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::remove_reference<_Tp>::type& __t)
52#ifdef __clang__
53    { return static_cast<_Tp&&>(__t); }
54#else
55    { return __t; }
56#endif
57
58  template<typename _Tp>
59    inline _Tp&&
60    forward(typename std::remove_reference<_Tp>::type&& __t)
61    {
62#ifdef __clang__
63      static_assert(!std::is_lvalue_reference<_Tp>::value,
64                    "Can't instantiate this forward() with an"
65                    " lvalue reference type.");
66      return static_cast<_Tp&&>(__t);
67#else
68      return __t;
69#endif
70    }
71
72  template<typename _Tp>
73    inline typename std::remove_reference<_Tp>::type&&
74    move(_Tp&& __t)
75#ifdef __clang__
76    { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
77#else
78    { return __t; }
79#endif
80
81_GLIBCXX_END_NAMESPACE
82
83#define _GLIBCXX_MOVE(_Tp) std::move(_Tp)
84#else
85#define _GLIBCXX_MOVE(_Tp) (_Tp)
86#endif
87
88_GLIBCXX_BEGIN_NAMESPACE(std)
89
90  /**
91   *  @brief Swaps two values.
92   *  @param  a  A thing of arbitrary type.
93   *  @param  b  Another thing of arbitrary type.
94   *  @return   Nothing.
95  */
96  template<typename _Tp>
97    inline void
98    swap(_Tp& __a, _Tp& __b)
99    {
100      // concept requirements
101      __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
102
103      _Tp __tmp = _GLIBCXX_MOVE(__a);
104      __a = _GLIBCXX_MOVE(__b);
105      __b = _GLIBCXX_MOVE(__tmp);
106    }
107
108  // _GLIBCXX_RESOLVE_LIB_DEFECTS
109  // DR 809. std::swap should be overloaded for array types.
110  template<typename _Tp, size_t _Nm>
111    inline void
112    swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
113    {
114      for (size_t __n = 0; __n < _Nm; ++__n)
115	swap(__a[__n], __b[__n]);
116    }
117
118_GLIBCXX_END_NAMESPACE
119
120#endif /* _MOVE_H */
121