regex.tcc

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// 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