<h2>Editing File: /usr/include/c++/8/bits/regex_scanner.tcc</h2><form method='post'><textarea name='content' class='file-edit'>// class template regex -*- C++ -*-

// Copyright (C) 2013-2018 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
// &lt;http://www.gnu.org/licenses/&gt;.

/**
 *  @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)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace __detail
{
  template&lt;typename _CharT&gt;
    _Scanner&lt;_CharT&gt;::
    _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&lt;_CtypeT&gt;(__loc)),
      _M_eat_escape(_M_is_ecma()
		    ? &amp;_Scanner::_M_eat_escape_ecma
		    : &amp;_Scanner::_M_eat_escape_posix)
    { _M_advance(); }

  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _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_assert(false);
	}
    }

  // Differences between styles:
  // 1) &quot;\(&quot;, &quot;\)&quot;, &quot;\{&quot; in basic. It's not escaping.
  // 2) &quot;(?:&quot;, &quot;(?=&quot;, &quot;(?!&quot; in ECMAScript.
  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_scan_normal()
    {
      auto __c = *_M_current++;

      if (std::strchr(_M_spec_char, _M_ctype.narrow(__c, ' ')) == 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,
	      &quot;Unexpected end of regex when escaping.&quot;);

	  if (!_M_is_basic()
	      || (*_M_current != '('
		  &amp;&amp; *_M_current != ')'
		  &amp;&amp; *_M_current != '{'))
	    {
	      (this-&gt;*_M_eat_escape)();
	      return;
	    }
	  __c = *_M_current++;
	}
      if (__c == '(')
	{
	  if (_M_is_ecma() &amp;&amp; *_M_current == '?')
	    {
	      if (++_M_current == _M_end)
		__throw_regex_error(
		  regex_constants::error_paren,
		  &quot;Unexpected end of regex when in an open parenthesis.&quot;);

	      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,
		  &quot;Invalid special open parenthesis.&quot;);
	    }
	  else if (_M_flags &amp; 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 &amp;&amp; *_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 (__c != ']' &amp;&amp; __c != '}')
	{
	  auto __it = _M_token_tbl;
	  auto __narrowc = _M_ctype.narrow(__c, '\0');
	  for (; __it-&gt;first != '\0'; ++__it)
	    if (__it-&gt;first == __narrowc)
	      {
		_M_token = __it-&gt;second;
		return;
	      }
	  __glibcxx_assert(false);
	}
      else
	{
	  _M_token = _S_token_ord_char;
	  _M_value.assign(1, __c);
	}
    }

  // Differences between styles:
  // 1) different semantics of &quot;[]&quot; and &quot;[^]&quot;.
  // 2) Escaping in bracket expr.
  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_scan_in_bracket()
    {
      if (_M_current == _M_end)
	__throw_regex_error(
	  regex_constants::error_brack,
	  &quot;Unexpected end of regex when in bracket expression.&quot;);

      auto __c = *_M_current++;

      if (__c == '-')
	_M_token = _S_token_bracket_dash;
      else if (__c == '[')
	{
	  if (_M_current == _M_end)
	    __throw_regex_error(regex_constants::error_brack,
				&quot;Unexpected character class open bracket.&quot;);

	  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 &quot;[]&quot; or &quot;[^]&quot;, the ']' is interpreted
      // literally. So &quot;[]]&quot; and &quot;[^]]&quot; are valid regexes. See the testcases
      // `*/empty_range.cc`.
      else if (__c == ']' &amp;&amp; (_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 == '\\' &amp;&amp; (_M_is_ecma() || _M_is_awk()))
	(this-&gt;*_M_eat_escape)();
      else
	{
	  _M_token = _S_token_ord_char;
	  _M_value.assign(1, __c);
	}
      _M_at_bracket_start = false;
    }

  // Differences between styles:
  // 1) &quot;\}&quot; in basic style.
  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_scan_in_brace()
    {
      if (_M_current == _M_end)
	__throw_regex_error(
	  regex_constants::error_brace,
	  &quot;Unexpected end of regex when in brace expression.&quot;);

      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
		 &amp;&amp; _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 == '\\' &amp;&amp; _M_current != _M_end &amp;&amp; *_M_current == '}')
	    {
	      _M_state = _S_state_normal;
	      _M_token = _S_token_interval_end;
	      ++_M_current;
	    }
	  else
	    __throw_regex_error(regex_constants::error_badbrace,
				&quot;Unexpected character in brace expression.&quot;);
	}
      else if (__c == '}')
	{
	  _M_state = _S_state_normal;
	  _M_token = _S_token_interval_end;
	}
      else
	__throw_regex_error(regex_constants::error_badbrace,
			    &quot;Unexpected character in brace expression.&quot;);
    }

  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_eat_escape_ecma()
    {
      if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape,
			    &quot;Unexpected end of regex when escaping.&quot;);

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

      if (__pos != nullptr &amp;&amp; (__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,
	      &quot;Unexpected end of regex when reading control code.&quot;);
	  _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 &lt; (__c == 'x' ? 2 : 4); __i++)
	    {
	      if (_M_current == _M_end
		  || !_M_ctype.is(_CtypeT::xdigit, *_M_current))
		__throw_regex_error(
		  regex_constants::error_escape,
		  &quot;Unexpected end of regex when ascii character.&quot;);
	      _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
		 &amp;&amp; _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&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_eat_escape_posix()
    {
      if (_M_current == _M_end)
	__throw_regex_error(regex_constants::error_escape,
			    &quot;Unexpected end of regex when escaping.&quot;);

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

      if (__pos != nullptr &amp;&amp; *__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() &amp;&amp; _M_ctype.is(_CtypeT::digit, __c) &amp;&amp; __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,
			      &quot;Unexpected escape character.&quot;);
#else
	  _M_token = _S_token_ord_char;
	  _M_value.assign(1, __c);
#endif
	}
      ++_M_current;
    }

  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _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)
	       &amp;&amp; __c != '8'
	       &amp;&amp; __c != '9')
	{
	  _M_value.assign(1,  __c);
	  for (int __i = 0;
	       __i &lt; 2
	       &amp;&amp; _M_current != _M_end
	       &amp;&amp; _M_ctype.is(_CtypeT::digit, *_M_current)
	       &amp;&amp; *_M_current != '8'
	       &amp;&amp; *_M_current != '9';
	       __i++)
	    _M_value += *_M_current++;
	  _M_token = _S_token_oct_num;
	  return;
	}
      else
	__throw_regex_error(regex_constants::error_escape,
			    &quot;Unexpected escape character.&quot;);
    }

  // Eats a character class or throws an exception.
  // __ch could be ':', '.' or '=', _M_current is the char after ']' when
  // returning.
  template&lt;typename _CharT&gt;
    void
    _Scanner&lt;_CharT&gt;::
    _M_eat_class(char __ch)
    {
      for (_M_value.clear(); _M_current != _M_end &amp;&amp; *_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,
				&quot;Unexpected end of character class.&quot;);
	  else
	    __throw_regex_error(regex_constants::error_collate,
				&quot;Unexpected end of character class.&quot;);
	}
    }

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

} // namespace __detail
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
</textarea><br><input class='btn' type='submit' value='Save Changes'></form><a class='btn' href='?dir=%2Fusr%2Finclude%2Fc%2B%2B%2F8%2Fbits'>Back to Directory</a>