string_conversions.h

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// String Conversions -*- C++ -*-
 
// Copyright (C) 2008-2025 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 ext/string_conversions.h
 *  This file is a GNU extension to the Standard C++ Library.
 */
 
#ifndef _STRING_CONVERSIONS_H
#define _STRING_CONVERSIONS_H 1
 
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
 
#include <bits/requires_hosted.h> // GNU extensions are currently omitted
 
#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else
 
#include <bits/c++config.h>
#include <ext/numeric_traits.h>
#include <bits/functexcept.h>
#include <cstdlib>
#include <cwchar>
#include <cstdio>
#include <cerrno>
 
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
 
  // Helper for all the sto* functions.
  template<typename _TRet, typename _Ret = _TRet, typename _CharT,
           typename... _Base>
    _Ret
    __stoa(_TRet (*__convf) (const _CharT*, _CharT**, _Base...),
           const char* __name, const _CharT* __str, std::size_t* __idx,
           _Base... __base)
    {
      _Ret __ret;
 
      _CharT* __endptr;
 
      struct _Save_errno {
        _Save_errno() : _M_errno(errno) { errno = 0; }
        ~_Save_errno() { if (errno == 0) errno = _M_errno; }
        int _M_errno;
      } const __save_errno;
 
      struct _Range_chk {
          static bool
          _S_chk(_TRet, std::false_type) { return false; }
 
          static bool
          _S_chk(_TRet __val, std::true_type) // only called when _Ret is int
          {
            return __val < _TRet(__numeric_traits<int>::__min)
              || __val > _TRet(__numeric_traits<int>::__max);
          }
      };
 
      const _TRet __tmp = __convf(__str, &__endptr, __base...);
 
      if (__endptr == __str)
        std::__throw_invalid_argument(__name);
      else if (errno == ERANGE
          || _Range_chk::_S_chk(__tmp, std::is_same<_Ret, int>{}))
        std::__throw_out_of_range(__name);
      else
        __ret = __tmp;
 
      if (__idx)
        *__idx = __endptr - __str;
 
      return __ret;
    }
 
  // Helper for the to_string / to_wstring functions.
  template<typename _String, typename _CharT = typename _String::value_type>
    _String
    __to_xstring(int (*__convf) (_CharT*, std::size_t, const _CharT*,
                                 __builtin_va_list), std::size_t __n,
                 const _CharT* __fmt, ...)
    {
      // XXX Eventually the result should be constructed in-place in
      // the __cxx11 string, likely with the help of internal hooks.
      _CharT* __s = static_cast<_CharT*>(__builtin_alloca(sizeof(_CharT)
                                                          * __n));
 
      __builtin_va_list __args;
      __builtin_va_start(__args, __fmt);
 
      const int __len = __convf(__s, __n, __fmt, __args);
 
      __builtin_va_end(__args);
 
      return _String(__s, __s + __len);
    }
 
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
 
#endif // C++11
 
#endif // _STRING_CONVERSIONS_H