1// <experimental/memory> -*- C++ -*-
2
3// Copyright (C) 2015-2023 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 experimental/memory
26 * This is a TS C++ Library header.
27 * @ingroup libfund-ts
28 */
29
30//
31// N4336 Working Draft, C++ Extensions for Library Fundamentals, Version 2
32//
33
34#ifndef _GLIBCXX_EXPERIMENTAL_MEMORY
35#define _GLIBCXX_EXPERIMENTAL_MEMORY 1
36
37#pragma GCC system_header
38
39#include <bits/requires_hosted.h> // experimental is currently omitted
40
41#if __cplusplus >= 201402L
42
43#include <memory>
44#include <type_traits>
45#include <experimental/bits/shared_ptr.h>
46#include <bits/functional_hash.h>
47
48namespace std _GLIBCXX_VISIBILITY(default)
49{
50_GLIBCXX_BEGIN_NAMESPACE_VERSION
51
52namespace experimental
53{
54inline namespace fundamentals_v2
55{
56#define __cpp_lib_experimental_observer_ptr 201411
57
58 template <typename _Tp>
59 class observer_ptr
60 {
61 public:
62 // publish our template parameter and variations thereof
63 using element_type = _Tp;
64 using __pointer = add_pointer_t<_Tp>; // exposition-only
65 using __reference = add_lvalue_reference_t<_Tp>; // exposition-only
66
67 // 3.2.2, observer_ptr constructors
68 // default c'tor
69 constexpr observer_ptr() noexcept
70 : __t()
71 { }
72
73 // pointer-accepting c'tors
74 constexpr observer_ptr(nullptr_t) noexcept
75 : __t()
76 { }
77
78 constexpr explicit observer_ptr(__pointer __p) noexcept
79 : __t(__p)
80 { }
81
82 // copying c'tors (in addition to compiler-generated copy c'tor)
83 template <typename _Up,
84 typename = typename enable_if<
85 is_convertible<typename add_pointer<_Up>::type, __pointer
86 >::value
87 >::type>
88 constexpr observer_ptr(observer_ptr<_Up> __p) noexcept
89 : __t(__p.get())
90 {
91 }
92
93 // 3.2.3, observer_ptr observers
94 constexpr __pointer
95 get() const noexcept
96 {
97 return __t;
98 }
99
100 constexpr __reference
101 operator*() const
102 {
103 return *get();
104 }
105
106 constexpr __pointer
107 operator->() const noexcept
108 {
109 return get();
110 }
111
112 constexpr explicit operator bool() const noexcept
113 {
114 return get() != nullptr;
115 }
116
117 // 3.2.4, observer_ptr conversions
118 constexpr explicit operator __pointer() const noexcept
119 {
120 return get();
121 }
122
123 // 3.2.5, observer_ptr modifiers
124 constexpr __pointer
125 release() noexcept
126 {
127 __pointer __tmp = get();
128 reset();
129 return __tmp;
130 }
131
132 constexpr void
133 reset(__pointer __p = nullptr) noexcept
134 {
135 __t = __p;
136 }
137
138 constexpr void
139 swap(observer_ptr& __p) noexcept
140 {
141 std::swap(__t, __p.__t);
142 }
143
144 private:
145 __pointer __t;
146 }; // observer_ptr<>
147
148 template<typename _Tp>
149 void
150 swap(observer_ptr<_Tp>& __p1, observer_ptr<_Tp>& __p2) noexcept
151 {
152 __p1.swap(__p2);
153 }
154
155 template<typename _Tp>
156 observer_ptr<_Tp>
157 make_observer(_Tp* __p) noexcept
158 {
159 return observer_ptr<_Tp>(__p);
160 }
161
162 template<typename _Tp, typename _Up>
163 bool
164 operator==(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
165 {
166 return __p1.get() == __p2.get();
167 }
168
169 template<typename _Tp, typename _Up>
170 bool
171 operator!=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
172 {
173 return !(__p1 == __p2);
174 }
175
176 template<typename _Tp>
177 bool
178 operator==(observer_ptr<_Tp> __p, nullptr_t) noexcept
179 {
180 return !__p;
181 }
182
183 template<typename _Tp>
184 bool
185 operator==(nullptr_t, observer_ptr<_Tp> __p) noexcept
186 {
187 return !__p;
188 }
189
190 template<typename _Tp>
191 bool
192 operator!=(observer_ptr<_Tp> __p, nullptr_t) noexcept
193 {
194 return bool(__p);
195 }
196
197 template<typename _Tp>
198 bool
199 operator!=(nullptr_t, observer_ptr<_Tp> __p) noexcept
200 {
201 return bool(__p);
202 }
203
204 template<typename _Tp, typename _Up>
205 bool
206 operator<(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
207 {
208 return std::less<typename common_type<typename add_pointer<_Tp>::type,
209 typename add_pointer<_Up>::type
210 >::type
211 >{}(__p1.get(), __p2.get());
212 }
213
214 template<typename _Tp, typename _Up>
215 bool
216 operator>(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
217 {
218 return __p2 < __p1;
219 }
220
221 template<typename _Tp, typename _Up>
222 bool
223 operator<=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
224 {
225 return !(__p2 < __p1);
226 }
227
228 template<typename _Tp, typename _Up>
229 bool
230 operator>=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
231 {
232 return !(__p1 < __p2);
233 }
234} // namespace fundamentals_v2
235} // namespace experimental
236
237template <typename _Tp>
238 struct hash<experimental::observer_ptr<_Tp>>
239 {
240 using result_type = size_t;
241 using argument_type = experimental::observer_ptr<_Tp>;
242
243 size_t
244 operator()(const experimental::observer_ptr<_Tp>& __t) const
245 noexcept(noexcept(hash<typename add_pointer<_Tp>::type> {}(__t.get())))
246 {
247 return hash<typename add_pointer<_Tp>::type> {}(__t.get());
248 }
249 };
250
251
252_GLIBCXX_END_NAMESPACE_VERSION
253} // namespace std
254
255#endif // __cplusplus <= 201103L
256
257#endif // _GLIBCXX_EXPERIMENTAL_MEMORY
258

source code of include/c++/13/experimental/memory