git.sesse.net Git - casparcg/blob - dependencies/boost/boost/xpressive/detail/core/matcher/repeat_end_matcher.hpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // repeat_end_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_REPEAT_END_MATCHER_HPP_EAN_10_04_2005
   9 #define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_REPEAT_END_MATCHER_HPP_EAN_10_04_2005
  10
  11 // MS compatible compilers support #pragma once
  12 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
  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     // repeat_end_matcher
  26     //
  27     template<typename Greedy>
  28     struct repeat_end_matcher
  29       : quant_style<quant_none, 0, false>
  30     {
  31         typedef Greedy greedy_type;
  32         int mark_number_;
  33         unsigned int min_, max_;
  34         mutable void const *back_;
  35
  36         repeat_end_matcher(int mark_nbr, unsigned int min, unsigned int max)
  37           : mark_number_(mark_nbr)
  38           , min_(min)
  39           , max_(max)
  40           , back_(0)
  41         {
  42         }
  43
  44         template<typename BidiIter, typename Next>
  45         bool match(match_state<BidiIter> &state, Next const &next) const
  46         {
  47             // prevent repeated zero-width sub-matches from causing infinite recursion
  48             sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
  49
  50             if(br.zero_width_ && br.begin_ == state.cur_)
  51             {
  52                 return next.skip_match(state);
  53             }
  54
  55             bool old_zero_width = br.zero_width_;
  56             br.zero_width_ = (br.begin_ == state.cur_);
  57
  58             if(this->match_(state, next, greedy_type()))
  59             {
  60                 return true;
  61             }
  62
  63             br.zero_width_ = old_zero_width;
  64             return false;
  65         }
  66
  67         // greedy, variable-width quantifier
  68         template<typename BidiIter, typename Next>
  69         bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const
  70         {
  71             sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
  72
  73             if(this->max_ > br.repeat_count_)
  74             {
  75                 ++br.repeat_count_;
  76                 // loop back to the expression "pushed" in repeat_begin_matcher::match
  77                 if(next.top_match(state, this->back_))
  78                 {
  79                     return true;
  80                 }
  81                 else if(--br.repeat_count_ < this->min_)
  82                 {
  83                     return false;
  84                 }
  85             }
  86
  87             // looping finished, continue matching the rest of the pattern
  88             return next.skip_match(state);
  89         }
  90
  91         // non-greedy, variable-width quantifier
  92         template<typename BidiIter, typename Next>
  93         bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const
  94         {
  95             sub_match_impl<BidiIter> &br = state.sub_match(this->mark_number_);
  96
  97             if(this->min_ <= br.repeat_count_)
  98             {
  99                 if(next.skip_match(state))
 100                 {
 101                     return true;
 102                 }
 103             }
 104
 105             if(this->max_ > br.repeat_count_)
 106             {
 107                 ++br.repeat_count_;
 108                 if(next.top_match(state, this->back_))
 109                 {
 110                     return true;
 111                 }
 112                 --br.repeat_count_;
 113             }
 114
 115             return false;
 116         }
 117     };
 118
 119 }}}
 120
 121 #endif