244 lines
7.5 KiB
C++
244 lines
7.5 KiB
C++
// class template regex -*- C++ -*-
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// Copyright (C) 2010-2013 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/**
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* @file bits/regex_grep_matcher.tcc
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{regex}
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*/
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#include <regex>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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namespace
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{
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// A stack of states used in evaluating the NFA.
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typedef std::stack<std::__detail::_StateIdT,
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std::vector<std::__detail::_StateIdT>
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> _StateStack;
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// Obtains the next state set given the current state set __s and the current
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// input character.
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inline std::__detail::_StateSet
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__move(const std::__detail::_PatternCursor& __p,
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const std::__detail::_Nfa& __nfa,
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const std::__detail::_StateSet& __s)
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{
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std::__detail::_StateSet __m;
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for (std::__detail::_StateSet::const_iterator __i = __s.begin();
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__i != __s.end(); ++__i)
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{
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if (*__i == std::__detail::_S_invalid_state_id)
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continue;
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const std::__detail::_State& __state = __nfa[*__i];
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if (__state._M_opcode == std::__detail::_S_opcode_match
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&& __state._M_matches(__p))
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__m.insert(__state._M_next);
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}
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return __m;
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}
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// returns true if (__s intersect __t) is not empty
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inline bool
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__includes_some(const std::__detail::_StateSet& __s,
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const std::__detail::_StateSet& __t)
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{
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if (__s.size() > 0 && __t.size() > 0)
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{
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std::__detail::_StateSet::const_iterator __first = __s.begin();
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std::__detail::_StateSet::const_iterator __second = __t.begin();
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while (__first != __s.end() && __second != __t.end())
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{
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if (*__first < *__second)
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++__first;
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else if (*__second < *__first)
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++__second;
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else
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return true;
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}
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}
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return false;
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}
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// If an identified state __u is not already in the current state set __e,
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// insert it and push it on the current state stack __s.
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inline void
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__add_visited_state(const std::__detail::_StateIdT __u,
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_StateStack& __s,
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std::__detail::_StateSet& __e)
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{
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if (__e.count(__u) == 0)
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{
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__e.insert(__u);
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__s.push(__u);
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}
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}
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} // anonymous namespace
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namespace __detail
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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// _M_dfs() take a state, along with current string cursor(_M_pattern),
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// trying to match current state with current character.
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// Only _S_opcode_match will consume a character.
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// TODO: This is too slow. Try to compile the NFA to a DFA.
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template<bool __match_mode>
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bool _Grep_matcher::
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_M_dfs(_StateIdT __i)
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{
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if (__i == _S_invalid_state_id)
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// This is not that certain. Need deeper investigate.
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return false;
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const auto& __state = (*_M_nfa)[__i];
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bool __ret = false;
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switch (__state._M_opcode)
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{
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case _S_opcode_alternative:
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// Greedy mode by default. For non-greedy mode,
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// swap _M_alt and _M_next.
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// TODO: Add greedy mode option.
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__ret = _M_dfs<__match_mode>(__state._M_alt)
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|| _M_dfs<__match_mode>(__state._M_next);
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break;
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case _S_opcode_subexpr_begin:
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__state._M_tagger(_M_pattern, _M_results);
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__ret = _M_dfs<__match_mode>(__state._M_next);
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break;
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case _S_opcode_subexpr_end:
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__state._M_tagger(_M_pattern, _M_results);
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__ret = _M_dfs<__match_mode>(__state._M_next);
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_M_results._M_set_matched(__state._M_subexpr, __ret);
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break;
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case _S_opcode_match:
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if (!_M_pattern._M_at_end() && __state._M_matches(_M_pattern))
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{
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_M_pattern._M_next();
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__ret = _M_dfs<__match_mode>(__state._M_next);
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_M_pattern._M_prev();
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}
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break;
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case _S_opcode_accept:
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if (__match_mode)
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__ret = _M_pattern._M_at_end();
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else
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__ret = true;
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break;
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default:
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_GLIBCXX_DEBUG_ASSERT( false );
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}
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return __ret;
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}
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inline void _Grep_matcher::
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_M_match()
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{
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__detail::_StateSet __t = this->_M_e_closure(_M_nfa->_M_start());
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for (; !_M_pattern._M_at_end(); _M_pattern._M_next())
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__t = this->_M_e_closure(__move(_M_pattern, *_M_nfa, __t));
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_M_results._M_set_matched(0,
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__includes_some(_M_nfa->_M_final_states(), __t));
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}
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inline void _Grep_matcher::
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_M_search_from_first()
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{
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__detail::_StateSet __t = this->_M_e_closure(_M_nfa->_M_start());
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for (; !_M_pattern._M_at_end(); _M_pattern._M_next())
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{
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if (__includes_some(_M_nfa->_M_final_states(), __t)) // KISS
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{
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_M_results._M_set_matched(0, true);
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return;
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}
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__t = this->_M_e_closure(__move(_M_pattern, *_M_nfa, __t));
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}
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_M_results._M_set_matched(0, false);
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}
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// Creates the e-closure set for the initial state __i.
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inline _StateSet _Grep_matcher::
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_M_e_closure(_StateIdT __i)
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{
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_StateSet __s;
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__s.insert(__i);
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_StateStack __stack;
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__stack.push(__i);
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return this->_M_e_closure(__stack, __s);
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}
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// Creates the e-closure set for an arbitrary state set __s.
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inline _StateSet _Grep_matcher::
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_M_e_closure(const _StateSet& __s)
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{
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_StateStack __stack;
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for (_StateSet::const_iterator __i = __s.begin(); __i != __s.end(); ++__i)
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__stack.push(*__i);
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return this->_M_e_closure(__stack, __s);
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}
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inline _StateSet _Grep_matcher::
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_M_e_closure(_StateStack& __stack, const _StateSet& __s)
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{
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_StateSet __e = __s;
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while (!__stack.empty())
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{
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_StateIdT __t = __stack.top(); __stack.pop();
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if (__t == _S_invalid_state_id)
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continue;
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// for each __u with edge from __t to __u labeled e do ...
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const _State& __state = _M_nfa->operator[](__t);
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switch (__state._M_opcode)
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{
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case _S_opcode_alternative:
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__add_visited_state(__state._M_next, __stack, __e);
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__add_visited_state(__state._M_alt, __stack, __e);
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break;
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case _S_opcode_subexpr_begin:
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__add_visited_state(__state._M_next, __stack, __e);
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__state._M_tagger(_M_pattern, _M_results);
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break;
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case _S_opcode_subexpr_end:
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__add_visited_state(__state._M_next, __stack, __e);
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__state._M_tagger(_M_pattern, _M_results);
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_M_results._M_set_matched(__state._M_subexpr, true);
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break;
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case _S_opcode_accept:
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__add_visited_state(__state._M_next, __stack, __e);
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break;
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default:
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break;
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}
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}
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return __e;
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace __detail
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} // namespace
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