/Src/Dependencies/Boost/boost/random/uniform_01.hpp

  1/* boost random/uniform_01.hpp header file
  2 *
  3 * Copyright Jens Maurer 2000-2001
  4 * Distributed under the Boost Software License, Version 1.0. (See
  5 * accompanying file LICENSE_1_0.txt or copy at
  6 * http://www.boost.org/LICENSE_1_0.txt)
  7 *
  8 * See http://www.boost.org for most recent version including documentation.
  9 *
 10 * $Id: uniform_01.hpp 71018 2011-04-05 21:27:52Z steven_watanabe $
 11 *
 12 * Revision history
 13 *  2001-02-18  moved to individual header files
 14 */
 15
 16#ifndef BOOST_RANDOM_UNIFORM_01_HPP
 17#define BOOST_RANDOM_UNIFORM_01_HPP
 18
 19#include <iostream>
 20#include <boost/config.hpp>
 21#include <boost/limits.hpp>
 22#include <boost/static_assert.hpp>
 23#include <boost/random/detail/config.hpp>
 24#include <boost/random/detail/ptr_helper.hpp>
 25
 26#include <boost/random/detail/disable_warnings.hpp>
 27
 28namespace boost {
 29namespace random {
 30
 31#ifdef BOOST_RANDOM_DOXYGEN
 32
 33/**
 34 * The distribution function uniform_01 models a \random_distribution.
 35 * On each invocation, it returns a random floating-point value
 36 * uniformly distributed in the range [0..1).
 37 *
 38 * The template parameter RealType shall denote a float-like value type
 39 * with support for binary operators +, -, and /.
 40 *
 41 * Note: The current implementation is buggy, because it may not fill
 42 * all of the mantissa with random bits. I'm unsure how to fill a
 43 * (to-be-invented) @c boost::bigfloat class with random bits efficiently.
 44 * It's probably time for a traits class.
 45 */
 46template<class RealType = double>
 47class uniform_01
 48{
 49public:
 50  typedef RealType input_type;
 51  typedef RealType result_type;
 52  result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const;
 53  result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const;
 54  void reset();
 55
 56  template<class Engine>
 57  result_type operator()(Engine& eng);
 58
 59#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
 60  template<class CharT, class Traits>
 61  friend std::basic_ostream<CharT,Traits>&
 62  operator<<(std::basic_ostream<CharT,Traits>& os, const new_uniform_01&)
 63  {
 64    return os;
 65  }
 66
 67  template<class CharT, class Traits>
 68  friend std::basic_istream<CharT,Traits>&
 69  operator>>(std::basic_istream<CharT,Traits>& is, new_uniform_01&)
 70  {
 71    return is;
 72  }
 73#endif
 74};
 75
 76#else
 77
 78namespace detail {
 79
 80template<class RealType>
 81class new_uniform_01
 82{
 83public:
 84  typedef RealType input_type;
 85  typedef RealType result_type;
 86  // compiler-generated copy ctor and copy assignment are fine
 87  result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(0); }
 88  result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(1); }
 89  void reset() { }
 90
 91  template<class Engine>
 92  result_type operator()(Engine& eng) {
 93    for (;;) {
 94      typedef typename Engine::result_type base_result;
 95      result_type factor = result_type(1) /
 96              (result_type((eng.max)()-(eng.min)()) +
 97               result_type(std::numeric_limits<base_result>::is_integer ? 1 : 0));
 98      result_type result = result_type(eng() - (eng.min)()) * factor;
 99      if (result < result_type(1))
100        return result;
101    }
102  }
103
104#ifndef BOOST_RANDOM_NO_STREAM_OPERATORS
105  template<class CharT, class Traits>
106  friend std::basic_ostream<CharT,Traits>&
107  operator<<(std::basic_ostream<CharT,Traits>& os, const new_uniform_01&)
108  {
109    return os;
110  }
111
112  template<class CharT, class Traits>
113  friend std::basic_istream<CharT,Traits>&
114  operator>>(std::basic_istream<CharT,Traits>& is, new_uniform_01&)
115  {
116    return is;
117  }
118#endif
119};
120
121template<class UniformRandomNumberGenerator, class RealType>
122class backward_compatible_uniform_01
123{
124  typedef boost::random::detail::ptr_helper<UniformRandomNumberGenerator> traits;
125public:
126  typedef UniformRandomNumberGenerator base_type;
127  typedef RealType result_type;
128
129  BOOST_STATIC_CONSTANT(bool, has_fixed_range = false);
130
131#if !defined(BOOST_NO_LIMITS_COMPILE_TIME_CONSTANTS) && !(defined(BOOST_MSVC) && BOOST_MSVC <= 1300)
132  BOOST_STATIC_ASSERT(!std::numeric_limits<RealType>::is_integer);
133#endif
134
135  explicit backward_compatible_uniform_01(typename traits::rvalue_type rng)
136    : _rng(rng),
137      _factor(result_type(1) /
138              (result_type((base().max)()-(base().min)()) +
139               result_type(std::numeric_limits<base_result>::is_integer ? 1 : 0)))
140  {
141  }
142  // compiler-generated copy ctor and copy assignment are fine
143
144  result_type min BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(0); }
145  result_type max BOOST_PREVENT_MACRO_SUBSTITUTION () const { return result_type(1); }
146  typename traits::value_type& base() { return traits::ref(_rng); }
147  const typename traits::value_type& base() const { return traits::ref(_rng); }
148  void reset() { }
149
150  result_type operator()() {
151    for (;;) {
152      result_type result = result_type(base()() - (base().min)()) * _factor;
153      if (result < result_type(1))
154        return result;
155    }
156  }
157
158#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
159  template<class CharT, class Traits>
160  friend std::basic_ostream<CharT,Traits>&
161  operator<<(std::basic_ostream<CharT,Traits>& os, const backward_compatible_uniform_01& u)
162  {
163    os << u._rng;
164    return os;
165  }
166
167  template<class CharT, class Traits>
168  friend std::basic_istream<CharT,Traits>&
169  operator>>(std::basic_istream<CharT,Traits>& is, backward_compatible_uniform_01& u)
170  {
171    is >> u._rng;
172    return is;
173  }
174#endif
175
176private:
177  typedef typename traits::value_type::result_type base_result;
178  UniformRandomNumberGenerator _rng;
179  result_type _factor;
180};
181
182#ifndef BOOST_NO_INCLASS_MEMBER_INITIALIZATION
183//  A definition is required even for integral static constants
184template<class UniformRandomNumberGenerator, class RealType>
185const bool backward_compatible_uniform_01<UniformRandomNumberGenerator, RealType>::has_fixed_range;
186#endif
187
188template<class UniformRandomNumberGenerator>
189struct select_uniform_01
190{
191  template<class RealType>
192  struct apply
193  {
194    typedef backward_compatible_uniform_01<UniformRandomNumberGenerator, RealType> type;
195  };
196};
197
198template<>
199struct select_uniform_01<float>
200{
201  template<class RealType>
202  struct apply
203  {
204    typedef new_uniform_01<float> type;
205  };
206};
207
208template<>
209struct select_uniform_01<double>
210{
211  template<class RealType>
212  struct apply
213  {
214    typedef new_uniform_01<double> type;
215  };
216};
217
218template<>
219struct select_uniform_01<long double>
220{
221  template<class RealType>
222  struct apply
223  {
224    typedef new_uniform_01<long double> type;
225  };
226};
227
228}
229
230// Because it is so commonly used: uniform distribution on the real [0..1)
231// range.  This allows for specializations to avoid a costly int -> float
232// conversion plus float multiplication
233template<class UniformRandomNumberGenerator = double, class RealType = double>
234class uniform_01
235  : public detail::select_uniform_01<UniformRandomNumberGenerator>::BOOST_NESTED_TEMPLATE apply<RealType>::type
236{
237  typedef typename detail::select_uniform_01<UniformRandomNumberGenerator>::BOOST_NESTED_TEMPLATE apply<RealType>::type impl_type;
238  typedef boost::random::detail::ptr_helper<UniformRandomNumberGenerator> traits;
239public:
240
241  uniform_01() {}
242
243  explicit uniform_01(typename traits::rvalue_type rng)
244    : impl_type(rng)
245  {
246  }
247
248#if !defined(BOOST_NO_OPERATORS_IN_NAMESPACE) && !defined(BOOST_NO_MEMBER_TEMPLATE_FRIENDS)
249  template<class CharT, class Traits>
250  friend std::basic_ostream<CharT,Traits>&
251  operator<<(std::basic_ostream<CharT,Traits>& os, const uniform_01& u)
252  {
253    os << static_cast<const impl_type&>(u);
254    return os;
255  }
256
257  template<class CharT, class Traits>
258  friend std::basic_istream<CharT,Traits>&
259  operator>>(std::basic_istream<CharT,Traits>& is, uniform_01& u)
260  {
261    is >> static_cast<impl_type&>(u);
262    return is;
263  }
264#endif
265};
266
267#endif
268
269} // namespace random
270
271using random::uniform_01;
272
273} // namespace boost
274
275#include <boost/random/detail/enable_warnings.hpp>
276
277#endif // BOOST_RANDOM_UNIFORM_01_HPP