libstdc++-v3/include/bits/regex.tcc

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

// Copyright (C) 2013-2026 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.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)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace __detail
{
  /// @cond undocumented

  // Result of merging regex_match and regex_search.
  //
  // __policy now can be _S_auto (auto dispatch) and _S_alternate (use
  // the other one if possible, for test purpose).
  //
  // That __match_mode is true means regex_match, else regex_search.
  template<typename _BiIter, typename _Alloc,
	   typename _CharT, typename _TraitsT>
    bool
    __regex_algo_impl(_BiIter                              __s,
		      _BiIter                              __e,
		      match_results<_BiIter, _Alloc>&      __m,
		      const basic_regex<_CharT, _TraitsT>& __re,
		      regex_constants::match_flag_type     __flags,
		      _RegexExecutorPolicy		   __policy,
		      bool				   __match_mode)
    {
      if (__re._M_automaton == nullptr)
	return false;

      typename match_results<_BiIter, _Alloc>::_Unchecked& __res = __m;
      __m._M_begin = __s;
      __m._M_resize(__re._M_automaton->_M_sub_count());

      bool __ret;
      bool __use_dfs = true;
      if ((__re.flags() & regex_constants::__polynomial)
	  || (__policy == _RegexExecutorPolicy::_S_alternate
	      && !__re._M_automaton->_M_has_backref))
	__use_dfs = false;

      _Executor<_BiIter, _Alloc, _TraitsT>
	__executor(__s, __e, __res, __re, __flags, __use_dfs);
      if (__match_mode)
	__ret = __executor._M_match();
      else
	__ret = __executor._M_search();

      if (__ret)
	{
	  for (auto& __it : __res)
	    if (!__it.matched)
	      __it.first = __it.second = __e;
	  auto& __pre = __m._M_prefix();
	  auto& __suf = __m._M_suffix();
	  if (__match_mode)
	    {
	      __pre.matched = false;
	      __pre.first = __s;
	      __pre.second = __s;
	      __suf.matched = false;
	      __suf.first = __e;
	      __suf.second = __e;
	    }
	  else
	    {
	      __pre.first = __s;
	      __pre.second = __res[0].first;
	      __pre.matched = (__pre.first != __pre.second);
	      __suf.first = __res[0].second;
	      __suf.second = __e;
	      __suf.matched = (__suf.first != __suf.second);
	    }
	}
      else
	{
	  __m._M_establish_failed_match(__e);
	}
      return __ret;
    }

  inline void
  __lookup_collatename(string& __name) noexcept
  {
    static const char* const __collatenames[] =
      {
	"NUL",
	"SOH",
	"STX",
	"ETX",
	"EOT",
	"ENQ",
	"ACK",
	"alert",
	"backspace",
	"tab",
	"newline",
	"vertical-tab",
	"form-feed",
	"carriage-return",
	"SO",
	"SI",
	"DLE",
	"DC1",
	"DC2",
	"DC3",
	"DC4",
	"NAK",
	"SYN",
	"ETB",
	"CAN",
	"EM",
	"SUB",
	"ESC",
	"IS4",
	"IS3",
	"IS2",
	"IS1",
	"space",
	"exclamation-mark",
	"quotation-mark",
	"number-sign",
	"dollar-sign",
	"percent-sign",
	"ampersand",
	"apostrophe",
	"left-parenthesis",
	"right-parenthesis",
	"asterisk",
	"plus-sign",
	"comma",
	"hyphen",
	"period",
	"slash",
	"zero",
	"one",
	"two",
	"three",
	"four",
	"five",
	"six",
	"seven",
	"eight",
	"nine",
	"colon",
	"semicolon",
	"less-than-sign",
	"equals-sign",
	"greater-than-sign",
	"question-mark",
	"commercial-at",
	"A",
	"B",
	"C",
	"D",
	"E",
	"F",
	"G",
	"H",
	"I",
	"J",
	"K",
	"L",
	"M",
	"N",
	"O",
	"P",
	"Q",
	"R",
	"S",
	"T",
	"U",
	"V",
	"W",
	"X",
	"Y",
	"Z",
	"left-square-bracket",
	"backslash",
	"right-square-bracket",
	"circumflex",
	"underscore",
	"grave-accent",
	"a",
	"b",
	"c",
	"d",
	"e",
	"f",
	"g",
	"h",
	"i",
	"j",
	"k",
	"l",
	"m",
	"n",
	"o",
	"p",
	"q",
	"r",
	"s",
	"t",
	"u",
	"v",
	"w",
	"x",
	"y",
	"z",
	"left-curly-bracket",
	"vertical-line",
	"right-curly-bracket",
	"tilde",
	"DEL",
      };

    for (const auto& __it : __collatenames)
      if (__name == __it)
	{
	  __name.assign(1, static_cast<char>(&__it - __collatenames));
	  return;
	}

    __name.clear();
  }

  /// @endcond
} // namespace __detail

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wc++17-extensions" // if constexpr

  template<typename _Ch_type>
  template<typename _Fwd_iter>
    typename regex_traits<_Ch_type>::string_type
    regex_traits<_Ch_type>::
    lookup_collatename(_Fwd_iter __first, _Fwd_iter __last) const
    {
      // TODO Add digraph support:
      // http://boost.sourceforge.net/libs/regex/doc/collating_names.html

      if constexpr (is_same<char_type, char>::value)
	{
	  string __s(__first, __last);
	  __detail::__lookup_collatename(__s);
	  return __s;
	}
      else
	{
	  typedef std::ctype<char_type> __ctype_type;
	  const __ctype_type& __fctyp(use_facet<__ctype_type>(_M_locale));

	  string __s;
	  for (; __first != __last; ++__first)
	    __s += __fctyp.narrow(*__first, 0);
	  __detail::__lookup_collatename(__s);
	  if (__s.empty())
	    return string_type();
	  else
	    return string_type(1, __fctyp.widen(__s[0]));
	}
    }

  template<typename _Ch_type>
  template<typename _Fwd_iter>
    typename regex_traits<_Ch_type>::char_class_type
    regex_traits<_Ch_type>::
    lookup_classname(_Fwd_iter __first, _Fwd_iter __last, bool __icase) const
    {
      if constexpr (__is_any_random_access_iter<_Fwd_iter>::value)
	if ((__last - __first) > 6) [[__unlikely__]]
	  return {}; // "xdigit" is the longest classname

      typedef std::ctype<char_type> __ctype_type;
      const __ctype_type& __fctyp(use_facet<__ctype_type>(_M_locale));

      auto __read_ch = [&]() -> char {
	if (__first == __last)
	  return '\0';
	char __c = __fctyp.narrow(__fctyp.tolower(*__first), 0);
	++__first;
	return __c;
      };

      auto __match = [&](const char* __s) -> bool {
	do
	  if (__read_ch() != *__s)
	    return false;
	while (*++__s);
	return __first == __last;
      };

      switch(__read_ch())
	{
	case 'a':
	  if (__read_ch() == 'l')
	    switch (__read_ch())
	      {
	      case 'n':
		if (__match("um")) // "alnum"
		  return ctype_base::alnum;
		break;
	      case 'p':
		if (__match("ha")) // "alpha"
		  return ctype_base::alpha;
		break;
	      }
	  break;
	case 'b':
	  if (__match("lank")) // "blank"
	    return ctype_base::blank;
	  break;
	case 'c':
	  if (__match("ntrl")) // "cntrl"
	    return ctype_base::cntrl;
	  break;
	case 'd':
	  if (__first == __last || __match("igit")) // "d" or "digit"
	    return ctype_base::digit;
	  break;
	case 'g':
	  if (__match("raph")) // "graph"
	    return ctype_base::graph;
	  break;
	case 'l':
	  if (__match("ower")) // "lower"
	    return __icase ? ctype_base::alpha : ctype_base::lower;
	  break;
	case 'p':
	  switch (__read_ch())
	  {
	  case 'r':
	    if (__match("int")) // "print"
	      return ctype_base::print;
	    break;
	  case 'u':
	    if (__match("nct")) // "punct"
	      return ctype_base::punct;
	    break;
	  }
	  break;
	case 's':
	  if (__first == __last || __match("pace")) // "s" or "space"
	    return ctype_base::space;
	  break;
	case 'u':
	  if (__match("pper")) // "upper"
	    return __icase ? ctype_base::alpha : ctype_base::upper;
	  break;
	case 'w':
	  if (__first == __last) // "w"
	    return {ctype_base::alnum, char_class_type::_S_under};
	  break;
	case 'x':
	  if (__match("digit")) // "xdigit"
	    return ctype_base::xdigit;
	  break;
	}

      return {};
    }

  template<typename _Ch_type>
    bool
    regex_traits<_Ch_type>::
    isctype(_Ch_type __c, char_class_type __f) const
    {
      typedef std::ctype<char_type> __ctype_type;
      const __ctype_type& __fctyp(use_facet<__ctype_type>(_M_locale));

      return __fctyp.is(__f._M_base, __c)
	// [[:w:]]
	|| ((__f._M_extended & _RegexMask::_S_under)
	    && __c == __fctyp.widen('_'));
    }

  template<typename _Ch_type>
    int
    regex_traits<_Ch_type>::
    value(_Ch_type __ch, int __radix) const
    {
      if constexpr (sizeof(_Ch_type) > 1)
	{
	  const auto& __ctyp = std::use_facet<ctype<_Ch_type>>(_M_locale);
	  const char __c = __ctyp.narrow(__ch, '\0');
	  return regex_traits<char>{}.value(__c, __radix);
	}
      else
	{
	  const char __c = static_cast<char>(__ch);
	  const char __max_digit = __radix == 8 ? '7' : '9';
	  if ('0' <= __c && __c <= __max_digit)
	    return __c - '0';
	  if (__radix < 16)
	    return -1;
	  switch (__c)
	  {
	    case 'a':
	    case 'A':
	      return 10;
	    case 'b':
	    case 'B':
	      return 11;
	    case 'c':
	    case 'C':
	      return 12;
	    case 'd':
	    case 'D':
	      return 13;
	    case 'e':
	    case 'E':
	      return 14;
	    case 'f':
	    case 'F':
	      return 15;
	    default:
	      return -1;
	    }
	}
    }
#pragma GCC diagnostic pop

  template<typename _Bi_iter, typename _Alloc>
  template<typename _Out_iter>
    _Out_iter
    match_results<_Bi_iter, _Alloc>::
    format(_Out_iter __out,
	   const match_results<_Bi_iter, _Alloc>::char_type* __fmt_first,
	   const match_results<_Bi_iter, _Alloc>::char_type* __fmt_last,
	   match_flag_type __flags) const
    {
      __glibcxx_assert( ready() );
      regex_traits<char_type> __traits;
      typedef std::ctype<char_type> __ctype_type;
      const __ctype_type&
	__fctyp(use_facet<__ctype_type>(__traits.getloc()));

      auto __output = [&](size_t __idx)
	{
	  auto& __sub = (*this)[__idx];
	  if (__sub.matched)
	    __out = std::copy(__sub.first, __sub.second, __out);
	};

      if (__flags & regex_constants::format_sed)
	{
	  bool __escaping = false;
	  for (; __fmt_first != __fmt_last; __fmt_first++)
	    {
	      if (__escaping)
		{
		  __escaping = false;
		  if (__fctyp.is(__ctype_type::digit, *__fmt_first))
		    __output(__traits.value(*__fmt_first, 10));
		  else
		    *__out++ = *__fmt_first;
		  continue;
		}
	      if (*__fmt_first == '\\')
		{
		  __escaping = true;
		  continue;
		}
	      if (*__fmt_first == '&')
		{
		  __output(0);
		  continue;
		}
	      *__out++ = *__fmt_first;
	    }
	  if (__escaping)
	    *__out++ = '\\';
	}
      else
	{
	  while (1)
	    {
	      auto __next = std::find(__fmt_first, __fmt_last, '$');
	      if (__next == __fmt_last)
		break;

	      __out = std::copy(__fmt_first, __next, __out);

	      auto __eat = [&](char __ch) -> bool
		{
		  if (*__next == __ch)
		    {
		      ++__next;
		      return true;
		    }
		  return false;
		};

	      if (++__next == __fmt_last)
		*__out++ = '$';
	      else if (__eat('$'))
		*__out++ = '$';
	      else if (__eat('&'))
		__output(0);
	      else if (__eat('`'))
		{
		  auto& __sub = _M_prefix();
		  if (__sub.matched)
		    __out = std::copy(__sub.first, __sub.second, __out);
		}
	      else if (__eat('\''))
		{
		  auto& __sub = _M_suffix();
		  if (__sub.matched)
		    __out = std::copy(__sub.first, __sub.second, __out);
		}
	      else if (__fctyp.is(__ctype_type::digit, *__next))
		{
		  long __num = __traits.value(*__next, 10);
		  if (++__next != __fmt_last
		      && __fctyp.is(__ctype_type::digit, *__next))
		    {
		      __num *= 10;
		      __num += __traits.value(*__next++, 10);
		    }
		  if (0 <= __num && size_t(__num) < this->size())
		    __output(__num);
		}
	      else
		*__out++ = '$';
	      __fmt_first = __next;
	    }
	  __out = std::copy(__fmt_first, __fmt_last, __out);
	}
      return __out;
    }

  template<typename _Out_iter, typename _Bi_iter,
	   typename _Rx_traits, typename _Ch_type>
    _Out_iter
    __regex_replace(_Out_iter __out, _Bi_iter __first, _Bi_iter __last,
		    const basic_regex<_Ch_type, _Rx_traits>& __e,
		    const _Ch_type* __fmt, size_t __len,
		    regex_constants::match_flag_type __flags)
    {
      typedef regex_iterator<_Bi_iter, _Ch_type, _Rx_traits> _IterT;
      _IterT __i(__first, __last, __e, __flags);
      _IterT __end;
      if (__i == __end)
	{
	  if (!(__flags & regex_constants::format_no_copy))
	    __out = std::copy(__first, __last, __out);
	}
      else
	{
	  sub_match<_Bi_iter> __last;
	  for (; __i != __end; ++__i)
	    {
	      if (!(__flags & regex_constants::format_no_copy))
		__out = std::copy(__i->prefix().first, __i->prefix().second,
				  __out);
	      __out = __i->format(__out, __fmt, __fmt + __len, __flags);
	      __last = __i->suffix();
	      if (__flags & regex_constants::format_first_only)
		break;
	    }
	  if (!(__flags & regex_constants::format_no_copy))
	    __out = std::copy(__last.first, __last.second, __out);
	}
      return __out;
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    bool
    regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    operator==(const regex_iterator& __rhs) const noexcept
    {
      if (_M_pregex == nullptr && __rhs._M_pregex == nullptr)
	return true;
      return _M_pregex == __rhs._M_pregex
	  && _M_begin == __rhs._M_begin
	  && _M_end == __rhs._M_end
	  && _M_flags == __rhs._M_flags
	  && _M_match[0] == __rhs._M_match[0];
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>&
    regex_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    operator++()
    {
      // In all cases in which the call to regex_search returns true,
      // match.prefix().first shall be equal to the previous value of
      // match[0].second, and for each index i in the half-open range
      // [0, match.size()) for which match[i].matched is true,
      // match[i].position() shall return distance(begin, match[i].first).
      // [28.12.1.4.5]
      if (_M_match[0].matched)
	{
	  auto __start = _M_match[0].second;
	  auto __prefix_first = _M_match[0].second;
	  if (_M_match[0].first == _M_match[0].second)
	    {
	      if (__start == _M_end)
		{
		  _M_pregex = nullptr;
		  return *this;
		}
	      else
		{
		  if (regex_search(__start, _M_end, _M_match, *_M_pregex,
				   _M_flags
				   | regex_constants::match_not_null
				   | regex_constants::match_continuous))
		    {
		      __glibcxx_assert(_M_match[0].matched);
		      auto& __prefix = _M_match._M_prefix();
		      __prefix.first = __prefix_first;
		      __prefix.matched = __prefix.first != __prefix.second;
		      // [28.12.1.4.5]
		      _M_match._M_begin = _M_begin;
		      return *this;
		    }
		  else
		    ++__start;
		}
	    }
	  _M_flags |= regex_constants::match_prev_avail;
	  if (regex_search(__start, _M_end, _M_match, *_M_pregex, _M_flags))
	    {
	      __glibcxx_assert(_M_match[0].matched);
	      auto& __prefix = _M_match._M_prefix();
	      __prefix.first = __prefix_first;
	      __prefix.matched = __prefix.first != __prefix.second;
	      // [28.12.1.4.5]
	      _M_match._M_begin = _M_begin;
	    }
	  else
	    _M_pregex = nullptr;
	}
      return *this;
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>&
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    operator=(const regex_token_iterator& __rhs)
    {
      _M_position = __rhs._M_position;
      _M_subs = __rhs._M_subs;
      _M_n = __rhs._M_n;
      _M_suffix = __rhs._M_suffix;
      _M_has_m1 = __rhs._M_has_m1;
      _M_normalize_result();
      return *this;
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    bool
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    operator==(const regex_token_iterator& __rhs) const
    {
      if (_M_end_of_seq() && __rhs._M_end_of_seq())
	return true;
      if (_M_suffix.matched && __rhs._M_suffix.matched
	  && _M_suffix == __rhs._M_suffix)
	return true;
      if (_M_end_of_seq() || _M_suffix.matched
	  || __rhs._M_end_of_seq() || __rhs._M_suffix.matched)
	return false;
      return _M_position == __rhs._M_position
	&& _M_n == __rhs._M_n
	&& _M_subs == __rhs._M_subs;
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>&
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    operator++()
    {
      _Position __prev = _M_position;
      if (_M_suffix.matched)
	*this = regex_token_iterator();
      else if (_M_n + 1 < _M_subs.size())
	{
	  _M_n++;
	  _M_result = &_M_current_match();
	}
      else
	{
	  _M_n = 0;
	  ++_M_position;
	  if (_M_position != _Position())
	    _M_result = &_M_current_match();
	  else if (_M_has_m1 && __prev->suffix().length() != 0)
	    {
	      _M_suffix.matched = true;
	      _M_suffix.first = __prev->suffix().first;
	      _M_suffix.second = __prev->suffix().second;
	      _M_result = &_M_suffix;
	    }
	  else
	    *this = regex_token_iterator();
	}
      return *this;
    }

  template<typename _Bi_iter,
	   typename _Ch_type,
	   typename _Rx_traits>
    void
    regex_token_iterator<_Bi_iter, _Ch_type, _Rx_traits>::
    _M_init(_Bi_iter __a, _Bi_iter __b)
    {
      _M_has_m1 = false;
      for (auto __it : _M_subs)
	if (__it == -1)
	  {
	    _M_has_m1 = true;
	    break;
	  }
      if (_M_position != _Position())
	_M_result = &_M_current_match();
      else if (_M_has_m1)
	{
	  _M_suffix.matched = true;
	  _M_suffix.first = __a;
	  _M_suffix.second = __b;
	  _M_result = &_M_suffix;
	}
      else
	_M_result = nullptr;
    }

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace