<h2>Editing File: /usr/include/c++/8/experimental/tuple</h2><form method='post'><textarea name='content' class='file-edit'>// &lt;experimental/tuple&gt; -*- C++ -*-

// Copyright (C) 2014-2018 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
// &lt;http://www.gnu.org/licenses/&gt;.

/** @file experimental/tuple
 *  This is a TS C++ Library header.
 */

#ifndef _GLIBCXX_EXPERIMENTAL_TUPLE
#define _GLIBCXX_EXPERIMENTAL_TUPLE 1

#pragma GCC system_header

#if __cplusplus &gt;= 201402L

#include &lt;tuple&gt;
#include &lt;bits/invoke.h&gt;
#include &lt;experimental/bits/lfts_config.h&gt;

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 &lt;typename _Tp&gt;
    constexpr size_t tuple_size_v = tuple_size&lt;_Tp&gt;::value;

#define __cpp_lib_experimental_tuple 201402

  template &lt;typename _Fn, typename _Tuple, std::size_t... _Idx&gt;
    constexpr decltype(auto)
    __apply_impl(_Fn&amp;&amp; __f, _Tuple&amp;&amp; __t, std::index_sequence&lt;_Idx...&gt;)
    {
      return std::__invoke(std::forward&lt;_Fn&gt;(__f),
			   std::get&lt;_Idx&gt;(std::forward&lt;_Tuple&gt;(__t))...);
    }

  template &lt;typename _Fn, typename _Tuple&gt;
    constexpr decltype(auto)
    apply(_Fn&amp;&amp; __f, _Tuple&amp;&amp; __t)
    {
      using _Indices =
	std::make_index_sequence&lt;tuple_size_v&lt;std::decay_t&lt;_Tuple&gt;&gt;&gt;;
      return experimental::__apply_impl(std::forward&lt;_Fn&gt;(__f),
					std::forward&lt;_Tuple&gt;(__t),
					_Indices{});
    }
} // namespace fundamentals_v1
} // namespace experimental

_GLIBCXX_END_NAMESPACE_VERSION
} // namespace std

#endif // C++14

#endif // _GLIBCXX_EXPERIMENTAL_TUPLE
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