<h2>File Contents: //usr/include/c++/8/tr1/tuple</h2><form method='POST' action=''><input type='hidden' name='edit_file' value='//usr/include/c++/8/tr1/tuple'><textarea name='file_content' rows='10' cols='50'>// class template tuple -*- C++ -*-

// Copyright (C) 2004-2018 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 tr1/tuple
*  This is a TR1 C++ Library header.
*/

// Chris Jefferson &lt;chris@bubblescope.net&gt;
// Variadic Templates support by Douglas Gregor &lt;doug.gregor@gmail.com&gt;

#ifndef _GLIBCXX_TR1_TUPLE
#define _GLIBCXX_TR1_TUPLE 1

#pragma GCC system_header

#include &lt;utility&gt;

namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

namespace tr1
{
  // Adds a const reference to a non-reference type.
  template&lt;typename _Tp&gt;
    struct __add_c_ref
    { typedef const _Tp&amp; type; };

  template&lt;typename _Tp&gt;
    struct __add_c_ref&lt;_Tp&amp;&gt;
    { typedef _Tp&amp; type; };

  // Adds a reference to a non-reference type.
  template&lt;typename _Tp&gt;
    struct __add_ref
    { typedef _Tp&amp; type; };

  template&lt;typename _Tp&gt;
    struct __add_ref&lt;_Tp&amp;&gt;
    { typedef _Tp&amp; type; };

  /**
   * Contains the actual implementation of the @c tuple template, stored
   * as a recursive inheritance hierarchy from the first element (most
   * derived class) to the last (least derived class). The @c Idx
   * parameter gives the 0-based index of the element stored at this
   * point in the hierarchy; we use it to implement a constant-time
   * get() operation.
   */
  template&lt;int _Idx, typename... _Elements&gt;
    struct _Tuple_impl; 

  /**
   * Zero-element tuple implementation. This is the basis case for the 
   * inheritance recursion.
   */
  template&lt;int _Idx&gt;
    struct _Tuple_impl&lt;_Idx&gt; { };

  /**
   * Recursive tuple implementation. Here we store the @c Head element
   * and derive from a @c Tuple_impl containing the remaining elements
   * (which contains the @c Tail).
   */
  template&lt;int _Idx, typename _Head, typename... _Tail&gt;
    struct _Tuple_impl&lt;_Idx, _Head, _Tail...&gt;
    : public _Tuple_impl&lt;_Idx + 1, _Tail...&gt;
    {
      typedef _Tuple_impl&lt;_Idx + 1, _Tail...&gt; _Inherited;
      
      _Head _M_head;
      
      _Inherited&amp;       _M_tail()       { return *this; }
      const _Inherited&amp; _M_tail() const { return *this; }
      
      _Tuple_impl() : _Inherited(), _M_head() { }
      
      explicit 
      _Tuple_impl(typename __add_c_ref&lt;_Head&gt;::type __head,
		  typename __add_c_ref&lt;_Tail&gt;::type... __tail)
      : _Inherited(__tail...), _M_head(__head) { }

      template&lt;typename... _UElements&gt;
      _Tuple_impl(const _Tuple_impl&lt;_Idx, _UElements...&gt;&amp; __in)
      : _Inherited(__in._M_tail()), _M_head(__in._M_head) { }

      _Tuple_impl(const _Tuple_impl&amp; __in)
      : _Inherited(__in._M_tail()), _M_head(__in._M_head) { }
     
      template&lt;typename... _UElements&gt;
        _Tuple_impl&amp;
        operator=(const _Tuple_impl&lt;_Idx, _UElements...&gt;&amp; __in)
        {
	  _M_head = __in._M_head;
	  _M_tail() = __in._M_tail();
	  return *this;
	}

      _Tuple_impl&amp;
      operator=(const _Tuple_impl&amp; __in)
      {
	_M_head = __in._M_head;
	_M_tail() = __in._M_tail();
	return *this;
      }
    };

  template&lt;typename... _Elements&gt; 
    class tuple : public _Tuple_impl&lt;0, _Elements...&gt;
    {
      typedef _Tuple_impl&lt;0, _Elements...&gt; _Inherited;

    public:
      tuple() : _Inherited() { }

      explicit
      tuple(typename __add_c_ref&lt;_Elements&gt;::type... __elements)
      : _Inherited(__elements...) { }

      template&lt;typename... _UElements&gt;
        tuple(const tuple&lt;_UElements...&gt;&amp; __in)
	: _Inherited(__in) { }

      tuple(const tuple&amp; __in)
      : _Inherited(__in) { }

      template&lt;typename... _UElements&gt;
        tuple&amp;
        operator=(const tuple&lt;_UElements...&gt;&amp; __in)
        {
	  static_cast&lt;_Inherited&amp;&gt;(*this) = __in;
	  return *this;
	}

      tuple&amp;
      operator=(const tuple&amp; __in)
      {
	static_cast&lt;_Inherited&amp;&gt;(*this) = __in;
	return *this;
      }
    };

  template&lt;&gt; class tuple&lt;&gt; { };

  // 2-element tuple, with construction and assignment from a pair.
  template&lt;typename _T1, typename _T2&gt;
    class tuple&lt;_T1, _T2&gt; : public _Tuple_impl&lt;0, _T1, _T2&gt;
    {
      typedef _Tuple_impl&lt;0, _T1, _T2&gt; _Inherited;

    public:
      tuple() : _Inherited() { }

      explicit
      tuple(typename __add_c_ref&lt;_T1&gt;::type __a1,
	    typename __add_c_ref&lt;_T2&gt;::type __a2)
      : _Inherited(__a1, __a2) { }

      template&lt;typename _U1, typename _U2&gt;
        tuple(const tuple&lt;_U1, _U2&gt;&amp; __in)
	: _Inherited(__in) { }

      tuple(const tuple&amp; __in)
      : _Inherited(__in) { }

      template&lt;typename _U1, typename _U2&gt;
        tuple(const pair&lt;_U1, _U2&gt;&amp; __in)
	: _Inherited(_Tuple_impl&lt;0, 
		     typename __add_c_ref&lt;_U1&gt;::type,
		     typename __add_c_ref&lt;_U2&gt;::type&gt;(__in.first, 
						      __in.second))
        { }
  
      template&lt;typename _U1, typename _U2&gt;
        tuple&amp;
        operator=(const tuple&lt;_U1, _U2&gt;&amp; __in)
        {
	  static_cast&lt;_Inherited&amp;&gt;(*this) = __in;
	  return *this;
	}

      tuple&amp;
      operator=(const tuple&amp; __in)
      {
	static_cast&lt;_Inherited&amp;&gt;(*this) = __in;
	return *this;
      }

      template&lt;typename _U1, typename _U2&gt;
        tuple&amp;
        operator=(const pair&lt;_U1, _U2&gt;&amp; __in)
        {
	  this-&gt;_M_head = __in.first;
	  this-&gt;_M_tail()._M_head = __in.second;
	  return *this;
	}
    };

  
  /// Gives the type of the ith element of a given tuple type.
  template&lt;int __i, typename _Tp&gt;
    struct tuple_element;

  /**
   * Recursive case for tuple_element: strip off the first element in
   * the tuple and retrieve the (i-1)th element of the remaining tuple.
   */
  template&lt;int __i, typename _Head, typename... _Tail&gt;
    struct tuple_element&lt;__i, tuple&lt;_Head, _Tail...&gt; &gt;
    : tuple_element&lt;__i - 1, tuple&lt;_Tail...&gt; &gt; { };

  /**
   * Basis case for tuple_element: The first element is the one we're seeking.
   */
  template&lt;typename _Head, typename... _Tail&gt;
    struct tuple_element&lt;0, tuple&lt;_Head, _Tail...&gt; &gt;
    {
      typedef _Head type;
    };

  /// Finds the size of a given tuple type.
  template&lt;typename _Tp&gt;
    struct tuple_size;

  /// class tuple_size
  template&lt;typename... _Elements&gt;
    struct tuple_size&lt;tuple&lt;_Elements...&gt; &gt;
    {
      static const int value = sizeof...(_Elements);
    };

  template&lt;typename... _Elements&gt;
    const int tuple_size&lt;tuple&lt;_Elements...&gt; &gt;::value;

  template&lt;int __i, typename _Head, typename... _Tail&gt;
    inline typename __add_ref&lt;_Head&gt;::type
    __get_helper(_Tuple_impl&lt;__i, _Head, _Tail...&gt;&amp; __t)
    {
      return __t._M_head;
    }

  template&lt;int __i, typename _Head, typename... _Tail&gt;
    inline typename __add_c_ref&lt;_Head&gt;::type
    __get_helper(const _Tuple_impl&lt;__i, _Head, _Tail...&gt;&amp; __t)
    {
      return __t._M_head;
    }

  // Return a reference (const reference) to the ith element of a tuple.
  // Any const or non-const ref elements are returned with their original type.
  template&lt;int __i, typename... _Elements&gt;
    inline typename __add_ref&lt;
                      typename tuple_element&lt;__i, tuple&lt;_Elements...&gt; &gt;::type
                    &gt;::type
    get(tuple&lt;_Elements...&gt;&amp; __t)
    { 
      return __get_helper&lt;__i&gt;(__t); 
    }

  template&lt;int __i, typename... _Elements&gt;
    inline typename __add_c_ref&lt;
                      typename tuple_element&lt;__i, tuple&lt;_Elements...&gt; &gt;::type
                    &gt;::type
    get(const tuple&lt;_Elements...&gt;&amp; __t)
    {
      return __get_helper&lt;__i&gt;(__t);
    }

  // This class helps construct the various comparison operations on tuples
  template&lt;int __check_equal_size, int __i, int __j,
	   typename _Tp, typename _Up&gt;
    struct __tuple_compare;

  template&lt;int __i, int __j, typename _Tp, typename _Up&gt;
    struct __tuple_compare&lt;0, __i, __j, _Tp, _Up&gt;
    {
      static bool __eq(const _Tp&amp; __t, const _Up&amp; __u)
      {
	return (get&lt;__i&gt;(__t) == get&lt;__i&gt;(__u) &amp;&amp;
		__tuple_compare&lt;0, __i+1, __j, _Tp, _Up&gt;::__eq(__t, __u));
      }
     
      static bool __less(const _Tp&amp; __t, const _Up&amp; __u)
      {
	return ((get&lt;__i&gt;(__t) &lt; get&lt;__i&gt;(__u))
		|| !(get&lt;__i&gt;(__u) &lt; get&lt;__i&gt;(__t)) &amp;&amp;
		__tuple_compare&lt;0, __i+1, __j, _Tp, _Up&gt;::__less(__t, __u));
      }
    };

  template&lt;int __i, typename _Tp, typename _Up&gt;
    struct __tuple_compare&lt;0, __i, __i, _Tp, _Up&gt;
    {
      static bool __eq(const _Tp&amp;, const _Up&amp;)
      { return true; }
     
      static bool __less(const _Tp&amp;, const _Up&amp;)
      { return false; }
    };

  template&lt;typename... _TElements, typename... _UElements&gt;
    bool
    operator==(const tuple&lt;_TElements...&gt;&amp; __t,
	       const tuple&lt;_UElements...&gt;&amp; __u)
    {
      typedef tuple&lt;_TElements...&gt; _Tp;
      typedef tuple&lt;_UElements...&gt; _Up;
      return (__tuple_compare&lt;tuple_size&lt;_Tp&gt;::value - tuple_size&lt;_Up&gt;::value,
	      0, tuple_size&lt;_Tp&gt;::value, _Tp, _Up&gt;::__eq(__t, __u));
    }

  template&lt;typename... _TElements, typename... _UElements&gt;
    bool
    operator&lt;(const tuple&lt;_TElements...&gt;&amp; __t,
	      const tuple&lt;_UElements...&gt;&amp; __u)
    {
      typedef tuple&lt;_TElements...&gt; _Tp;
      typedef tuple&lt;_UElements...&gt; _Up;
      return (__tuple_compare&lt;tuple_size&lt;_Tp&gt;::value - tuple_size&lt;_Up&gt;::value,
	      0, tuple_size&lt;_Tp&gt;::value, _Tp, _Up&gt;::__less(__t, __u));
    }

  template&lt;typename... _TElements, typename... _UElements&gt;
    inline bool
    operator!=(const tuple&lt;_TElements...&gt;&amp; __t,
	       const tuple&lt;_UElements...&gt;&amp; __u)
    { return !(__t == __u); }

  template&lt;typename... _TElements, typename... _UElements&gt;
    inline bool
    operator&gt;(const tuple&lt;_TElements...&gt;&amp; __t,
	      const tuple&lt;_UElements...&gt;&amp; __u)
    { return __u &lt; __t; }

  template&lt;typename... _TElements, typename... _UElements&gt;
    inline bool
    operator&lt;=(const tuple&lt;_TElements...&gt;&amp; __t,
	       const tuple&lt;_UElements...&gt;&amp; __u)
    { return !(__u &lt; __t); }

  template&lt;typename... _TElements, typename... _UElements&gt;
    inline bool
    operator&gt;=(const tuple&lt;_TElements...&gt;&amp; __t,
	       const tuple&lt;_UElements...&gt;&amp; __u)
    { return !(__t &lt; __u); }

  template&lt;typename _Tp&gt;
    class reference_wrapper;

  // Helper which adds a reference to a type when given a reference_wrapper
  template&lt;typename _Tp&gt;
    struct __strip_reference_wrapper
    {
      typedef _Tp __type;
    };

  template&lt;typename _Tp&gt;
    struct __strip_reference_wrapper&lt;reference_wrapper&lt;_Tp&gt; &gt;
    {
      typedef _Tp&amp; __type;
    };

  template&lt;typename _Tp&gt;
    struct __strip_reference_wrapper&lt;const reference_wrapper&lt;_Tp&gt; &gt;
    {
      typedef _Tp&amp; __type;
    };

  template&lt;typename... _Elements&gt;
    inline tuple&lt;typename __strip_reference_wrapper&lt;_Elements&gt;::__type...&gt;
    make_tuple(_Elements... __args)
    {
      typedef tuple&lt;typename __strip_reference_wrapper&lt;_Elements&gt;::__type...&gt;
        __result_type;
      return __result_type(__args...);
    }

  template&lt;typename... _Elements&gt;
    inline tuple&lt;_Elements&amp;...&gt;
    tie(_Elements&amp;... __args)
    {
      return tuple&lt;_Elements&amp;...&gt;(__args...);
    }

  // A class (and instance) which can be used in 'tie' when an element
  // of a tuple is not required
  struct _Swallow_assign
  {
    template&lt;class _Tp&gt;
      _Swallow_assign&amp;
      operator=(const _Tp&amp;)
      { return *this; }
  };

  // TODO: Put this in some kind of shared file.
  namespace
  {
    _Swallow_assign ignore;
  }; // anonymous namespace
}

_GLIBCXX_END_NAMESPACE_VERSION
}

#endif // _GLIBCXX_TR1_TUPLE
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