master
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_EXPERIMENTAL_MEMORY
11#define _LIBCPP_EXPERIMENTAL_MEMORY
12
13/*
14 experimental/memory synopsis
15
16namespace std::experimental::inline fundamentals_v2 {
17
18template <class W> class observer_ptr {
19public:
20 using element_type = W;
21 using pointer = add_pointer_t<W>; // exposition-only
22 using reference = add_lvalue_reference_t<W>; // exposition-only
23
24 // default ctor
25 constexpr observer_ptr() noexcept;
26
27 // pointer-accepting ctors
28 constexpr observer_ptr(nullptr_t) noexcept;
29 constexpr explicit observer_ptr(pointer) noexcept;
30
31 // copying ctors (in addition to compiler-generated copy ctor)
32 template <class W2> constexpr observer_ptr(observer_ptr<W2>) noexcept;
33
34 // observers
35 constexpr pointer get() const noexcept;
36 constexpr reference operator*() const;
37 constexpr pointer operator->() const noexcept;
38 constexpr explicit operator bool() const noexcept;
39
40 // conversions
41 constexpr explicit operator pointer() const noexcept;
42
43 // modifiers
44 constexpr pointer release() noexcept;
45 constexpr void reset(pointer = nullptr) noexcept;
46 constexpr void swap(observer_ptr&) noexcept;
47};
48
49}
50*/
51
52#if __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
53# include <__cxx03/__config>
54#else
55# include <__config>
56# include <__cstddef/nullptr_t.h>
57# include <__cstddef/size_t.h>
58# include <__functional/hash.h>
59# include <__functional/operations.h>
60# include <__type_traits/add_pointer.h>
61# include <__type_traits/add_reference.h>
62# include <__type_traits/common_type.h>
63# include <__type_traits/enable_if.h>
64# include <__type_traits/is_convertible.h>
65# include <version>
66
67# if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
68# pragma GCC system_header
69# endif
70
71# ifdef _LIBCPP_ENABLE_EXPERIMENTAL
72
73_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
74
75# if _LIBCPP_STD_VER >= 17
76
77template <class _Wp>
78class observer_ptr {
79public:
80 using element_type = _Wp;
81
82 // constructors
83 _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr() noexcept : __ptr_(nullptr) {}
84 _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr(nullptr_t) noexcept : __ptr_(nullptr) {}
85 _LIBCPP_HIDE_FROM_ABI constexpr explicit observer_ptr(element_type* __p) noexcept : __ptr_(__p) {}
86
87 template <class _W2, __enable_if_t<is_convertible<_W2*, _Wp*>::value, int> = 0>
88 _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr(observer_ptr<_W2> __other) noexcept : __ptr_(__other.get()) {}
89
90 // observers
91 _LIBCPP_HIDE_FROM_ABI constexpr element_type* get() const noexcept { return __ptr_; }
92 _LIBCPP_HIDE_FROM_ABI constexpr add_lvalue_reference_t<_Wp> operator*() const { return *__ptr_; }
93 _LIBCPP_HIDE_FROM_ABI constexpr element_type* operator->() const noexcept { return __ptr_; }
94 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const noexcept { return __ptr_ != nullptr; }
95
96 // conversions
97 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator element_type*() const noexcept { return __ptr_; }
98
99 // modifiers
100 _LIBCPP_HIDE_FROM_ABI constexpr void reset(element_type* __p = nullptr) noexcept { __ptr_ = __p; }
101 _LIBCPP_HIDE_FROM_ABI constexpr void swap(observer_ptr& __other) noexcept {
102 observer_ptr __tmp = __other;
103 __other = *this;
104 *this = __tmp;
105 }
106 _LIBCPP_HIDE_FROM_ABI constexpr element_type* release() noexcept {
107 observer_ptr __p;
108 __p.swap(*this);
109 return __p.get();
110 }
111
112private:
113 element_type* __ptr_;
114};
115
116// specializations
117
118template <class _Wp>
119_LIBCPP_HIDE_FROM_ABI constexpr void swap(observer_ptr<_Wp>& __a, observer_ptr<_Wp>& __b) noexcept {
120 __a.swap(__b);
121}
122
123template <class _Wp>
124_LIBCPP_HIDE_FROM_ABI observer_ptr<_Wp> make_observer(_Wp* __ptr) noexcept {
125 return observer_ptr<_Wp>{__ptr};
126}
127
128template <class _W1, class _W2>
129_LIBCPP_HIDE_FROM_ABI bool operator==(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
130 return __a.get() == __b.get();
131}
132
133template <class _W1, class _W2>
134_LIBCPP_HIDE_FROM_ABI bool operator!=(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
135 return !(__a == __b);
136}
137
138template <class _Wp>
139_LIBCPP_HIDE_FROM_ABI bool operator==(observer_ptr<_Wp> __p, nullptr_t) {
140 return !__p;
141}
142
143template <class _Wp>
144_LIBCPP_HIDE_FROM_ABI bool operator==(nullptr_t, observer_ptr<_Wp> __p) {
145 return !__p;
146}
147
148template <class _Wp>
149_LIBCPP_HIDE_FROM_ABI bool operator!=(observer_ptr<_Wp> __p, nullptr_t) {
150 return (bool)__p;
151}
152
153template <class _Wp>
154_LIBCPP_HIDE_FROM_ABI bool operator!=(nullptr_t, observer_ptr<_Wp> __p) {
155 return (bool)__p;
156}
157
158template <class _W1, class _W2>
159_LIBCPP_HIDE_FROM_ABI bool operator<(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
160 return std::less<typename std::common_type<_W1*, _W2*>::type>()(__a.get(), __b.get());
161}
162
163template <class _W1, class _W2>
164_LIBCPP_HIDE_FROM_ABI bool operator>(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
165 return __b < __a;
166}
167
168template <class _W1, class _W2>
169_LIBCPP_HIDE_FROM_ABI bool operator<=(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
170 return !(__a > __b);
171}
172
173template <class _W1, class _W2>
174_LIBCPP_HIDE_FROM_ABI bool operator>=(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
175 return !(__a < __b);
176}
177
178# endif // _LIBCPP_STD_VER >= 17
179
180_LIBCPP_END_NAMESPACE_LFTS_V2
181
182_LIBCPP_BEGIN_NAMESPACE_STD
183
184// hash
185
186# if _LIBCPP_STD_VER >= 17
187template <class _Tp>
188struct hash<experimental::observer_ptr<_Tp>> {
189 _LIBCPP_HIDE_FROM_ABI size_t operator()(const experimental::observer_ptr<_Tp>& __ptr) const noexcept {
190 return hash<_Tp*>()(__ptr.get());
191 }
192};
193# endif // _LIBCPP_STD_VER >= 17
194
195_LIBCPP_END_NAMESPACE_STD
196
197# endif // _LIBCPP_ENABLE_EXPERIMENTAL
198
199# if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
200# include <cstddef>
201# include <limits>
202# endif
203#endif // __cplusplus < 201103L && defined(_LIBCPP_USE_FROZEN_CXX03_HEADERS)
204
205#endif /* _LIBCPP_EXPERIMENTAL_MEMORY */