115 lines
4.1 KiB
C++
115 lines
4.1 KiB
C++
/*=============================================================================
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Copyright (c) 2001-2011 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_QI_OPERATOR_DIFFERENCE_HPP
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#define BOOST_SPIRIT_QI_OPERATOR_DIFFERENCE_HPP
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#if defined(_MSC_VER)
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#pragma once
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#endif
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#include <boost/spirit/home/qi/domain.hpp>
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#include <boost/spirit/home/qi/meta_compiler.hpp>
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#include <boost/spirit/home/qi/parser.hpp>
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#include <boost/spirit/home/qi/detail/attributes.hpp>
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#include <boost/spirit/home/support/info.hpp>
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#include <boost/spirit/home/support/has_semantic_action.hpp>
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#include <boost/spirit/home/support/handles_container.hpp>
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#include <boost/fusion/include/at.hpp>
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#include <boost/proto/operators.hpp>
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#include <boost/proto/tags.hpp>
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namespace boost { namespace spirit
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{
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///////////////////////////////////////////////////////////////////////////
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// Enablers
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///////////////////////////////////////////////////////////////////////////
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template <>
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struct use_operator<qi::domain, proto::tag::minus> // enables -
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: mpl::true_ {};
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}}
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namespace boost { namespace spirit { namespace qi
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{
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template <typename Left, typename Right>
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struct difference : binary_parser<difference<Left, Right> >
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{
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typedef Left left_type;
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typedef Right right_type;
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template <typename Context, typename Iterator>
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struct attribute
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{
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typedef typename
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traits::attribute_of<left_type, Context, Iterator>::type
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type;
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};
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difference(Left const& left_, Right const& right_)
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: left(left_), right(right_) {}
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template <typename Iterator, typename Context
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, typename Skipper, typename Attribute>
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bool parse(Iterator& first, Iterator const& last
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, Context& context, Skipper const& skipper
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, Attribute& attr_) const
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{
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// Unlike classic Spirit, with this version of difference, the rule
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// lit("policeman") - "police" will always fail to match.
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// Spirit2 does not count the matching chars while parsing and
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// there is no reliable and fast way to check if the LHS matches
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// more than the RHS.
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// Try RHS first
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Iterator start = first;
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if (right.parse(first, last, context, skipper, unused))
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{
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// RHS succeeds, we fail.
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first = start;
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return false;
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}
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// RHS fails, now try LHS
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return left.parse(first, last, context, skipper, attr_);
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}
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template <typename Context>
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info what(Context& context) const
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{
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return info("difference",
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std::make_pair(left.what(context), right.what(context)));
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}
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Left left;
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Right right;
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};
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///////////////////////////////////////////////////////////////////////////
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// Parser generators: make_xxx function (objects)
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///////////////////////////////////////////////////////////////////////////
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template <typename Elements, typename Modifiers>
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struct make_composite<proto::tag::minus, Elements, Modifiers>
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: make_binary_composite<Elements, difference>
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{};
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}}}
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namespace boost { namespace spirit { namespace traits
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{
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///////////////////////////////////////////////////////////////////////////
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template <typename Left, typename Right>
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struct has_semantic_action<qi::difference<Left, Right> >
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: binary_has_semantic_action<Left, Right> {};
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///////////////////////////////////////////////////////////////////////////
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template <typename Left, typename Right, typename Attribute
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, typename Context, typename Iterator>
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struct handles_container<qi::difference<Left, Right>, Attribute, Context
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, Iterator>
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: binary_handles_container<Left, Right, Attribute, Context, Iterator> {};
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}}}
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#endif
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