72 lines
2.6 KiB
C++
72 lines
2.6 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2014 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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#if !defined(BOOST_SPIRIT_X3_DIFFERENCE_FEBRUARY_11_2007_1250PM)
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#define BOOST_SPIRIT_X3_DIFFERENCE_FEBRUARY_11_2007_1250PM
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#include <boost/spirit/home/x3/support/traits/attribute_of.hpp>
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#include <boost/spirit/home/x3/support/traits/has_attribute.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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template <typename Left, typename Right>
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struct difference : binary_parser<Left, Right, difference<Left, Right>>
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{
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typedef binary_parser<Left, Right, difference<Left, Right>> base_type;
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static bool const handles_container = Left::handles_container;
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constexpr difference(Left const& left, Right const& right)
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: base_type(left, right) {}
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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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// Try Right first
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Iterator start = first;
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if (this->right.parse(first, last, context, rcontext, unused))
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{
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// Right succeeds, we fail.
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first = start;
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return false;
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}
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// Right fails, now try Left
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return this->left.parse(first, last, context, rcontext, attr);
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}
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template <typename Left_, typename Right_>
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constexpr difference<Left_, Right_>
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make(Left_ const& left, Right_ const& right) const
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{
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return { left, right };
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}
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};
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template <typename Left, typename Right>
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constexpr difference<
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typename extension::as_parser<Left>::value_type
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, typename extension::as_parser<Right>::value_type>
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operator-(Left const& left, Right const& right)
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{
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return { as_parser(left), as_parser(right) };
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}
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}}}
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namespace boost { namespace spirit { namespace x3 { namespace traits
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{
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template <typename Left, typename Right, typename Context>
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struct attribute_of<x3::difference<Left, Right>, Context>
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: attribute_of<Left, Context> {};
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template <typename Left, typename Right, typename Context>
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struct has_attribute<x3::difference<Left, Right>, Context>
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: has_attribute<Left, Context> {};
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}}}}
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#endif
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