1 // Move, forward and identity for C++0x + swap -*- C++ -*-
2
3 // Copyright (C) 2007, 2008, 2009, 2010, 2011 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
_GLIBCXX_VISIBILITY(default)36 namespace std _GLIBCXX_VISIBILITY(default)
37 {
38 _GLIBCXX_BEGIN_NAMESPACE_VERSION
39
40 // Used, in C++03 mode too, by allocators, etc.
41 /**
42 * @brief Same as C++11 std::addressof
43 * @ingroup utilities
44 */
45 template<typename _Tp>
46 inline _Tp*
47 __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
48 {
49 return reinterpret_cast<_Tp*>
50 (&const_cast<char&>(reinterpret_cast<const volatile char&>(__r)));
51 }
52
53 _GLIBCXX_END_NAMESPACE_VERSION
54 } // namespace
55
56 #ifdef __GXX_EXPERIMENTAL_CXX0X__
57 #include <type_traits> // Brings in std::declval too.
58
_GLIBCXX_VISIBILITY(default)59 namespace std _GLIBCXX_VISIBILITY(default)
60 {
61 _GLIBCXX_BEGIN_NAMESPACE_VERSION
62
63 /**
64 * @addtogroup utilities
65 * @{
66 */
67
68 // forward (as per N3143)
69 /**
70 * @brief Forward an lvalue.
71 * @return The parameter cast to the specified type.
72 *
73 * This function is used to implement "perfect forwarding".
74 */
75 template<typename _Tp>
76 constexpr _Tp&&
77 forward(typename std::remove_reference<_Tp>::type& __t) noexcept
78 { return static_cast<_Tp&&>(__t); }
79
80 /**
81 * @brief Forward an rvalue.
82 * @return The parameter cast to the specified type.
83 *
84 * This function is used to implement "perfect forwarding".
85 */
86 template<typename _Tp>
87 constexpr _Tp&&
88 forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
89 {
90 static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
91 " substituting _Tp is an lvalue reference type");
92 return static_cast<_Tp&&>(__t);
93 }
94
95 /**
96 * @brief Convert a value to an rvalue.
97 * @param __t A thing of arbitrary type.
98 * @return The parameter cast to an rvalue-reference to allow moving it.
99 */
100 template<typename _Tp>
101 constexpr typename std::remove_reference<_Tp>::type&&
102 move(_Tp&& __t) noexcept
103 { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
104
105
106 template<typename _Tp>
107 struct __move_if_noexcept_cond
108 : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
109 is_copy_constructible<_Tp>>::type { };
110
111 /**
112 * @brief Conditionally convert a value to an rvalue.
113 * @param __x A thing of arbitrary type.
114 * @return The parameter, possibly cast to an rvalue-reference.
115 *
116 * Same as std::move unless the type's move constructor could throw and the
117 * type is copyable, in which case an lvalue-reference is returned instead.
118 */
119 template<typename _Tp>
120 inline typename
121 conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
122 move_if_noexcept(_Tp& __x) noexcept
123 { return std::move(__x); }
124
125 // declval, from type_traits.
126
127 /**
128 * @brief Returns the actual address of the object or function
129 * referenced by r, even in the presence of an overloaded
130 * operator&.
131 * @param __r Reference to an object or function.
132 * @return The actual address.
133 */
134 template<typename _Tp>
135 inline _Tp*
136 addressof(_Tp& __r) noexcept
137 { return std::__addressof(__r); }
138
139 /// @} group utilities
140 _GLIBCXX_END_NAMESPACE_VERSION
141 } // namespace
142
143 #define _GLIBCXX_MOVE(__val) std::move(__val)
144 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
145 #else
146 #define _GLIBCXX_MOVE(__val) (__val)
147 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
148 #endif
149
_GLIBCXX_VISIBILITY(default)150 namespace std _GLIBCXX_VISIBILITY(default)
151 {
152 _GLIBCXX_BEGIN_NAMESPACE_VERSION
153
154 /**
155 * @addtogroup utilities
156 * @{
157 */
158
159 /**
160 * @brief Swaps two values.
161 * @param __a A thing of arbitrary type.
162 * @param __b Another thing of arbitrary type.
163 * @return Nothing.
164 */
165 template<typename _Tp>
166 inline void
167 swap(_Tp& __a, _Tp& __b)
168 #ifdef __GXX_EXPERIMENTAL_CXX0X__
169 noexcept(__and_<is_nothrow_move_constructible<_Tp>,
170 is_nothrow_move_assignable<_Tp>>::value)
171 #endif
172 {
173 // concept requirements
174 __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
175
176 _Tp __tmp = _GLIBCXX_MOVE(__a);
177 __a = _GLIBCXX_MOVE(__b);
178 __b = _GLIBCXX_MOVE(__tmp);
179 }
180
181 // _GLIBCXX_RESOLVE_LIB_DEFECTS
182 // DR 809. std::swap should be overloaded for array types.
183 /// Swap the contents of two arrays.
184 template<typename _Tp, size_t _Nm>
185 inline void
186 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
187 #ifdef __GXX_EXPERIMENTAL_CXX0X__
188 noexcept(noexcept(swap(*__a, *__b)))
189 #endif
190 {
191 for (size_t __n = 0; __n < _Nm; ++__n)
192 swap(__a[__n], __b[__n]);
193 }
194
195 /// @} group utilities
196 _GLIBCXX_END_NAMESPACE_VERSION
197 } // namespace
198
199 #endif /* _MOVE_H */
200