libstdc++
experimental/memory
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1// <experimental/memory> -*- C++ -*-
2
3// Copyright (C) 2015-2022 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#if __cplusplus >= 201402L
40
41#include <memory>
42#include <type_traits>
43#include <experimental/bits/shared_ptr.h>
44#include <bits/functional_hash.h>
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50namespace experimental
51{
52inline namespace fundamentals_v2
53{
54#define __cpp_lib_experimental_observer_ptr 201411
55
56 template <typename _Tp>
57 class observer_ptr
58 {
59 public:
60 // publish our template parameter and variations thereof
61 using element_type = _Tp;
62 using __pointer = add_pointer_t<_Tp>; // exposition-only
63 using __reference = add_lvalue_reference_t<_Tp>; // exposition-only
64
65 // 3.2.2, observer_ptr constructors
66 // default c'tor
67 constexpr observer_ptr() noexcept
68 : __t()
69 { }
70
71 // pointer-accepting c'tors
72 constexpr observer_ptr(nullptr_t) noexcept
73 : __t()
74 { }
75
76 constexpr explicit observer_ptr(__pointer __p) noexcept
77 : __t(__p)
78 { }
79
80 // copying c'tors (in addition to compiler-generated copy c'tor)
81 template <typename _Up,
82 typename = typename enable_if<
83 is_convertible<typename add_pointer<_Up>::type, __pointer
84 >::value
85 >::type>
86 constexpr observer_ptr(observer_ptr<_Up> __p) noexcept
87 : __t(__p.get())
88 {
89 }
90
91 // 3.2.3, observer_ptr observers
92 constexpr __pointer
93 get() const noexcept
94 {
95 return __t;
96 }
97
98 constexpr __reference
99 operator*() const
100 {
101 return *get();
102 }
103
104 constexpr __pointer
105 operator->() const noexcept
106 {
107 return get();
108 }
109
110 constexpr explicit operator bool() const noexcept
111 {
112 return get() != nullptr;
113 }
114
115 // 3.2.4, observer_ptr conversions
116 constexpr explicit operator __pointer() const noexcept
117 {
118 return get();
119 }
120
121 // 3.2.5, observer_ptr modifiers
122 constexpr __pointer
123 release() noexcept
124 {
125 __pointer __tmp = get();
126 reset();
127 return __tmp;
128 }
129
130 constexpr void
131 reset(__pointer __p = nullptr) noexcept
132 {
133 __t = __p;
134 }
135
136 constexpr void
137 swap(observer_ptr& __p) noexcept
138 {
139 std::swap(__t, __p.__t);
140 }
141
142 private:
143 __pointer __t;
144 }; // observer_ptr<>
145
146 template<typename _Tp>
147 void
148 swap(observer_ptr<_Tp>& __p1, observer_ptr<_Tp>& __p2) noexcept
149 {
150 __p1.swap(__p2);
151 }
152
153 template<typename _Tp>
154 observer_ptr<_Tp>
155 make_observer(_Tp* __p) noexcept
156 {
157 return observer_ptr<_Tp>(__p);
158 }
159
160 template<typename _Tp, typename _Up>
161 bool
162 operator==(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
163 {
164 return __p1.get() == __p2.get();
165 }
166
167 template<typename _Tp, typename _Up>
168 bool
169 operator!=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
170 {
171 return !(__p1 == __p2);
172 }
173
174 template<typename _Tp>
175 bool
176 operator==(observer_ptr<_Tp> __p, nullptr_t) noexcept
177 {
178 return !__p;
179 }
180
181 template<typename _Tp>
182 bool
183 operator==(nullptr_t, observer_ptr<_Tp> __p) noexcept
184 {
185 return !__p;
186 }
187
188 template<typename _Tp>
189 bool
190 operator!=(observer_ptr<_Tp> __p, nullptr_t) noexcept
191 {
192 return bool(__p);
193 }
194
195 template<typename _Tp>
196 bool
197 operator!=(nullptr_t, observer_ptr<_Tp> __p) noexcept
198 {
199 return bool(__p);
200 }
201
202 template<typename _Tp, typename _Up>
203 bool
204 operator<(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
205 {
206 return std::less<typename common_type<typename add_pointer<_Tp>::type,
207 typename add_pointer<_Up>::type
208 >::type
209 >{}(__p1.get(), __p2.get());
210 }
211
212 template<typename _Tp, typename _Up>
213 bool
214 operator>(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
215 {
216 return __p2 < __p1;
217 }
218
219 template<typename _Tp, typename _Up>
220 bool
221 operator<=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
222 {
223 return !(__p2 < __p1);
224 }
225
226 template<typename _Tp, typename _Up>
227 bool
228 operator>=(observer_ptr<_Tp> __p1, observer_ptr<_Up> __p2)
229 {
230 return !(__p1 < __p2);
231 }
232} // namespace fundamentals_v2
233} // namespace experimental
234
235template <typename _Tp>
236 struct hash<experimental::observer_ptr<_Tp>>
237 {
238 using result_type = size_t;
239 using argument_type = experimental::observer_ptr<_Tp>;
240
241 size_t
242 operator()(const experimental::observer_ptr<_Tp>& __t) const
243 noexcept(noexcept(hash<typename add_pointer<_Tp>::type> {}(__t.get())))
244 {
245 return hash<typename add_pointer<_Tp>::type> {}(__t.get());
246 }
247 };
248
249
250_GLIBCXX_END_NAMESPACE_VERSION
251} // namespace std
252
253#endif // __cplusplus <= 201103L
254
255#endif // _GLIBCXX_EXPERIMENTAL_MEMORY