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#include <__functional/hash.h>
53#include <__functional/operations.h>
54#include <__type_traits/add_lvalue_reference.h>
55#include <__type_traits/add_pointer.h>
56#include <__type_traits/common_type.h>
57#include <__type_traits/enable_if.h>
58#include <__type_traits/is_convertible.h>
59#include <cstddef>
60#include <experimental/__config>
61
62#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
63#  pragma GCC system_header
64#endif
65
66#ifdef _LIBCPP_ENABLE_EXPERIMENTAL
67
68_LIBCPP_BEGIN_NAMESPACE_LFTS_V2
69
70#  if _LIBCPP_STD_VER >= 17
71
72template <class _Wp>
73class observer_ptr {
74public:
75  using element_type = _Wp;
76
77  // constructors
78  _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr() noexcept : __ptr_(nullptr) {}
79  _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr(nullptr_t) noexcept : __ptr_(nullptr) {}
80  _LIBCPP_HIDE_FROM_ABI constexpr explicit observer_ptr(element_type* __p) noexcept : __ptr_(__p) {}
81
82  template <class _W2, class = __enable_if_t<is_convertible<_W2*, _Wp*>::value>>
83  _LIBCPP_HIDE_FROM_ABI constexpr observer_ptr(observer_ptr<_W2> __other) noexcept : __ptr_(__other.get()) {}
84
85  // observers
86  _LIBCPP_HIDE_FROM_ABI constexpr element_type* get() const noexcept { return __ptr_; }
87  _LIBCPP_HIDE_FROM_ABI constexpr add_lvalue_reference_t<_Wp> operator*() const { return *__ptr_; }
88  _LIBCPP_HIDE_FROM_ABI constexpr element_type* operator->() const noexcept { return __ptr_; }
89  _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const noexcept { return __ptr_ != nullptr; }
90
91  // conversions
92  _LIBCPP_HIDE_FROM_ABI constexpr explicit operator element_type*() const noexcept { return __ptr_; }
93
94  // modifiers
95  _LIBCPP_HIDE_FROM_ABI constexpr void reset(element_type* __p = nullptr) noexcept { __ptr_ = __p; }
96  _LIBCPP_HIDE_FROM_ABI constexpr void swap(observer_ptr& __other) noexcept {
97    observer_ptr __tmp = __other;
98    __other            = *this;
99    *this              = __tmp;
100  }
101  _LIBCPP_HIDE_FROM_ABI constexpr element_type* release() noexcept {
102    observer_ptr __p;
103    __p.swap(*this);
104    return __p.get();
105  }
106
107private:
108  element_type* __ptr_;
109};
110
111// specializations
112
113template <class _Wp>
114_LIBCPP_HIDE_FROM_ABI constexpr void swap(observer_ptr<_Wp>& __a, observer_ptr<_Wp>& __b) noexcept {
115  __a.swap(__b);
116}
117
118template <class _Wp>
119_LIBCPP_HIDE_FROM_ABI observer_ptr<_Wp> make_observer(_Wp* __ptr) noexcept {
120  return observer_ptr<_Wp>{__ptr};
121}
122
123template <class _W1, class _W2>
124_LIBCPP_HIDE_FROM_ABI bool operator==(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
125  return __a.get() == __b.get();
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 == __b);
131}
132
133template <class _Wp>
134_LIBCPP_HIDE_FROM_ABI bool operator==(observer_ptr<_Wp> __p, nullptr_t) {
135  return !__p;
136}
137
138template <class _Wp>
139_LIBCPP_HIDE_FROM_ABI bool operator==(nullptr_t, observer_ptr<_Wp> __p) {
140  return !__p;
141}
142
143template <class _Wp>
144_LIBCPP_HIDE_FROM_ABI bool operator!=(observer_ptr<_Wp> __p, nullptr_t) {
145  return (bool)__p;
146}
147
148template <class _Wp>
149_LIBCPP_HIDE_FROM_ABI bool operator!=(nullptr_t, observer_ptr<_Wp> __p) {
150  return (bool)__p;
151}
152
153template <class _W1, class _W2>
154_LIBCPP_HIDE_FROM_ABI bool operator<(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
155  return std::less<typename std::common_type<_W1*, _W2*>::type>()(__a.get(), __b.get());
156}
157
158template <class _W1, class _W2>
159_LIBCPP_HIDE_FROM_ABI bool operator>(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
160  return __b < __a;
161}
162
163template <class _W1, class _W2>
164_LIBCPP_HIDE_FROM_ABI bool operator<=(observer_ptr<_W1> __a, observer_ptr<_W2> __b) {
165  return !(__a > __b);
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
173#  endif // _LIBCPP_STD_VER >= 17
174
175_LIBCPP_END_NAMESPACE_LFTS_V2
176
177_LIBCPP_BEGIN_NAMESPACE_STD
178
179// hash
180
181#  if _LIBCPP_STD_VER >= 17
182template <class _Tp>
183struct hash<experimental::observer_ptr<_Tp>> {
184  _LIBCPP_HIDE_FROM_ABI size_t operator()(const experimental::observer_ptr<_Tp>& __ptr) const noexcept {
185    return hash<_Tp*>()(__ptr.get());
186  }
187};
188#  endif // _LIBCPP_STD_VER >= 17
189
190_LIBCPP_END_NAMESPACE_STD
191
192#endif // _LIBCPP_ENABLE_EXPERIMENTAL
193
194#endif /* _LIBCPP_EXPERIMENTAL_MEMORY */
195