gcc/libstdc++-v3/include/bits/move.h

// Move, forward and identity for C++0x + swap -*- C++ -*-

// Copyright (C) 2007, 2008 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 2, 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.

// You should have received a copy of the GNU General Public License along
// with this library; see the file COPYING.  If not, write to the Free
// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
// USA.

// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License.  This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.

/** @file move.h
 *  This is an internal header file, included by other library headers.
 *  You should not attempt to use it directly.
 */

#ifndef _MOVE_H
#define _MOVE_H 1

#include <bits/c++config.h>
#include <cstddef>
#include <bits/concept_check.h>

#ifdef __GXX_EXPERIMENTAL_CXX0X__
#include <type_traits>

_GLIBCXX_BEGIN_NAMESPACE(std)

  // 20.2.2, forward/move
  template<typename _Tp>
    struct identity
    {
      typedef _Tp type;
    };

  template<typename _Tp>
    inline _Tp&&
    forward(typename std::identity<_Tp>::type&& __t)
    { return __t; }

  template<typename _Tp>
    inline typename std::remove_reference<_Tp>::type&&
    move(_Tp&& __t)
    { return __t; }

_GLIBCXX_END_NAMESPACE

#define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
#else
#define _GLIBCXX_MOVE(_Tp) (_Tp)
#endif

_GLIBCXX_BEGIN_NAMESPACE(std)

  /**
   *  @brief Swaps two values.
   *  @param  a  A thing of arbitrary type.
   *  @param  b  Another thing of arbitrary type.
   *  @return   Nothing.
  */
  template<typename _Tp>
    inline void
    swap(_Tp& __a, _Tp& __b)
    {
      // concept requirements
      __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)

      _Tp __tmp = _GLIBCXX_MOVE(__a);
      __a = _GLIBCXX_MOVE(__b);
      __b = _GLIBCXX_MOVE(__tmp);
    }

  // _GLIBCXX_RESOLVE_LIB_DEFECTS
  // DR 809. std::swap should be overloaded for array types.
  template<typename _Tp, size_t _Nm>
    inline void
    swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
    {
      for (size_t __n = 0; __n < _Nm; ++__n)
	swap(__a[__n], __b[__n]);
    }

_GLIBCXX_END_NAMESPACE

#endif /* _MOVE_H */