libstdc++
move.h
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1 // Move, forward and identity for C++0x + swap -*- C++ -*-
2 
3 // Copyright (C) 2007, 2008, 2009, 2010 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 bits/move.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{utility}
28  */
29 
30 #ifndef _MOVE_H
31 #define _MOVE_H 1
32 
33 #include <bits/c++config.h>
34 #include <bits/concept_check.h>
35 
36 namespace std _GLIBCXX_VISIBILITY(default)
37 {
38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
39 
40  // Used, in C++03 mode too, by allocators, etc.
41  template<typename _Tp>
42  inline _Tp*
43  __addressof(_Tp& __r)
44  {
45  return reinterpret_cast<_Tp*>
46  (&const_cast<char&>(reinterpret_cast<const volatile char&>(__r)));
47  }
48 
49 _GLIBCXX_END_NAMESPACE_VERSION
50 } // namespace
51 
52 #ifdef __GXX_EXPERIMENTAL_CXX0X__
53 #include <type_traits> // Brings in std::declval too.
54 
55 namespace std _GLIBCXX_VISIBILITY(default)
56 {
57 _GLIBCXX_BEGIN_NAMESPACE_VERSION
58 
59  /// forward (as per N3143)
60  template<typename _Tp>
61  inline _Tp&&
62  forward(typename std::remove_reference<_Tp>::type& __t)
63  { return static_cast<_Tp&&>(__t); }
64 
65  template<typename _Tp>
66  inline _Tp&&
67  forward(typename std::remove_reference<_Tp>::type&& __t)
68  {
69  static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
70  " substituting _Tp is an lvalue reference type");
71  return static_cast<_Tp&&>(__t);
72  }
73 
74  /**
75  * @brief Move a value.
76  * @ingroup mutating_algorithms
77  * @param __t A thing of arbitrary type.
78  * @return Same, moved.
79  */
80  template<typename _Tp>
81  inline typename std::remove_reference<_Tp>::type&&
82  move(_Tp&& __t)
83  { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
84 
85  /// declval, from type_traits.
86 
87  /**
88  * @brief Returns the actual address of the object or function
89  * referenced by r, even in the presence of an overloaded
90  * operator&.
91  * @param __r Reference to an object or function.
92  * @return The actual address.
93  */
94  template<typename _Tp>
95  inline _Tp*
96  addressof(_Tp& __r)
97  { return std::__addressof(__r); }
98 
99 _GLIBCXX_END_NAMESPACE_VERSION
100 } // namespace
101 
102 #define _GLIBCXX_MOVE(__val) std::move(__val)
103 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
104 #else
105 #define _GLIBCXX_MOVE(__val) (__val)
106 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
107 #endif
108 
109 namespace std _GLIBCXX_VISIBILITY(default)
110 {
111 _GLIBCXX_BEGIN_NAMESPACE_VERSION
112 
113  /**
114  * @brief Swaps two values.
115  * @ingroup mutating_algorithms
116  * @param __a A thing of arbitrary type.
117  * @param __b Another thing of arbitrary type.
118  * @return Nothing.
119  */
120  template<typename _Tp>
121  inline void
122  swap(_Tp& __a, _Tp& __b)
123  {
124  // concept requirements
125  __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
126 
127  _Tp __tmp = _GLIBCXX_MOVE(__a);
128  __a = _GLIBCXX_MOVE(__b);
129  __b = _GLIBCXX_MOVE(__tmp);
130  }
131 
132  // _GLIBCXX_RESOLVE_LIB_DEFECTS
133  // DR 809. std::swap should be overloaded for array types.
134  template<typename _Tp, size_t _Nm>
135  inline void
136  swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
137  {
138  for (size_t __n = 0; __n < _Nm; ++__n)
139  swap(__a[__n], __b[__n]);
140  }
141 
142 _GLIBCXX_END_NAMESPACE_VERSION
143 } // namespace
144 
145 #endif /* _MOVE_H */