libstdc++-v3/libsupc++/initializer_list

// std::initializer_list support -*- C++ -*-

// Copyright (C) 2008-2026 Free Software Foundation, Inc.
//
// This file is part of GCC.
//
// GCC 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.
//
// GCC 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 initializer_list
 *  This is a Standard C++ Library header.
 */

#ifndef _INITIALIZER_LIST
#define _INITIALIZER_LIST

#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif

#if __cplusplus < 201103L
# include <bits/c++0x_warning.h>
#else // C++0x

#include <bits/c++config.h>

#define __glibcxx_want_initializer_list
#include <bits/version.h>

namespace std _GLIBCXX_VISIBILITY(default)
{
  /// initializer_list
  template<class _E>
    // _GLIBCXX_RESOLVE_LIB_DEFECTS
    // 2129. User specializations of std::initializer_list
    class _GLIBCXX_NO_SPECIALIZATIONS initializer_list
    {
    public:
      typedef _E 		value_type;
      typedef const _E& 	reference;
      typedef const _E& 	const_reference;
      typedef size_t 		size_type;
      typedef const _E* 	iterator;
      typedef const _E* 	const_iterator;

    private:
      iterator			_M_array;
      size_type			_M_len;

      // The compiler can call a private constructor.
      constexpr initializer_list(const_iterator __a, size_type __l)
      : _M_array(__a), _M_len(__l) { }

    public:
      constexpr initializer_list() noexcept
      : _M_array(0), _M_len(0) { }

      // Number of elements.
      constexpr size_type
      size() const noexcept { return _M_len; }

      // First element.
      constexpr const_iterator
      begin() const noexcept { return _M_array; }

      // One past the last element.
      constexpr const_iterator
      end() const noexcept { return begin() + size(); }

#if __glibcxx_initializer_list >= 202511L
      constexpr bool
      empty() const noexcept { return _M_len == 0; }

      constexpr const value_type*
      data() const noexcept { return _M_array; }
#endif
    };

#if __glibcxx_initializer_list < 202511L
  /**
   *  @brief  Return an iterator pointing to the first element of
   *          the initializer_list.
   *  @param  __ils  Initializer list.
   *  @relates initializer_list
   */
  template<class _Tp>
    constexpr const _Tp*
    begin(initializer_list<_Tp> __ils) noexcept
    { return __ils.begin(); }

  /**
   *  @brief  Return an iterator pointing to one past the last element
   *          of the initializer_list.
   *  @param  __ils  Initializer list.
   *  @relates initializer_list
   */
  template<class _Tp>
    constexpr const _Tp*
    end(initializer_list<_Tp> __ils) noexcept
    { return __ils.end(); }
#endif // __glibcxx_initializer_list < 202511L
}

#endif // C++11

#endif // _INITIALIZER_LIST