usr/mipsel-buildroot-linux-uclibc/include/c++/5.3.0/bits/regex_executor.tcc - toolchains/bruno - Git at Google

 // class template regex -*- C++ -*-

 // Copyright (C) 2013-2015 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_executor.tcc
  *  This is an internal header file, included by other library headers.
  *  Do not attempt to use it directly. @headername{regex}
  */

 namespace std _GLIBCXX_VISIBILITY(default)
 {
 namespace __detail
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION

   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_search()
     {
       if (_M_search_from_first())
 	return true;
       if (_M_flags & regex_constants::match_continuous)
 	return false;
       _M_flags |= regex_constants::match_prev_avail;
       while (_M_begin != _M_end)
 	{
 	  ++_M_begin;
 	  if (_M_search_from_first())
 	    return true;
 	}
       return false;
     }

   // The _M_main function operates in different modes, DFS mode or BFS mode,
   // indicated by template parameter __dfs_mode, and dispatches to one of the
   // _M_main_dispatch overloads.
   //
   // ------------------------------------------------------------
   //
   // DFS mode:
   //
   // It applies a Depth-First-Search (aka backtracking) on given NFA and input
   // string.
   // At the very beginning the executor stands in the start state, then it
   // tries every possible state transition in current state recursively. Some
   // state transitions consume input string, say, a single-char-matcher or a
   // back-reference matcher; some don't, like assertion or other anchor nodes.
   // When the input is exhausted and/or the current state is an accepting
   // state, the whole executor returns true.
   //
   // TODO: This approach is exponentially slow for certain input.
   //       Try to compile the NFA to a DFA.
   //
   // Time complexity: \Omega(match_length), O(2^(_M_nfa.size()))
   // Space complexity: \theta(match_results.size() + match_length)
   //
   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_main_dispatch(_Match_mode __match_mode, __dfs)
     {
       _M_has_sol = false;
       *_M_states._M_get_sol_pos() = _BiIter();
       _M_cur_results = _M_results;
       _M_dfs(__match_mode, _M_states._M_start);
       return _M_has_sol;
     }

   // ------------------------------------------------------------
   //
   // BFS mode:
   //
   // Russ Cox's article (http://swtch.com/~rsc/regexp/regexp1.html)
   // explained this algorithm clearly.
   //
   // It first computes epsilon closure (states that can be achieved without
   // consuming characters) for every state that's still matching,
   // using the same DFS algorithm, but doesn't re-enter states (using
   // _M_states._M_visited to check), nor follow _S_opcode_match.
   //
   // Then apply DFS using every _S_opcode_match (in _M_states._M_match_queue)
   // as the start state.
   //
   // It significantly reduces potential duplicate states, so has a better
   // upper bound; but it requires more overhead.
   //
   // Time complexity: \Omega(match_length * match_results.size())
   //                  O(match_length * _M_nfa.size() * match_results.size())
   // Space complexity: \Omega(_M_nfa.size() + match_results.size())
   //                   O(_M_nfa.size() * match_results.size())
   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_main_dispatch(_Match_mode __match_mode, __bfs)
     {
       _M_states._M_queue(_M_states._M_start, _M_results);
       bool __ret = false;
       while (1)
 	{
 	  _M_has_sol = false;
 	  if (_M_states._M_match_queue.empty())
 	    break;
 	  std::fill_n(_M_states._M_visited_states.get(), _M_nfa.size(), false);
 	  auto __old_queue = std::move(_M_states._M_match_queue);
 	  for (auto& __task : __old_queue)
 	    {
 	      _M_cur_results = std::move(__task.second);
 	      _M_dfs(__match_mode, __task.first);
 	    }
 	  if (__match_mode == _Match_mode::_Prefix)
 	    __ret |= _M_has_sol;
 	  if (_M_current == _M_end)
 	    break;
 	  ++_M_current;
 	}
       if (__match_mode == _Match_mode::_Exact)
 	__ret = _M_has_sol;
       _M_states._M_match_queue.clear();
       return __ret;
     }

   // Return whether now match the given sub-NFA.
   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_lookahead(_State<_TraitsT> __state)
     {
       _ResultsVec __what(_M_cur_results.size());
       _Executor __sub(_M_current, _M_end, __what, _M_re, _M_flags);
       __sub._M_states._M_start = __state._M_alt;
       if (__sub._M_search_from_first())
 	{
 	  for (size_t __i = 0; __i < __what.size(); __i++)
 	    if (__what[__i].matched)
 	      _M_cur_results[__i] = __what[__i];
 	  return true;
 	}
       return false;
     }

   // __rep_count records how many times (__rep_count.second)
   // this node is visited under certain input iterator
   // (__rep_count.first). This prevent the executor from entering
   // infinite loop by refusing to continue when it's already been
   // visited more than twice. It's `twice` instead of `once` because
   // we need to spare one more time for potential group capture.
   template<typename _BiIter, typename _Alloc, typename _TraitsT,
     bool __dfs_mode>
     void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_rep_once_more(_Match_mode __match_mode, _StateIdT __i)
     {
       const auto& __state = _M_nfa[__i];
       auto& __rep_count = _M_rep_count[__i];
       if (__rep_count.second == 0 || __rep_count.first != _M_current)
 	{
 	  auto __back = __rep_count;
 	  __rep_count.first = _M_current;
 	  __rep_count.second = 1;
 	  _M_dfs(__match_mode, __state._M_alt);
 	  __rep_count = __back;
 	}
       else
 	{
 	  if (__rep_count.second < 2)
 	    {
 	      __rep_count.second++;
 	      _M_dfs(__match_mode, __state._M_alt);
 	      __rep_count.second--;
 	    }
 	}
     };

   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_dfs(_Match_mode __match_mode, _StateIdT __i)
     {
       if (_M_states._M_visited(__i))
 	return;

       const auto& __state = _M_nfa[__i];
       // Every change on _M_cur_results and _M_current will be rolled back after
       // finishing the recursion step.
       switch (__state._M_opcode)
 	{
 	// _M_alt branch is "match once more", while _M_next is "get me out
 	// of this quantifier". Executing _M_next first or _M_alt first don't
 	// mean the same thing, and we need to choose the correct order under
 	// given greedy mode.
 	case _S_opcode_repeat:
 	  {
 	    // Greedy.
 	    if (!__state._M_neg)
 	      {
 		_M_rep_once_more(__match_mode, __i);
 		// If it's DFS executor and already accepted, we're done.
 		if (!__dfs_mode || !_M_has_sol)
 		  _M_dfs(__match_mode, __state._M_next);
 	      }
 	    else // Non-greedy mode
 	      {
 		if (__dfs_mode)
 		  {
 		    // vice-versa.
 		    _M_dfs(__match_mode, __state._M_next);
 		    if (!_M_has_sol)
 		      _M_rep_once_more(__match_mode, __i);
 		  }
 		else
 		  {
 		    // DON'T attempt anything, because there's already another
 		    // state with higher priority accepted. This state cannot
 		    // be better by attempting its next node.
 		    if (!_M_has_sol)
 		      {
 			_M_dfs(__match_mode, __state._M_next);
 			// DON'T attempt anything if it's already accepted. An
 			// accepted state *must* be better than a solution that
 			// matches a non-greedy quantifier one more time.
 			if (!_M_has_sol)
 			  _M_rep_once_more(__match_mode, __i);
 		      }
 		  }
 	      }
 	    }
 	  break;
 	case _S_opcode_subexpr_begin:
 	  {
 	    auto& __res = _M_cur_results[__state._M_subexpr];
 	    auto __back = __res.first;
 	    __res.first = _M_current;
 	    _M_dfs(__match_mode, __state._M_next);
 	    __res.first = __back;
 	  }
 	  break;
 	case _S_opcode_subexpr_end:
 	  {
 	    auto& __res = _M_cur_results[__state._M_subexpr];
 	    auto __back = __res;
 	    __res.second = _M_current;
 	    __res.matched = true;
 	    _M_dfs(__match_mode, __state._M_next);
 	    __res = __back;
 	  }
 	  break;
 	case _S_opcode_line_begin_assertion:
 	  if (_M_at_begin())
 	    _M_dfs(__match_mode, __state._M_next);
 	  break;
 	case _S_opcode_line_end_assertion:
 	  if (_M_at_end())
 	    _M_dfs(__match_mode, __state._M_next);
 	  break;
 	case _S_opcode_word_boundary:
 	  if (_M_word_boundary() == !__state._M_neg)
 	    _M_dfs(__match_mode, __state._M_next);
 	  break;
 	// Here __state._M_alt offers a single start node for a sub-NFA.
 	// We recursively invoke our algorithm to match the sub-NFA.
 	case _S_opcode_subexpr_lookahead:
 	  if (_M_lookahead(__state) == !__state._M_neg)
 	    _M_dfs(__match_mode, __state._M_next);
 	  break;
 	case _S_opcode_match:
 	  if (_M_current == _M_end)
 	    break;
 	  if (__dfs_mode)
 	    {
 	      if (__state._M_matches(*_M_current))
 		{
 		  ++_M_current;
 		  _M_dfs(__match_mode, __state._M_next);
 		  --_M_current;
 		}
 	    }
 	  else
 	    if (__state._M_matches(*_M_current))
 	      _M_states._M_queue(__state._M_next, _M_cur_results);
 	  break;
 	// First fetch the matched result from _M_cur_results as __submatch;
 	// then compare it with
 	// (_M_current, _M_current + (__submatch.second - __submatch.first)).
 	// If matched, keep going; else just return and try another state.
 	case _S_opcode_backref:
 	  {
 	    _GLIBCXX_DEBUG_ASSERT(__dfs_mode);
 	    auto& __submatch = _M_cur_results[__state._M_backref_index];
 	    if (!__submatch.matched)
 	      break;
 	    auto __last = _M_current;
 	    for (auto __tmp = __submatch.first;
 		 __last != _M_end && __tmp != __submatch.second;
 		 ++__tmp)
 	      ++__last;
 	    if (_M_re._M_automaton->_M_traits.transform(__submatch.first,
 							__submatch.second)
 		== _M_re._M_automaton->_M_traits.transform(_M_current, __last))
 	      {
 		if (__last != _M_current)
 		  {
 		    auto __backup = _M_current;
 		    _M_current = __last;
 		    _M_dfs(__match_mode, __state._M_next);
 		    _M_current = __backup;
 		  }
 		else
 		  _M_dfs(__match_mode, __state._M_next);
 	      }
 	  }
 	  break;
 	case _S_opcode_accept:
 	  if (__dfs_mode)
 	    {
 	      _GLIBCXX_DEBUG_ASSERT(!_M_has_sol);
 	      if (__match_mode == _Match_mode::_Exact)
 		_M_has_sol = _M_current == _M_end;
 	      else
 		_M_has_sol = true;
 	      if (_M_current == _M_begin
 		  && (_M_flags & regex_constants::match_not_null))
 		_M_has_sol = false;
 	      if (_M_has_sol)
 		{
 		  if (_M_nfa._M_flags & regex_constants::ECMAScript)
 		    _M_results = _M_cur_results;
 		  else // POSIX
 		    {
 		      _GLIBCXX_DEBUG_ASSERT(_M_states._M_get_sol_pos());
 		      // Here's POSIX's logic: match the longest one. However
 		      // we never know which one (lhs or rhs of "|") is longer
 		      // unless we try both of them and compare the results.
 		      // The member variable _M_sol_pos records the end
 		      // position of the last successful match. It's better
 		      // to be larger, because POSIX regex is always greedy.
 		      // TODO: This could be slow.
 		      if (*_M_states._M_get_sol_pos() == _BiIter()
 			  || std::distance(_M_begin,
 					   *_M_states._M_get_sol_pos())
 			     < std::distance(_M_begin, _M_current))
 			{
 			  *_M_states._M_get_sol_pos() = _M_current;
 			  _M_results = _M_cur_results;
 			}
 		    }
 		}
 	    }
 	  else
 	    {
 	      if (_M_current == _M_begin
 		  && (_M_flags & regex_constants::match_not_null))
 		break;
 	      if (__match_mode == _Match_mode::_Prefix || _M_current == _M_end)
 		if (!_M_has_sol)
 		  {
 		    _M_has_sol = true;
 		    _M_results = _M_cur_results;
 		  }
 	    }
 	  break;
 	case _S_opcode_alternative:
 	  if (_M_nfa._M_flags & regex_constants::ECMAScript)
 	    {
 	      // TODO: Let BFS support ECMAScript's alternative operation.
 	      _GLIBCXX_DEBUG_ASSERT(__dfs_mode);
 	      _M_dfs(__match_mode, __state._M_alt);
 	      // Pick lhs if it matches. Only try rhs if it doesn't.
 	      if (!_M_has_sol)
 		_M_dfs(__match_mode, __state._M_next);
 	    }
 	  else
 	    {
 	      // Try both and compare the result.
 	      // See "case _S_opcode_accept:" handling above.
 	      _M_dfs(__match_mode, __state._M_alt);
 	      auto __has_sol = _M_has_sol;
 	      _M_has_sol = false;
 	      _M_dfs(__match_mode, __state._M_next);
 	      _M_has_sol |= __has_sol;
 	    }
 	  break;
 	default:
 	  _GLIBCXX_DEBUG_ASSERT(false);
 	}
     }

   // Return whether now is at some word boundary.
   template<typename _BiIter, typename _Alloc, typename _TraitsT,
 	   bool __dfs_mode>
     bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
     _M_word_boundary() const
     {
       bool __left_is_word = false;
       if (_M_current != _M_begin
 	  || (_M_flags & regex_constants::match_prev_avail))
 	{
 	  auto __prev = _M_current;
 	  if (_M_is_word(*std::prev(__prev)))
 	    __left_is_word = true;
 	}
       bool __right_is_word =
         _M_current != _M_end && _M_is_word(*_M_current);

       if (__left_is_word == __right_is_word)
 	return false;
       if (__left_is_word && !(_M_flags & regex_constants::match_not_eow))
 	return true;
       if (__right_is_word && !(_M_flags & regex_constants::match_not_bow))
 	return true;
       return false;
     }

 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace __detail
 } // namespace
	// class template regex -- C++ --

	// Copyright (C) 2013-2015 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_executor.tcc
	* This is an internal header file, included by other library headers.
	* Do not attempt to use it directly. @headername{regex}
	*/

	namespace std _GLIBCXX_VISIBILITY(default)
	{
	namespace __detail
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION

	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_search()
	{
	if (_M_search_from_first())
	return true;
	if (_M_flags & regex_constants::match_continuous)
	return false;
	_M_flags \|= regex_constants::match_prev_avail;
	while (_M_begin != _M_end)
	{
	++_M_begin;
	if (_M_search_from_first())
	return true;
	}
	return false;
	}

	// The _M_main function operates in different modes, DFS mode or BFS mode,
	// indicated by template parameter __dfs_mode, and dispatches to one of the
	// _M_main_dispatch overloads.
	//
	// ------------------------------------------------------------
	//
	// DFS mode:
	//
	// It applies a Depth-First-Search (aka backtracking) on given NFA and input
	// string.
	// At the very beginning the executor stands in the start state, then it
	// tries every possible state transition in current state recursively. Some
	// state transitions consume input string, say, a single-char-matcher or a
	// back-reference matcher; some don't, like assertion or other anchor nodes.
	// When the input is exhausted and/or the current state is an accepting
	// state, the whole executor returns true.
	//
	// TODO: This approach is exponentially slow for certain input.
	// Try to compile the NFA to a DFA.
	//
	// Time complexity: \Omega(match_length), O(2^(_M_nfa.size()))
	// Space complexity: \theta(match_results.size() + match_length)
	//
	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_main_dispatch(_Match_mode __match_mode, __dfs)
	{
	_M_has_sol = false;
	*_M_states._M_get_sol_pos() = _BiIter();
	_M_cur_results = _M_results;
	_M_dfs(__match_mode, _M_states._M_start);
	return _M_has_sol;
	}

	// ------------------------------------------------------------
	//
	// BFS mode:
	//
	// Russ Cox's article (http://swtch.com/~rsc/regexp/regexp1.html)
	// explained this algorithm clearly.
	//
	// It first computes epsilon closure (states that can be achieved without
	// consuming characters) for every state that's still matching,
	// using the same DFS algorithm, but doesn't re-enter states (using
	// _M_states._M_visited to check), nor follow _S_opcode_match.
	//
	// Then apply DFS using every _S_opcode_match (in _M_states._M_match_queue)
	// as the start state.
	//
	// It significantly reduces potential duplicate states, so has a better
	// upper bound; but it requires more overhead.
	//
	// Time complexity: \Omega(match_length * match_results.size())
	// O(match_length * _M_nfa.size() * match_results.size())
	// Space complexity: \Omega(_M_nfa.size() + match_results.size())
	// O(_M_nfa.size() * match_results.size())
	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_main_dispatch(_Match_mode __match_mode, __bfs)
	{
	_M_states._M_queue(_M_states._M_start, _M_results);
	bool __ret = false;
	while (1)
	{
	_M_has_sol = false;
	if (_M_states._M_match_queue.empty())
	break;
	std::fill_n(_M_states._M_visited_states.get(), _M_nfa.size(), false);
	auto __old_queue = std::move(_M_states._M_match_queue);
	for (auto& __task : __old_queue)
	{
	_M_cur_results = std::move(__task.second);
	_M_dfs(__match_mode, __task.first);
	}
	if (__match_mode == _Match_mode::_Prefix)
	__ret \|= _M_has_sol;
	if (_M_current == _M_end)
	break;
	++_M_current;
	}
	if (__match_mode == _Match_mode::_Exact)
	__ret = _M_has_sol;
	_M_states._M_match_queue.clear();
	return __ret;
	}

	// Return whether now match the given sub-NFA.
	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_lookahead(_State<_TraitsT> __state)
	{
	_ResultsVec __what(_M_cur_results.size());
	_Executor __sub(_M_current, _M_end, __what, _M_re, _M_flags);
	__sub._M_states._M_start = __state._M_alt;
	if (__sub._M_search_from_first())
	{
	for (size_t __i = 0; __i < __what.size(); __i++)
	if (__what[__i].matched)
	_M_cur_results[__i] = __what[__i];
	return true;
	}
	return false;
	}

	// __rep_count records how many times (__rep_count.second)
	// this node is visited under certain input iterator
	// (__rep_count.first). This prevent the executor from entering
	// infinite loop by refusing to continue when it's already been
	// visited more than twice. It's `twice` instead of `once` because
	// we need to spare one more time for potential group capture.
	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_rep_once_more(_Match_mode __match_mode, _StateIdT __i)
	{
	const auto& __state = _M_nfa[__i];
	auto& __rep_count = _M_rep_count[__i];
	if (__rep_count.second == 0 \|\| __rep_count.first != _M_current)
	{
	auto __back = __rep_count;
	__rep_count.first = _M_current;
	__rep_count.second = 1;
	_M_dfs(__match_mode, __state._M_alt);
	__rep_count = __back;
	}
	else
	{
	if (__rep_count.second < 2)
	{
	__rep_count.second++;
	_M_dfs(__match_mode, __state._M_alt);
	__rep_count.second--;
	}
	}
	};

	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	void _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_dfs(_Match_mode __match_mode, _StateIdT __i)
	{
	if (_M_states._M_visited(__i))
	return;

	const auto& __state = _M_nfa[__i];
	// Every change on _M_cur_results and _M_current will be rolled back after
	// finishing the recursion step.
	switch (__state._M_opcode)
	{
	// _M_alt branch is "match once more", while _M_next is "get me out
	// of this quantifier". Executing _M_next first or _M_alt first don't
	// mean the same thing, and we need to choose the correct order under
	// given greedy mode.
	case _S_opcode_repeat:
	{
	// Greedy.
	if (!__state._M_neg)
	{
	_M_rep_once_more(__match_mode, __i);
	// If it's DFS executor and already accepted, we're done.
	if (!__dfs_mode \|\| !_M_has_sol)
	_M_dfs(__match_mode, __state._M_next);
	}
	else // Non-greedy mode
	{
	if (__dfs_mode)
	{
	// vice-versa.
	_M_dfs(__match_mode, __state._M_next);
	if (!_M_has_sol)
	_M_rep_once_more(__match_mode, __i);
	}
	else
	{
	// DON'T attempt anything, because there's already another
	// state with higher priority accepted. This state cannot
	// be better by attempting its next node.
	if (!_M_has_sol)
	{
	_M_dfs(__match_mode, __state._M_next);
	// DON'T attempt anything if it's already accepted. An
	// accepted state must be better than a solution that
	// matches a non-greedy quantifier one more time.
	if (!_M_has_sol)
	_M_rep_once_more(__match_mode, __i);
	}
	}
	}
	}
	break;
	case _S_opcode_subexpr_begin:
	{
	auto& __res = _M_cur_results[__state._M_subexpr];
	auto __back = __res.first;
	__res.first = _M_current;
	_M_dfs(__match_mode, __state._M_next);
	__res.first = __back;
	}
	break;
	case _S_opcode_subexpr_end:
	{
	auto& __res = _M_cur_results[__state._M_subexpr];
	auto __back = __res;
	__res.second = _M_current;
	__res.matched = true;
	_M_dfs(__match_mode, __state._M_next);
	__res = __back;
	}
	break;
	case _S_opcode_line_begin_assertion:
	if (_M_at_begin())
	_M_dfs(__match_mode, __state._M_next);
	break;
	case _S_opcode_line_end_assertion:
	if (_M_at_end())
	_M_dfs(__match_mode, __state._M_next);
	break;
	case _S_opcode_word_boundary:
	if (_M_word_boundary() == !__state._M_neg)
	_M_dfs(__match_mode, __state._M_next);
	break;
	// Here __state._M_alt offers a single start node for a sub-NFA.
	// We recursively invoke our algorithm to match the sub-NFA.
	case _S_opcode_subexpr_lookahead:
	if (_M_lookahead(__state) == !__state._M_neg)
	_M_dfs(__match_mode, __state._M_next);
	break;
	case _S_opcode_match:
	if (_M_current == _M_end)
	break;
	if (__dfs_mode)
	{
	if (__state._M_matches(*_M_current))
	{
	++_M_current;
	_M_dfs(__match_mode, __state._M_next);
	--_M_current;
	}
	}
	else
	if (__state._M_matches(*_M_current))
	_M_states._M_queue(__state._M_next, _M_cur_results);
	break;
	// First fetch the matched result from _M_cur_results as __submatch;
	// then compare it with
	// (_M_current, _M_current + (__submatch.second - __submatch.first)).
	// If matched, keep going; else just return and try another state.
	case _S_opcode_backref:
	{
	_GLIBCXX_DEBUG_ASSERT(__dfs_mode);
	auto& __submatch = _M_cur_results[__state._M_backref_index];
	if (!__submatch.matched)
	break;
	auto __last = _M_current;
	for (auto __tmp = __submatch.first;
	__last != _M_end && __tmp != __submatch.second;
	++__tmp)
	++__last;
	if (_M_re._M_automaton->_M_traits.transform(__submatch.first,
	__submatch.second)
	== _M_re._M_automaton->_M_traits.transform(_M_current, __last))
	{
	if (__last != _M_current)
	{
	auto __backup = _M_current;
	_M_current = __last;
	_M_dfs(__match_mode, __state._M_next);
	_M_current = __backup;
	}
	else
	_M_dfs(__match_mode, __state._M_next);
	}
	}
	break;
	case _S_opcode_accept:
	if (__dfs_mode)
	{
	_GLIBCXX_DEBUG_ASSERT(!_M_has_sol);
	if (__match_mode == _Match_mode::_Exact)
	_M_has_sol = _M_current == _M_end;
	else
	_M_has_sol = true;
	if (_M_current == _M_begin
	&& (_M_flags & regex_constants::match_not_null))
	_M_has_sol = false;
	if (_M_has_sol)
	{
	if (_M_nfa._M_flags & regex_constants::ECMAScript)
	_M_results = _M_cur_results;
	else // POSIX
	{
	_GLIBCXX_DEBUG_ASSERT(_M_states._M_get_sol_pos());
	// Here's POSIX's logic: match the longest one. However
	// we never know which one (lhs or rhs of "\|") is longer
	// unless we try both of them and compare the results.
	// The member variable _M_sol_pos records the end
	// position of the last successful match. It's better
	// to be larger, because POSIX regex is always greedy.
	// TODO: This could be slow.
	if (*_M_states._M_get_sol_pos() == _BiIter()
	\|\| std::distance(_M_begin,
	*_M_states._M_get_sol_pos())
	< std::distance(_M_begin, _M_current))
	{
	*_M_states._M_get_sol_pos() = _M_current;
	_M_results = _M_cur_results;
	}
	}
	}
	}
	else
	{
	if (_M_current == _M_begin
	&& (_M_flags & regex_constants::match_not_null))
	break;
	if (__match_mode == _Match_mode::_Prefix \|\| _M_current == _M_end)
	if (!_M_has_sol)
	{
	_M_has_sol = true;
	_M_results = _M_cur_results;
	}
	}
	break;
	case _S_opcode_alternative:
	if (_M_nfa._M_flags & regex_constants::ECMAScript)
	{
	// TODO: Let BFS support ECMAScript's alternative operation.
	_GLIBCXX_DEBUG_ASSERT(__dfs_mode);
	_M_dfs(__match_mode, __state._M_alt);
	// Pick lhs if it matches. Only try rhs if it doesn't.
	if (!_M_has_sol)
	_M_dfs(__match_mode, __state._M_next);
	}
	else
	{
	// Try both and compare the result.
	// See "case _S_opcode_accept:" handling above.
	_M_dfs(__match_mode, __state._M_alt);
	auto __has_sol = _M_has_sol;
	_M_has_sol = false;
	_M_dfs(__match_mode, __state._M_next);
	_M_has_sol \|= __has_sol;
	}
	break;
	default:
	_GLIBCXX_DEBUG_ASSERT(false);
	}
	}

	// Return whether now is at some word boundary.
	template<typename _BiIter, typename _Alloc, typename _TraitsT,
	bool __dfs_mode>
	bool _Executor<_BiIter, _Alloc, _TraitsT, __dfs_mode>::
	_M_word_boundary() const
	{
	bool __left_is_word = false;
	if (_M_current != _M_begin
	\|\| (_M_flags & regex_constants::match_prev_avail))
	{
	auto __prev = _M_current;
	if (_M_is_word(*std::prev(__prev)))
	__left_is_word = true;
	}
	bool __right_is_word =
	_M_current != _M_end && _M_is_word(*_M_current);

	if (__left_is_word == __right_is_word)
	return false;
	if (__left_is_word && !(_M_flags & regex_constants::match_not_eow))
	return true;
	if (__right_is_word && !(_M_flags & regex_constants::match_not_bow))
	return true;
	return false;
	}

	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace __detail
	} // namespace