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/Src/Dependencies/Boost/boost/spirit/home/karma/auxiliary/eps.hpp

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C++ Header | 137 lines | 100 code | 22 blank | 15 comment | 1 complexity | abfb9a012a3cdd4040176b1d212809fd MD5 | raw file
  1//  Copyright (c) 2001-2011 Hartmut Kaiser
  2//
  3//  Distributed under the Boost Software License, Version 1.0. (See accompanying
  4//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  5
  6#if !defined(BOOST_SPIRIT_KARMA_EPS_APRIL_21_2007_0246PM)
  7#define BOOST_SPIRIT_KARMA_EPS_APRIL_21_2007_0246PM
  8
  9#if defined(_MSC_VER)
 10#pragma once
 11#endif
 12
 13#include <boost/spirit/home/support/common_terminals.hpp>
 14#include <boost/spirit/home/support/info.hpp>
 15#include <boost/spirit/home/karma/domain.hpp>
 16#include <boost/spirit/home/karma/meta_compiler.hpp>
 17#include <boost/spirit/home/karma/delimit_out.hpp>
 18#include <boost/spirit/home/support/unused.hpp>
 19#include <boost/fusion/include/at.hpp>
 20
 21namespace boost { namespace spirit 
 22{
 23    ///////////////////////////////////////////////////////////////////////////
 24    // Enablers
 25    ///////////////////////////////////////////////////////////////////////////
 26
 27    // enables eps
 28    template <>
 29    struct use_terminal<karma::domain, tag::eps>
 30      : mpl::true_ {};
 31
 32    // enables eps(bool-condition)
 33    template <typename A0>
 34    struct use_terminal<karma::domain
 35        , terminal_ex<tag::eps, fusion::vector1<A0> > > 
 36      : is_convertible<A0, bool> {};
 37
 38    // enables lazy eps(f)
 39    template <>
 40    struct use_lazy_terminal<karma::domain, tag::eps, 1>
 41      : mpl::true_ {};
 42
 43}}
 44
 45///////////////////////////////////////////////////////////////////////////////
 46namespace boost { namespace spirit { namespace karma
 47{
 48#ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
 49    using boost::spirit::eps;
 50#endif
 51    using boost::spirit::eps_type;
 52
 53    struct eps_generator : primitive_generator<eps_generator>
 54    {
 55        template <typename Context, typename Unused>
 56        struct attribute
 57        {
 58            typedef unused_type type;
 59        };
 60
 61        template <
 62            typename OutputIterator, typename Context, typename Delimiter
 63          , typename Attribute>
 64        static bool generate(OutputIterator& sink, Context&, Delimiter const& d
 65          , Attribute const& /*attr*/)
 66        {
 67            return karma::delimit_out(sink, d); // always do post-delimiting
 68        }
 69
 70        template <typename Context>
 71        info what(Context const& /*context*/) const
 72        {
 73            return info("eps");
 74        }
 75    };
 76
 77    struct semantic_predicate : primitive_generator<semantic_predicate>
 78    {
 79        template <typename Context, typename Unused>
 80        struct attribute
 81        {
 82            typedef unused_type type;
 83        };
 84
 85        semantic_predicate(bool predicate)
 86          : predicate_(predicate) 
 87        {}
 88
 89        template <
 90            typename OutputIterator, typename Context, typename Delimiter
 91          , typename Attribute>
 92        bool generate(OutputIterator& sink, Context&, Delimiter const& d
 93          , Attribute const& /*attr*/) const
 94        {
 95            // only do post-delimiting when predicate is true
 96            return predicate_ && karma::delimit_out(sink, d);
 97        }
 98
 99        template <typename Context>
100        info what(Context const& /*context*/) const
101        {
102            return info("semantic-predicate");
103        }
104
105        bool predicate_;
106    };
107
108    ///////////////////////////////////////////////////////////////////////////
109    // Generator generators: make_xxx function (objects)
110    ///////////////////////////////////////////////////////////////////////////
111    template <typename Modifiers>
112    struct make_primitive<tag::eps, Modifiers>
113    {
114        typedef eps_generator result_type;
115        result_type operator()(unused_type, unused_type) const
116        {
117            return result_type();
118        }
119    };
120
121    template <typename Modifiers, typename A0>
122    struct make_primitive<
123        terminal_ex<tag::eps, fusion::vector1<A0> >
124      , Modifiers>
125    {
126        typedef semantic_predicate result_type;
127
128        template <typename Terminal>
129        result_type operator()(Terminal const& term, unused_type) const
130        {
131            return result_type(fusion::at_c<0>(term.args));
132        }
133    };
134
135}}}
136
137#endif