87 lines
3.0 KiB
C++
87 lines
3.0 KiB
C++
/*=============================================================================
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Copyright (c) 2014 Joel de Guzman
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#ifndef BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
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#define BOOST_SPIRIT_X3_DIRECTIVE_WITH_HPP
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#include <boost/spirit/home/x3/support/unused.hpp>
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#include <boost/spirit/home/x3/core/parser.hpp>
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namespace boost { namespace spirit { namespace x3
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{
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///////////////////////////////////////////////////////////////////////////
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// with directive injects a value into the context prior to parsing.
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///////////////////////////////////////////////////////////////////////////
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template <typename Subject, typename Derived, typename T>
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struct with_value_holder
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: unary_parser<Subject, Derived>
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{
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typedef unary_parser<Subject, Derived> base_type;
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mutable T val;
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constexpr with_value_holder(Subject const& subject, T&& val)
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: base_type(subject)
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, val(std::forward<T>(val)) {}
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};
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template <typename Subject, typename Derived, typename T>
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struct with_value_holder<Subject, Derived, T&>
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: unary_parser<Subject, Derived>
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{
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typedef unary_parser<Subject, Derived> base_type;
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T& val;
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constexpr with_value_holder(Subject const& subject, T& val)
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: base_type(subject)
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, val(val) {}
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};
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template <typename Subject, typename ID, typename T>
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struct with_directive
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: with_value_holder<Subject, with_directive<Subject, ID, T>, T>
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{
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typedef with_value_holder<Subject, with_directive<Subject, ID, T>, T> base_type;
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static bool const is_pass_through_unary = true;
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static bool const handles_container = Subject::handles_container;
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typedef Subject subject_type;
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constexpr with_directive(Subject const& subject, T&& val)
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: base_type(subject, std::forward<T>(val)) {}
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template <typename Iterator, typename Context
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, typename RContext, typename Attribute>
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bool parse(Iterator& first, Iterator const& last
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, Context const& context, RContext& rcontext, Attribute& attr) const
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{
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return this->subject.parse(
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first, last
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, make_context<ID>(this->val, context)
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, rcontext
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, attr);
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}
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};
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template <typename ID, typename T>
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struct with_gen
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{
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T&& val;
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template <typename Subject>
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constexpr with_directive<typename extension::as_parser<Subject>::value_type, ID, T>
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operator[](Subject const& subject) const
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{
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return { as_parser(subject), std::forward<T>(val) };
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}
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};
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template <typename ID, typename T>
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constexpr with_gen<ID, T> with(T&& val)
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{
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return { std::forward<T>(val) };
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}
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}}}
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#endif
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