libstdc++
regex_grep_matcher.tcc
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00001 // class template regex -*- C++ -*-
00002 
00003 // Copyright (C) 2010 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /**
00026  *  @file bits/regex_grep_matcher.tcc
00027  *  This is an internal header file, included by other library headers.
00028  *  Do not attempt to use it directly. @headername{regex}
00029  */
00030 
00031 #include <regex>
00032 
00033 namespace std _GLIBCXX_VISIBILITY(default)
00034 {
00035 namespace
00036 {
00037   // A stack of states used in evaluating the NFA.
00038   typedef std::stack<std::__regex::_StateIdT,
00039                      std::vector<std::__regex::_StateIdT>
00040              > _StateStack;
00041 
00042   // Obtains the next state set given the current state set __s and the current
00043   // input character.
00044   inline std::__regex::_StateSet
00045   __move(const std::__regex::_PatternCursor& __p,
00046          const std::__regex::_Nfa& __nfa,
00047          const std::__regex::_StateSet& __s)
00048   {
00049     std::__regex::_StateSet __m;
00050     for (std::__regex::_StateSet::const_iterator __i = __s.begin();
00051      __i != __s.end(); ++__i)
00052       {
00053     if (*__i == std::__regex::_S_invalid_state_id)
00054       continue;
00055 
00056     const std::__regex::_State& __state = __nfa[*__i];
00057     if (__state._M_opcode == std::__regex::_S_opcode_match
00058         && __state._M_matches(__p))
00059       __m.insert(__state._M_next);
00060       }
00061     return __m;
00062   }
00063 
00064   // returns true if (__s intersect __t) is not empty
00065   inline bool
00066   __includes_some(const std::__regex::_StateSet& __s,
00067                   const std::__regex::_StateSet& __t)
00068   {
00069     if (__s.size() > 0 && __t.size() > 0)
00070       {
00071     std::__regex::_StateSet::const_iterator __first = __s.begin();
00072     std::__regex::_StateSet::const_iterator __second = __t.begin();
00073     while (__first != __s.end() && __second != __t.end())
00074       {
00075         if (*__first < *__second)
00076           ++__first;
00077         else if (*__second < *__first)
00078           ++__second;
00079         else
00080           return true;
00081       }
00082       }
00083     return false;
00084   }
00085 
00086   // If an identified state __u is not already in the current state set __e,
00087   // insert it and push it on the current state stack __s.
00088   inline void
00089   __add_visited_state(const std::__regex::_StateIdT __u,
00090                       _StateStack&                  __s,
00091                       std::__regex::_StateSet&      __e)
00092   {
00093     if (__e.count(__u) == 0)
00094       {
00095     __e.insert(__u);
00096     __s.push(__u);
00097       }
00098   }
00099 
00100 } // anonymous namespace
00101 
00102 namespace __regex
00103 {
00104 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00105 
00106   inline _Grep_matcher::
00107   _Grep_matcher(_PatternCursor& __p, _Results& __r,
00108         const _AutomatonPtr& __nfa,
00109         regex_constants::match_flag_type __flags)
00110   : _M_nfa(static_pointer_cast<_Nfa>(__nfa)), _M_pattern(__p), _M_results(__r)
00111   {
00112     __regex::_StateSet __t = this->_M_e_closure(_M_nfa->_M_start());
00113     for (; !_M_pattern._M_at_end(); _M_pattern._M_next())
00114       __t = this->_M_e_closure(__move(_M_pattern, *_M_nfa, __t));
00115 
00116     _M_results._M_set_matched(0,
00117                               __includes_some(_M_nfa->_M_final_states(), __t));
00118   }
00119 
00120   // Creates the e-closure set for the initial state __i.
00121   inline _StateSet _Grep_matcher::
00122   _M_e_closure(_StateIdT __i)
00123   {
00124     _StateSet __s;
00125     __s.insert(__i);
00126     _StateStack __stack;
00127     __stack.push(__i);
00128     return this->_M_e_closure(__stack, __s);
00129   }
00130 
00131   // Creates the e-closure set for an arbitrary state set __s.
00132   inline _StateSet _Grep_matcher::
00133   _M_e_closure(const _StateSet& __s)
00134   {
00135     _StateStack __stack;
00136     for (_StateSet::const_iterator __i = __s.begin(); __i != __s.end(); ++__i)
00137       __stack.push(*__i);
00138     return this->_M_e_closure(__stack, __s);
00139   }
00140 
00141   inline _StateSet _Grep_matcher::
00142   _M_e_closure(_StateStack& __stack, const _StateSet& __s)
00143   {
00144     _StateSet __e = __s;
00145     while (!__stack.empty())
00146       {
00147     _StateIdT __t = __stack.top(); __stack.pop();
00148     if (__t == _S_invalid_state_id)
00149       continue;
00150     // for each __u with edge from __t to __u labeled e do ...
00151     const _State& __state = _M_nfa->operator[](__t);
00152     switch (__state._M_opcode)
00153       {
00154       case _S_opcode_alternative:
00155         __add_visited_state(__state._M_next, __stack, __e);
00156         __add_visited_state(__state._M_alt, __stack, __e);
00157         break;
00158       case _S_opcode_subexpr_begin:
00159         __add_visited_state(__state._M_next, __stack, __e);
00160         __state._M_tagger(_M_pattern, _M_results);
00161         break;
00162       case _S_opcode_subexpr_end:
00163         __add_visited_state(__state._M_next, __stack, __e);
00164         __state._M_tagger(_M_pattern, _M_results);
00165         _M_results._M_set_matched(__state._M_subexpr, true);
00166         break;
00167       case _S_opcode_accept:
00168         __add_visited_state(__state._M_next, __stack, __e);
00169         break;
00170       default:
00171         break;
00172       }
00173       }
00174     return __e;
00175   }
00176 
00177 _GLIBCXX_END_NAMESPACE_VERSION
00178 } // namespace __regex
00179 } // namespace