core/matcher/mark_begin_matcher.hpp

0001 ///////////////////////////////////////////////////////////////////////////////
0002 // mark_begin_matcher.hpp
0003 //
0004 //  Copyright 2008 Eric Niebler. Distributed under the Boost
0005 //  Software License, Version 1.0. (See accompanying file
0006 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0007
0008 #ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_MARK_BEGIN_MATCHER_HPP_EAN_10_04_2005
0009 #define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_MARK_BEGIN_MATCHER_HPP_EAN_10_04_2005
0010
0011 // MS compatible compilers support #pragma once
0012 #if defined(_MSC_VER)
0013 # pragma once
0014 #endif
0015
0016 #include <boost/xpressive/detail/detail_fwd.hpp>
0017 #include <boost/xpressive/detail/core/quant_style.hpp>
0018 #include <boost/xpressive/detail/core/state.hpp>
0019
0020 namespace boost { namespace xpressive { namespace detail
0021 {
0022
0023     ///////////////////////////////////////////////////////////////////////////////
0024     // mark_begin_matcher
0025     //
0026     struct mark_begin_matcher
0027       : quant_style<quant_fixed_width, 0, false>
0028     {
0029         int mark_number_; // signed because it could be negative
0030
0031         mark_begin_matcher(int mark_number)
0032           : mark_number_(mark_number)
0033         {
0034         }
0035
0036         template<typename BidiIter, typename Next>
0037         bool match(match_state<BidiIter> &state, Next const &next) const
0038         {
0039             sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
0040
0041             BidiIter old_begin = br.begin_;
0042             br.begin_ = state.cur_;
0043
0044             if(next.match(state))
0045             {
0046                 return true;
0047             }
0048
0049             br.begin_ = old_begin;
0050             return false;
0051         }
0052     };
0053
0054 }}}
0055
0056 #endif