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  */
00028 #include <regex>
00029 
00030 namespace std
00031 {
00032 
00033 namespace
00034 {
00035 
00036   // A stack of states used in evaluating the NFA.
00037   typedef std::stack<std::__regex::_StateIdT,
00038                      std::vector<std::__regex::_StateIdT>
00039              > _StateStack;
00040 
00041   // Obtains the next state set given the current state set __s and the current
00042   // input character.
00043   inline std::__regex::_StateSet
00044   __move(const std::__regex::_PatternCursor& __p,
00045          const std::__regex::_Nfa& __nfa,
00046          const std::__regex::_StateSet& __s)
00047   {
00048     std::__regex::_StateSet __m;
00049     for (std::__regex::_StateSet::const_iterator __i = __s.begin();
00050      __i != __s.end(); ++__i)
00051       {
00052     if (*__i == std::__regex::_S_invalid_state_id)
00053       continue;
00054 
00055     const std::__regex::_State& __state = __nfa[*__i];
00056     if (__state._M_opcode == std::__regex::_S_opcode_match
00057         && __state._M_matches(__p))
00058       __m.insert(__state._M_next);
00059       }
00060     return __m;
00061   }
00062 
00063   // returns true if (__s intersect __t) is not empty
00064   inline bool
00065   __includes_some(const std::__regex::_StateSet& __s,
00066                   const std::__regex::_StateSet& __t)
00067   {
00068     if (__s.size() > 0 && __t.size() > 0)
00069       {
00070     std::__regex::_StateSet::const_iterator __first = __s.begin();
00071     std::__regex::_StateSet::const_iterator __second = __t.begin();
00072     while (__first != __s.end() && __second != __t.end())
00073       {
00074         if (*__first < *__second)
00075           ++__first;
00076         else if (*__second < *__first)
00077           ++__second;
00078         else
00079           return true;
00080       }
00081       }
00082     return false;
00083   }
00084 
00085   // If an identified state __u is not already in the current state set __e,
00086   // insert it and push it on the current state stack __s.
00087   inline void
00088   __add_visited_state(const std::__regex::_StateIdT __u,
00089                       _StateStack&                  __s,
00090                       std::__regex::_StateSet&      __e)
00091   {
00092     if (__e.count(__u) == 0)
00093       {
00094     __e.insert(__u);
00095     __s.push(__u);
00096       }
00097   }
00098 
00099 } // anonymous namespace
00100 
00101 namespace __regex
00102 {
00103   inline _Grep_matcher::
00104   _Grep_matcher(_PatternCursor& __p, _Results& __r,
00105         const _AutomatonPtr& __nfa,
00106         regex_constants::match_flag_type __flags)
00107   : _M_nfa(static_pointer_cast<_Nfa>(__nfa)), _M_pattern(__p), _M_results(__r)
00108   {
00109     __regex::_StateSet __t = this->_M_e_closure(_M_nfa->_M_start());
00110     for (; !_M_pattern._M_at_end(); _M_pattern._M_next())
00111       __t = this->_M_e_closure(__move(_M_pattern, *_M_nfa, __t));
00112 
00113     _M_results._M_set_matched(0,
00114                               __includes_some(_M_nfa->_M_final_states(), __t));
00115   }
00116 
00117   // Creates the e-closure set for the initial state __i.
00118   inline _StateSet _Grep_matcher::
00119   _M_e_closure(_StateIdT __i)
00120   {
00121     _StateSet __s;
00122     __s.insert(__i);
00123     _StateStack __stack;
00124     __stack.push(__i);
00125     return this->_M_e_closure(__stack, __s);
00126   }
00127 
00128   // Creates the e-closure set for an arbitrary state set __s.
00129   inline _StateSet _Grep_matcher::
00130   _M_e_closure(const _StateSet& __s)
00131   {
00132     _StateStack __stack;
00133     for (_StateSet::const_iterator __i = __s.begin(); __i != __s.end(); ++__i)
00134       __stack.push(*__i);
00135     return this->_M_e_closure(__stack, __s);
00136   }
00137 
00138   inline _StateSet _Grep_matcher::
00139   _M_e_closure(_StateStack& __stack, const _StateSet& __s)
00140   {
00141     _StateSet __e = __s;
00142     while (!__stack.empty())
00143       {
00144     _StateIdT __t = __stack.top(); __stack.pop();
00145     if (__t == _S_invalid_state_id)
00146       continue;
00147     // for each __u with edge from __t to __u labeled e do ...
00148     const _State& __state = _M_nfa->operator[](__t);
00149     switch (__state._M_opcode)
00150       {
00151       case _S_opcode_alternative:
00152         __add_visited_state(__state._M_next, __stack, __e);
00153         __add_visited_state(__state._M_alt, __stack, __e);
00154         break;
00155       case _S_opcode_subexpr_begin:
00156         __add_visited_state(__state._M_next, __stack, __e);
00157         __state._M_tagger(_M_pattern, _M_results);
00158         break;
00159       case _S_opcode_subexpr_end:
00160         __add_visited_state(__state._M_next, __stack, __e);
00161         __state._M_tagger(_M_pattern, _M_results);
00162         _M_results._M_set_matched(__state._M_subexpr, true);
00163         break;
00164       case _S_opcode_accept:
00165         __add_visited_state(__state._M_next, __stack, __e);
00166         break;
00167       default:
00168         break;
00169       }
00170       }
00171     return __e;
00172   }
00173 
00174 } // namespace __regex
00175 } // namespace std
00176 
00177 /* vim: set ts=8 sw=2 sts=2: */