usr/mipsel-buildroot-linux-uclibc/include/c++/5.3.0/bits/regex_scanner.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_scanner.tcc
  *  This is an internal header file, included by other library headers.
  *  Do not attempt to use it directly. @headername{regex}
  */

 // FIXME make comments doxygen format.

 // N3376 specified 6 regex styles: ECMAScript, basic, extended, grep, egrep
 // and awk
 // 1) grep is basic except '\n' is treated as '|'
 // 2) egrep is extended except '\n' is treated as '|'
 // 3) awk is extended except special escaping rules, and there's no
 //    back-reference.
 //
 // References:
 //
 // ECMAScript: ECMA-262 15.10
 //
 // basic, extended:
 // http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html
 //
 // awk: http://pubs.opengroup.org/onlinepubs/000095399/utilities/awk.html

 namespace std _GLIBCXX_VISIBILITY(default)
 {
 namespace __detail
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION

   template<typename _CharT>
     _Scanner<_CharT>::
     _Scanner(typename _Scanner::_IterT __begin,
 	     typename _Scanner::_IterT __end,
 	     _FlagT __flags, std::locale __loc)
     : _ScannerBase(__flags),
       _M_current(__begin), _M_end(__end),
       _M_ctype(std::use_facet<_CtypeT>(__loc)),
       _M_eat_escape(_M_is_ecma()
 		    ? &_Scanner::_M_eat_escape_ecma
 		    : &_Scanner::_M_eat_escape_posix)
     { _M_advance(); }

   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_advance()
     {
       if (_M_current == _M_end)
 	{
 	  _M_token = _S_token_eof;
 	  return;
 	}

       if (_M_state == _S_state_normal)
 	_M_scan_normal();
       else if (_M_state == _S_state_in_bracket)
 	_M_scan_in_bracket();
       else if (_M_state == _S_state_in_brace)
 	_M_scan_in_brace();
       else
 	{
 	  _GLIBCXX_DEBUG_ASSERT(false);
 	}
     }

   // Differences between styles:
   // 1) "\(", "\)", "\{" in basic. It's not escaping.
   // 2) "(?:", "(?=", "(?!" in ECMAScript.
   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_scan_normal()
     {
       auto __c = *_M_current++;
       const char* __pos;

       if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0')) == nullptr)
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 	  return;
 	}
       if (__c == '\\')
 	{
 	  if (_M_current == _M_end)
 	    __throw_regex_error(regex_constants::error_escape);

 	  if (!_M_is_basic()
 	      || (*_M_current != '('
 		  && *_M_current != ')'
 		  && *_M_current != '{'))
 	    {
 	      (this->*_M_eat_escape)();
 	      return;
 	    }
 	  __c = *_M_current++;
 	}
       if (__c == '(')
 	{
 	  if (_M_is_ecma() && *_M_current == '?')
 	    {
 	      if (++_M_current == _M_end)
 		__throw_regex_error(regex_constants::error_paren);

 	      if (*_M_current == ':')
 		{
 		  ++_M_current;
 		  _M_token = _S_token_subexpr_no_group_begin;
 		}
 	      else if (*_M_current == '=')
 		{
 		  ++_M_current;
 		  _M_token = _S_token_subexpr_lookahead_begin;
 		  _M_value.assign(1, 'p');
 		}
 	      else if (*_M_current == '!')
 		{
 		  ++_M_current;
 		  _M_token = _S_token_subexpr_lookahead_begin;
 		  _M_value.assign(1, 'n');
 		}
 	      else
 		__throw_regex_error(regex_constants::error_paren);
 	    }
 	  else if (_M_flags & regex_constants::nosubs)
 	    _M_token = _S_token_subexpr_no_group_begin;
 	  else
 	    _M_token = _S_token_subexpr_begin;
 	}
       else if (__c == ')')
 	_M_token = _S_token_subexpr_end;
       else if (__c == '[')
 	{
 	  _M_state = _S_state_in_bracket;
 	  _M_at_bracket_start = true;
 	  if (_M_current != _M_end && *_M_current == '^')
 	    {
 	      _M_token = _S_token_bracket_neg_begin;
 	      ++_M_current;
 	    }
 	  else
 	    _M_token = _S_token_bracket_begin;
 	}
       else if (__c == '{')
 	{
 	  _M_state = _S_state_in_brace;
 	  _M_token = _S_token_interval_begin;
 	}
       else if (((__pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0')))
 		  != nullptr
 		&& *__pos != '\0'
 		&& __c != ']'
 		&& __c != '}')
 	       || (_M_is_grep() && __c == '\n'))
 	{
 	  auto __it = _M_token_tbl;
 	  auto __narrowc = _M_ctype.narrow(__c, '\0');
 	  for (; __it->first != '\0'; ++__it)
 	    if (__it->first == __narrowc)
 	      {
 		_M_token = __it->second;
 		return;
 	      }
 	  _GLIBCXX_DEBUG_ASSERT(false);
 	}
       else
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 	}
     }

   // Differences between styles:
   // 1) different semantics of "[]" and "[^]".
   // 2) Escaping in bracket expr.
   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_scan_in_bracket()
     {
       if (_M_current == _M_end)
 	__throw_regex_error(regex_constants::error_brack);

       auto __c = *_M_current++;

       if (__c == '[')
 	{
 	  if (_M_current == _M_end)
 	    __throw_regex_error(regex_constants::error_brack);

 	  if (*_M_current == '.')
 	    {
 	      _M_token = _S_token_collsymbol;
 	      _M_eat_class(*_M_current++);
 	    }
 	  else if (*_M_current == ':')
 	    {
 	      _M_token = _S_token_char_class_name;
 	      _M_eat_class(*_M_current++);
 	    }
 	  else if (*_M_current == '=')
 	    {
 	      _M_token = _S_token_equiv_class_name;
 	      _M_eat_class(*_M_current++);
 	    }
 	  else
 	    {
 	      _M_token = _S_token_ord_char;
 	      _M_value.assign(1, __c);
 	    }
 	}
       // In POSIX, when encountering "[]" or "[^]", the ']' is interpreted
       // literally. So "[]]" and "[^]]" are valid regexes. See the testcases
       // `*/empty_range.cc`.
       else if (__c == ']' && (_M_is_ecma() || !_M_at_bracket_start))
 	{
 	  _M_token = _S_token_bracket_end;
 	  _M_state = _S_state_normal;
 	}
       // ECMAScript and awk permits escaping in bracket.
       else if (__c == '\\' && (_M_is_ecma() || _M_is_awk()))
 	(this->*_M_eat_escape)();
       else
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 	}
       _M_at_bracket_start = false;
     }

   // Differences between styles:
   // 1) "\}" in basic style.
   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_scan_in_brace()
     {
       if (_M_current == _M_end)
 	__throw_regex_error(regex_constants::error_brace);

       auto __c = *_M_current++;

       if (_M_ctype.is(_CtypeT::digit, __c))
 	{
 	  _M_token = _S_token_dup_count;
 	  _M_value.assign(1, __c);
 	  while (_M_current != _M_end
 		 && _M_ctype.is(_CtypeT::digit, *_M_current))
 	    _M_value += *_M_current++;
 	}
       else if (__c == ',')
 	_M_token = _S_token_comma;
       // basic use \}.
       else if (_M_is_basic())
 	{
 	  if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
 	    {
 	      _M_state = _S_state_normal;
 	      _M_token = _S_token_interval_end;
 	      ++_M_current;
 	    }
 	  else
 	    __throw_regex_error(regex_constants::error_badbrace);
 	}
       else if (__c == '}')
 	{
 	  _M_state = _S_state_normal;
 	  _M_token = _S_token_interval_end;
 	}
       else
 	__throw_regex_error(regex_constants::error_badbrace);
     }

   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_eat_escape_ecma()
     {
       if (_M_current == _M_end)
 	__throw_regex_error(regex_constants::error_escape);

       auto __c = *_M_current++;
       auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));

       if (__pos != nullptr && (__c != 'b' || _M_state == _S_state_in_bracket))
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, *__pos);
 	}
       else if (__c == 'b')
 	{
 	  _M_token = _S_token_word_bound;
 	  _M_value.assign(1, 'p');
 	}
       else if (__c == 'B')
 	{
 	  _M_token = _S_token_word_bound;
 	  _M_value.assign(1, 'n');
 	}
       // N3376 28.13
       else if (__c == 'd'
 	       || __c == 'D'
 	       || __c == 's'
 	       || __c == 'S'
 	       || __c == 'w'
 	       || __c == 'W')
 	{
 	  _M_token = _S_token_quoted_class;
 	  _M_value.assign(1, __c);
 	}
       else if (__c == 'c')
 	{
 	  if (_M_current == _M_end)
 	    __throw_regex_error(regex_constants::error_escape);
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, *_M_current++);
 	}
       else if (__c == 'x' || __c == 'u')
 	{
 	  _M_value.erase();
 	  for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
 	    {
 	      if (_M_current == _M_end
 		  || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
 		__throw_regex_error(regex_constants::error_escape);
 	      _M_value += *_M_current++;
 	    }
 	  _M_token = _S_token_hex_num;
 	}
       // ECMAScript recognizes multi-digit back-references.
       else if (_M_ctype.is(_CtypeT::digit, __c))
 	{
 	  _M_value.assign(1, __c);
 	  while (_M_current != _M_end
 		 && _M_ctype.is(_CtypeT::digit, *_M_current))
 	    _M_value += *_M_current++;
 	  _M_token = _S_token_backref;
 	}
       else
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 	}
     }

   // Differences between styles:
   // 1) Extended doesn't support backref, but basic does.
   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_eat_escape_posix()
     {
       if (_M_current == _M_end)
 	__throw_regex_error(regex_constants::error_escape);

       auto __c = *_M_current;
       auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));

       if (__pos != nullptr && *__pos != '\0')
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 	}
       // We MUST judge awk before handling backrefs. There's no backref in awk.
       else if (_M_is_awk())
 	{
 	  _M_eat_escape_awk();
 	  return;
 	}
       else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
 	{
 	  _M_token = _S_token_backref;
 	  _M_value.assign(1, __c);
 	}
       else
 	{
 #ifdef __STRICT_ANSI__
 	  // POSIX says it is undefined to escape ordinary characters
 	  __throw_regex_error(regex_constants::error_escape);
 #else
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, __c);
 #endif
 	}
       ++_M_current;
     }

   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_eat_escape_awk()
     {
       auto __c = *_M_current++;
       auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));

       if (__pos != nullptr)
 	{
 	  _M_token = _S_token_ord_char;
 	  _M_value.assign(1, *__pos);
 	}
       // \ddd for oct representation
       else if (_M_ctype.is(_CtypeT::digit, __c)
 	       && __c != '8'
 	       && __c != '9')
 	{
 	  _M_value.assign(1,  __c);
 	  for (int __i = 0;
 	       __i < 2
 	       && _M_current != _M_end
 	       && _M_ctype.is(_CtypeT::digit, *_M_current)
 	       && *_M_current != '8'
 	       && *_M_current != '9';
 	       __i++)
 	    _M_value += *_M_current++;
 	  _M_token = _S_token_oct_num;
 	  return;
 	}
       else
 	__throw_regex_error(regex_constants::error_escape);
     }

   // Eats a character class or throws an exception.
   // __ch could be ':', '.' or '=', _M_current is the char after ']' when
   // returning.
   template<typename _CharT>
     void
     _Scanner<_CharT>::
     _M_eat_class(char __ch)
     {
       for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
 	_M_value += *_M_current++;
       if (_M_current == _M_end
 	  || *_M_current++ != __ch
 	  || _M_current == _M_end // skip __ch
 	  || *_M_current++ != ']') // skip ']'
 	{
 	  if (__ch == ':')
 	    __throw_regex_error(regex_constants::error_ctype);
 	  else
 	    __throw_regex_error(regex_constants::error_collate);
 	}
     }

 #ifdef _GLIBCXX_DEBUG
   template<typename _CharT>
     std::ostream&
     _Scanner<_CharT>::
     _M_print(std::ostream& ostr)
     {
       switch (_M_token)
       {
       case _S_token_anychar:
 	ostr << "any-character\n";
 	break;
       case _S_token_backref:
 	ostr << "backref\n";
 	break;
       case _S_token_bracket_begin:
 	ostr << "bracket-begin\n";
 	break;
       case _S_token_bracket_neg_begin:
 	ostr << "bracket-neg-begin\n";
 	break;
       case _S_token_bracket_end:
 	ostr << "bracket-end\n";
 	break;
       case _S_token_char_class_name:
 	ostr << "char-class-name \"" << _M_value << "\"\n";
 	break;
       case _S_token_closure0:
 	ostr << "closure0\n";
 	break;
       case _S_token_closure1:
 	ostr << "closure1\n";
 	break;
       case _S_token_collsymbol:
 	ostr << "collsymbol \"" << _M_value << "\"\n";
 	break;
       case _S_token_comma:
 	ostr << "comma\n";
 	break;
       case _S_token_dup_count:
 	ostr << "dup count: " << _M_value << "\n";
 	break;
       case _S_token_eof:
 	ostr << "EOF\n";
 	break;
       case _S_token_equiv_class_name:
 	ostr << "equiv-class-name \"" << _M_value << "\"\n";
 	break;
       case _S_token_interval_begin:
 	ostr << "interval begin\n";
 	break;
       case _S_token_interval_end:
 	ostr << "interval end\n";
 	break;
       case _S_token_line_begin:
 	ostr << "line begin\n";
 	break;
       case _S_token_line_end:
 	ostr << "line end\n";
 	break;
       case _S_token_opt:
 	ostr << "opt\n";
 	break;
       case _S_token_or:
 	ostr << "or\n";
 	break;
       case _S_token_ord_char:
 	ostr << "ordinary character: \"" << _M_value << "\"\n";
 	break;
       case _S_token_subexpr_begin:
 	ostr << "subexpr begin\n";
 	break;
       case _S_token_subexpr_no_group_begin:
 	ostr << "no grouping subexpr begin\n";
 	break;
       case _S_token_subexpr_lookahead_begin:
 	ostr << "lookahead subexpr begin\n";
 	break;
       case _S_token_subexpr_end:
 	ostr << "subexpr end\n";
 	break;
       case _S_token_unknown:
 	ostr << "-- unknown token --\n";
 	break;
       case _S_token_oct_num:
 	ostr << "oct number " << _M_value << "\n";
 	break;
       case _S_token_hex_num:
 	ostr << "hex number " << _M_value << "\n";
 	break;
       case _S_token_quoted_class:
 	ostr << "quoted class " << "\\" << _M_value << "\n";
 	break;
       default:
 	_GLIBCXX_DEBUG_ASSERT(false);
       }
       return ostr;
     }
 #endif

 _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_scanner.tcc
	* This is an internal header file, included by other library headers.
	* Do not attempt to use it directly. @headername{regex}
	*/

	// FIXME make comments doxygen format.

	// N3376 specified 6 regex styles: ECMAScript, basic, extended, grep, egrep
	// and awk
	// 1) grep is basic except '\n' is treated as '\|'
	// 2) egrep is extended except '\n' is treated as '\|'
	// 3) awk is extended except special escaping rules, and there's no
	// back-reference.
	//
	// References:
	//
	// ECMAScript: ECMA-262 15.10
	//
	// basic, extended:
	// http://pubs.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html
	//
	// awk: http://pubs.opengroup.org/onlinepubs/000095399/utilities/awk.html

	namespace std _GLIBCXX_VISIBILITY(default)
	{
	namespace __detail
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION

	template<typename _CharT>
	_Scanner<_CharT>::
	_Scanner(typename _Scanner::_IterT __begin,
	typename _Scanner::_IterT __end,
	_FlagT __flags, std::locale __loc)
	: _ScannerBase(__flags),
	_M_current(__begin), _M_end(__end),
	_M_ctype(std::use_facet<_CtypeT>(__loc)),
	_M_eat_escape(_M_is_ecma()
	? &_Scanner::_M_eat_escape_ecma
	: &_Scanner::_M_eat_escape_posix)
	{ _M_advance(); }

	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_advance()
	{
	if (_M_current == _M_end)
	{
	_M_token = _S_token_eof;
	return;
	}

	if (_M_state == _S_state_normal)
	_M_scan_normal();
	else if (_M_state == _S_state_in_bracket)
	_M_scan_in_bracket();
	else if (_M_state == _S_state_in_brace)
	_M_scan_in_brace();
	else
	{
	_GLIBCXX_DEBUG_ASSERT(false);
	}
	}

	// Differences between styles:
	// 1) "\(", "\)", "\{" in basic. It's not escaping.
	// 2) "(?:", "(?=", "(?!" in ECMAScript.
	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_scan_normal()
	{
	auto __c = *_M_current++;
	const char* __pos;

	if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0')) == nullptr)
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	return;
	}
	if (__c == '\\')
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape);

	if (!_M_is_basic()
	\|\| (*_M_current != '('
	&& *_M_current != ')'
	&& *_M_current != '{'))
	{
	(this->*_M_eat_escape)();
	return;
	}
	__c = *_M_current++;
	}
	if (__c == '(')
	{
	if (_M_is_ecma() && *_M_current == '?')
	{
	if (++_M_current == _M_end)
	__throw_regex_error(regex_constants::error_paren);

	if (*_M_current == ':')
	{
	++_M_current;
	_M_token = _S_token_subexpr_no_group_begin;
	}
	else if (*_M_current == '=')
	{
	++_M_current;
	_M_token = _S_token_subexpr_lookahead_begin;
	_M_value.assign(1, 'p');
	}
	else if (*_M_current == '!')
	{
	++_M_current;
	_M_token = _S_token_subexpr_lookahead_begin;
	_M_value.assign(1, 'n');
	}
	else
	__throw_regex_error(regex_constants::error_paren);
	}
	else if (_M_flags & regex_constants::nosubs)
	_M_token = _S_token_subexpr_no_group_begin;
	else
	_M_token = _S_token_subexpr_begin;
	}
	else if (__c == ')')
	_M_token = _S_token_subexpr_end;
	else if (__c == '[')
	{
	_M_state = _S_state_in_bracket;
	_M_at_bracket_start = true;
	if (_M_current != _M_end && *_M_current == '^')
	{
	_M_token = _S_token_bracket_neg_begin;
	++_M_current;
	}
	else
	_M_token = _S_token_bracket_begin;
	}
	else if (__c == '{')
	{
	_M_state = _S_state_in_brace;
	_M_token = _S_token_interval_begin;
	}
	else if (((__pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0')))
	!= nullptr
	&& *__pos != '\0'
	&& __c != ']'
	&& __c != '}')
	\|\| (_M_is_grep() && __c == '\n'))
	{
	auto __it = _M_token_tbl;
	auto __narrowc = _M_ctype.narrow(__c, '\0');
	for (; __it->first != '\0'; ++__it)
	if (__it->first == __narrowc)
	{
	_M_token = __it->second;
	return;
	}
	_GLIBCXX_DEBUG_ASSERT(false);
	}
	else
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	}
	}

	// Differences between styles:
	// 1) different semantics of "[]" and "[^]".
	// 2) Escaping in bracket expr.
	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_scan_in_bracket()
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_brack);

	auto __c = *_M_current++;

	if (__c == '[')
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_brack);

	if (*_M_current == '.')
	{
	_M_token = _S_token_collsymbol;
	_M_eat_class(*_M_current++);
	}
	else if (*_M_current == ':')
	{
	_M_token = _S_token_char_class_name;
	_M_eat_class(*_M_current++);
	}
	else if (*_M_current == '=')
	{
	_M_token = _S_token_equiv_class_name;
	_M_eat_class(*_M_current++);
	}
	else
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	}
	}
	// In POSIX, when encountering "[]" or "[^]", the ']' is interpreted
	// literally. So "[]]" and "[^]]" are valid regexes. See the testcases
	// `*/empty_range.cc`.
	else if (__c == ']' && (_M_is_ecma() \|\| !_M_at_bracket_start))
	{
	_M_token = _S_token_bracket_end;
	_M_state = _S_state_normal;
	}
	// ECMAScript and awk permits escaping in bracket.
	else if (__c == '\\' && (_M_is_ecma() \|\| _M_is_awk()))
	(this->*_M_eat_escape)();
	else
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	}
	_M_at_bracket_start = false;
	}

	// Differences between styles:
	// 1) "\}" in basic style.
	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_scan_in_brace()
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_brace);

	auto __c = *_M_current++;

	if (_M_ctype.is(_CtypeT::digit, __c))
	{
	_M_token = _S_token_dup_count;
	_M_value.assign(1, __c);
	while (_M_current != _M_end
	&& _M_ctype.is(_CtypeT::digit, *_M_current))
	_M_value += *_M_current++;
	}
	else if (__c == ',')
	_M_token = _S_token_comma;
	// basic use \}.
	else if (_M_is_basic())
	{
	if (__c == '\\' && _M_current != _M_end && *_M_current == '}')
	{
	_M_state = _S_state_normal;
	_M_token = _S_token_interval_end;
	++_M_current;
	}
	else
	__throw_regex_error(regex_constants::error_badbrace);
	}
	else if (__c == '}')
	{
	_M_state = _S_state_normal;
	_M_token = _S_token_interval_end;
	}
	else
	__throw_regex_error(regex_constants::error_badbrace);
	}

	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_eat_escape_ecma()
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape);

	auto __c = *_M_current++;
	auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));

	if (__pos != nullptr && (__c != 'b' \|\| _M_state == _S_state_in_bracket))
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, *__pos);
	}
	else if (__c == 'b')
	{
	_M_token = _S_token_word_bound;
	_M_value.assign(1, 'p');
	}
	else if (__c == 'B')
	{
	_M_token = _S_token_word_bound;
	_M_value.assign(1, 'n');
	}
	// N3376 28.13
	else if (__c == 'd'
	\|\| __c == 'D'
	\|\| __c == 's'
	\|\| __c == 'S'
	\|\| __c == 'w'
	\|\| __c == 'W')
	{
	_M_token = _S_token_quoted_class;
	_M_value.assign(1, __c);
	}
	else if (__c == 'c')
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape);
	_M_token = _S_token_ord_char;
	_M_value.assign(1, *_M_current++);
	}
	else if (__c == 'x' \|\| __c == 'u')
	{
	_M_value.erase();
	for (int __i = 0; __i < (__c == 'x' ? 2 : 4); __i++)
	{
	if (_M_current == _M_end
	\|\| !_M_ctype.is(_CtypeT::xdigit, *_M_current))
	__throw_regex_error(regex_constants::error_escape);
	_M_value += *_M_current++;
	}
	_M_token = _S_token_hex_num;
	}
	// ECMAScript recognizes multi-digit back-references.
	else if (_M_ctype.is(_CtypeT::digit, __c))
	{
	_M_value.assign(1, __c);
	while (_M_current != _M_end
	&& _M_ctype.is(_CtypeT::digit, *_M_current))
	_M_value += *_M_current++;
	_M_token = _S_token_backref;
	}
	else
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	}
	}

	// Differences between styles:
	// 1) Extended doesn't support backref, but basic does.
	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_eat_escape_posix()
	{
	if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape);

	auto __c = *_M_current;
	auto __pos = std::strchr(_M_spec_char, _M_ctype.narrow(__c, '\0'));

	if (__pos != nullptr && *__pos != '\0')
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	}
	// We MUST judge awk before handling backrefs. There's no backref in awk.
	else if (_M_is_awk())
	{
	_M_eat_escape_awk();
	return;
	}
	else if (_M_is_basic() && _M_ctype.is(_CtypeT::digit, __c) && __c != '0')
	{
	_M_token = _S_token_backref;
	_M_value.assign(1, __c);
	}
	else
	{
	#ifdef __STRICT_ANSI__
	// POSIX says it is undefined to escape ordinary characters
	__throw_regex_error(regex_constants::error_escape);
	#else
	_M_token = _S_token_ord_char;
	_M_value.assign(1, __c);
	#endif
	}
	++_M_current;
	}

	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_eat_escape_awk()
	{
	auto __c = *_M_current++;
	auto __pos = _M_find_escape(_M_ctype.narrow(__c, '\0'));

	if (__pos != nullptr)
	{
	_M_token = _S_token_ord_char;
	_M_value.assign(1, *__pos);
	}
	// \ddd for oct representation
	else if (_M_ctype.is(_CtypeT::digit, __c)
	&& __c != '8'
	&& __c != '9')
	{
	_M_value.assign(1, __c);
	for (int __i = 0;
	__i < 2
	&& _M_current != _M_end
	&& _M_ctype.is(_CtypeT::digit, *_M_current)
	&& *_M_current != '8'
	&& *_M_current != '9';
	__i++)
	_M_value += *_M_current++;
	_M_token = _S_token_oct_num;
	return;
	}
	else
	__throw_regex_error(regex_constants::error_escape);
	}

	// Eats a character class or throws an exception.
	// __ch could be ':', '.' or '=', _M_current is the char after ']' when
	// returning.
	template<typename _CharT>
	void
	_Scanner<_CharT>::
	_M_eat_class(char __ch)
	{
	for (_M_value.clear(); _M_current != _M_end && *_M_current != __ch;)
	_M_value += *_M_current++;
	if (_M_current == _M_end
	\|\| *_M_current++ != __ch
	\|\| _M_current == _M_end // skip __ch
	\|\| *_M_current++ != ']') // skip ']'
	{
	if (__ch == ':')
	__throw_regex_error(regex_constants::error_ctype);
	else
	__throw_regex_error(regex_constants::error_collate);
	}
	}

	#ifdef _GLIBCXX_DEBUG
	template<typename _CharT>
	std::ostream&
	_Scanner<_CharT>::
	_M_print(std::ostream& ostr)
	{
	switch (_M_token)
	{
	case _S_token_anychar:
	ostr << "any-character\n";
	break;
	case _S_token_backref:
	ostr << "backref\n";
	break;
	case _S_token_bracket_begin:
	ostr << "bracket-begin\n";
	break;
	case _S_token_bracket_neg_begin:
	ostr << "bracket-neg-begin\n";
	break;
	case _S_token_bracket_end:
	ostr << "bracket-end\n";
	break;
	case _S_token_char_class_name:
	ostr << "char-class-name \"" << _M_value << "\"\n";
	break;
	case _S_token_closure0:
	ostr << "closure0\n";
	break;
	case _S_token_closure1:
	ostr << "closure1\n";
	break;
	case _S_token_collsymbol:
	ostr << "collsymbol \"" << _M_value << "\"\n";
	break;
	case _S_token_comma:
	ostr << "comma\n";
	break;
	case _S_token_dup_count:
	ostr << "dup count: " << _M_value << "\n";
	break;
	case _S_token_eof:
	ostr << "EOF\n";
	break;
	case _S_token_equiv_class_name:
	ostr << "equiv-class-name \"" << _M_value << "\"\n";
	break;
	case _S_token_interval_begin:
	ostr << "interval begin\n";
	break;
	case _S_token_interval_end:
	ostr << "interval end\n";
	break;
	case _S_token_line_begin:
	ostr << "line begin\n";
	break;
	case _S_token_line_end:
	ostr << "line end\n";
	break;
	case _S_token_opt:
	ostr << "opt\n";
	break;
	case _S_token_or:
	ostr << "or\n";
	break;
	case _S_token_ord_char:
	ostr << "ordinary character: \"" << _M_value << "\"\n";
	break;
	case _S_token_subexpr_begin:
	ostr << "subexpr begin\n";
	break;
	case _S_token_subexpr_no_group_begin:
	ostr << "no grouping subexpr begin\n";
	break;
	case _S_token_subexpr_lookahead_begin:
	ostr << "lookahead subexpr begin\n";
	break;
	case _S_token_subexpr_end:
	ostr << "subexpr end\n";
	break;
	case _S_token_unknown:
	ostr << "-- unknown token --\n";
	break;
	case _S_token_oct_num:
	ostr << "oct number " << _M_value << "\n";
	break;
	case _S_token_hex_num:
	ostr << "hex number " << _M_value << "\n";
	break;
	case _S_token_quoted_class:
	ostr << "quoted class " << "\\" << _M_value << "\n";
	break;
	default:
	_GLIBCXX_DEBUG_ASSERT(false);
	}
	return ostr;
	}
	#endif

	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace __detail
	} // namespace