ceph/src/boost/boost/xpressive/detail/core/matcher/keeper_matcher.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // keeper_matcher.hpp
   3 //
   4 //  Copyright 2008 Eric Niebler. Distributed under the Boost
   5 //  Software License, Version 1.0. (See accompanying file
   6 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifndef BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_KEEPER_MATCHER_HPP_EAN_10_04_2005
   9 #define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_KEEPER_MATCHER_HPP_EAN_10_04_2005
  10
  11 // MS compatible compilers support #pragma once
  12 #if defined(_MSC_VER)
  13 # pragma once
  14 #endif
  15
  16 #include <boost/mpl/bool.hpp>
  17 #include <boost/xpressive/detail/detail_fwd.hpp>
  18 #include <boost/xpressive/detail/core/quant_style.hpp>
  19 #include <boost/xpressive/detail/core/state.hpp>
  20
  21 namespace boost { namespace xpressive { namespace detail
  22 {
  23
  24     ///////////////////////////////////////////////////////////////////////////////
  25     // keeper_matcher
  26     //  Xpr can be either a static_xpression, or a shared_matchable
  27     template<typename Xpr>
  28     struct keeper_matcher
  29       : quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
  30     {
  31         keeper_matcher(Xpr const &xpr, bool pure = Xpr::pure)
  32           : xpr_(xpr)
  33           , pure_(pure)
  34         {
  35         }
  36
  37         template<typename BidiIter, typename Next>
  38         bool match(match_state<BidiIter> &state, Next const &next) const
  39         {
  40             return Xpr::pure || this->pure_
  41               ? this->match_(state, next, mpl::true_())
  42               : this->match_(state, next, mpl::false_());
  43         }
  44
  45         template<typename BidiIter, typename Next>
  46         bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const
  47         {
  48             BidiIter const tmp = state.cur_;
  49
  50             // matching xpr is guaranteed to not produce side-effects, don't bother saving state
  51             if(!this->xpr_.match(state))
  52             {
  53                 return false;
  54             }
  55             else if(next.match(state))
  56             {
  57                 return true;
  58             }
  59
  60             state.cur_ = tmp;
  61             return false;
  62         }
  63
  64         template<typename BidiIter, typename Next>
  65         bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const
  66         {
  67             BidiIter const tmp = state.cur_;
  68
  69             // matching xpr could produce side-effects, save state
  70             memento<BidiIter> mem = save_sub_matches(state);
  71
  72             if(!this->xpr_.match(state))
  73             {
  74                 restore_action_queue(mem, state);
  75                 reclaim_sub_matches(mem, state, false);
  76                 return false;
  77             }
  78             restore_action_queue(mem, state);
  79             if(next.match(state))
  80             {
  81                 reclaim_sub_matches(mem, state, true);
  82                 return true;
  83             }
  84
  85             restore_sub_matches(mem, state);
  86             state.cur_ = tmp;
  87             return false;
  88         }
  89
  90         Xpr xpr_;
  91         bool pure_; // false if matching xpr_ could modify the sub-matches
  92     };
  93
  94 }}}
  95
  96 #endif