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File indexing completed on 2025-02-27 09:55:39

0001 /*=============================================================================
0002     Copyright (c) 2014 Joel de Guzman
0003 
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 =============================================================================*/
0007 #ifndef BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
0008 #define BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
0009 
0010 #include <boost/spirit/home/x3/support/unused.hpp>
0011 #include <boost/spirit/home/x3/core/parser.hpp>
0012 
0013 namespace boost { namespace spirit { namespace x3
0014 {
0015     ///////////////////////////////////////////////////////////////////////////
0016     // with directive injects a value into the context prior to parsing.
0017     ///////////////////////////////////////////////////////////////////////////
0018     template <typename Subject, typename Derived, typename T>
0019     struct with_value_holder
0020       : unary_parser<Subject, Derived>
0021     {
0022         typedef unary_parser<Subject, Derived> base_type;
0023         mutable T val;
0024         constexpr with_value_holder(Subject const& subject, T&& val)
0025           : base_type(subject)
0026           , val(std::forward<T>(val)) {}
0027     };
0028     
0029     template <typename Subject, typename Derived, typename T>
0030     struct with_value_holder<Subject, Derived, T&>
0031       : unary_parser<Subject, Derived>
0032     {
0033         typedef unary_parser<Subject, Derived> base_type;
0034         T& val;
0035         constexpr with_value_holder(Subject const& subject, T& val)
0036           : base_type(subject)
0037           , val(val) {}
0038     };
0039 
0040     template <typename Subject, typename ID, typename T>
0041     struct with_directive
0042       : with_value_holder<Subject, with_directive<Subject, ID, T>, T>
0043     {
0044         typedef with_value_holder<Subject, with_directive<Subject, ID, T>, T> base_type;
0045         static bool const is_pass_through_unary = true;
0046         static bool const handles_container = Subject::handles_container;
0047 
0048         typedef Subject subject_type;
0049 
0050         constexpr with_directive(Subject const& subject, T&& val)
0051           : base_type(subject, std::forward<T>(val)) {}
0052 
0053         template <typename Iterator, typename Context
0054           , typename RContext, typename Attribute>
0055         bool parse(Iterator& first, Iterator const& last
0056           , Context const& context, RContext& rcontext, Attribute& attr) const
0057         {
0058             return this->subject.parse(
0059                 first, last
0060               , make_context<ID>(this->val, context)
0061               , rcontext
0062               , attr);
0063         }
0064     };
0065    
0066     template <typename ID, typename T>
0067     struct with_gen
0068     {
0069         T&& val;
0070 
0071         template <typename Subject>
0072         constexpr with_directive<typename extension::as_parser<Subject>::value_type, ID, T>
0073         operator[](Subject const& subject) const
0074         {
0075             return { as_parser(subject), std::forward<T>(val) };
0076         }
0077     };
0078 
0079     template <typename ID, typename T>
0080     constexpr with_gen<ID, T> with(T&& val)
0081     {
0082         return { std::forward<T>(val) };
0083     }
0084 }}}
0085 
0086 #endif