// class template regex -*- C++ -*-
	
	// Copyright (C) 2013-2019 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.h
	 *  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)
	{
	_GLIBCXX_BEGIN_NAMESPACE_VERSION
	
	namespace __detail
	{
	  /**
	   * @addtogroup regex-detail
	   * @{
	   */
	
	  struct _ScannerBase
	  {
	  public:
	    /// Token types returned from the scanner.
	    enum _TokenT : unsigned
	    {
	      _S_token_anychar,
	      _S_token_ord_char,
	      _S_token_oct_num,
	      _S_token_hex_num,
	      _S_token_backref,
	      _S_token_subexpr_begin,
	      _S_token_subexpr_no_group_begin,
	      _S_token_subexpr_lookahead_begin, // neg if _M_value[0] == 'n'
	      _S_token_subexpr_end,
	      _S_token_bracket_begin,
	      _S_token_bracket_neg_begin,
	      _S_token_bracket_end,
	      _S_token_interval_begin,
	      _S_token_interval_end,
	      _S_token_quoted_class,
	      _S_token_char_class_name,
	      _S_token_collsymbol,
	      _S_token_equiv_class_name,
	      _S_token_opt,
	      _S_token_or,
	      _S_token_closure0,
	      _S_token_closure1,
	      _S_token_line_begin,
	      _S_token_line_end,
	      _S_token_word_bound, // neg if _M_value[0] == 'n'
	      _S_token_comma,
	      _S_token_dup_count,
	      _S_token_eof,
	      _S_token_bracket_dash,
	      _S_token_unknown = -1u
	    };
	
	  protected:
	    typedef regex_constants::syntax_option_type _FlagT;
	
	    enum _StateT
	    {
	      _S_state_normal,
	      _S_state_in_brace,
	      _S_state_in_bracket,
	    };
	
	  protected:
	    _ScannerBase(_FlagT __flags)
	    : _M_state(_S_state_normal),
	    _M_flags(__flags),

	    _M_escape_tbl(_M_is_ecma()
			  ? _M_ecma_escape_tbl
			  : _M_awk_escape_tbl),

	    _M_spec_char(_M_is_ecma()
			 ? _M_ecma_spec_char
			 : _M_flags & regex_constants::basic
			 ? _M_basic_spec_char
			 : _M_flags & regex_constants::extended
			 ? _M_extended_spec_char
			 : _M_flags & regex_constants::grep
			 ?  ".[\\*^$\n"
			 : _M_flags & regex_constants::egrep
			 ? ".[\\()*+?{|^$\n"
			 : _M_flags & regex_constants::awk
			 ? _M_extended_spec_char
			 : nullptr),
	    _M_at_bracket_start(false)

	    { __glibcxx_assert(_M_spec_char); }
	
	  protected:
	    const char*
	    _M_find_escape(char __c)
	    {
	      auto __it = _M_escape_tbl;
	      for (; __it->first != '\0'; ++__it)
		if (__it->first == __c)
		  return &__it->second;
	      return nullptr;
	    }
	
	    bool
	    _M_is_ecma() const
	    { return _M_flags & regex_constants::ECMAScript; }
	
	    bool
	    _M_is_basic() const
	    { return _M_flags & (regex_constants::basic | regex_constants::grep); }
	
	    bool
	    _M_is_extended() const
	    {
	      return _M_flags & (regex_constants::extended
				 | regex_constants::egrep
				 | regex_constants::awk);
	    }
	
	    bool
	    _M_is_grep() const
	    { return _M_flags & (regex_constants::grep | regex_constants::egrep); }
	
	    bool
	    _M_is_awk() const
	    { return _M_flags & regex_constants::awk; }
	
	  protected:
	    // TODO: Make them static in the next abi change.
	    const std::pair<char, _TokenT> _M_token_tbl[9] =
	      {
		{'^', _S_token_line_begin},
		{'$', _S_token_line_end},
		{'.', _S_token_anychar},
		{'*', _S_token_closure0},
		{'+', _S_token_closure1},
		{'?', _S_token_opt},
		{'|', _S_token_or},
		{'\n', _S_token_or}, // grep and egrep
		{'\0', _S_token_or},
	      };
	    const std::pair<char, char> _M_ecma_escape_tbl[8] =
	      {
		{'0', '\0'},
		{'b', '\b'},
		{'f', '\f'},
		{'n', '\n'},
		{'r', '\r'},
		{'t', '\t'},
		{'v', '\v'},
		{'\0', '\0'},
	      };
	    const std::pair<char, char> _M_awk_escape_tbl[11] =
	      {
		{'"', '"'},
		{'/', '/'},
		{'\\', '\\'},
		{'a', '\a'},
		{'b', '\b'},
		{'f', '\f'},
		{'n', '\n'},
		{'r', '\r'},
		{'t', '\t'},
		{'v', '\v'},
		{'\0', '\0'},
	      };
	    const char* _M_ecma_spec_char = "^$\\.*+?()[]{}|";
	    const char* _M_basic_spec_char = ".[\\*^$";
	    const char* _M_extended_spec_char = ".[\\()*+?{|^$";
	
	    _StateT                       _M_state;
	    _FlagT                        _M_flags;

	    _TokenT                       _M_token;
	    const std::pair<char, char>*  _M_escape_tbl;
	    const char*                   _M_spec_char;
	    bool                          _M_at_bracket_start;
	  };
	
	  /**
	   * @brief Scans an input range for regex tokens.
	   *
	   * The %_Scanner class interprets the regular expression pattern in
	   * the input range passed to its constructor as a sequence of parse
	   * tokens passed to the regular expression compiler.  The sequence
	   * of tokens provided depends on the flag settings passed to the
	   * constructor: different regular expression grammars will interpret
	   * the same input pattern in syntactically different ways.
	   */
	  template<typename _CharT>
	    class _Scanner
	    : public _ScannerBase
	    {
	    public:
	      typedef const _CharT*                                       _IterT;
	      typedef std::basic_string<_CharT>                           _StringT;
	      typedef regex_constants::syntax_option_type                 _FlagT;
	      typedef const std::ctype<_CharT>                            _CtypeT;
	
	      _Scanner(_IterT __begin, _IterT __end,
		       _FlagT __flags, std::locale __loc);
	
	      void
	      _M_advance();
	
	      _TokenT
	      _M_get_token() const
	      { return _M_token; }
	
	      const _StringT&
	      _M_get_value() const
	      { return _M_value; }
	
	#ifdef _GLIBCXX_DEBUG
	      std::ostream&
	      _M_print(std::ostream&);
	#endif
	
	    private:
	      void
	      _M_scan_normal();
	
	      void
	      _M_scan_in_bracket();
	
	      void
	      _M_scan_in_brace();
	
	      void
	      _M_eat_escape_ecma();
	
	      void
	      _M_eat_escape_posix();
	
	      void
	      _M_eat_escape_awk();
	
	      void
	      _M_eat_class(char);
	
	      _IterT                        _M_current;
	      _IterT                        _M_end;
	      _CtypeT&                      _M_ctype;
	      _StringT                      _M_value;
	      void (_Scanner::* _M_eat_escape)();
	    };
	
	 //@} regex-detail
	} // namespace __detail
	_GLIBCXX_END_NAMESPACE_VERSION
	} // namespace std
	
	#include <bits/regex_scanner.tcc>