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

// Copyright (C) 2007, 2008, 2009 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

// <http://www.gnu.org/licenses/>.

/** @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> // Brings in std::declval too.

_GLIBCXX_BEGIN_NAMESPACE(std)

  /// identity

  template<typename _Tp>

    struct identity

    {

      typedef _Tp type;

    };

  /// forward (as per N2835)

  /// Forward lvalues as rvalues.

  template<typename _Tp>

    inline typename enable_if<!is_lvalue_reference<_Tp>::value, _Tp&&>::type

    forward(typename std::identity<_Tp>::type& __t)

    { return static_cast<_Tp&&>(__t); }

  /// Forward rvalues as rvalues.

  template<typename _Tp>

    inline typename enable_if<!is_lvalue_reference<_Tp>::value, _Tp&&>::type

    forward(typename std::identity<_Tp>::type&& __t)

    { return static_cast<_Tp&&>(__t); }

  // Forward lvalues as lvalues.

  template<typename _Tp>

    inline typename enable_if<is_lvalue_reference<_Tp>::value, _Tp>::type

    forward(typename std::identity<_Tp>::type __t)

    { return __t; }

  // Prevent forwarding rvalues as const lvalues.

  template<typename _Tp>

    inline typename enable_if<is_lvalue_reference<_Tp>::value, _Tp>::type

    forward(typename std::remove_reference<_Tp>::type&& __t) = delete;

  /**

   *  @brief Move a value.

   *  @ingroup mutating_algorithms

   *  @param  __t  A thing of arbitrary type.

   *  @return Same, moved.

  */

  template<typename _Tp>

    inline typename std::remove_reference<_Tp>::type&&

    move(_Tp&& __t)

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

  /// declval, defined in <type_traits>.

_GLIBCXX_END_NAMESPACE

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

#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)

#else

#define _GLIBCXX_MOVE(_Tp) (_Tp)

#define _GLIBCXX_FORWARD(_Tp, __val) (__val)

#endif

_GLIBCXX_BEGIN_NAMESPACE(std)

  /**

   *  @brief Swaps two values.

   *  @ingroup mutating_algorithms

   *  @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 */