1// Move, forward and identity for C++0x + swap -*- C++ -*-
2
3// Copyright (C) 2007-2015 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
36namespace 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#if __cplusplus >= 201103L
57#include <type_traits> // Brings in std::declval too.
58
59namespace std _GLIBCXX_VISIBILITY(default)
60{
61_GLIBCXX_BEGIN_NAMESPACE_VERSION
62
63 /**
64 * @addtogroup utilities
65 * @{
66 */
67
68 /**
69 * @brief Forward an lvalue.
70 * @return The parameter cast to the specified type.
71 *
72 * This function is used to implement "perfect forwarding".
73 */
74 template<typename _Tp>
75 constexpr _Tp&&
76 forward(typename std::remove_reference<_Tp>::type& __t) noexcept
77 { return static_cast<_Tp&&>(__t); }
78
79 /**
80 * @brief Forward an rvalue.
81 * @return The parameter cast to the specified type.
82 *
83 * This function is used to implement "perfect forwarding".
84 */
85 template<typename _Tp>
86 constexpr _Tp&&
87 forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
88 {
89 static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
90 " substituting _Tp is an lvalue reference type");
91 return static_cast<_Tp&&>(__t);
92 }
93
94 /**
95 * @brief Convert a value to an rvalue.
96 * @param __t A thing of arbitrary type.
97 * @return The parameter cast to an rvalue-reference to allow moving it.
98 */
99 template<typename _Tp>
100 constexpr typename std::remove_reference<_Tp>::type&&
101 move(_Tp&& __t) noexcept
102 { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
103
104
105 template<typename _Tp>
106 struct __move_if_noexcept_cond
107 : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
108 is_copy_constructible<_Tp>>::type { };
109
110 /**
111 * @brief Conditionally convert a value to an rvalue.
112 * @param __x A thing of arbitrary type.
113 * @return The parameter, possibly cast to an rvalue-reference.
114 *
115 * Same as std::move unless the type's move constructor could throw and the
116 * type is copyable, in which case an lvalue-reference is returned instead.
117 */
118 template<typename _Tp>
119 constexpr typename
120 conditional<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>::type
121 move_if_noexcept(_Tp& __x) noexcept
122 { return std::move(__x); }
123
124 // declval, from type_traits.
125
126 /**
127 * @brief Returns the actual address of the object or function
128 * referenced by r, even in the presence of an overloaded
129 * operator&.
130 * @param __r Reference to an object or function.
131 * @return The actual address.
132 */
133 template<typename _Tp>
134 inline _Tp*
135 addressof(_Tp& __r) noexcept
136 { return std::__addressof(__r); }
137
138 // C++11 version of std::exchange for internal use.
139 template <typename _Tp, typename _Up = _Tp>
140 inline _Tp
141 __exchange(_Tp& __obj, _Up&& __new_val)
142 {
143 _Tp __old_val = std::move(__obj);
144 __obj = std::forward<_Up>(__new_val);
145 return __old_val;
146 }
147
148 /// @} group utilities
149_GLIBCXX_END_NAMESPACE_VERSION
150} // namespace
151
152#define _GLIBCXX_MOVE(__val) std::move(__val)
153#define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
154#else
155#define _GLIBCXX_MOVE(__val) (__val)
156#define _GLIBCXX_FORWARD(_Tp, __val) (__val)
157#endif
158
159namespace std _GLIBCXX_VISIBILITY(default)
160{
161_GLIBCXX_BEGIN_NAMESPACE_VERSION
162
163 /**
164 * @addtogroup utilities
165 * @{
166 */
167
168 /**
169 * @brief Swaps two values.
170 * @param __a A thing of arbitrary type.
171 * @param __b Another thing of arbitrary type.
172 * @return Nothing.
173 */
174 template<typename _Tp>
175 inline void
176 swap(_Tp& __a, _Tp& __b)
177#if __cplusplus >= 201103L
178 noexcept(__and_<is_nothrow_move_constructible<_Tp>,
179 is_nothrow_move_assignable<_Tp>>::value)
180#endif
181 {
182 // concept requirements
183 __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
184
185 _Tp __tmp = _GLIBCXX_MOVE(__a);
186 __a = _GLIBCXX_MOVE(__b);
187 __b = _GLIBCXX_MOVE(__tmp);
188 }
189
190 // _GLIBCXX_RESOLVE_LIB_DEFECTS
191 // DR 809. std::swap should be overloaded for array types.
192 /// Swap the contents of two arrays.
193 template<typename _Tp, size_t _Nm>
194 inline void
195 swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
196#if __cplusplus >= 201103L
197 noexcept(noexcept(swap(*__a, *__b)))
198#endif
199 {
200 for (size_t __n = 0; __n < _Nm; ++__n)
201 swap(__a[__n], __b[__n]);
202 }
203
204 /// @} group utilities
205_GLIBCXX_END_NAMESPACE_VERSION
206} // namespace
207
208#endif /* _MOVE_H */
209