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122 lines
3.9 KiB
122 lines
3.9 KiB
///////////////////////////////////////////////////////////////////////////////
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// optional_matcher.hpp
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//
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// Copyright 2008 Eric Niebler. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005
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#define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005
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// MS compatible compilers support #pragma once
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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/mpl/bool.hpp>
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#include <boost/xpressive/detail/detail_fwd.hpp>
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#include <boost/xpressive/detail/core/quant_style.hpp>
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#include <boost/xpressive/detail/core/state.hpp>
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namespace boost { namespace xpressive { namespace detail
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{
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///////////////////////////////////////////////////////////////////////////////
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// optional_matcher
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template<typename Xpr, typename Greedy>
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struct optional_matcher
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: quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
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{
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Xpr xpr_;
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explicit optional_matcher(Xpr const &xpr)
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: xpr_(xpr)
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{
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}
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template<typename BidiIter, typename Next>
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bool match(match_state<BidiIter> &state, Next const &next) const
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{
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return this->match_(state, next, Greedy());
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}
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private:
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template<typename BidiIter, typename Next>
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bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy
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{
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return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state)
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|| next.match(state);
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}
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template<typename BidiIter, typename Next>
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bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy
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{
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return next.match(state)
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|| this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state);
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}
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optional_matcher &operator =(optional_matcher const &);
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};
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///////////////////////////////////////////////////////////////////////////////
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// optional_mark_matcher
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template<typename BidiIter, typename Next>
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inline bool match_next(match_state<BidiIter> &state, Next const &next, int mark_number)
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{
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sub_match_impl<BidiIter> &br = state.sub_match(mark_number);
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bool old_matched = br.matched;
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br.matched = false;
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if(next.match(state))
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{
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return true;
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}
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br.matched = old_matched;
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return false;
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}
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///////////////////////////////////////////////////////////////////////////////
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// optional_mark_matcher
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template<typename Xpr, typename Greedy>
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struct optional_mark_matcher
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: quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
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{
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Xpr xpr_;
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int mark_number_;
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explicit optional_mark_matcher(Xpr const &xpr, int mark_number)
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: xpr_(xpr)
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, mark_number_(mark_number)
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{
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}
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template<typename BidiIter, typename Next>
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bool match(match_state<BidiIter> &state, Next const &next) const
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{
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return this->match_(state, next, Greedy());
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}
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private:
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template<typename BidiIter, typename Next>
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bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy
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{
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return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state)
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|| match_next(state, next, this->mark_number_);
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}
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template<typename BidiIter, typename Next>
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bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy
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{
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return match_next(state, next, this->mark_number_)
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|| this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state);
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}
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optional_mark_matcher &operator =(optional_mark_matcher const &);
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};
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}}}
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#endif
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