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122 lines
3.6 KiB
122 lines
3.6 KiB
///////////////////////////////////////////////////////////////////////////////
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// repeat_end_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_REPEAT_END_MATCHER_HPP_EAN_10_04_2005
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#define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_REPEAT_END_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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// repeat_end_matcher
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//
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template<typename Greedy>
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struct repeat_end_matcher
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: quant_style<quant_none, 0, false>
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{
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typedef Greedy greedy_type;
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int mark_number_;
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unsigned int min_, max_;
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mutable void const *back_;
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repeat_end_matcher(int mark_nbr, unsigned int min, unsigned int max)
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: mark_number_(mark_nbr)
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, min_(min)
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, max_(max)
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, back_(0)
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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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// prevent repeated zero-width sub-matches from causing infinite recursion
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sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
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if(br.zero_width_ && br.begin_ == state.cur_)
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{
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return next.skip_match(state);
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}
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bool old_zero_width = br.zero_width_;
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br.zero_width_ = (br.begin_ == state.cur_);
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if(this->match_(state, next, greedy_type()))
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{
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return true;
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}
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br.zero_width_ = old_zero_width;
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return false;
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}
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// greedy, variable-width quantifier
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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
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{
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sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
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if(this->max_ > br.repeat_count_)
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{
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++br.repeat_count_;
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// loop back to the expression "pushed" in repeat_begin_matcher::match
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if(next.top_match(state, this->back_))
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{
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return true;
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}
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else if(--br.repeat_count_ < this->min_)
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{
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return false;
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}
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}
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// looping finished, continue matching the rest of the pattern
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return next.skip_match(state);
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}
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// non-greedy, variable-width quantifier
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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
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{
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sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
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if(this->min_ <= br.repeat_count_)
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{
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if(next.skip_match(state))
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{
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return true;
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}
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}
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if(this->max_ > br.repeat_count_)
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{
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++br.repeat_count_;
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if(next.top_match(state, this->back_))
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{
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return true;
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}
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--br.repeat_count_;
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}
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return false;
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}
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};
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}}}
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#endif
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