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112 lines
4.0 KiB
112 lines
4.0 KiB
/*============================================================================= |
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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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#if !defined(SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM) |
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#define SPIRIT_DIFFERENCE_FEBRUARY_11_2007_1250PM |
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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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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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