Line data Source code
1 : // Move, forward and identity for C++11 + swap -*- C++ -*-
2 :
3 : // Copyright (C) 2007-2023 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 : #if __cplusplus < 201103L
35 : # include <bits/concept_check.h>
36 : #else
37 : # include <type_traits> // Brings in std::declval too.
38 : #endif
39 :
40 : namespace std _GLIBCXX_VISIBILITY(default)
41 : {
42 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 :
44 : // Used, in C++03 mode too, by allocators, etc.
45 : /**
46 : * @brief Same as C++11 std::addressof
47 : * @ingroup utilities
48 : */
49 : template<typename _Tp>
50 : inline _GLIBCXX_CONSTEXPR _Tp*
51 587049110 : __addressof(_Tp& __r) _GLIBCXX_NOEXCEPT
52 587049110 : { return __builtin_addressof(__r); }
53 :
54 : #if __cplusplus >= 201103L
55 :
56 : /**
57 : * @addtogroup utilities
58 : * @{
59 : */
60 :
61 : /**
62 : * @brief Forward an lvalue.
63 : * @return The parameter cast to the specified type.
64 : *
65 : * This function is used to implement "perfect forwarding".
66 : */
67 : template<typename _Tp>
68 : _GLIBCXX_NODISCARD
69 : constexpr _Tp&&
70 1452065534 : forward(typename std::remove_reference<_Tp>::type& __t) noexcept
71 1452065534 : { return static_cast<_Tp&&>(__t); }
72 :
73 : /**
74 : * @brief Forward an rvalue.
75 : * @return The parameter cast to the specified type.
76 : *
77 : * This function is used to implement "perfect forwarding".
78 : */
79 : template<typename _Tp>
80 : _GLIBCXX_NODISCARD
81 : constexpr _Tp&&
82 : forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
83 : {
84 : static_assert(!std::is_lvalue_reference<_Tp>::value,
85 : "std::forward must not be used to convert an rvalue to an lvalue");
86 : return static_cast<_Tp&&>(__t);
87 : }
88 :
89 : /**
90 : * @brief Convert a value to an rvalue.
91 : * @param __t A thing of arbitrary type.
92 : * @return The parameter cast to an rvalue-reference to allow moving it.
93 : */
94 : template<typename _Tp>
95 : _GLIBCXX_NODISCARD
96 : constexpr typename std::remove_reference<_Tp>::type&&
97 1779966736 : move(_Tp&& __t) noexcept
98 1779966736 : { return static_cast<typename std::remove_reference<_Tp>::type&&>(__t); }
99 :
100 :
101 : template<typename _Tp>
102 : struct __move_if_noexcept_cond
103 : : public __and_<__not_<is_nothrow_move_constructible<_Tp>>,
104 : is_copy_constructible<_Tp>>::type { };
105 :
106 : /**
107 : * @brief Conditionally convert a value to an rvalue.
108 : * @param __x A thing of arbitrary type.
109 : * @return The parameter, possibly cast to an rvalue-reference.
110 : *
111 : * Same as std::move unless the type's move constructor could throw and the
112 : * type is copyable, in which case an lvalue-reference is returned instead.
113 : */
114 : template<typename _Tp>
115 : _GLIBCXX_NODISCARD
116 : constexpr
117 : __conditional_t<__move_if_noexcept_cond<_Tp>::value, const _Tp&, _Tp&&>
118 : move_if_noexcept(_Tp& __x) noexcept
119 : { return std::move(__x); }
120 :
121 : // declval, from type_traits.
122 :
123 : #if __cplusplus > 201402L
124 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
125 : // 2296. std::addressof should be constexpr
126 : # define __cpp_lib_addressof_constexpr 201603L
127 : #endif
128 : /**
129 : * @brief Returns the actual address of the object or function
130 : * referenced by r, even in the presence of an overloaded
131 : * operator&.
132 : * @param __r Reference to an object or function.
133 : * @return The actual address.
134 : */
135 : template<typename _Tp>
136 : _GLIBCXX_NODISCARD
137 : inline _GLIBCXX17_CONSTEXPR _Tp*
138 106071838 : addressof(_Tp& __r) noexcept
139 106071838 : { return std::__addressof(__r); }
140 :
141 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
142 : // 2598. addressof works on temporaries
143 : template<typename _Tp>
144 : const _Tp* addressof(const _Tp&&) = delete;
145 :
146 : // C++11 version of std::exchange for internal use.
147 : template <typename _Tp, typename _Up = _Tp>
148 : _GLIBCXX20_CONSTEXPR
149 : inline _Tp
150 : __exchange(_Tp& __obj, _Up&& __new_val)
151 : {
152 : _Tp __old_val = std::move(__obj);
153 : __obj = std::forward<_Up>(__new_val);
154 : return __old_val;
155 : }
156 :
157 : /// @} group utilities
158 :
159 : #define _GLIBCXX_FWDREF(_Tp) _Tp&&
160 : #define _GLIBCXX_MOVE(__val) std::move(__val)
161 : #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
162 : #else
163 : #define _GLIBCXX_FWDREF(_Tp) const _Tp&
164 : #define _GLIBCXX_MOVE(__val) (__val)
165 : #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
166 : #endif
167 :
168 : /**
169 : * @addtogroup utilities
170 : * @{
171 : */
172 :
173 : /**
174 : * @brief Swaps two values.
175 : * @param __a A thing of arbitrary type.
176 : * @param __b Another thing of arbitrary type.
177 : * @return Nothing.
178 : */
179 : template<typename _Tp>
180 : _GLIBCXX20_CONSTEXPR
181 : inline
182 : #if __cplusplus >= 201103L
183 : typename enable_if<__and_<__not_<__is_tuple_like<_Tp>>,
184 : is_move_constructible<_Tp>,
185 : is_move_assignable<_Tp>>::value>::type
186 : #else
187 : void
188 : #endif
189 1567088 : swap(_Tp& __a, _Tp& __b)
190 : _GLIBCXX_NOEXCEPT_IF(__and_<is_nothrow_move_constructible<_Tp>,
191 : is_nothrow_move_assignable<_Tp>>::value)
192 : {
193 : #if __cplusplus < 201103L
194 : // concept requirements
195 : __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
196 : #endif
197 1567088 : _Tp __tmp = _GLIBCXX_MOVE(__a);
198 1567088 : __a = _GLIBCXX_MOVE(__b);
199 1567088 : __b = _GLIBCXX_MOVE(__tmp);
200 1567088 : }
201 :
202 : // _GLIBCXX_RESOLVE_LIB_DEFECTS
203 : // DR 809. std::swap should be overloaded for array types.
204 : /// Swap the contents of two arrays.
205 : template<typename _Tp, size_t _Nm>
206 : _GLIBCXX20_CONSTEXPR
207 : inline
208 : #if __cplusplus >= 201103L
209 : typename enable_if<__is_swappable<_Tp>::value>::type
210 : #else
211 : void
212 : #endif
213 : swap(_Tp (&__a)[_Nm], _Tp (&__b)[_Nm])
214 : _GLIBCXX_NOEXCEPT_IF(__is_nothrow_swappable<_Tp>::value)
215 : {
216 : for (size_t __n = 0; __n < _Nm; ++__n)
217 : swap(__a[__n], __b[__n]);
218 : }
219 :
220 : /// @} group utilities
221 : _GLIBCXX_END_NAMESPACE_VERSION
222 : } // namespace
223 :
224 : #endif /* _MOVE_H */
|
