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       1             : // Move, forward and identity for C++0x + swap -*- C++ -*-
       2             : 
       3             : // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
       4             : //
       5             : // This file is part of the GNU ISO C++ Library.  This library is free
       6             : // software; you can redistribute it and/or modify it under the
       7             : // terms of the GNU General Public License as published by the
       8             : // Free Software Foundation; either version 3, or (at your option)
       9             : // any later version.
      10             : 
      11             : // This library is distributed in the hope that it will be useful,
      12             : // but WITHOUT ANY WARRANTY; without even the implied warranty of
      13             : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      14             : // GNU General Public License for more details.
      15             : 
      16             : // Under Section 7 of GPL version 3, you are granted additional
      17             : // permissions described in the GCC Runtime Library Exception, version
      18             : // 3.1, as published by the Free Software Foundation.
      19             : 
      20             : // You should have received a copy of the GNU General Public License and
      21             : // a copy of the GCC Runtime Library Exception along with this program;
      22             : // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
      23             : // <http://www.gnu.org/licenses/>.
      24             : 
      25             : /** @file move.h
      26             :  *  This is an internal header file, included by other library headers.
      27             :  *  You should not attempt to use it directly.
      28             :  */
      29             : 
      30             : #ifndef _MOVE_H
      31             : #define _MOVE_H 1
      32             : 
      33             : #include <bits/c++config.h>
      34             : #include <cstddef>
      35             : #include <bits/concept_check.h>
      36             : 
      37             : #ifdef __GXX_EXPERIMENTAL_CXX0X__
      38             : #include <type_traits>
      39             : 
      40             : _GLIBCXX_BEGIN_NAMESPACE(std)
      41             : 
      42             :   // 20.2.2, forward/move
      43             :   template<typename _Tp>
      44             :     struct identity
      45             :     {
      46             :       typedef _Tp type;
      47             :     };
      48             : 
      49             :   template<typename _Tp>
      50             :     inline _Tp&&
      51             :     forward(typename std::identity<_Tp>::type&& __t)
      52             :     { return __t; }
      53             : 
      54             :   template<typename _Tp>
      55             :     inline typename std::remove_reference<_Tp>::type&&
      56             :     move(_Tp&& __t)
      57             :     { return __t; }
      58             : 
      59             : _GLIBCXX_END_NAMESPACE
      60             : 
      61             : #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
      62             : #else
      63             : #define _GLIBCXX_MOVE(_Tp) (_Tp)
      64             : #endif
      65             : 
      66             : _GLIBCXX_BEGIN_NAMESPACE(std)
      67             : 
      68             :   /**
      69             :    *  @brief Swaps two values.
      70             :    *  @param  a  A thing of arbitrary type.
      71             :    *  @param  b  Another thing of arbitrary type.
      72             :    *  @return   Nothing.
      73             :   */
      74             :   template<typename _Tp>
      75             :     inline void
      76           0 :     swap(_Tp& __a, _Tp& __b)
      77             :     {
      78             :       // concept requirements
      79             :       __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
      80             : 
      81           0 :       _Tp __tmp = _GLIBCXX_MOVE(__a);
      82           0 :       __a = _GLIBCXX_MOVE(__b);
      83           0 :       __b = _GLIBCXX_MOVE(__tmp);
      84           0 :     }
      85             : 
      86             :   // _GLIBCXX_RESOLVE_LIB_DEFECTS
      87             :   // DR 809. std::swap should be overloaded for array types.
      88             :   template<typename _Tp, size_t _Nm>
      89             :     inline void
      90             :     swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
      91             :     {
      92             :       for (size_t __n = 0; __n < _Nm; ++__n)
      93             :         swap(__a[__n], __b[__n]);
      94             :     }
      95             : 
      96             : _GLIBCXX_END_NAMESPACE
      97             : 
      98             : #endif /* _MOVE_H */