regex_grep_matcher.tcc
Go to the documentation of this file.
// class template regex -*- C++ -*-
// Copyright (C) 2010-2013 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/**
* @file bits/regex_grep_matcher.tcc
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{regex}
*/
#include <regex>
namespace std _GLIBCXX_VISIBILITY(default)
{
namespace __detail
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
// TODO: This is too slow. Try to compile the NFA to a DFA.
template<bool __match_mode>
bool _DFSMatcher::
_M_dfs(_StateIdT __i)
{
if (__i == _S_invalid_state_id)
// This is not that certain. Need deeper investigate.
return false;
const auto& __state = (*_M_nfa)[__i];
bool __ret = false;
switch (__state._M_opcode)
{
case _S_opcode_alternative:
// Greedy mode by default. For non-greedy mode,
// swap _M_alt and _M_next.
// TODO: Add greedy mode option.
__ret = _M_dfs<__match_mode>(__state._M_alt)
|| _M_dfs<__match_mode>(__state._M_next);
break;
case _S_opcode_subexpr_begin:
__state._M_tagger(_M_str_cur, _M_results);
__ret = _M_dfs<__match_mode>(__state._M_next);
break;
case _S_opcode_subexpr_end:
__state._M_tagger(_M_str_cur, _M_results);
__ret = _M_dfs<__match_mode>(__state._M_next);
_M_results._M_set_matched(__state._M_subexpr, __ret);
break;
case _S_opcode_match:
if (!_M_str_cur._M_at_end() && __state._M_matches(_M_str_cur))
{
_M_str_cur._M_next();
__ret = _M_dfs<__match_mode>(__state._M_next);
_M_str_cur._M_prev();
}
break;
case _S_opcode_accept:
if (__match_mode)
__ret = _M_str_cur._M_at_end();
else
__ret = true;
break;
default:
_GLIBCXX_DEBUG_ASSERT(false);
}
return __ret;
}
template<bool __match_mode>
bool _BFSMatcher::
_M_main_loop()
{
while (!_M_str_cur._M_at_end())
{
if (!__match_mode)
if (_M_includes_some())
return true;
_M_move();
_M_str_cur._M_next();
_M_e_closure();
}
return _M_includes_some();
}
// The SPFA approach.
// FIXME: move it to src/c++11 when it's stable, and make it not inlined.
inline
void _BFSMatcher::
_M_e_closure()
{
std::queue<_StateIdT> __q;
std::vector<bool> __in_q(_M_nfa->size(), false);
for (auto& __it : _M_current)
{
__in_q[__it.first] = true;
__q.push(__it.first);
}
while (!__q.empty())
{
auto __u = __q.front();
__q.pop();
__in_q[__u] = false;
const auto& __state = (*_M_nfa)[__u];
// Can be implemented using method, but there're too much arguments.
auto __add_visited_state = [&](_StateIdT __v)
{
if (__v == _S_invalid_state_id)
return;
if (_M_match_less_than(__u, __v))
{
_M_current[__v] = _M_current[__u]->_M_clone();
// if a state is updated, it's outgoing neighbors should be
// reconsidered too. Push them to the queue.
if (!__in_q[__v])
{
__in_q[__v] = true;
__q.push(__v);
}
}
};
switch (__state._M_opcode)
{
case _S_opcode_alternative:
__add_visited_state(__state._M_next);
__add_visited_state(__state._M_alt);
break;
case _S_opcode_subexpr_begin:
__state._M_tagger(_M_str_cur, *_M_current[__u]);
__add_visited_state(__state._M_next);
break;
case _S_opcode_subexpr_end:
__state._M_tagger(_M_str_cur, *_M_current[__u]);
_M_current[__u]->_M_set_matched(__state._M_subexpr, true);
__add_visited_state(__state._M_next);
break;
case _S_opcode_match:
break;
case _S_opcode_accept:
__add_visited_state(__state._M_next);
break;
default:
_GLIBCXX_DEBUG_ASSERT(false);
}
}
}
// FIXME: move it to src/c++11 when it's stable, and make it not inlined.
inline
void _BFSMatcher::
_M_move()
{
decltype(_M_current) __next;
for (auto& __it : _M_current)
{
const auto& __state = (*_M_nfa)[__it.first];
if (__state._M_opcode == _S_opcode_match
&& __state._M_matches(_M_str_cur))
if (_M_match_less_than(__it.first, __state._M_next)
&& __state._M_next != _S_invalid_state_id)
__next[__state._M_next] = __it.second->_M_clone();
}
_M_current = move(__next);
}
// FIXME: move it to src/c++11 when it's stable, and make it not inlined.
inline
bool _BFSMatcher::
_M_match_less_than(_StateIdT __u, _StateIdT __v) const
{
if (_M_current.count(__u) == 0)
return false;
if (_M_current.count(__v) > 0)
return true;
// TODO: Greedy and Non-greedy support
return true;
}
// FIXME: move it to src/c++11 when it's stable, and make it not inlined.
inline
bool _BFSMatcher::
_M_includes_some() const
{
auto& __s = _M_nfa->_M_final_states();
auto& __t = _M_current;
if (__s.size() > 0 && __t.size() > 0)
{
auto __first = __s.begin();
auto __second = __t.begin();
while (__first != __s.end() && __second != __t.end())
{
if (*__first < __second->first)
++__first;
else if (__second->first < *__first)
++__second;
else
{
_M_results._M_assign(*__second->second);
return true;
}
}
}
return false;
}
// FIXME: move it to src/c++11 when it's stable, and make it not inlined.
inline
std::unique_ptr<_Grep_matcher> _Nfa::
_M_get_matcher(_PatternCursor& __p,
_Results& __r,
const _AutomatonPtr& __a,
regex_constants::match_flag_type __flags)
{
if (_M_has_back_ref)
return unique_ptr<_Grep_matcher>(
new _DFSMatcher(__p, __r, __a, __flags));
else
return unique_ptr<_Grep_matcher>(
new _BFSMatcher(__p, __r, __a, __flags));
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace __detail
} // namespace