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 <__config>
13 #include <__debug>
14 #include <__functional/hash.h>
15 #include <__memory/addressof.h>
16 #include <compare>
17 #include <type_traits>
18 
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 #pragma GCC system_header
21 #endif
22 
23 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CXX20_COROUTINES)
24 
25 _LIBCPP_BEGIN_NAMESPACE_STD
26 
27 // [coroutine.handle]
28 template <class _Promise = void>
29 struct _LIBCPP_TEMPLATE_VIS coroutine_handle;
30 
31 template <>
32 struct _LIBCPP_TEMPLATE_VIS coroutine_handle<void> {
33 public:
34     // [coroutine.handle.con], construct/reset
35     _LIBCPP_HIDE_FROM_ABI
36     constexpr coroutine_handle() noexcept = default;
37 
38     _LIBCPP_HIDE_FROM_ABI
39     constexpr coroutine_handle(nullptr_t) noexcept {}
40 
41     _LIBCPP_HIDE_FROM_ABI
42     coroutine_handle& operator=(nullptr_t) noexcept {
43         __handle_ = nullptr;
44         return *this;
45     }
46 
47     // [coroutine.handle.export.import], export/import
48     _LIBCPP_HIDE_FROM_ABI
49     constexpr void* address() const noexcept { return __handle_; }
50 
51     _LIBCPP_HIDE_FROM_ABI
52     static constexpr coroutine_handle from_address(void* __addr) noexcept {
53         coroutine_handle __tmp;
54         __tmp.__handle_ = __addr;
55         return __tmp;
56     }
57 
58     // [coroutine.handle.observers], observers
59     _LIBCPP_HIDE_FROM_ABI
60     constexpr explicit operator bool() const noexcept {
61         return __handle_ != nullptr;
62     }
63 
64     _LIBCPP_HIDE_FROM_ABI
65     bool done() const {
66         _LIBCPP_ASSERT(__is_suspended(), "done() can be called only on suspended coroutines");
67         return __builtin_coro_done(__handle_);
68     }
69 
70     // [coroutine.handle.resumption], resumption
71     _LIBCPP_HIDE_FROM_ABI
72     void operator()() const { resume(); }
73 
74     _LIBCPP_HIDE_FROM_ABI
75     void resume() const {
76         _LIBCPP_ASSERT(__is_suspended(), "resume() can be called only on suspended coroutines");
77         _LIBCPP_ASSERT(!done(), "resume() has undefined behavior when the coroutine is done");
78         __builtin_coro_resume(__handle_);
79     }
80 
81     _LIBCPP_HIDE_FROM_ABI
82     void destroy() const {
83         _LIBCPP_ASSERT(__is_suspended(), "destroy() can be called only on suspended coroutines");
84         __builtin_coro_destroy(__handle_);
85     }
86 
87 private:
88     bool __is_suspended() const {
89         // FIXME actually implement a check for if the coro is suspended.
90         return __handle_ != nullptr;
91     }
92 
93     void* __handle_ = nullptr;
94 };
95 
96 // [coroutine.handle.compare]
97 inline _LIBCPP_HIDE_FROM_ABI
98 constexpr bool operator==(coroutine_handle<> __x, coroutine_handle<> __y) noexcept {
99     return __x.address() == __y.address();
100 }
101 inline _LIBCPP_HIDE_FROM_ABI
102 constexpr strong_ordering operator<=>(coroutine_handle<> __x, coroutine_handle<> __y) noexcept {
103     return compare_three_way()(__x.address(), __y.address());
104 }
105 
106 template <class _Promise>
107 struct _LIBCPP_TEMPLATE_VIS coroutine_handle {
108 public:
109     // [coroutine.handle.con], construct/reset
110     _LIBCPP_HIDE_FROM_ABI
111     constexpr coroutine_handle() noexcept = default;
112 
113     _LIBCPP_HIDE_FROM_ABI
114     constexpr coroutine_handle(nullptr_t) noexcept {}
115 
116     _LIBCPP_HIDE_FROM_ABI
117     static coroutine_handle from_promise(_Promise& __promise) {
118         using _RawPromise = typename remove_cv<_Promise>::type;
119         coroutine_handle __tmp;
120         __tmp.__handle_ =
121             __builtin_coro_promise(_VSTD::addressof(const_cast<_RawPromise&>(__promise)), alignof(_Promise), true);
122         return __tmp;
123     }
124 
125     _LIBCPP_HIDE_FROM_ABI
126     coroutine_handle& operator=(nullptr_t) noexcept {
127         __handle_ = nullptr;
128         return *this;
129     }
130 
131     // [coroutine.handle.export.import], export/import
132     _LIBCPP_HIDE_FROM_ABI
133     constexpr void* address() const noexcept { return __handle_; }
134 
135     _LIBCPP_HIDE_FROM_ABI
136     static constexpr coroutine_handle from_address(void* __addr) noexcept {
137         coroutine_handle __tmp;
138         __tmp.__handle_ = __addr;
139         return __tmp;
140     }
141 
142     // [coroutine.handle.conv], conversion
143     _LIBCPP_HIDE_FROM_ABI
144     constexpr operator coroutine_handle<>() const noexcept {
145         return coroutine_handle<>::from_address(address());
146     }
147 
148     // [coroutine.handle.observers], observers
149     _LIBCPP_HIDE_FROM_ABI
150     constexpr explicit operator bool() const noexcept {
151         return __handle_ != nullptr;
152     }
153 
154     _LIBCPP_HIDE_FROM_ABI
155     bool done() const {
156         _LIBCPP_ASSERT(__is_suspended(), "done() can be called only on suspended coroutines");
157         return __builtin_coro_done(__handle_);
158     }
159 
160     // [coroutine.handle.resumption], resumption
161     _LIBCPP_HIDE_FROM_ABI
162     void operator()() const { resume(); }
163 
164     _LIBCPP_HIDE_FROM_ABI
165     void resume() const {
166         _LIBCPP_ASSERT(__is_suspended(), "resume() can be called only on suspended coroutines");
167         _LIBCPP_ASSERT(!done(), "resume() has undefined behavior when the coroutine is done");
168         __builtin_coro_resume(__handle_);
169     }
170 
171     _LIBCPP_HIDE_FROM_ABI
172     void destroy() const {
173         _LIBCPP_ASSERT(__is_suspended(), "destroy() can be called only on suspended coroutines");
174         __builtin_coro_destroy(__handle_);
175     }
176 
177     // [coroutine.handle.promise], promise access
178     _LIBCPP_HIDE_FROM_ABI
179     _Promise& promise() const {
180         return *static_cast<_Promise*>(__builtin_coro_promise(this->__handle_, alignof(_Promise), false));
181     }
182 
183 private:
184     bool __is_suspended() const {
185         // FIXME actually implement a check for if the coro is suspended.
186         return __handle_ != nullptr;
187     }
188     void* __handle_ = nullptr;
189 };
190 
191 // [coroutine.handle.hash]
192 template <class _Tp>
193 struct hash<coroutine_handle<_Tp>> {
194     _LIBCPP_HIDE_FROM_ABI
195     size_t operator()(const coroutine_handle<_Tp>& __v) const noexcept { return hash<void*>()(__v.address()); }
196 };
197 
198 _LIBCPP_END_NAMESPACE_STD
199 
200 #endif // __LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CXX20_COROUTINES)
201 
202 #endif // _LIBCPP___COROUTINE_COROUTINE_HANDLE_H
203