experimental/tuple

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// <experimental/tuple> -*- C++ -*-
 
// Copyright (C) 2014-2025 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 experimental/tuple
 *  This is a TS C++ Library header.
 *  @ingroup libfund-ts
 */
 
#ifndef _GLIBCXX_EXPERIMENTAL_TUPLE
#define _GLIBCXX_EXPERIMENTAL_TUPLE 1
 
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
 
#include <bits/requires_hosted.h> // experimental is currently omitted
 
#if __cplusplus >= 201402L
 
#include <tuple>
#include <bits/invoke.h>
#include <experimental/bits/lfts_config.h>
 
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
 
namespace experimental
{
inline namespace fundamentals_v1
{
  // See C++14 20.4.2.5, tuple helper classes
  template <typename _Tp>
    constexpr size_t tuple_size_v = tuple_size<_Tp>::value;
 
#define __cpp_lib_experimental_tuple 201402
 
  template <typename _Fn, typename _Tuple, std::size_t... _Idx>
    constexpr decltype(auto)
    __apply_impl(_Fn&& __f, _Tuple&& __t, std::index_sequence<_Idx...>)
    {
      return std::__invoke(std::forward<_Fn>(__f),
                           std::get<_Idx>(std::forward<_Tuple>(__t))...);
    }
 
  template <typename _Fn, typename _Tuple>
    constexpr decltype(auto)
    apply(_Fn&& __f, _Tuple&& __t)
    {
      using _Indices =
        std::make_index_sequence<tuple_size_v<std::decay_t<_Tuple>>>;
      return experimental::__apply_impl(std::forward<_Fn>(__f),
                                        std::forward<_Tuple>(__t),
                                        _Indices{});
    }
} // namespace fundamentals_v1
} // namespace experimental
 
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std
 
#endif // C++14
 
#endif // _GLIBCXX_EXPERIMENTAL_TUPLE