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4f5f9962 | 1 | // Move, forward and identity for C++11 + swap -*- C++ -*- |
1476e59c | 2 | |
6441eb6d | 3 | // Copyright (C) 2007-2025 Free Software Foundation, Inc. |
1476e59c PC |
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 | |
748086b7 | 8 | // Free Software Foundation; either version 3, or (at your option) |
1476e59c PC |
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 | ||
748086b7 JJ |
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/>. | |
1476e59c | 24 | |
f910786b | 25 | /** @file bits/move.h |
1476e59c | 26 | * This is an internal header file, included by other library headers. |
f910786b | 27 | * Do not attempt to use it directly. @headername{utility} |
1476e59c PC |
28 | */ |
29 | ||
caa8b3c6 PC |
30 | #ifndef _MOVE_H |
31 | #define _MOVE_H 1 | |
1476e59c | 32 | |
e14e932b | 33 | #include <bits/c++config.h> |
6d0dff49 JW |
34 | #if __cplusplus < 201103L |
35 | # include <bits/concept_check.h> | |
5c8b154c JW |
36 | #else |
37 | # include <type_traits> // Brings in std::declval too. | |
6d0dff49 | 38 | #endif |
e14e932b | 39 | |
12ffa228 BK |
40 | namespace std _GLIBCXX_VISIBILITY(default) |
41 | { | |
42 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
882b3d5c PC |
43 | |
44 | // Used, in C++03 mode too, by allocators, etc. | |
13901e4b JW |
45 | /** |
46 | * @brief Same as C++11 std::addressof | |
47 | * @ingroup utilities | |
48 | */ | |
882b3d5c | 49 | template<typename _Tp> |
96c32a59 | 50 | __attribute__((__always_inline__)) |
9e023e33 | 51 | inline _GLIBCXX_CONSTEXPR _Tp* |
5d861bf2 | 52 | __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT |
9e023e33 | 53 | { return __builtin_addressof(__r); } |
882b3d5c | 54 | |
4a15d842 FD |
55 | #if __cplusplus >= 201103L |
56 | ||
13901e4b JW |
57 | /** |
58 | * @addtogroup utilities | |
59 | * @{ | |
60 | */ | |
61 | ||
13901e4b JW |
62 | /** |
63 | * @brief Forward an lvalue. | |
64 | * @return The parameter cast to the specified type. | |
65 | * | |
66 | * This function is used to implement "perfect forwarding". | |
4a4e5394 | 67 | * @since C++11 |
13901e4b | 68 | */ |
4c7aaebf | 69 | template<typename _Tp> |
96c32a59 | 70 | [[__nodiscard__,__gnu__::__always_inline__]] |
a4eeb822 | 71 | constexpr _Tp&& |
5d861bf2 | 72 | forward(typename std::remove_reference<_Tp>::type& __t) noexcept |
4c7aaebf PC |
73 | { return static_cast<_Tp&&>(__t); } |
74 | ||
13901e4b JW |
75 | /** |
76 | * @brief Forward an rvalue. | |
77 | * @return The parameter cast to the specified type. | |
78 | * | |
79 | * This function is used to implement "perfect forwarding". | |
4a4e5394 | 80 | * @since C++11 |
13901e4b | 81 | */ |
4c7aaebf | 82 | template<typename _Tp> |
96c32a59 | 83 | [[__nodiscard__,__gnu__::__always_inline__]] |
a4eeb822 | 84 | constexpr _Tp&& |
5d861bf2 | 85 | forward(typename std::remove_reference<_Tp>::type&& __t) noexcept |
ad269884 | 86 | { |
a11052d9 JW |
87 | static_assert(!std::is_lvalue_reference<_Tp>::value, |
88 | "std::forward must not be used to convert an rvalue to an lvalue"); | |
ad269884 PC |
89 | return static_cast<_Tp&&>(__t); |
90 | } | |
e7f1930f | 91 | |
55cf4f84 JW |
92 | #if __glibcxx_forward_like // C++ >= 23 |
93 | template<typename _Tp, typename _Up> | |
8256d5c0 PP |
94 | struct __like_impl; // _Tp must be a reference and _Up an lvalue reference |
95 | ||
96 | template<typename _Tp, typename _Up> | |
97 | struct __like_impl<_Tp&, _Up&> | |
98 | { using type = _Up&; }; | |
99 | ||
100 | template<typename _Tp, typename _Up> | |
101 | struct __like_impl<const _Tp&, _Up&> | |
102 | { using type = const _Up&; }; | |
103 | ||
104 | template<typename _Tp, typename _Up> | |
105 | struct __like_impl<_Tp&&, _Up&> | |
106 | { using type = _Up&&; }; | |
107 | ||
108 | template<typename _Tp, typename _Up> | |
109 | struct __like_impl<const _Tp&&, _Up&> | |
110 | { using type = const _Up&&; }; | |
d2cb4693 PP |
111 | |
112 | template<typename _Tp, typename _Up> | |
8256d5c0 PP |
113 | using __like_t = typename __like_impl<_Tp&&, _Up&>::type; |
114 | ||
4a4e5394 JW |
115 | /** @brief Forward with the cv-qualifiers and value category of another type. |
116 | * @tparam _Tp An lvalue reference or rvalue reference. | |
117 | * @tparam _Up An lvalue reference type deduced from the function argument. | |
118 | * @param __x An lvalue. | |
119 | * @return `__x` converted to match the qualifiers of `_Tp`. | |
120 | * @since C++23 | |
121 | */ | |
8256d5c0 | 122 | template<typename _Tp, typename _Up> |
96c32a59 | 123 | [[nodiscard,__gnu__::__always_inline__]] |
8256d5c0 PP |
124 | constexpr __like_t<_Tp, _Up> |
125 | forward_like(_Up&& __x) noexcept | |
126 | { return static_cast<__like_t<_Tp, _Up>>(__x); } | |
55cf4f84 JW |
127 | #endif |
128 | ||
fd9380a6 | 129 | /** |
13901e4b | 130 | * @brief Convert a value to an rvalue. |
fd9380a6 | 131 | * @param __t A thing of arbitrary type. |
13901e4b | 132 | * @return The parameter cast to an rvalue-reference to allow moving it. |
4a4e5394 | 133 | * @since C++11 |
fd9380a6 | 134 | */ |
1476e59c | 135 | template<typename _Tp> |
96c32a59 | 136 | [[__nodiscard__,__gnu__::__always_inline__]] |
a4eeb822 | 137 | constexpr typename std::remove_reference<_Tp>::type&& |
5d861bf2 | 138 | move(_Tp&& __t) noexcept |
e7f1930f | 139 | { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); } |
1476e59c | 140 | |
74a2a1b4 PC |
141 | |
142 | template<typename _Tp> | |
143 | struct __move_if_noexcept_cond | |
144 | : public __and_<__not_<is_nothrow_move_constructible<_Tp>>, | |
145 | is_copy_constructible<_Tp>>::type { }; | |
146 | ||
1f428429 | 147 | /** |
13901e4b | 148 | * @brief Conditionally convert a value to an rvalue. |
1f428429 | 149 | * @param __x A thing of arbitrary type. |
13901e4b JW |
150 | * @return The parameter, possibly cast to an rvalue-reference. |
151 | * | |
152 | * Same as std::move unless the type's move constructor could throw and the | |
153 | * type is copyable, in which case an lvalue-reference is returned instead. | |
4a4e5394 | 154 | * @since C++11 |
1f428429 PC |
155 | */ |
156 | template<typename _Tp> | |
96c32a59 | 157 | [[__nodiscard__,__gnu__::__always_inline__]] |
a09bb4a8 JW |
158 | constexpr |
159 | __conditional_t<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&> | |
1f428429 PC |
160 | move_if_noexcept(_Tp& __x) noexcept |
161 | { return std::move(__x); } | |
162 | ||
13901e4b | 163 | // declval, from type_traits. |
7274deff | 164 | |
882b3d5c PC |
165 | /** |
166 | * @brief Returns the actual address of the object or function | |
167 | * referenced by r, even in the presence of an overloaded | |
168 | * operator&. | |
169 | * @param __r Reference to an object or function. | |
170 | * @return The actual address. | |
4a4e5394 | 171 | * @since C++11 |
882b3d5c PC |
172 | */ |
173 | template<typename _Tp> | |
96c32a59 | 174 | [[__nodiscard__,__gnu__::__always_inline__]] |
9e023e33 | 175 | inline _GLIBCXX17_CONSTEXPR _Tp* |
5d861bf2 | 176 | addressof(_Tp& __r) noexcept |
c91eb5a5 | 177 | { return __builtin_addressof(__r); } |
882b3d5c | 178 | |
3ce96851 JW |
179 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
180 | // 2598. addressof works on temporaries | |
181 | template<typename _Tp> | |
182 | const _Tp* addressof(const _Tp&&) = delete; | |
183 | ||
9b817548 JW |
184 | // C++11 version of std::exchange for internal use. |
185 | template <typename _Tp, typename _Up = _Tp> | |
3a66e68a | 186 | _GLIBCXX20_CONSTEXPR |
9b817548 JW |
187 | inline _Tp |
188 | __exchange(_Tp& __obj, _Up&& __new_val) | |
189 | { | |
190 | _Tp __old_val = std::move(__obj); | |
191 | __obj = std::forward<_Up>(__new_val); | |
192 | return __old_val; | |
193 | } | |
194 | ||
13901e4b | 195 | /// @} group utilities |
1476e59c | 196 | |
90bf60c3 | 197 | #define _GLIBCXX_FWDREF(_Tp) _Tp&& |
5f1fd346 | 198 | #define _GLIBCXX_MOVE(__val) std::move(__val) |
55dd8445 | 199 | #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val) |
d98f312c | 200 | #else |
90bf60c3 | 201 | #define _GLIBCXX_FWDREF(_Tp) const _Tp& |
5f1fd346 | 202 | #define _GLIBCXX_MOVE(__val) (__val) |
55dd8445 | 203 | #define _GLIBCXX_FORWARD(_Tp, __val) (__val) |
1476e59c PC |
204 | #endif |
205 | ||
13901e4b JW |
206 | /** |
207 | * @addtogroup utilities | |
208 | * @{ | |
209 | */ | |
210 | ||
e14e932b PC |
211 | /** |
212 | * @brief Swaps two values. | |
fd9380a6 BK |
213 | * @param __a A thing of arbitrary type. |
214 | * @param __b Another thing of arbitrary type. | |
e14e932b PC |
215 | * @return Nothing. |
216 | */ | |
217 | template<typename _Tp> | |
7a91c710 | 218 | _GLIBCXX20_CONSTEXPR |
ddb63209 | 219 | inline |
734f5023 | 220 | #if __cplusplus >= 201103L |
a2863bde VV |
221 | typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>, |
222 | is_move_constructible<_Tp>, | |
ddb63209 | 223 | is_move_assignable<_Tp>>::value>::type |
ddb63209 VV |
224 | #else |
225 | void | |
173f26ae | 226 | #endif |
81912fb3 | 227 | swap(_Tp& __a, _Tp& __b) |
315f8b5f JW |
228 | _GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>, |
229 | is_nothrow_move_assignable<_Tp>>::value) | |
e14e932b | 230 | { |
6d0dff49 | 231 | #if __cplusplus < 201103L |
e14e932b PC |
232 | // concept requirements |
233 | __glibcxx_function_requires(_SGIAssignableConcept<_Tp>) | |
6d0dff49 | 234 | #endif |
e14e932b PC |
235 | _Tp __tmp = _GLIBCXX_MOVE(__a); |
236 | __a = _GLIBCXX_MOVE(__b); | |
237 | __b = _GLIBCXX_MOVE(__tmp); | |
238 | } | |
239 | ||
caa8b3c6 PC |
240 | // _GLIBCXX_RESOLVE_LIB_DEFECTS |
241 | // DR 809. std::swap should be overloaded for array types. | |
13901e4b | 242 | /// Swap the contents of two arrays. |
caa8b3c6 | 243 | template<typename _Tp, size_t _Nm> |
7a91c710 | 244 | _GLIBCXX20_CONSTEXPR |
ddb63209 | 245 | inline |
734f5023 | 246 | #if __cplusplus >= 201103L |
26b5ace7 | 247 | typename enable_if<__is_swappable<_Tp>::value>::type |
ddb63209 VV |
248 | #else |
249 | void | |
ccb4f5a7 | 250 | #endif |
81912fb3 JW |
251 | swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm]) |
252 | _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value) | |
caa8b3c6 PC |
253 | { |
254 | for (size_t __n = 0; __n < _Nm; ++__n) | |
255 | swap(__a[__n], __b[__n]); | |
256 | } | |
257 | ||
13901e4b | 258 | /// @} group utilities |
12ffa228 BK |
259 | _GLIBCXX_END_NAMESPACE_VERSION |
260 | } // namespace | |
e14e932b | 261 | |
caa8b3c6 | 262 | #endif /* _MOVE_H */ |