_list[2]),value(arg_list[3])));
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return std::max<T>(
                   std::max<T>(std::max<T>(value(arg_list[0]),value(arg_list[1])),
                               std::max<T>(value(arg_list[2]),value(arg_list[3]))),
                               value(arg_list[4]));
         }
      };

      template <typename T>
      struct vararg_mand_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                               if (std::equal_to<T>()(T(0),value(arg_list[i])))
                                  return T(0);
                            }

                            return T(1);
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return std::not_equal_to<T>()
                      (T(0),value(arg_list[0])) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[1]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[2]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[2])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[3]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[2])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[3])) &&
                     std::not_equal_to<T>()(T(0),value(arg_list[4]))
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      struct vararg_mor_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               default :
                         {
                            for (std::size_t i = 0; i < arg_list.size(); ++i)
                            {
                               if (std::not_equal_to<T>()(T(0),value(arg_list[i])))
                                  return T(1);
                            }

                            return T(0);
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return std::not_equal_to<T>()
                      (T(0),value(arg_list[0])) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[1]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[2]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[2])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[3]))
                   ) ? T(1) : T(0);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
            return (
                     std::not_equal_to<T>()(T(0),value(arg_list[0])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[1])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[2])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[3])) ||
                     std::not_equal_to<T>()(T(0),value(arg_list[4]))
                   ) ? T(1) : T(0);
         }
      };

      template <typename T>
      struct vararg_multi_op : public opr_base<T>
      {
         typedef typename opr_base<T>::Type Type;

         template <typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         static inline T process(const Sequence<Type,Allocator>& arg_list)
         {
            switch (arg_list.size())
            {
               case 0  : return std::numeric_limits<T>::quiet_NaN();
               case 1  : return process_1(arg_list);
               case 2  : return process_2(arg_list);
               case 3  : return process_3(arg_list);
               case 4  : return process_4(arg_list);
               case 5  : return process_5(arg_list);
               case 6  : return process_6(arg_list);
               case 7  : return process_7(arg_list);
               case 8  : return process_8(arg_list);
               default :
                         {
                            for (std::size_t i = 0; i < (arg_list.size() - 1); ++i)
                            {
                               value(arg_list[i]);
                            }

                            return value(arg_list.back());
                         }
            }
         }

         template <typename Sequence>
         static inline T process_1(const Sequence& arg_list)
         {
            return value(arg_list[0]);
         }

         template <typename Sequence>
         static inline T process_2(const Sequence& arg_list)
         {
                   value(arg_list[0]);
            return value(arg_list[1]);
         }

         template <typename Sequence>
         static inline T process_3(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
            return value(arg_list[2]);
         }

         template <typename Sequence>
         static inline T process_4(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
            return value(arg_list[3]);
         }

         template <typename Sequence>
         static inline T process_5(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
            return value(arg_list[4]);
         }

         template <typename Sequence>
         static inline T process_6(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
            return value(arg_list[5]);
         }

         template <typename Sequence>
         static inline T process_7(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
                   value(arg_list[5]);
            return value(arg_list[6]);
         }

         template <typename Sequence>
         static inline T process_8(const Sequence& arg_list)
         {
                   value(arg_list[0]);
                   value(arg_list[1]);
                   value(arg_list[2]);
                   value(arg_list[3]);
                   value(arg_list[4]);
                   value(arg_list[5]);
                   value(arg_list[6]);
            return value(arg_list[7]);
         }
      };

      template <typename T>
      struct vec_add_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            vector_holder<T>& vec = v->vec()->ref();

            T result = T(0);

            for (std::size_t i = 0; i < vec.size(); ++i)
            {
              result += (*vec[i]);
            }

            return result;
         }
      };

      template <typename T>
      struct vec_mul_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            vector_holder<T>& vec = v->vec()->ref();

            T result = (*vec[0]);

            for (std::size_t i = 1; i < vec.size(); ++i)
            {
              result *= (*vec[i]);
            }

            return result;
         }
      };

      template <typename T>
      struct vec_avg_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            vector_holder<T>& vec = v->vec()->ref();

            T result = T(0);

            for (std::size_t i = 0; i < vec.size(); ++i)
            {
              result += (*vec[i]);
            }

            return result / vec.size();
         }
      };

      template <typename T>
      struct vec_min_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            vector_holder<T>& vec = v->vec()->ref();

            T result = (*vec[0]);

            for (std::size_t i = 1; i < vec.size(); ++i)
            {
              T v_i = (*vec[i]);

              if (v_i < result)
                result = v_i;
            }

            return result;
         }
      };

      template <typename T>
      struct vec_max_op
      {
         typedef vector_interface<T>* ivector_ptr;

         static inline T process(const ivector_ptr v)
         {
            vector_holder<T>& vec = v->vec()->ref();

            T result = (*vec[0]);

            for (std::size_t i = 1; i < vec.size(); ++i)
            {
              T v_i = (*vec[i]);
              if (v_i > result)
                result = v_i;
            }

            return result;
         }
      };

      template <typename T>
      class vov_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T& v0() const = 0;

         virtual const T& v1() const = 0;
      };

      template <typename T>
      class cov_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual const T& v() const = 0;
      };

      template <typename T>
      class voc_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual const T& v() const = 0;
      };

      template <typename T>
      class vob_base_node : public expression_node<T>
      {
      public:

         virtual const T& v() const = 0;
      };

      template <typename T>
      class bov_base_node : public expression_node<T>
      {
      public:

         virtual const T& v() const = 0;
      };

      template <typename T>
      class cob_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual void set_c(const T) = 0;

         virtual expression_node<T>* move_branch(const std::size_t& index) = 0;
      };

      template <typename T>
      class boc_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T c() const = 0;

         virtual void set_c(const T) = 0;

         virtual expression_node<T>* move_branch(const std::size_t& index) = 0;
      };

      template <typename T>
      class uv_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }

         virtual const T& v() const = 0;
      };

      template <typename T>
      class sos_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }
      };

      template <typename T>
      class sosos_base_node : public expression_node<T>
      {
      public:

         inline virtual operator_type operation() const
         {
            return details::e_default;
         }
      };

      template <typename T>
      class T0oT1oT2_base_node : public expression_node<T>
      {
      public:

         virtual std::string type_id() const = 0;
      };

      template <typename T>
      class T0oT1oT2oT3_base_node : public expression_node<T>
      {
      public:

         virtual std::string type_id() const = 0;
      };

      template <typename T, typename Operation>
      class unary_variable_node : public uv_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         explicit unary_variable_node(const T& var)
         : v_(var)
         {}

         inline T value() const
         {
            return Operation::process(v_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T& v() const
         {
            return v_;
         }

      private:

         unary_variable_node(unary_variable_node<T,Operation>&);
         unary_variable_node<T,Operation>& operator=(unary_variable_node<T,Operation>&);

         const T& v_;
      };

      template <typename T>
      class uvouv_node : public expression_node<T>
      {
      public:

         // UOpr1(v0) Op UOpr2(v1)

         typedef expression_node<T>* expression_ptr;
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;
         typedef typename functor_t::ufunc_t      ufunc_t;

         explicit uvouv_node(const T& var0,const T& var1,
                             ufunc_t uf0, ufunc_t uf1, bfunc_t bf)
         : v0_(var0),
           v1_(var1),
           u0_(uf0),
           u1_(uf1),
           f_ (bf)
         {}

         inline T value() const
         {
            return f_(u0_(v0_),u1_(v1_));
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_uvouv;
         }

         inline operator_type operation() const
         {
            return details::e_default;
         }

         inline const T& v0()
         {
            return v0_;
         }

         inline const T& v1()
         {
            return v1_;
         }

         inline ufunc_t u0()
         {
            return u0_;
         }

         inline ufunc_t u1()
         {
            return u1_;
         }

         inline ufunc_t f()
         {
            return f_;
         }

      private:

         uvouv_node(uvouv_node<T>&);
         uvouv_node<T>& operator=(uvouv_node<T>&);

         const T& v0_;
         const T& v1_;
         const ufunc_t u0_;
         const ufunc_t u1_;
         const bfunc_t f_;
      };

      template <typename T, typename Operation>
      class unary_branch_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         explicit unary_branch_node(expression_ptr brnch)
         : branch_(brnch),
           branch_deletable_(branch_deletable(branch_))
         {}

        ~unary_branch_node()
         {
            if (branch_ && branch_deletable_)
            {
               delete branch_;
               branch_ = 0;
            }
         }

         inline T value() const
         {
            return Operation::process(branch_->value());
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_;
         }

         inline void release()
         {
            branch_deletable_ = false;
         }

      private:

         unary_branch_node(unary_branch_node<T,Operation>&);
         unary_branch_node<T,Operation>& operator=(unary_branch_node<T,Operation>&);

         expression_ptr branch_;
         bool           branch_deletable_;
      };

      template <typename T> struct is_const                { enum {result = 0}; };
      template <typename T> struct is_const <const T>      { enum {result = 1}; };
      template <typename T> struct is_const_ref            { enum {result = 0}; };
      template <typename T> struct is_const_ref <const T&> { enum {result = 1}; };
      template <typename T> struct is_ref                  { enum {result = 0}; };
      template <typename T> struct is_ref<T&>              { enum {result = 1}; };
      template <typename T> struct is_ref<const T&>        { enum {result = 0}; };

      template <std::size_t State>
      struct param_to_str { static std::string result() { static const std::string r("v"); return r; } };

      template <>
      struct param_to_str<0> { static std::string result() { static const std::string r("c"); return r; } };

      #define exprtk_crtype(Type)                          \
      param_to_str<is_const_ref< Type >::result>::result() \

      template <typename T>
      struct T0oT1oT2process
      {
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;

         struct mode0
         {
            static inline T process(const T& t0, const T& t1, const T& t2, const bfunc_t bf0, const bfunc_t bf1)
            {
               // (T0 o0 T1) o1 T2
               return bf1(bf0(t0,t1),t2);
            }

            template <typename T0, typename T1, typename T2>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + "o"   +
                                                       exprtk_crtype(T1) + ")o(" +
                                                       exprtk_crtype(T2) + ")"   ;
               return result;
            }
         };

         struct mode1
         {
            static inline T process(const T& t0, const T& t1, const T& t2, const bfunc_t bf0, const bfunc_t bf1)
            {
               // T0 o0 (T1 o1 T2)
               return bf0(t0,bf1(t1,t2));
            }

            template <typename T0, typename T1, typename T2>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + ")o(" +
                                                       exprtk_crtype(T1) + "o"   +
                                                       exprtk_crtype(T2) + ")"   ;
               return result;
            }
         };
      };

      template <typename T>
      struct T0oT1oT20T3process
      {
         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;

         struct mode0
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 T1) o1 (T2 o2 T3)
               return bf1(bf0(t0,t1),bf2(t2,t3));
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + "o"  +
                                                       exprtk_crtype(T1) + ")o" +
                                                 "(" + exprtk_crtype(T2) + "o"  +
                                                       exprtk_crtype(T3) + ")"  ;
               return result;
            }
         };

         struct mode1
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 (T1 o1 (T2 o2 T3))
               return bf0(t0,bf1(t1,bf2(t2,t3)));
            }
            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) +  ")o((" +
                                                       exprtk_crtype(T1) +  ")o("  +
                                                       exprtk_crtype(T2) +  "o"    +
                                                       exprtk_crtype(T3) +  "))"   ;
               return result;
            }
         };

         struct mode2
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (T0 o0 ((T1 o1 T2) o2 T3)
               return bf0(t0,bf2(bf1(t1,t2),t3));
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "(" + exprtk_crtype(T0) + ")o((" +
                                                       exprtk_crtype(T1) + "o"    +
                                                       exprtk_crtype(T2) + ")o("  +
                                                       exprtk_crtype(T3) + "))"   ;
               return result;
            }
         };

         struct mode3
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // (((T0 o0 T1) o1 T2) o2 T3)
               return bf2(bf1(bf0(t0,t1),t2),t3);
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "((" + exprtk_crtype(T0) + "o"    +
                                                        exprtk_crtype(T1) + ")o("  +
                                                        exprtk_crtype(T2) + "))o(" +
                                                        exprtk_crtype(T3) + ")";
               return result;
            }
         };

         struct mode4
         {
            static inline T process(const T& t0, const T& t1,
                                    const T& t2, const T& t3,
                                    const bfunc_t bf0, const bfunc_t bf1, const bfunc_t bf2)
            {
               // ((T0 o0 (T1 o1 T2)) o2 T3
               return bf2(bf0(t0,bf1(t1,t2)),t3);
            }

            template <typename T0, typename T1, typename T2, typename T3>
            static inline std::string id()
            {
               static const std::string result = "((" + exprtk_crtype(T0) + ")o("  +
                                                        exprtk_crtype(T1) + "o"    +
                                                        exprtk_crtype(T2) + "))o(" +
                                                        exprtk_crtype(T3) + ")"    ;
               return result;
            }
         };
      };

      #undef exprtk_crtype

      template <typename T, typename T0, typename T1>
      struct nodetype_T0oT1 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1>
      const typename expression_node<T>::node_type nodetype_T0oT1<T,T0,T1>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_,T1_,v_)                                                            \
      template <typename T, typename T0, typename T1>                                                           \
      struct nodetype_T0oT1<T,T0_,T1_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1>                                                           \
      const typename expression_node<T>::node_type nodetype_T0oT1<T,T0_,T1_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&,const T1&, e_vov)
      synthesis_node_type_define(const T0&,const T1 , e_voc)
      synthesis_node_type_define(const T0 ,const T1&, e_cov)
      synthesis_node_type_define(      T0&,      T1&,e_none)
      synthesis_node_type_define(const T0 ,const T1 ,e_none)
      synthesis_node_type_define(      T0&,const T1 ,e_none)
      synthesis_node_type_define(const T0 ,      T1&,e_none)
      synthesis_node_type_define(const T0&,      T1&,e_none)
      synthesis_node_type_define(      T0&,const T1&,e_none)
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1, typename T2>
      struct nodetype_T0oT1oT2 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1, typename T2>
      const typename expression_node<T>::node_type nodetype_T0oT1oT2<T,T0,T1,T2>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_,T1_,T2_,v_)                                                               \
      template <typename T, typename T0, typename T1, typename T2>                                                     \
      struct nodetype_T0oT1oT2<T,T0_,T1_,T2_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1, typename T2>                                                     \
      const typename expression_node<T>::node_type nodetype_T0oT1oT2<T,T0_,T1_,T2_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&,const T1&,const T2&, e_vovov)
      synthesis_node_type_define(const T0&,const T1&,const T2 , e_vovoc)
      synthesis_node_type_define(const T0&,const T1 ,const T2&, e_vocov)
      synthesis_node_type_define(const T0 ,const T1&,const T2&, e_covov)
      synthesis_node_type_define(const T0 ,const T1&,const T2 , e_covoc)
      synthesis_node_type_define(const T0 ,const T1 ,const T2 , e_none )
      synthesis_node_type_define(const T0 ,const T1 ,const T2&, e_none )
      synthesis_node_type_define(const T0&,const T1 ,const T2 , e_none )
      synthesis_node_type_define(      T0&,      T1&,      T2&, e_none )
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      struct nodetype_T0oT1oT2oT3 { static const typename expression_node<T>::node_type result; };
      template <typename T, typename T0, typename T1, typename T2, typename T3>
      const typename expression_node<T>::node_type nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result = expression_node<T>::e_none;

      #define synthesis_node_type_define(T0_,T1_,T2_,T3_,v_)                                                                  \
      template <typename T, typename T0, typename T1, typename T2, typename T3>                                               \
      struct nodetype_T0oT1oT2oT3<T,T0_,T1_,T2_,T3_> { static const typename expression_node<T>::node_type result; };         \
      template <typename T, typename T0, typename T1, typename T2, typename T3>                                               \
      const typename expression_node<T>::node_type nodetype_T0oT1oT2oT3<T,T0_,T1_,T2_,T3_>::result = expression_node<T>:: v_; \

      synthesis_node_type_define(const T0&,const T1&,const T2&, const T3&,e_vovovov)
      synthesis_node_type_define(const T0&,const T1&,const T2&, const T3 ,e_vovovoc)
      synthesis_node_type_define(const T0&,const T1&,const T2 , const T3&,e_vovocov)
      synthesis_node_type_define(const T0&,const T1 ,const T2&, const T3&,e_vocovov)
      synthesis_node_type_define(const T0 ,const T1&,const T2&, const T3&,e_covovov)
      synthesis_node_type_define(const T0 ,const T1&,const T2 , const T3&,e_covocov)
      synthesis_node_type_define(const T0&,const T1 ,const T2&, const T3 ,e_vocovoc)
      synthesis_node_type_define(const T0 ,const T1&,const T2&, const T3 ,e_covovoc)
      synthesis_node_type_define(const T0&,const T1 ,const T2 , const T3&,e_vococov)
      synthesis_node_type_define(const T0 ,const T1 ,const T2 , const T3 ,e_none   )
      synthesis_node_type_define(const T0 ,const T1 ,const T2 , const T3&,e_none   )
      synthesis_node_type_define(const T0 ,const T1 ,const T2&, const T3 ,e_none   )
      synthesis_node_type_define(const T0 ,const T1&,const T2 , const T3 ,e_none   )
      synthesis_node_type_define(const T0&,const T1 ,const T2 , const T3 ,e_none   )
      synthesis_node_type_define(const T0 ,const T1 ,const T2&, const T3&,e_none   )
      synthesis_node_type_define(const T0&,const T1&,const T2 , const T3 ,e_none   )
      #undef synthesis_node_type_define

      template <typename T, typename T0, typename T1>
      class T0oT1 : public expression_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;
         typedef T value_type;
         typedef T0oT1<T,T0,T1> node_type;

         T0oT1(T0 p0, T1 p1, const bfunc_t p2)
         : t0_(p0),
           t1_(p1),
           f_ (p2)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1<T,T0,T1>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return f_(t0_,t1_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline bfunc_t f() const
         {
            return f_;
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator,
                                                    T0 p0, T1 p1,
                                                    bfunc_t p2)
         {
            return allocator.template allocate_type<node_type,T0,T1,bfunc_t&>(p0,p1,p2);
         }

      private:

         T0oT1(T0oT1<T,T0,T1>&) {}
         T0oT1<T,T0,T1>& operator=(T0oT1<T,T0,T1>&) { return *this; }

         T0 t0_;
         T1 t1_;
         const bfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2, typename ProcessMode>
      class T0oT1oT2 : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;
         typedef T value_type;
         typedef T0oT1oT2<T,T0,T1,T2,ProcessMode> node_type;
         typedef ProcessMode process_mode_t;

         T0oT1oT2(T0 p0, T1 p1, T2 p2, const bfunc_t p3, const bfunc_t p4)
         : t0_(p0),
           t1_(p1),
           t2_(p2),
           f0_(p3),
           f1_(p4)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return ProcessMode::process(t0_,t1_,t2_,f0_,f1_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         bfunc_t f0() const
         {
            return f0_;
         }

         bfunc_t f1() const
         {
            return f1_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return process_mode_t::template id<T0,T1,T2>();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, bfunc_t p3, bfunc_t p4)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2,bfunc_t,bfunc_t>(p0,p1,p2,p3,p4);
         }

      private:

         T0oT1oT2(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
         const bfunc_t f0_;
         const bfunc_t f1_;
      };

      template <typename T, typename T0_, typename T1_, typename T2_, typename T3_, typename ProcessMode>
      class T0oT1oT2oT3 : public T0oT1oT2oT3_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::bfunc_t      bfunc_t;
         typedef T value_type;
         typedef T0_ T0;
         typedef T1_ T1;
         typedef T2_ T2;
         typedef T3_ T3;
         typedef T0oT1oT2oT3<T,T0,T1,T2,T3,ProcessMode> node_type;
         typedef ProcessMode process_mode_t;

         T0oT1oT2oT3(T0 p0, T1 p1, T2 p2, T3 p3, bfunc_t p4, bfunc_t p5, bfunc_t p6)
         : t0_(p0),
           t1_(p1),
           t2_(p2),
           t3_(p3),
           f0_(p4),
           f1_(p5),
           f2_(p6)
         {}

         inline T value() const
         {
            return ProcessMode::process(t0_,t1_,t2_,t3_,f0_,f1_,f2_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t3_;
         }

         inline bfunc_t f0() const
         {
            return f0_;
         }

         inline bfunc_t f1() const
         {
            return f1_;
         }

         inline bfunc_t f2() const
         {
            return f2_;
         }

         inline std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return process_mode_t::template id<T0,T1,T2,T3>();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator,
                                                    T0 p0, T1 p1, T2 p2, T3 p3,
                                                    bfunc_t p4, bfunc_t p5, bfunc_t p6)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2,T3,bfunc_t,bfunc_t>(p0,p1,p2,p3,p4,p5,p6);
         }

      private:

         T0oT1oT2oT3(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
         const bfunc_t f0_;
         const bfunc_t f1_;
         const bfunc_t f2_;
      };

      template <typename T, typename T0, typename T1, typename T2>
      class T0oT1oT2_sf3 : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::tfunc_t      tfunc_t;
         typedef T value_type;
         typedef T0oT1oT2_sf3<T,T0,T1,T2> node_type;

         T0oT1oT2_sf3(T0 p0, T1 p1, T2 p2, const tfunc_t p3)
         : t0_(p0),
           t1_(p1),
           t2_(p2),
           f_ (p3)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return f_(t0_,t1_,t2_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         tfunc_t f() const
         {
            return f_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return "sf3";
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, tfunc_t p3)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2,tfunc_t>(p0,p1,p2,p3);
         }

      private:

         T0oT1oT2_sf3(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
         const tfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2>
      class sf3ext_type_node : public T0oT1oT2_base_node<T>
      {
      public:

         virtual T0 t0() const = 0;

         virtual T1 t1() const = 0;

         virtual T2 t2() const = 0;
      };

      template <typename T, typename T0, typename T1, typename T2, typename SF3Operation>
      class T0oT1oT2_sf3ext : public sf3ext_type_node<T,T0,T1,T2>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::tfunc_t      tfunc_t;
         typedef T value_type;
         typedef T0oT1oT2_sf3ext<T,T0,T1,T2,SF3Operation> node_type;

         T0oT1oT2_sf3ext(T0 p0, T1 p1, T2 p2)
         : t0_(p0),
           t1_(p1),
           t2_(p2)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2<T,T0,T1,T2>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return SF3Operation::process(t0_,t1_,t2_);
         }

         T0 t0() const
         {
            return t0_;
         }

         T1 t1() const
         {
            return t1_;
         }

         T2 t2() const
         {
            return t2_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return SF3Operation::id();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2>(p0,p1,p2);
         }

      private:

         T0oT1oT2_sf3ext(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
      };

      template <typename T>
      inline bool is_sf3ext_node(const expression_node<T>* n)
      {
         switch (n->type())
         {
            case expression_node<T>::e_vovov : return true;
            case expression_node<T>::e_vovoc : return true;
            case expression_node<T>::e_vocov : return true;
            case expression_node<T>::e_covov : return true;
            case expression_node<T>::e_covoc : return true;
            default                          : return false;
         }
      }

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      class T0oT1oT2oT3_sf4 : public T0oT1oT2_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::qfunc_t      qfunc_t;
         typedef T value_type;
         typedef T0oT1oT2oT3_sf4<T,T0,T1,T2,T3> node_type;

         T0oT1oT2oT3_sf4(T0 p0, T1 p1, T2 p2, T3 p3, const qfunc_t p4)
         : t0_(p0),
           t1_(p1),
           t2_(p2),
           t3_(p3),
           f_ (p4)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return f_(t0_,t1_,t2_,t3_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t3_;
         }

         qfunc_t f() const
         {
            return f_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return "sf4";
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, T3 p3, qfunc_t p4)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2,T3,qfunc_t>(p0,p1,p2,p3,p4);
         }

      private:

         T0oT1oT2oT3_sf4(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
         const qfunc_t f_;
      };

      template <typename T, typename T0, typename T1, typename T2, typename T3, typename SF4Operation>
      class T0oT1oT2oT3_sf4ext : public T0oT1oT2oT3_base_node<T>
      {
      public:

         typedef typename details::functor_t<T> functor_t;
         typedef typename functor_t::tfunc_t      tfunc_t;
         typedef T value_type;
         typedef T0oT1oT2oT3_sf4ext<T,T0,T1,T2,T3,SF4Operation> node_type;

         T0oT1oT2oT3_sf4ext(T0 p0, T1 p1, T2 p2, T3 p3)
         : t0_(p0),
           t1_(p1),
           t2_(p2),
           t3_(p3)
         {}

         inline typename expression_node<T>::node_type type() const
         {
            static const typename expression_node<T>::node_type result = nodetype_T0oT1oT2oT3<T,T0,T1,T2,T3>::result;
            return result;
         }

         inline operator_type operation() const
         {
            return e_default;
         }

         inline T value() const
         {
            return SF4Operation::process(t0_,t1_,t2_,t3_);
         }

         inline T0 t0() const
         {
            return t0_;
         }

         inline T1 t1() const
         {
            return t1_;
         }

         inline T2 t2() const
         {
            return t2_;
         }

         inline T3 t3() const
         {
            return t2_;
         }

         std::string type_id() const
         {
            return id();
         }

         static inline std::string id()
         {
            return SF4Operation::id();
         }

         template <typename Allocator>
         static inline expression_node<T>* allocate(Allocator& allocator, T0 p0, T1 p1, T2 p2, T3 p3)
         {
            return allocator.template allocate_type<node_type,T0,T1,T2,T3>(p0,p1,p2,p3);
         }

      private:

         T0oT1oT2oT3_sf4ext(node_type&) {}
         node_type& operator=(node_type&) { return *this; }

         T0 t0_;
         T1 t1_;
         T2 t2_;
         T3 t3_;
      };

      template <typename T>
      inline bool is_sf4ext_node(const expression_node<T>* n)
      {
         switch (n->type())
         {
            case expression_node<T>::e_vovovov : return true;
            case expression_node<T>::e_vovovoc : return true;
            case expression_node<T>::e_vovocov : return true;
            case expression_node<T>::e_vocovov : return true;
            case expression_node<T>::e_covovov : return true;
            case expression_node<T>::e_covocov : return true;
            case expression_node<T>::e_vocovoc : return true;
            case expression_node<T>::e_covovoc : return true;
            case expression_node<T>::e_vococov : return true;
            default                            : return false;
         }
      }

      template <typename T, typename T0, typename T1>
      struct T0oT1_define
      {
         typedef details::T0oT1<T,T0,T1> type0;
      };

      template <typename T, typename T0, typename T1, typename T2>
      struct T0oT1oT2_define
      {
         typedef details::T0oT1oT2<T,T0,T1,T2,typename T0oT1oT2process<T>::mode0> type0;
         typedef details::T0oT1oT2<T,T0,T1,T2,typename T0oT1oT2process<T>::mode1> type1;
         typedef details::T0oT1oT2_sf3<T,T0,T1,T2> sf3_type;
         typedef details::sf3ext_type_node<T,T0,T1,T2> sf3_type_node;
      };

      template <typename T, typename T0, typename T1, typename T2, typename T3>
      struct T0oT1oT2oT3_define
      {
         typedef details::T0oT1oT2oT3<T,T0,T1,T2,T3,typename T0oT1oT20T3process<T>::mode0> type0;
         typedef details::T0oT1oT2oT3<T,T0,T1,T2,T3,typename T0oT1oT20T3process<T>::mode1> type1;
         typedef details::T0oT1oT2oT3<T,T0,T1,T2,T3,typename T0oT1oT20T3process<T>::mode2> type2;
         typedef details::T0oT1oT2oT3<T,T0,T1,T2,T3,typename T0oT1oT20T3process<T>::mode3> type3;
         typedef details::T0oT1oT2oT3<T,T0,T1,T2,T3,typename T0oT1oT20T3process<T>::mode4> type4;
         typedef details::T0oT1oT2oT3_sf4<T,T0,T1,T2,T3> sf4_type;
      };

      template <typename T, typename Operation>
      class vov_node : public vov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // variable op variable node
         explicit vov_node(const T& var0, const T& var1)
         : v0_(var0),
           v1_(var1)
         {}

         inline T value() const
         {
            return Operation::process(v0_,v1_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T& v0() const
         {
            return v0_;
         }

         inline const T& v1() const
         {
            return v1_;
         }

      protected:

         const T& v0_;
         const T& v1_;

      private:

         vov_node(vov_node<T,Operation>&);
         vov_node<T,Operation>& operator=(vov_node<T,Operation>&);
      };

      template <typename T, typename Operation>
      class cov_node : public cov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // constant op variable node
         explicit cov_node(const T& const_var, const T& var)
         : c_(const_var),
           v_(var)
         {}

         inline T value() const
         {
            return Operation::process(c_,v_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T c() const
         {
            return c_;
         }

         inline const T& v() const
         {
            return v_;
         }

      protected:

         const T  c_;
         const T& v_;

      private:

         cov_node(const cov_node<T,Operation>&);
         cov_node<T,Operation>& operator=(const cov_node<T,Operation>&);
      };

      template <typename T, typename Operation>
      class voc_node : public voc_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // variable op constant node
         explicit voc_node(const T& var, const T& const_var)
         : v_(var),
           c_(const_var)
         {}

         inline T value() const
         {
            return Operation::process(v_,c_);
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T c() const
         {
            return c_;
         }

         inline const T& v() const
         {
            return v_;
         }

      protected:

         const T& v_;
         const T  c_;

      private:

         voc_node(const voc_node<T,Operation>&);
         voc_node<T,Operation>& operator=(const voc_node<T,Operation>&);
      };

      template <typename T, typename Operation>
      class vob_node : public vob_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // variable op constant node
         explicit vob_node(const T& var, const expression_ptr brnch)
         : v_(var)
         {
            init_branches<1>(branch_,brnch);
         }

        ~vob_node()
         {
            cleanup_branches::execute<T,1>(branch_);
         }

         inline T value() const
         {
            return Operation::process(v_,branch_[0].first->value());
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T& v() const
         {
            return v_;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_[0].first;
         }

      private:

         vob_node(const vob_node<T,Operation>&);
         vob_node<T,Operation>& operator=(const vob_node<T,Operation>&);

         const T& v_;
         branch_t branch_[1];
      };

      template <typename T, typename Operation>
      class bov_node : public bov_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // variable op constant node
         explicit bov_node(const expression_ptr brnch, const T& var)
         : v_(var)
         {
            init_branches<1>(branch_,brnch);
         }

        ~bov_node()
         {
            cleanup_branches::execute<T,1>(branch_);
         }

         inline T value() const
         {
            return Operation::process(branch_[0].first->value(),v_);
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T& v() const
         {
            return v_;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_[0].first;
         }

      private:

         bov_node(const bov_node<T,Operation>&);
         bov_node<T,Operation>& operator=(const bov_node<T,Operation>&);

         const T& v_;
         branch_t branch_[1];
      };

      template <typename T, typename Operation>
      class cob_node : public cob_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // variable op constant node
         explicit cob_node(const T const_var, const expression_ptr brnch)
         : c_(const_var)
         {
            init_branches<1>(branch_,brnch);
         }

        ~cob_node()
         {
            cleanup_branches::execute<T,1>(branch_);
         }

         inline T value() const
         {
            return Operation::process(c_,branch_[0].first->value());
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T c() const
         {
            return c_;
         }

         inline void set_c(const T new_c)
         {
            (*const_cast<T*>(&c_)) = new_c;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_[0].first;
         }

         inline expression_node<T>* move_branch(const std::size_t&)
         {
            branch_[0].second = false;
            return branch_[0].first;
         }

      private:

         cob_node(const cob_node<T,Operation>&);
         cob_node<T,Operation>& operator=(const cob_node<T,Operation>&);

         const T c_;
         branch_t branch_[1];
      };

      template <typename T, typename Operation>
      class boc_node : public boc_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef std::pair<expression_ptr,bool> branch_t;
         typedef Operation operation_t;

         // variable op constant node
         explicit boc_node(const expression_ptr brnch, const T const_var)
         : c_(const_var)
         {
            init_branches<1>(branch_,brnch);
         }

        ~boc_node()
         {
            cleanup_branches::execute<T,1>(branch_);
         }

         inline T value() const
         {
            return Operation::process(branch_[0].first->value(),c_);
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline const T c() const
         {
            return c_;
         }

         inline void set_c(const T new_c)
         {
            (*const_cast<T*>(&c_)) = new_c;
         }

         inline expression_node<T>* branch(const std::size_t&) const
         {
            return branch_[0].first;
         }

         inline expression_node<T>* move_branch(const std::size_t&)
         {
            branch_[0].second = false;
            return branch_[0].first;
         }

      private:

         boc_node(const boc_node<T,Operation>&);
         boc_node<T,Operation>& operator=(const boc_node<T,Operation>&);

         const T c_;
         branch_t branch_[1];
      };

      #ifndef exprtk_disable_string_capabilities
      template <typename T, typename SType0, typename SType1, typename Operation>
      class sos_node : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // string op string node
         explicit sos_node(SType0 p0, SType1 p1)
         : s0_(p0),
           s1_(p1)
         {}

         inline T value() const
         {
            return Operation::process(s0_,s1_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0 s0_;
         SType1 s1_;

      private:

         sos_node(sos_node<T,SType0,SType1,Operation>&);
         sos_node<T,SType0,SType1,Operation>& operator=(sos_node<T,SType0,SType1,Operation>&);
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xrox_node : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // string-range op string node
         explicit str_xrox_node(SType0 p0, SType1 p1, RangePack rp0)
         : s0_(p0),
           s1_(p1),
           rp0_(rp0)
         {}

        ~str_xrox_node()
         {
            rp0_.free();
         }

         inline T value() const
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            if (rp0_(r0,r1,s0_.size()))
               return Operation::process(s0_.substr(r0,(r1 - r0) + 1),s1_);
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp0_;

      private:

         str_xrox_node(str_xrox_node<T,SType0,SType1,RangePack,Operation>&);
         str_xrox_node<T,SType0,SType1,RangePack,Operation>& operator=(str_xrox_node<T,SType0,SType1,RangePack,Operation>&);
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xoxr_node : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // string op string range node
         explicit str_xoxr_node(SType0 p0, SType1 p1, RangePack rp1)
         : s0_ (p0 ),
           s1_ (p1 ),
           rp1_(rp1)
         {}

        ~str_xoxr_node()
         {
            rp1_.free();
         }

         inline T value() const
         {
            std::size_t r0 = 0;
            std::size_t r1 = 0;

            if (rp1_(r0,r1,s1_.size()))
               return Operation::process(s0_,s1_.substr(r0,(r1 - r0) + 1));
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp1_;

      private:

         str_xoxr_node(str_xoxr_node<T,SType0,SType1,RangePack,Operation>&);
         str_xoxr_node<T,SType0,SType1,RangePack,Operation>& operator=(str_xoxr_node<T,SType0,SType1,RangePack,Operation>&);
      };

      template <typename T, typename SType0, typename SType1, typename RangePack, typename Operation>
      class str_xroxr_node : public sos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // string-range op string-range node
         explicit str_xroxr_node(SType0 p0, SType1 p1, RangePack rp0, RangePack rp1)
         : s0_ (p0 ),
           s1_ (p1 ),
           rp0_(rp0),
           rp1_(rp1)
         {}

        ~str_xroxr_node()
         {
            rp0_.free();
            rp1_.free();
         }

         inline T value() const
         {
            std::size_t r0_0 = 0;
            std::size_t r0_1 = 0;
            std::size_t r1_0 = 0;
            std::size_t r1_1 = 0;
            if (
                 rp0_(r0_0,r1_0,s0_.size()) &&
                 rp1_(r0_1,r1_1,s1_.size())
               )
            {
               return Operation::process(
                                          s0_.substr(r0_0,(r1_0 - r0_0) + 1),
                                          s1_.substr(r0_1,(r1_1 - r0_1) + 1)
                                        );
            }
            else
               return T(0);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

      protected:

         SType0    s0_;
         SType1    s1_;
         RangePack rp0_;
         RangePack rp1_;

      private:

         str_xroxr_node(str_xroxr_node<T,SType0,SType1,RangePack,Operation>&);
         str_xroxr_node<T,SType0,SType1,RangePack,Operation>& operator=(str_xroxr_node<T,SType0,SType1,RangePack,Operation>&);
      };

      template <typename T, typename Operation>
      class str_sogens_node : public binary_node<T>
      {
      public:

         typedef expression_node <T>* expression_ptr;
         typedef string_base_node<T>*   str_base_ptr;
         typedef range_pack      <T>         range_t;
         typedef range_t*                  range_ptr;
         typedef range_interface<T>         irange_t;
         typedef irange_t*                irange_ptr;

         str_sogens_node(const operator_type& opr,
                         expression_ptr branch0,
                         expression_ptr branch1)
         : binary_node<T>(opr,branch0,branch1),
           str0_base_ptr_ (0),
           str1_base_ptr_ (0),
           str0_range_ptr_(0),
           str1_range_ptr_(0)
         {
            if (is_generally_string_node(binary_node<T>::branch_[0].first))
            {
               str0_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[0].first);

               if (0 == str0_base_ptr_)
                  return;

               irange_ptr range_ptr = dynamic_cast<irange_ptr>(binary_node<T>::branch_[0].first);

               if (0 == range_ptr)
                  return;

               str0_range_ptr_ = &(range_ptr->range_ref());
            }

            if (is_generally_string_node(binary_node<T>::branch_[1].first))
            {
               str1_base_ptr_ = dynamic_cast<str_base_ptr>(binary_node<T>::branch_[1].first);

               if (0 == str1_base_ptr_)
                  return;

               irange_ptr range_ptr = dynamic_cast<irange_ptr>(binary_node<T>::branch_[1].first);

               if (0 == range_ptr)
                  return;

               str1_range_ptr_ = &(range_ptr->range_ref());
            }
         }

         inline T value() const
         {
            if (
                 str0_base_ptr_  &&
                 str1_base_ptr_  &&
                 str0_range_ptr_ &&
                 str1_range_ptr_
               )
            {
               binary_node<T>::branch_[0].first->value();
               binary_node<T>::branch_[1].first->value();

               std::size_t str0_r0 = 0;
               std::size_t str0_r1 = 0;

               std::size_t str1_r0 = 0;
               std::size_t str1_r1 = 0;

               range_t& range0 = (*str0_range_ptr_);
               range_t& range1 = (*str1_range_ptr_);

               if (
                    range0(str0_r0,str0_r1,str0_base_ptr_->size()) &&
                    range1(str1_r0,str1_r1,str1_base_ptr_->size())
                  )
               {
                  return Operation::process(
                                             str0_base_ptr_->str().substr(str0_r0,(str0_r1 - str0_r0) + 1),
                                             str1_base_ptr_->str().substr(str1_r0,(str1_r1 - str1_r0) + 1)
                                           );
               }
            }

            return std::numeric_limits<T>::quiet_NaN();
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

      private:

         str_sogens_node(str_sogens_node<T,Operation>&);
         str_sogens_node<T,Operation>& operator=(str_sogens_node<T,Operation>&);

         str_base_ptr str0_base_ptr_;
         str_base_ptr str1_base_ptr_;
         range_ptr    str0_range_ptr_;
         range_ptr    str1_range_ptr_;
      };

      template <typename T, typename SType0, typename SType1, typename SType2, typename Operation>
      class sosos_node : public sosos_base_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef Operation operation_t;

         // variable op variable node
         explicit sosos_node(SType0 p0, SType1 p1, SType2 p2)
         : s0_(p0),
           s1_(p1),
           s2_(p2)
         {}

         inline T value() const
         {
            return Operation::process(s0_,s1_,s2_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return Operation::type();
         }

         inline operator_type operation() const
         {
            return Operation::operation();
         }

         inline std::string& s0()
         {
            return s0_;
         }

         inline std::string& s1()
         {
            return s1_;
         }

         inline std::string& s2()
         {
            return s2_;
         }

      protected:

         SType0 s0_;
         SType1 s1_;
         SType2 s2_;

      private:

         sosos_node(sosos_node<T,SType0,SType1,SType2,Operation>&);
         sosos_node<T,SType0,SType1,SType2,Operation>& operator=(sosos_node<T,SType0,SType1,SType2,Operation>&);
      };
      #endif

      template <typename T, typename PowOp>
      class ipow_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef PowOp operation_t;

         explicit ipow_node(const T& v)
         : v_(v)
         {}

         inline T value() const
         {
            return PowOp::result(v_);
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_ipow;
         }

      private:

         ipow_node(const ipow_node<T,PowOp>&);
         ipow_node<T,PowOp>& operator=(const ipow_node<T,PowOp>&);

         const T& v_;
      };

      template <typename T, typename PowOp>
      class ipowinv_node : public expression_node<T>
      {
      public:

         typedef expression_node<T>* expression_ptr;
         typedef PowOp operation_t;

         explicit ipowinv_node(const T& v)
         : v_(v)
         {}

         inline T value() const
         {
            return (T(1) / PowOp::result(v_));
         }

         inline typename expression_node<T>::node_type type() const
         {
            return expression_node<T>::e_ipowinv;
         }

      private:

         ipowinv_node(const ipowinv_node<T,PowOp>&);
         ipowinv_node<T,PowOp>& operator=(const ipowinv_node<T,PowOp>&);

         const T& v_;
      };

      template <typename T>
      inline bool is_vov_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const vov_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_cov_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const cov_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_voc_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const voc_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_cob_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const cob_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_boc_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const boc_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_t0ot1ot2_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const T0oT1oT2_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_t0ot1ot2ot3_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const T0oT1oT2oT3_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_uv_node(const expression_node<T>* node)
      {
         return (0 != dynamic_cast<const uv_base_node<T>*>(node));
      }

      template <typename T>
      inline bool is_string_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringvar == node->type());
      }

      template <typename T>
      inline bool is_string_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringvarrng == node->type());
      }

      template <typename T>
      inline bool is_const_string_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_stringconst == node->type());
      }

      template <typename T>
      inline bool is_const_string_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_cstringvarrng == node->type());
      }

      template <typename T>
      inline bool is_string_assignment_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strass == node->type());
      }

      template <typename T>
      inline bool is_string_concat_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strconcat == node->type());
      }

      template <typename T>
      inline bool is_string_function_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strfunction == node->type());
      }

      template <typename T>
      inline bool is_string_condition_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strcondition == node->type());
      }

      template <typename T>
      inline bool is_string_ccondition_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strccondition == node->type());
      }

      template <typename T>
      inline bool is_genricstring_range_node(const expression_node<T>* node)
      {
         return node && (expression_node<T>::e_strgenrange == node->type());
      }

      template <typename T>
      inline bool is_generally_string_node(const expression_node<T>* node)
      {
         if (node)
         {
            switch (node->type())
            {
               case expression_node<T>::e_stringvar     :
               case expression_node<T>::e_stringconst   :
               case expression_node<T>::e_stringvarrng  :
               case expression_node<T>::e_cstringvarrng :
               case expression_node<T>::e_strgenrange   :
               case expression_node<T>::e_strass        :
               case expression_node<T>::e_strconcat     :
               case expression_node<T>::e_strfunction   :
               case expression_node<T>::e_strcondition  :
               case expression_node<T>::e_strccondition : return true;
               default                                  : return false;
            }
         }

         return false;
      }

      class node_allocator
      {
      public:

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[1])
         {
            return allocate<ResultNode>(operation,branch[0]);
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[2])
         {
            return allocate<ResultNode>(operation,branch[0],branch[1]);
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[3])
         {
            return allocate<ResultNode>(operation,branch[0],branch[1],branch[2]);
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[4])
         {
            return allocate<ResultNode>(operation,branch[0],branch[1],branch[2],branch[3]);
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[5])
         {
            return allocate<ResultNode>(operation,branch[0],branch[1],branch[2],branch[3],branch[4]);
         }

         template <typename ResultNode, typename OpType, typename ExprNode>
         inline expression_node<typename ResultNode::value_type>* allocate(OpType& operation, ExprNode (&branch)[6])
         {
            return allocate<ResultNode>(operation,branch[0],branch[1],branch[2],branch[3],branch[4],branch[5]);
         }

         template <typename node_type>
         inline expression_node<typename node_type::value_type>* allocate() const
         {
            return new node_type();
         }

         template <typename node_type,
                   typename Type,
                   typename Allocator,
                   template <typename,typename> class Sequence>
         inline expression_node<typename node_type::value_type>* allocate(const Sequence<Type,Allocator>& seq) const
         {
            return new node_type(seq);
         }

         template <typename node_type, typename T1>
         inline expression_node<typename node_type::value_type>* allocate(T1& t1) const
         {
            return new node_type(t1);
         }

         template <typename node_type, typename T1>
         inline expression_node<typename node_type::value_type>* allocate_c(const T1& t1) const
         {
            return new node_type(t1);
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2) const
         {
            return new node_type(t1,t2);
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_cr(const T1& t1, T2& t2) const
         {
            return new node_type(t1,t2);
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_rc(T1& t1, const T2& t2) const
         {
            return new node_type(t1,t2);
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_rr(T1& t1, T2& t2) const
         {
            return new node_type(t1,t2);
         }

         template <typename node_type,
                   typename T1, typename T2>
         inline expression_node<typename node_type::value_type>* allocate_tt(T1 t1, T2 t2) const
         {
            return new node_type(t1,t2);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_ttt(T1 t1, T2 t2, T3 t3) const
         {
            return new node_type(t1,t2,t3);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_tttt(T1 t1, T2 t2, T3 t3, T4 t4) const
         {
            return new node_type(t1,t2,t3,t4);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_rrr(T1& t1, T2& t2, T3& t3) const
         {
            return new node_type(t1,t2,t3);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_rrrr(T1& t1, T2& t2, T3& t3, T4& t4) const
         {
            return new node_type(t1,t2,t3,t4);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3, typename T4, typename T5>
         inline expression_node<typename node_type::value_type>* allocate_rrrrr(T1& t1, T2& t2, T3& t3, T4& t4, T5& t5) const
         {
            return new node_type(t1,t2,t3,t4,t5);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3) const
         {
            return new node_type(t1,t2,t3);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4) const
         {
            return new node_type(t1,t2,t3,t4);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4, typename T5>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5) const
         {
            return new node_type(t1,t2,t3,t4,t5);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4, typename T5, typename T6>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6, typename T7>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6,t7);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7, const T8& t8) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6,t7,t8);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8, typename T9>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const T2& t2,
                                                                          const T3& t3, const T4& t4,
                                                                          const T5& t5, const T6& t6,
                                                                          const T7& t7, const T8& t8,
                                                                          const T9& t9) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6,t7,t8,t9);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6,
                   typename T7, typename T8,
                   typename T9, typename T10>
         inline expression_node<typename node_type::value_type>* allocate(const T1& t1, const  T2&  t2,
                                                                          const T3& t3, const  T4&  t4,
                                                                          const T5& t5, const  T6&  t6,
                                                                          const T7& t7, const  T8&  t8,
                                                                          const T9& t9, const T10& t10) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6,t7,t8,t9,t10);
         }

         template <typename node_type,
                   typename T1, typename T2, typename T3>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2, T3 t3) const
         {
            return new node_type(t1,t2,t3);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4) const
         {
            return new node_type(t1,t2,t3,t4);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4,
                                                                               T5 t5) const
         {
            return new node_type(t1,t2,t3,t4,t5);
         }

         template <typename node_type,
                   typename T1, typename T2,
                   typename T3, typename T4,
                   typename T5, typename T6, typename T7>
         inline expression_node<typename node_type::value_type>* allocate_type(T1 t1, T2 t2,
                                                                               T3 t3, T4 t4,
                                                                               T5 t5, T6 t6,
                                                                               T7 t7) const
         {
            return new node_type(t1,t2,t3,t4,t5,t6,t7);
         }

         template <typename T>
         void inline free(expression_node<T>*& e) const
         {
            delete e;
            e = 0;
         }
      };

      inline void load_operations_map(std::multimap<std::string,details::base_operation_t,details::ilesscompare>& m)
      {
         #define register_op(Symbol,Type,Args)                                               \
         m.insert(std::make_pair(std::string(Symbol),details::base_operation_t(Type,Args))); \

         register_op(      "abs",e_abs     , 1)
         register_op(     "acos",e_acos    , 1)
         register_op(    "acosh",e_acosh   , 1)
         register_op(     "asin",e_asin    , 1)
         register_op(    "asinh",e_asinh   , 1)
         register_op(     "atan",e_atan    , 1)
         register_op(    "atanh",e_atanh   , 1)
         register_op(     "ceil",e_ceil    , 1)
         register_op(      "cos",e_cos     , 1)
         register_op(     "cosh",e_cosh    , 1)
         register_op(      "exp",e_exp     , 1)
         register_op(    "expm1",e_expm1   , 1)
         register_op(    "floor",e_floor   , 1)
         register_op(      "log",e_log     , 1)
         register_op(    "log10",e_log10   , 1)
         register_op(     "log2",e_log2    , 1)
         register_op(    "log1p",e_log1p   , 1)
         register_op(    "round",e_round   , 1)
         register_op(      "sin",e_sin     , 1)
         register_op(     "sinc",e_sinc    , 1)
         register_op(     "sinh",e_sinh    , 1)
         register_op(      "sec",e_sec     , 1)
         register_op(      "csc",e_csc     , 1)
         register_op(     "sqrt",e_sqrt    , 1)
         register_op(      "tan",e_tan     , 1)
         register_op(     "tanh",e_tanh    , 1)
         register_op(      "cot",e_cot     , 1)
         register_op(  "rad2deg",e_r2d     , 1)
         register_op(  "deg2rad",e_d2r     , 1)
         register_op( "deg2grad",e_d2g     , 1)
         register_op( "grad2deg",e_g2d     , 1)
         register_op(      "sgn",e_sgn     , 1)
         register_op(      "not",e_notl    , 1)
         register_op(      "erf",e_erf     , 1)
         register_op(     "erfc",e_erfc    , 1)
         register_op(     "ncdf",e_ncdf    , 1)
         register_op(     "frac",e_frac    , 1)
         register_op(    "trunc",e_trunc   , 1)
         register_op(    "atan2",e_atan2   , 2)
         register_op(      "mod",e_mod     , 2)
         register_op(     "logn",e_logn    , 2)
         register_op(      "pow",e_pow     , 2)
         register_op(     "root",e_root    , 2)
         register_op(   "roundn",e_roundn  , 2)
         register_op(    "equal",e_equal   , 2)
         register_op("not_equal",e_nequal  , 2)
         register_op(    "hypot",e_hypot   , 2)
         register_op(      "shr",e_shr     , 2)
         register_op(      "shl",e_shl     , 2)
         register_op(    "clamp",e_clamp   , 3)
         register_op(   "iclamp",e_iclamp  , 3)
         register_op(  "inrange",e_inrange , 3)
         #undef register_op
      }

   } // namespace details

   class function_traits
   {
   public:

      function_traits()
      : allow_zero_parameters_(false),
        has_side_effects_(true)
      {}

      inline bool& allow_zero_parameters()
      {
         return allow_zero_parameters_;
      }

      inline bool& has_side_effects()
      {
         return has_side_effects_;
      }

   private:

      bool allow_zero_parameters_;
      bool has_side_effects_;
   };

   template <typename FunctionType>
   void enable_zero_parameters(FunctionType& func)
   {
      func.allow_zero_parameters() = true;
   }

   template <typename FunctionType>
   void disable_zero_parameters(FunctionType& func)
   {
      func.allow_zero_parameters() = false;
   }

   template <typename FunctionType>
   void enable_has_side_effects(FunctionType& func)
   {
      func.has_side_effects() = true;
   }

   template <typename FunctionType>
   void disable_has_side_effects(FunctionType& func)
   {
      func.has_side_effects() = false;
   }

   template <typename T>
   class ifunction : public function_traits
   {
   public:

      explicit ifunction(const std::size_t& pc)
      : param_count(pc)
      {}

      virtual ~ifunction()
      {}

      inline virtual T operator()()
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&,const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      inline virtual T operator()(const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&,
                                  const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&, const T&)
      {
         return std::numeric_limits<T>::quiet_NaN();
      }

      std::size_t param_count;
   };

   template <typename T>
   class ivararg_function : public function_traits
   {
   public:

      virtual ~ivararg_function()
      {}

      inline virtual T operator()(const std::vector<T>&)
      {
         exprtk_debug(("ivararg_function::operator() - Operator has not been overridden.\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }
   };

   template <typename T>
   class igeneric_function : public function_traits
   {
   public:

      typedef T type;
      typedef type_store<T> generic_type;
      typedef typename generic_type::parameter_list parameter_list_t;

      igeneric_function(const std::string& param_seq = "")
      : parameter_sequence(param_seq)
      {}

      virtual ~igeneric_function()
      {}

      // f(i_0,i_1,....,i_N) --> Number
      inline virtual T operator()(parameter_list_t)
      {
         exprtk_debug(("igeneric_function::operator() - Operator has not been overridden. [1]\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }

      // f(i_0,i_1,....,i_N) --> String
      inline virtual T operator()(std::string&, parameter_list_t)
      {
         exprtk_debug(("igeneric_function::operator() - Operator has not been overridden. [2]\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }

      // f(psi,i_0,i_1,....,i_N) --> Number
      inline virtual T operator()(const std::size_t&, parameter_list_t)
      {
         exprtk_debug(("igeneric_function::operator() - Operator has not been overridden. [3]\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }

      // f(psi,i_0,i_1,....,i_N) --> String
      inline virtual T operator()(const std::size_t&, std::string&, parameter_list_t)
      {
         exprtk_debug(("igeneric_function::operator() - Operator has not been overridden. [4]\n"));
         return std::numeric_limits<T>::quiet_NaN();
      }

      std::string parameter_sequence;
   };

   template <typename T> class parser;
   template <typename T> class expression_helper;

   template <typename T>
   class symbol_table
   {
   protected:

      template <typename Type, typename RawType>
      struct type_store
      {
         typedef details::expression_node<T>*        expression_ptr;
         typedef typename details::variable_node<T>  variable_node_t;
         typedef ifunction<T>                        ifunction_t;
         typedef ivararg_function<T>                 ivararg_function_t;
         typedef igeneric_function<T>                igeneric_function_t;
         typedef details::vector_holder<T>           vector_t;
         #ifndef exprtk_disable_string_capabilities
         typedef typename details::stringvar_node<T> stringvar_node_t;
         #endif

         typedef Type type_t;
         typedef type_t* type_ptr;
         typedef std::pair<bool,type_ptr> type_pair_t;
         typedef std::map<std::string,type_pair_t,details::ilesscompare> type_map_t;
         typedef typename type_map_t::iterator tm_itr_t;
         typedef typename type_map_t::const_iterator tm_const_itr_t;

         enum { lut_size = 256 };

         type_map_t  map;
         std::size_t size;

         type_store()
         : size(0)
         {}

         inline bool symbol_exists(const std::string& symbol_name) const
         {
            if (symbol_name.empty())
               return false;
            else if (map.end() != map.find(symbol_name))
               return true;
            else
               return false;
         }

         template <typename PtrType>
         inline std::string entity_name(const PtrType& ptr) const
         {
            if (map.empty())
               return std::string();

            tm_const_itr_t itr = map.begin();

            while (map.end() != itr)
            {
               if (itr->second.second == ptr)
               {
                  return itr->first;
               }
               else
                  ++itr;
            }

            return std::string();
         }

         inline bool is_constant(const std::string& symbol_name) const
         {
            if (symbol_name.empty())
               return false;
            else
            {
               tm_const_itr_t itr = map.find(symbol_name);

               if (map.end() == itr)
                  return false;
               else
                  return (*itr).second.first;
            }
         }

         template <typename Tie, typename RType>
         inline bool add_impl(const std::string& symbol_name, RType t, const bool is_const)
         {
            if (symbol_name.size() > 1)
            {
               for (std::size_t i = 0; i < details::reserved_symbols_size; ++i)
               {
                  if (details::imatch(symbol_name,details::reserved_symbols[i]))
                  {
                     return false;
                  }
               }
            }

            tm_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
            {
               map[symbol_name] = Tie::make(t,is_const);
               ++size;
            }

            return true;
         }

         struct tie_array
         {
            static inline std::pair<bool,vector_t*> make(std::pair<T*,std::size_t> v, const bool is_const = false)
            {
               return std::make_pair(is_const,new vector_t(v.first,v.second));
            }
         };

         struct tie_stdvec
         {
            template <typename Allocator>
            static inline std::pair<bool,vector_t*> make(std::vector<T,Allocator>& v, const bool is_const = false)
            {
               return std::make_pair(is_const,new vector_t(v));
            }
         };

         struct tie_stddeq
         {
            template <typename Allocator>
            static inline std::pair<bool,vector_t*> make(std::deque<T,Allocator>& v, const bool is_const = false)
            {
               return std::make_pair(is_const,new vector_t(v));
            }
         };

         template <std::size_t v_size>
         inline bool add(const std::string& symbol_name, T (&v)[v_size], const bool is_const = false)
         {
            return add_impl<tie_array,std::pair<T*,std::size_t> >(symbol_name,std::make_pair(v,v_size),is_const);
         }

         inline bool add(const std::string& symbol_name, T* v, const std::size_t v_size, const bool is_const = false)
         {
            return add_impl<tie_array,std::pair<T*,std::size_t> >(symbol_name,std::make_pair(v,v_size),is_const);
         }

         template <typename Allocator>
         inline bool add(const std::string& symbol_name, std::vector<T,Allocator>& v, const bool is_const = false)
         {
            return add_impl<tie_stdvec,std::vector<T,Allocator>&>(symbol_name,v,is_const);
         }

         template <typename Allocator>
         inline bool add(const std::string& symbol_name, std::deque<T,Allocator>& v, const bool is_const = false)
         {
            return add_impl<tie_stddeq,std::deque<T,Allocator>&>(symbol_name,v,is_const);
         }

         inline bool add(const std::string& symbol_name, RawType& t, const bool is_const = false)
         {
            struct tie
            {
               static inline std::pair<bool,variable_node_t*> make(T& t,const bool is_const = false)
               {
                  return std::make_pair(is_const,new variable_node_t(t));
               }

               #ifndef exprtk_disable_string_capabilities
               static inline std::pair<bool,stringvar_node_t*> make(std::string& t,const bool is_const = false)
               {
                  return std::make_pair(is_const,new stringvar_node_t(t));
               }
               #endif

               static inline std::pair<bool,function_t*> make(function_t& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant,&t);
               }

               static inline std::pair<bool,vararg_function_t*> make(vararg_function_t& t, const bool is_const = false)
               {
                  return std::make_pair(is_const,&t);
               }

               static inline std::pair<bool,generic_function_t*> make(generic_function_t& t, const bool is_constant = false)
               {
                  return std::make_pair(is_constant,&t);
               }
            };

            tm_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
            {
               map[symbol_name] = tie::make(t,is_const);
               ++size;
            }

            return true;
         }

         inline type_ptr get(const std::string& symbol_name) const
         {
            tm_const_itr_t itr = map.find(symbol_name);

            if (map.end() == itr)
               return reinterpret_cast<type_ptr>(0);
            else
               return itr->second.second;
         }

         template <typename TType, typename TRawType, typename PtrType>
         struct ptr_match
         {
            static inline bool test(const PtrType, const void*)
            {
               return false;
            }
         };

         template <typename TType, typename TRawType>
         struct ptr_match<TType,TRawType,variable_node_t*>
         {
            static inline bool test(const variable_node_t* p, const void* ptr)
            {
               exprtk_debug(("ptr_match::test() - %p <--> %p\n",(void*)(&(p->ref())),ptr));
               return (&(p->ref()) == ptr);
            }
         };

         inline type_ptr get_from_varptr(const void* ptr) const
         {
            tm_const_itr_t itr = map.begin();

            while (map.end() != itr)
            {
               type_ptr ret_ptr = itr->second.second;

               if (ptr_match<Type,RawType,type_ptr>::test(ret_ptr,ptr))
               {
                  return ret_ptr;
               }

               ++itr;
            }

            return type_ptr(0);
         }

         inline bool remove(const std::string& symbol_name, const bool delete_node = true)
         {
            tm_itr_t itr = map.find(symbol_name);

            if (map.end() != itr)
            {
               struct deleter
               {
                  static inline void process(std::pair<bool,variable_node_t*>& n)  { delete n.second; }
                  static inline void process(std::pair<bool,vector_t*>& n)         { delete n.second; }
                  #ifndef exprtk_disable_string_capabilities
                  static inline void process(std::pair<bool,stringvar_node_t*>& n) { delete n.second; }
                  #endif
                  static inline void process(std::pair<bool,function_t*>&)         {                  }
               };

               if (delete_node)
               {
                  deleter::process((*itr).second);
               }

               map.erase(itr);
               --size;

               return true;
            }
            else
               return false;
         }

         inline RawType& type_ref(const std::string& symbol_name)
         {
            struct init_type
            {
               static inline double set(double)           { return (0.0);           }
               static inline double set(long double)      { return (0.0);           }
               static inline float  set(float)            { return (0.0f);          }
               static inline std::string set(std::string) { return std::string(""); }
            };

            static RawType null_type = init_type::set(RawType());

            tm_const_itr_t itr = map.find(symbol_name);
            if (map.end() == itr)
               return null_type;
            else
               return itr->second.second->ref();
         }

         inline void clear(const bool delete_node = true)
         {
            struct deleter
            {
               static inline void process(std::pair<bool,variable_node_t*>& n)  { delete n.second; }
               static inline void process(std::pair<bool,vector_t*>& n)         { delete n.second; }
               static inline void process(std::pair<bool,function_t*>&)         {                  }
               #ifndef exprtk_disable_string_capabilities
               static inline void process(std::pair<bool,stringvar_node_t*>& n) { delete n.second; }
               #endif
            };

            if (!map.empty())
            {
               if (delete_node)
               {
                  tm_itr_t itr = map.begin();
                  tm_itr_t end = map.end();

                  while (end != itr)
                  {
                     deleter::process((*itr).second);
                     ++itr;
                  }
               }

               map.clear();
            }

            size = 0;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t get_list(Sequence<std::pair<std::string,RawType>,Allocator>& list) const
         {
            std::size_t count = 0;

            if (!map.empty())
            {
               tm_const_itr_t itr = map.begin();
               tm_const_itr_t end = map.end();

               while (end != itr)
               {
                  list.push_back(std::make_pair((*itr).first,itr->second.second->ref()));
                  ++itr;
                  ++count;
               }
            }

            return count;
         }

         template <typename Allocator,
                   template <typename, typename> class Sequence>
         inline std::size_t get_list(Sequence<std::string,Allocator>& vlist) const
         {
            std::size_t count = 0;

            if (!map.empty())
            {
               tm_const_itr_t itr = map.begin();
               tm_const_itr_t end = map.end();

               while (end != itr)
               {
                  vlist.push_back((*itr).first);
                  ++itr;
                  ++count;
               }
            }

            return count;
         }
      };

      typedef details::expression_node<T>* expression_ptr;
      typedef typename details::variable_node<T> variable_t;
      typedef typename details::vector_holder<T> vector_holder_t;
      typedef variable_t* variable_ptr;
      #ifndef exprtk_disable_string_capabilities
      typedef typename details::stringvar_node<T> stringvar_t;
      typedef stringvar_t* stringvar_ptr;
      #endif
      typedef ifunction        <T> function_t;
      typedef ivararg_function <T> vararg_function_t;
      typedef igeneric_function<T> generic_function_t;
      typedef function_t* function_ptr;
      typedef vararg_function_t*  vararg_function_ptr;
      typedef generic_function_t* generic_function_ptr;

      static const std::size_t lut_size = 256;

      // Symbol Table Holder
      struct st_holder
      {
         struct st_data
         {
            type_store<typename details::variable_node<T>,T> variable_store;
            #ifndef exprtk_disable_string_capabilities
            type_store<typename details::stringvar_node<T>,std::string> stringvar_store;
            #endif
            type_store<ifunction<T>,ifunction<T> > function_store;
            type_store<ivararg_function <T>,ivararg_function <T> > vararg_function_store;
            type_store<igeneric_function<T>,igeneric_function<T> > generic_function_store;
            type_store<igeneric_function<T>,igeneric_function<T> > string_function_store;
            type_store<vector_holder_t,vector_holder_t> vector_store;

            st_data()
            {
               for (std::size_t i = 0; i < details::reserved_words_size; ++i)
               {
                  reserved_symbol_table_.insert(details::reserved_words[i]);
               }

               for (std::size_t i = 0; i < details::reserved_symbols_size; ++i)
               {
                  reserved_symbol_table_.insert(details::reserved_symbols[i]);
               }
            }

            inline bool is_reserved_symbol(const std::string& symbol) const
            {
               return (reserved_symbol_table_.end() != reserved_symbol_table_.find(symbol));
            }

            std::list<T> local_symbol_list_;
            std::list<std::string> local_stringvar_list_;
            std::set<std::string> reserved_symbol_table_;
         };

         st_holder()
         : ref_count(1),
           data_(new st_data)
         {}

         st_holder(st_data* data)
         : ref_count(1),
           data_(data)
         {}

        ~st_holder()
         {
            if (data_ && (0 == ref_count))
            {
               delete data_;
               data_ = 0;
            }
         }

         std::size_t ref_count;
         st_data* data_;
      };

   public:

      symbol_table()
      : holder_(new st_holder)
      {
         clear();
      }

     ~symbol_table()
      {
         if (holder_)
         {
            if (0 == --holder_->ref_count)
            {
               clear();
               delete holder_;
            }
         }
      }

      symbol_table(const symbol_table<T>& st)
      {
         holder_ = st.holder_;
         holder_->ref_count++;
      }

      inline symbol_table<T>& operator=(const symbol_table<T>& st)
      {
         if (holder_)
         {
            if (0 == --holder_->ref_count)
            {
               delete holder_;
            }

            holder_ = 0;
         }

         holder_ = st.holder_;
         holder_->ref_count++;

         return *this;
      }

      inline bool operator==(const symbol_table<T>& st)
      {
         return (this == &st) || (holder_ == st.holder_);
      }

      inline void clear_variables(const bool delete_node = true)
      {
         local_data().variable_store.clear(delete_node);
      }

      inline void clear_functions()
      {
         local_data().function_store.clear();
      }

      inline void clear_strings()
      {
         #ifndef exprtk_disable_string_capabilities
         local_data().stringvar_store.clear();
         #endif
      }

      inline void clear_vectors()
      {
         local_data().vector_store.clear();
      }

      inline void clear()
      {
         if (!valid()) return;
         clear_variables();
         clear_functions();
         clear_strings  ();
         clear_vectors  ();
      }

      inline std::size_t variable_count() const
      {
         if (valid())
            return local_data().variable_store.size;
         else
            return 0;
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::size_t stringvar_count() const
      {
         if (valid())
            return local_data().stringvar_store.size;
         else
            return 0;
      }
      #endif

      inline std::size_t function_count() const
      {
         if (valid())
            return local_data().function_store.size;
         else
            return 0;
      }

      inline std::size_t vector_count() const
      {
         if (valid())
            return local_data().vector_store.size;
         else
            return 0;
      }

      inline variable_ptr get_variable(const std::string& variable_name) const
      {
         if (!valid())
            return reinterpret_cast<variable_ptr>(0);
         else if (!valid_symbol(variable_name))
            return reinterpret_cast<variable_ptr>(0);
         else
            return local_data().variable_store.get(variable_name);
      }

      inline variable_ptr get_variable(const T& var_ref) const
      {
         if (!valid())
            return reinterpret_cast<variable_ptr>(0);
         else
            return local_data().variable_store.get_from_varptr(
                                                  reinterpret_cast<const void*>(&var_ref));
      }

      #ifndef exprtk_disable_string_capabilities
      inline stringvar_ptr get_stringvar(const std::string& string_name) const
      {
         if (!valid())
            return reinterpret_cast<stringvar_ptr>(0);
         else if (!valid_symbol(string_name))
            return reinterpret_cast<stringvar_ptr>(0);
         else
            return local_data().stringvar_store.get(string_name);
      }
      #endif

      inline function_ptr get_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<function_ptr>(0);
         else
            return local_data().function_store.get(function_name);
      }

      inline vararg_function_ptr get_vararg_function(const std::string& vararg_function_name) const
      {
         if (!valid())
            return reinterpret_cast<vararg_function_ptr>(0);
         else if (!valid_symbol(vararg_function_name))
            return reinterpret_cast<vararg_function_ptr>(0);
         else
            return local_data().vararg_function_store.get(vararg_function_name);
      }

      inline generic_function_ptr get_generic_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<generic_function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<generic_function_ptr>(0);
         else
            return local_data().generic_function_store.get(function_name);
      }

      inline generic_function_ptr get_string_function(const std::string& function_name) const
      {
         if (!valid())
            return reinterpret_cast<generic_function_ptr>(0);
         else if (!valid_symbol(function_name))
            return reinterpret_cast<generic_function_ptr>(0);
         else
            return local_data().string_function_store.get(function_name);
      }

      typedef vector_holder_t* vector_holder_ptr;

      inline vector_holder_ptr get_vector(const std::string& vector_name) const
      {
         if (!valid())
            return reinterpret_cast<vector_holder_ptr>(0);
         else if (!valid_symbol(vector_name))
            return reinterpret_cast<vector_holder_ptr>(0);
         else
            return local_data().vector_store.get(vector_name);
      }

      inline T& variable_ref(const std::string& symbol_name)
      {
         static T null_var = T(0);
         if (!valid())
            return null_var;
         else if (!valid_symbol(symbol_name))
            return null_var;
         else
            return local_data().variable_store.type_ref(symbol_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::string& stringvar_ref(const std::string& symbol_name)
      {
         static std::string null_stringvar;
         if (!valid())
            return null_stringvar;
         else if (!valid_symbol(symbol_name))
            return null_stringvar;
         else
            return local_data().stringvar_store.type_ref(symbol_name);
      }
      #endif

      inline bool is_constant_node(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else
            return local_data().variable_store.is_constant(symbol_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool is_constant_string(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else if (!local_data().stringvar_store.symbol_exists(symbol_name))
            return false;
         else
            return local_data().stringvar_store.is_constant(symbol_name);
      }
      #endif

      inline bool create_variable(const std::string& variable_name, const T& value = T(0))
      {
         if (!valid())
            return false;
         else if (!valid_symbol(variable_name))
            return false;
         else if (symbol_exists(variable_name))
            return false;

         local_data().local_symbol_list_.push_back(value);
         T& t = local_data().local_symbol_list_.back();

         return add_variable(variable_name,t);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool create_stringvar(const std::string& stringvar_name, const std::string& value = std::string(""))
      {
         if (!valid())
            return false;
         else if (!valid_symbol(stringvar_name))
            return false;
         else if (symbol_exists(stringvar_name))
            return false;

         local_data().local_stringvar_list_.push_back(value);
         std::string& s = local_data().local_stringvar_list_.back();

         return add_stringvar(stringvar_name,s);
      }
      #endif

      inline bool add_variable(const std::string& variable_name, T& t, const bool is_constant = false)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(variable_name))
            return false;
         else if (symbol_exists(variable_name))
            return false;
         else
            return local_data().variable_store.add(variable_name,t,is_constant);
      }

      inline bool add_constant(const std::string& constant_name, const T& value)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(constant_name))
            return false;
         else if (symbol_exists(constant_name))
            return false;

         local_data().local_symbol_list_.push_back(value);
         T& t = local_data().local_symbol_list_.back();

         return add_variable(constant_name,t,true);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool add_stringvar(const std::string& stringvar_name, std::string& s, const bool is_constant = false)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(stringvar_name))
            return false;
         else if (symbol_exists(stringvar_name))
            return false;
         else
            return local_data().stringvar_store.add(stringvar_name,s,is_constant);
      }
      #endif

      inline bool add_function(const std::string& function_name, function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name))
            return false;
         else if (symbol_exists(function_name))
            return false;
         else
            return local_data().function_store.add(function_name,function);
      }

      inline bool add_function(const std::string& vararg_function_name, vararg_function_t& vararg_function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vararg_function_name))
            return false;
         else if (symbol_exists(vararg_function_name))
            return false;
         else
            return local_data().vararg_function_store.add(vararg_function_name,vararg_function);
      }

      enum func_type
      {
         e_ft_unknown   = 0,
         e_ft_basicfunc = 1,
         e_ft_strfunc   = 2
      };

      inline bool add_function(const std::string& function_name, generic_function_t& function, const func_type ft = e_ft_basicfunc)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name))
            return false;
         else if (symbol_exists(function_name))
            return false;
         else if (std::string::npos != function.parameter_sequence.find_first_not_of("STV*?|"))
            return false;
         else if (e_ft_basicfunc == ft)
            return local_data().generic_function_store.add(function_name,function);
         else if (e_ft_strfunc == ft)
            return local_data().string_function_store.add(function_name, function);
         else
            return false;
      }

      inline bool add_reserved_function(const std::string& function_name, function_t& function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name,false))
            return false;
         else if (symbol_exists(function_name,false))
            return false;
         else
            return local_data().function_store.add(function_name,function);
      }

      inline bool add_reserved_function(const std::string& vararg_function_name, vararg_function_t& vararg_function)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vararg_function_name,false))
            return false;
         else if (symbol_exists(vararg_function_name,false))
            return false;
         else
            return local_data().vararg_function_store.add(vararg_function_name,vararg_function);
      }

      inline bool add_reserved_function(const std::string& function_name, generic_function_t& function, const func_type ft = e_ft_basicfunc)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(function_name,false))
            return false;
         else if (symbol_exists(function_name,false))
            return false;
         else if (std::string::npos != function.parameter_sequence.find_first_not_of("STV*?|"))
            return false;
         else if (e_ft_basicfunc == ft)
            return local_data().generic_function_store.add(function_name,function);
         else if (e_ft_strfunc == ft)
            return local_data().string_function_store.add(function_name, function);
         else
            return false;
      }

      template <std::size_t N>
      inline bool add_vector(const std::string& vector_name, T (&v)[N])
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      inline bool add_vector(const std::string& vector_name, T* v, const std::size_t& v_size)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else
            return local_data().vector_store.add(vector_name,v,v_size);
      }

      template <typename Allocator>
      inline bool add_vector(const std::string& vector_name, std::vector<T,Allocator>& v)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      template <typename Allocator>
      inline bool add_vector(const std::string& vector_name, std::deque<T,Allocator>& v)
      {
         if (!valid())
            return false;
         else if (!valid_symbol(vector_name))
            return false;
         else if (symbol_exists(vector_name))
            return false;
         else
            return local_data().vector_store.add(vector_name,v);
      }

      inline bool remove_variable(const std::string& variable_name, const bool delete_node = true)
      {
         if (!valid())
            return false;
         else
            return local_data().variable_store.remove(variable_name, delete_node);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool remove_stringvar(const std::string& string_name)
      {
         if (!valid())
            return false;
         else
            return local_data().stringvar_store.remove(string_name);
      }
      #endif

      inline bool remove_function(const std::string& function_name)
      {
         if (!valid())
            return false;
         else
            return local_data().function_store.remove(function_name);
      }

      inline bool remove_vararg_function(const std::string& vararg_function_name)
      {
         if (!valid())
            return false;
         else
            return local_data().vararg_function_store.remove(vararg_function_name);
      }

      inline bool remove_vector(const std::string& vector_name)
      {
         if (!valid())
            return false;
         else
            return local_data().vector_store.remove(vector_name);
      }

      inline bool add_constants()
      {
         return add_pi      () &&
                add_epsilon () &&
                add_infinity();
      }

      inline bool add_pi()
      {
         static const T local_pi = T(details::numeric::constant::pi);
         return add_constant("pi",local_pi);
      }

      inline bool add_epsilon()
      {
         static const T local_epsilon = details::numeric::details::epsilon_type<T>::value();
         return add_constant("epsilon",local_epsilon);
      }

      inline bool add_infinity()
      {
         static const T local_infinity = std::numeric_limits<T>::infinity();
         return add_constant("inf",local_infinity);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_variable_list(Sequence<std::pair<std::string,T>,Allocator>& vlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().variable_store.get_list(vlist);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_variable_list(Sequence<std::string,Allocator>& vlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().variable_store.get_list(vlist);
      }

      #ifndef exprtk_disable_string_capabilities
      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_stringvar_list(Sequence<std::pair<std::string,std::string>,Allocator>& svlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().stringvar_store.get_list(svlist);
      }

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_stringvar_list(Sequence<std::string,Allocator>& svlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().stringvar_store.get_list(svlist);
      }
      #endif

      template <typename Allocator,
                template <typename, typename> class Sequence>
      inline std::size_t get_vector_list(Sequence<std::string,Allocator>& vlist) const
      {
         if (!valid())
            return 0;
         else
            return local_data().vector_store.get_list(vlist);
      }

      inline bool symbol_exists(const std::string& symbol_name, const bool check_reserved_symb = true) const
      {
         /*
            Will return true if symbol_name exists as either a reserved symbol,
            variable, stringvar or function name in any of the type stores.
         */
         if (!valid())
            return false;
         else if (local_data().variable_store.symbol_exists(symbol_name))
            return true;
         #ifndef exprtk_disable_string_capabilities
         else if (local_data().stringvar_store.symbol_exists(symbol_name))
            return true;
         #endif
         else if (local_data().function_store.symbol_exists(symbol_name))
            return true;
         else if (check_reserved_symb && local_data().is_reserved_symbol(symbol_name))
            return true;
         else
            return false;
      }

      inline bool is_variable(const std::string& variable_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().variable_store.symbol_exists(variable_name);
      }

      #ifndef exprtk_disable_string_capabilities
      inline bool is_stringvar(const std::string& stringvar_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().stringvar_store.symbol_exists(stringvar_name);
      }

      inline bool is_conststr_stringvar(const std::string& symbol_name) const
      {
         if (!valid())
            return false;
         else if (!valid_symbol(symbol_name))
            return false;
         else if (!local_data().stringvar_store.symbol_exists(symbol_name))
            return false;

         return (
                  local_data().stringvar_store.symbol_exists(symbol_name) ||
                  local_data().stringvar_store.is_constant  (symbol_name)
                );
      }
      #endif

      inline bool is_function(const std::string& function_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().function_store.symbol_exists(function_name);
      }

      inline bool is_vararg_function(const std::string& vararg_function_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().vararg_function_store.symbol_exists(vararg_function_name);
      }

      inline bool is_vector(const std::string& vector_name) const
      {
         if (!valid())
            return false;
         else
            return local_data().vector_store.symbol_exists(vector_name);
      }

      inline std::string get_variable_name(const expression_ptr& ptr) const
      {
         return local_data().variable_store.entity_name(ptr);
      }

      inline std::string get_vector_name(const vector_holder_ptr& ptr) const
      {
         return local_data().vector_store.entity_name(ptr);
      }

      #ifndef exprtk_disable_string_capabilities
      inline std::string get_stringvar_name(const expression_ptr& ptr) const
      {
         return local_data().stringvar_store.entity_name(ptr);
      }

      inline std::string get_conststr_stringvar_name(const expression_ptr& ptr) const
      {
         return local_data().stringvar_store.entity_name(ptr);
      }
      #endif

      inline bool valid() const
      {
         // Symbol table sanity check.
         return holder_ && holder_->data_;
      }

      inline void load_from(const symbol_table<T>& st)
      {
         {
            std::vector<std::string> name_list;

            st.local_data().function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::ifunction<T>& ifunc = *st.get_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().vararg_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::ivararg_function<T>& ivafunc = *st.get_vararg_function(name_list[i]);
                  add_function(name_list[i],ivafunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().generic_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::igeneric_function<T>& ifunc = *st.get_generic_function(name_list[i]);
                  add_function(name_list[i],ifunc);
               }
            }
         }

         {
            std::vector<std::string> name_list;

            st.local_data().string_function_store.get_list(name_list);

            if (!name_list.empty())
            {
               for (std::size_t i = 0; i < name_list.size(); ++i)
               {
                  exprtk::igeneric_function<T>& ifunc = *st.get_string_function(name_list[i]);
                  add_function(name_list[i],ifunc,e_ft_strfunc);
               }
            }
         }
      }

   private:

      inline bool valid_symbol(const std::string& symbol, const bool check_reserved_symb = true) const
      {
         if (symbol.empty())
            return false;
         if (!details::is_letter(symbol[0]))
            return false;
         else if (symbol.size() > 1)
         {
            for (std::size_t i = 1; i < symbol.size(); ++i)
            {
               if (
                    (!details::is_letter(symbol[i])) &&
                    (!details:: is_digit(symbol[i])) &&
                    ('_' != symbol[i])
                  )
               {
                  return false;
               }
            }
         }

         return (check_reserved_symb) ? (!local_data().is_reserved_symbol(symbol)) : true;
      }

      inline bool valid_function(const std::string& symbol) const
      {
         if (symbol.empty())
            return false;
         if (!details::is_letter(symbol[0]))
            return false;
         else if (symbol.size() > 1)
         {
            for (std::size_t i = 1; i < symbol.size(); ++i)
            {
               if (
                    (!details::is_letter(symbol[i])) &&
                    (!details:: is_digit(symbol[i])) &&
                    ('_' != symbol[i])
                  )
               {
                  return false;
               }
            }
         }

         return true;
      }

      typedef typename st_holder::st_data local_data_t;

      inline local_data_t& local_data()
      {
         return *(holder_->data_);
      }

      inline const local_data_t& local_data() const
      {
         return *(holder_->data_);
      }

      st_holder* holder_;

      friend class parser<T>;
   };

   template <typename T>
   class function_compositor;

   template <typename T>
   class expression
   {
   private:

      typedef details::expression_node<T>*  expression_ptr;
      typedef details::vector_holder<T>* vector_holder_ptr;
      typedef std::vector<symbol_table<T> >  symtab_list_t;

      struct expression_holder
      {
         enum data_type
         {
            e_unknown  ,
            e_expr     ,
            e_vecholder,
            e_data     ,
            e_vecdata  ,
            e_string
         };

         struct data_pack
         {
            data_pack()
            : pointer(0),
              type(e_unknown),
              size(0)
            {}

            data_pack(void* ptr, data_type dt, std::size_t sz = 0)
            : pointer(ptr),
              type(dt),
              size(sz)
            {}

            void*       pointer;
            data_type   type;
            std::size_t size;
         };

         typedef std::vector<data_pack> local_data_list_t;
         typedef results_context<T>     results_context_t;

         expression_holder()
         : ref_count(0),
           expr     (0),
           results  (0),
           retinv_null(false),
           return_invoked(&retinv_null)
         {}

         expression_holder(expression_ptr e)
         : ref_count(1),
           expr     (e),
           results  (0),
           retinv_null(false),
           return_invoked(&retinv_null)
         {}

        ~expression_holder()
         {
            if (expr && details::branch_deletable(expr))
            {
               delete expr;
            }

            if (!local_data_list.empty())
            {
               for (std::size_t i = 0; i < local_data_list.size(); ++i)
               {
                  switch (local_data_list[i].type)
                  {
                     case e_expr      : delete reinterpret_cast<expression_ptr>(local_data_list[i].pointer);
                                        break;

                     case e_vecholder : delete reinterpret_cast<vector_holder_ptr>(local_data_list[i].pointer);
                                        break;

                     case e_data      : delete (T*)(local_data_list[i].pointer);
                                        break;

                     case e_vecdata   : delete [] (T*)(local_data_list[i].pointer);
                                        break;

                     case e_string    : delete (std::string*)(local_data_list[i].pointer);
                                        break;

                     default          : break;
                  }
               }
            }

            if (results)
            {
               delete results;
            }
         }

         std::size_t ref_count;
         expression_ptr expr;
         local_data_list_t local_data_list;
         results_context_t* results;
         bool  retinv_null;
         bool* return_invoked;

         friend class function_compositor<T>;
      };

   public:

      expression()
      : expression_holder_(0)
      {
         set_expression(new details::null_node<T>());
      }

      expression(const expression<T>& e)
      : expression_holder_(e.expression_holder_),
        symbol_table_list_(e.symbol_table_list_)
      {
         expression_holder_->ref_count++;
      }

      inline expression<T>& operator=(const expression<T>& e)
      {
         if (this != &e)
         {
            if (expression_holder_)
            {
               if (0 == --expression_holder_->ref_count)
               {
                  delete expression_holder_;
               }

               expression_holder_ = 0;
            }

            expression_holder_ = e.expression_holder_;
            expression_holder_->ref_count++;
            symbol_table_list_ = e.symbol_table_list_;
         }

         return *this;
      }

      inline bool operator==(const expression<T>& e)
      {
         return (this == &e);
      }

      inline bool operator!() const
      {
         return (
                  (0 == expression_holder_      ) ||
                  (0 == expression_holder_->expr)
                );
      }

      inline expression<T>& release()
      {
         if (expression_holder_)
         {
            if (0 == --expression_holder_->ref_count)
            {
               delete expression_holder_;
            }

            expression_holder_ = 0;
         }

         return *this;
      }

     ~expression()
      {
         if (expression_holder_)
         {
            if (0 == --expression_holder_->ref_count)
            {
               delete expression_holder_;
            }
         }
      }

      inline T value() const
      {
         return expression_holder_->expr->value();
      }

      inline T operator()() const
      {
         return value();
      }

      inline operator T() const
      {
         return value();
      }

      inline operator bool() const
      {
         return details::is_true(value());
      }

      inline void register_symbol_table(symbol_table<T>& st)
      {
         symbol_table_list_.push_back(st);
      }

      inline const symbol_table<T>& get_symbol_table(const std::size_t& index = 0) const
      {
         return symbol_table_list_[index];
      }

      inline symbol_table<T>& get_symbol_table(const std::size_t& index = 0)
      {
         return symbol_table_list_[index];
      }

      typedef results_context<T> results_context_t;

      inline const results_context_t& results() const
      {
         if (expression_holder_->results)
            return (*expression_holder_->results);
         else
         {
            static const results_context_t null_results;
            return null_results;
         }
      }

      inline bool return_invoked() const
      {
         return (*expression_holder_->return_invoked);
      }

   private:

      inline symtab_list_t get_symbol_table_list() const
      {
         return symbol_table_list_;
      }

      inline void set_expression(const expression_ptr expr)
      {
         if (expr)
         {
            if (expression_holder_)
            {
               if (0 == --expression_holder_->ref_count)
               {
                  delete expression_holder_;
               }
            }

            expression_holder_ = new expression_holder(expr);
         }
      }

      inline void register_local_var(expression_ptr expr)
      {
         if (expr)
         {
            if (expression_holder_)
            {
               expression_holder_->
                  local_data_list.push_back(
                     typename expression<T>::expression_holder::
                        data_pack(reinterpret_cast<void*>(expr),
                                  expression_holder::e_expr));
            }
         }
      }

      inline void register_local_var(vector_holder_ptr vec_holder)
      {
         if (vec_holder)
         {
            if (expression_holder_)
            {
               expression_holder_->
                  local_data_list.push_back(
                     typename expression<T>::expression_holder::
                        data_pack(reinterpret_cast<void*>(vec_holder),
                                  expression_holder::e_vecholder));
            }
         }
      }

      inline void register_local_data(void* data, const std::size_t& size = 0, const std::size_t data_mode = 0)
      {
         if (data)
         {
            if (expression_holder_)
            {
               typename expression_holder::data_type dt = expression_holder::e_data;

               switch(data_mode)
               {
                  case 0 : dt = expression_holder::e_data;    break;
                  case 1 : d