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1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___COROUTINE_COROUTINE_HANDLE_H
10#define _LIBCPP___COROUTINE_COROUTINE_HANDLE_H
11
12#include <__assert>
13#include <__config>
14#include <__cstddef/nullptr_t.h>
15#include <__cstddef/size_t.h>
16#include <__functional/hash.h>
17#include <__memory/addressof.h>
18#include <__type_traits/remove_cv.h>
19#include <compare>
20
21#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
22# pragma GCC system_header
23#endif
24
25#if _LIBCPP_STD_VER >= 20
26
27_LIBCPP_BEGIN_NAMESPACE_STD
28
29// [coroutine.handle]
30template <class _Promise = void>
31struct coroutine_handle;
32
33template <>
34struct coroutine_handle<void> {
35public:
36 // [coroutine.handle.con], construct/reset
37 constexpr coroutine_handle() noexcept = default;
38
39 _LIBCPP_HIDE_FROM_ABI constexpr coroutine_handle(nullptr_t) noexcept {}
40
41 _LIBCPP_HIDE_FROM_ABI coroutine_handle& operator=(nullptr_t) noexcept {
42 __handle_ = nullptr;
43 return *this;
44 }
45
46 // [coroutine.handle.export.import], export/import
47 _LIBCPP_HIDE_FROM_ABI constexpr void* address() const noexcept { return __handle_; }
48
49 _LIBCPP_HIDE_FROM_ABI static constexpr coroutine_handle from_address(void* __addr) noexcept {
50 coroutine_handle __tmp;
51 __tmp.__handle_ = __addr;
52 return __tmp;
53 }
54
55 // [coroutine.handle.observers], observers
56 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const noexcept { return __handle_ != nullptr; }
57
58 _LIBCPP_HIDE_FROM_ABI bool done() const {
59 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "done() can be called only on suspended coroutines");
60 return __builtin_coro_done(__handle_);
61 }
62
63 // [coroutine.handle.resumption], resumption
64 _LIBCPP_HIDE_FROM_ABI void operator()() const { resume(); }
65
66 _LIBCPP_HIDE_FROM_ABI void resume() const {
67 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "resume() can be called only on suspended coroutines");
68 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(!done(), "resume() has undefined behavior when the coroutine is done");
69 __builtin_coro_resume(__handle_);
70 }
71
72 _LIBCPP_HIDE_FROM_ABI void destroy() const {
73 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "destroy() can be called only on suspended coroutines");
74 __builtin_coro_destroy(__handle_);
75 }
76
77private:
78 _LIBCPP_HIDE_FROM_ABI bool __is_suspended() const {
79 // FIXME actually implement a check for if the coro is suspended.
80 return __handle_ != nullptr;
81 }
82
83 void* __handle_ = nullptr;
84};
85
86// [coroutine.handle.compare]
87inline _LIBCPP_HIDE_FROM_ABI constexpr bool operator==(coroutine_handle<> __x, coroutine_handle<> __y) noexcept {
88 return __x.address() == __y.address();
89}
90inline _LIBCPP_HIDE_FROM_ABI constexpr strong_ordering
91operator<=>(coroutine_handle<> __x, coroutine_handle<> __y) noexcept {
92 return compare_three_way()(__x.address(), __y.address());
93}
94
95template <class _Promise>
96struct coroutine_handle {
97public:
98 // [coroutine.handle.con], construct/reset
99 constexpr coroutine_handle() noexcept = default;
100
101 _LIBCPP_HIDE_FROM_ABI constexpr coroutine_handle(nullptr_t) noexcept {}
102
103 _LIBCPP_HIDE_FROM_ABI static coroutine_handle from_promise(_Promise& __promise) {
104 using _RawPromise = __remove_cv_t<_Promise>;
105 coroutine_handle __tmp;
106 __tmp.__handle_ =
107 __builtin_coro_promise(std::addressof(const_cast<_RawPromise&>(__promise)), alignof(_Promise), true);
108 return __tmp;
109 }
110
111 _LIBCPP_HIDE_FROM_ABI coroutine_handle& operator=(nullptr_t) noexcept {
112 __handle_ = nullptr;
113 return *this;
114 }
115
116 // [coroutine.handle.export.import], export/import
117 _LIBCPP_HIDE_FROM_ABI constexpr void* address() const noexcept { return __handle_; }
118
119 _LIBCPP_HIDE_FROM_ABI static constexpr coroutine_handle from_address(void* __addr) noexcept {
120 coroutine_handle __tmp;
121 __tmp.__handle_ = __addr;
122 return __tmp;
123 }
124
125 // [coroutine.handle.conv], conversion
126 _LIBCPP_HIDE_FROM_ABI constexpr operator coroutine_handle<>() const noexcept {
127 return coroutine_handle<>::from_address(address());
128 }
129
130 // [coroutine.handle.observers], observers
131 _LIBCPP_HIDE_FROM_ABI constexpr explicit operator bool() const noexcept { return __handle_ != nullptr; }
132
133 _LIBCPP_HIDE_FROM_ABI bool done() const {
134 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "done() can be called only on suspended coroutines");
135 return __builtin_coro_done(__handle_);
136 }
137
138 // [coroutine.handle.resumption], resumption
139 _LIBCPP_HIDE_FROM_ABI void operator()() const { resume(); }
140
141 _LIBCPP_HIDE_FROM_ABI void resume() const {
142 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "resume() can be called only on suspended coroutines");
143 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(!done(), "resume() has undefined behavior when the coroutine is done");
144 __builtin_coro_resume(__handle_);
145 }
146
147 _LIBCPP_HIDE_FROM_ABI void destroy() const {
148 _LIBCPP_ASSERT_VALID_EXTERNAL_API_CALL(__is_suspended(), "destroy() can be called only on suspended coroutines");
149 __builtin_coro_destroy(__handle_);
150 }
151
152 // [coroutine.handle.promise], promise access
153 _LIBCPP_HIDE_FROM_ABI _Promise& promise() const {
154 return *static_cast<_Promise*>(__builtin_coro_promise(this->__handle_, alignof(_Promise), false));
155 }
156
157private:
158 _LIBCPP_HIDE_FROM_ABI bool __is_suspended() const {
159 // FIXME actually implement a check for if the coro is suspended.
160 return __handle_ != nullptr;
161 }
162 void* __handle_ = nullptr;
163};
164
165// [coroutine.handle.hash]
166template <class _Tp>
167struct hash<coroutine_handle<_Tp>> {
168 _LIBCPP_HIDE_FROM_ABI size_t operator()(const coroutine_handle<_Tp>& __v) const noexcept {
169 return hash<void*>()(__v.address());
170 }
171};
172
173_LIBCPP_END_NAMESPACE_STD
174
175#endif // _LIBCPP_STD_VER >= 20
176
177#endif // _LIBCPP___COROUTINE_COROUTINE_HANDLE_H