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