move.h

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00001 // Move, forward and identity for C++0x + swap -*- C++ -*-
00002 
00003 // Copyright (C) 2007, 2008, 2009 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file move.h
00026  *  This is an internal header file, included by other library headers.
00027  *  You should not attempt to use it directly.
00028  */
00029 
00030 #ifndef _MOVE_H
00031 #define _MOVE_H 1
00032 
00033 #include <bits/c++config.h>
00034 #include <cstddef>
00035 #include <bits/concept_check.h>
00036 
00037 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00038 #include <type_traits>
00039 
00040 _GLIBCXX_BEGIN_NAMESPACE(std)
00041 
00042   // 20.2.2, forward/move
00043   template<typename _Tp>
00044     struct identity
00045     {
00046       typedef _Tp type;
00047     };
00048 
00049   template<typename _Tp>
00050     inline _Tp&&
00051     forward(typename std::identity<_Tp>::type&& __t)
00052     { return __t; }
00053 
00054   template<typename _Tp>
00055     inline typename std::remove_reference<_Tp>::type&&
00056     move(_Tp&& __t)
00057     { return __t; }
00058 
00059 _GLIBCXX_END_NAMESPACE
00060 
00061 #define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
00062 #else
00063 #define _GLIBCXX_MOVE(_Tp) (_Tp)
00064 #endif
00065 
00066 _GLIBCXX_BEGIN_NAMESPACE(std)
00067 
00068   /**
00069    *  @brief Swaps two values.
00070    *  @param  a  A thing of arbitrary type.
00071    *  @param  b  Another thing of arbitrary type.
00072    *  @return   Nothing.
00073   */
00074   template<typename _Tp>
00075     inline void
00076     swap(_Tp& __a, _Tp& __b)
00077     {
00078       // concept requirements
00079       __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
00080 
00081       _Tp __tmp = _GLIBCXX_MOVE(__a);
00082       __a = _GLIBCXX_MOVE(__b);
00083       __b = _GLIBCXX_MOVE(__tmp);
00084     }
00085 
00086   // _GLIBCXX_RESOLVE_LIB_DEFECTS
00087   // DR 809. std::swap should be overloaded for array types.
00088   template<typename _Tp, size_t _Nm>
00089     inline void
00090     swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
00091     {
00092       for (size_t __n = 0; __n < _Nm; ++__n)
00093     swap(__a[__n], __b[__n]);
00094     }
00095 
00096 _GLIBCXX_END_NAMESPACE
00097 
00098 #endif /* _MOVE_H */

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