libstdc++-v3/include/bits/stl_move.h

   1 // Move, forward and identity for C++0x + swap -*- C++ -*-
   2
   3 // Copyright (C) 2007 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 2, 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 // You should have received a copy of the GNU General Public License along
  17 // with this library; see the file COPYING.  If not, write to the Free
  18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19 // USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file stl_move.h
  31  *  This is an internal header file, included by other library headers.
  32  *  You should not attempt to use it directly.
  33  */
  34
  35 #ifndef _STL_MOVE_H
  36 #define _STL_MOVE_H 1
  37
  38 #include <bits/c++config.h>
  39 #include <bits/concept_check.h>
  40
  41 #ifdef __GXX_EXPERIMENTAL_CXX0X__
  42 #include <type_traits>
  43
  44 _GLIBCXX_BEGIN_NAMESPACE(std)
  45
  46   // 20.2.2, forward/move
  47   template<typename _Tp>
  48     struct identity
  49     {
  50       typedef _Tp type;
  51     };
  52
  53   template<typename _Tp>
  54     inline _Tp&&
  55     forward(typename std::identity<_Tp>::type&& __t)
  56     { return __t; }
  57
  58   template<typename _Tp>
  59     inline typename std::remove_reference<_Tp>::type&&
  60     move(_Tp&& __t)
  61     { return __t; }
  62
  63 _GLIBCXX_END_NAMESPACE
  64
  65 #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
  66 #else
  67 #define _GLIBCXX_MOVE(_Tp) (_Tp)
  68 #endif
  69
  70 _GLIBCXX_BEGIN_NAMESPACE(std)
  71
  72   /**
  73    *  @brief Swaps two values.
  74    *  @param  a  A thing of arbitrary type.
  75    *  @param  b  Another thing of arbitrary type.
  76    *  @return   Nothing.
  77   */
  78   template<typename _Tp>
  79     inline void
  80     swap(_Tp& __a, _Tp& __b)
  81     {
  82       // concept requirements
  83       __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
  84
  85       _Tp __tmp = _GLIBCXX_MOVE(__a);
  86       __a = _GLIBCXX_MOVE(__b);
  87       __b = _GLIBCXX_MOVE(__tmp);
  88     }
  89
  90 _GLIBCXX_END_NAMESPACE
  91
  92 #endif /* _STL_MOVE_H */