1// <coroutine> -*- C++ -*- 2 3// Copyright (C) 2019-2021 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 include/coroutine 26 * This is a Standard C++ Library header. 27 */ 28 29#ifndef _GLIBCXX_COROUTINE 30#define _GLIBCXX_COROUTINE 1 31 32#pragma GCC system_header 33 34// It is very likely that earlier versions would work, but they are untested. 35#if __cplusplus >= 201402L 36 37#include <bits/c++config.h> 38 39/** 40 * @defgroup coroutines Coroutines 41 * 42 * Components for supporting coroutine implementations. 43 */ 44 45#if __cplusplus > 201703L && __cpp_impl_three_way_comparison >= 201907L 46# include <compare> 47# define _COROUTINES_USE_SPACESHIP 1 48#else 49# include <bits/stl_function.h> // for std::less 50# define _COROUTINES_USE_SPACESHIP 0 51#endif 52 53namespace std _GLIBCXX_VISIBILITY (default) 54{ 55_GLIBCXX_BEGIN_NAMESPACE_VERSION 56 57#if __cpp_impl_coroutine 58 59#define __cpp_lib_coroutine 201902L 60 61 inline namespace __n4861 { 62 63 // 17.12.2 coroutine traits 64 /// [coroutine.traits] 65 /// [coroutine.traits.primary] 66 /// If _Result::promise_type is valid and denotes a type then the traits 67 /// have a single publicly accessible member, otherwise they are empty. 68 template <typename _Result, typename = void> 69 struct __coroutine_traits_impl {}; 70 71 template <typename _Result> 72 struct __coroutine_traits_impl<_Result, 73 __void_t<typename _Result::promise_type>> 74 { 75 using promise_type = typename _Result::promise_type; 76 }; 77 78 template <typename _Result, typename...> 79 struct coroutine_traits : __coroutine_traits_impl<_Result> {}; 80 81 // 17.12.3 Class template coroutine_handle 82 /// [coroutine.handle] 83 template <typename _Promise = void> 84 struct coroutine_handle; 85 86 template <> struct 87 coroutine_handle<void> 88 { 89 public: 90 // [coroutine.handle.con], construct/reset 91 constexpr coroutine_handle() noexcept : _M_fr_ptr(0) {} 92 93 constexpr coroutine_handle(std::nullptr_t __h) noexcept 94 : _M_fr_ptr(__h) 95 {} 96 97 coroutine_handle& operator=(std::nullptr_t) noexcept 98 { 99 _M_fr_ptr = nullptr; 100 return *this; 101 } 102 103 public: 104 // [coroutine.handle.export.import], export/import 105 constexpr void* address() const noexcept { return _M_fr_ptr; } 106 107 constexpr static coroutine_handle from_address(void* __a) noexcept 108 { 109 coroutine_handle __self; 110 __self._M_fr_ptr = __a; 111 return __self; 112 } 113 114 public: 115 // [coroutine.handle.observers], observers 116 constexpr explicit operator bool() const noexcept 117 { 118 return bool(_M_fr_ptr); 119 } 120 121 bool done() const noexcept { return __builtin_coro_done(_M_fr_ptr); } 122 123 // [coroutine.handle.resumption], resumption 124 void operator()() const { resume(); } 125 126 void resume() const { __builtin_coro_resume(_M_fr_ptr); } 127 128 void destroy() const { __builtin_coro_destroy(_M_fr_ptr); } 129 130 protected: 131 void* _M_fr_ptr; 132 }; 133 134 // [coroutine.handle.compare], comparison operators 135 136 constexpr bool 137 operator==(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 138 { 139 return __a.address() == __b.address(); 140 } 141 142#if _COROUTINES_USE_SPACESHIP 143 constexpr strong_ordering 144 operator<=>(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 145 { 146 return std::compare_three_way()(__a.address(), __b.address()); 147 } 148#else 149 // These are to enable operation with std=c++14,17. 150 constexpr bool 151 operator!=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 152 { 153 return !(__a == __b); 154 } 155 156 constexpr bool 157 operator<(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 158 { 159 return less<void*>()(__a.address(), __b.address()); 160 } 161 162 constexpr bool 163 operator>(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 164 { 165 return __b < __a; 166 } 167 168 constexpr bool 169 operator<=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 170 { 171 return !(__a > __b); 172 } 173 174 constexpr bool 175 operator>=(coroutine_handle<> __a, coroutine_handle<> __b) noexcept 176 { 177 return !(__a < __b); 178 } 179#endif 180 181 template <typename _Promise> 182 struct coroutine_handle 183 { 184 // [coroutine.handle.con], construct/reset 185 186 constexpr coroutine_handle() noexcept { } 187 188 constexpr coroutine_handle(nullptr_t) noexcept { } 189 190 static coroutine_handle 191 from_promise(_Promise& __p) 192 { 193 coroutine_handle __self; 194 __self._M_fr_ptr 195 = __builtin_coro_promise((char*) &__p, __alignof(_Promise), true); 196 return __self; 197 } 198 199 coroutine_handle& operator=(nullptr_t) noexcept 200 { 201 _M_fr_ptr = nullptr; 202 return *this; 203 } 204 205 // [coroutine.handle.export.import], export/import 206 207 constexpr void* address() const noexcept { return _M_fr_ptr; } 208 209 constexpr static coroutine_handle from_address(void* __a) noexcept 210 { 211 coroutine_handle __self; 212 __self._M_fr_ptr = __a; 213 return __self; 214 } 215 216 // [coroutine.handle.conv], conversion 217 constexpr operator coroutine_handle<>() const noexcept 218 { return coroutine_handle<>::from_address(address()); } 219 220 // [coroutine.handle.observers], observers 221 constexpr explicit operator bool() const noexcept 222 { 223 return bool(_M_fr_ptr); 224 } 225 226 bool done() const noexcept { return __builtin_coro_done(_M_fr_ptr); } 227 228 // [coroutine.handle.resumption], resumption 229 void operator()() const { resume(); } 230 231 void resume() const { __builtin_coro_resume(_M_fr_ptr); } 232 233 void destroy() const { __builtin_coro_destroy(_M_fr_ptr); } 234 235 // [coroutine.handle.promise], promise access 236 _Promise& promise() const 237 { 238 void* __t 239 = __builtin_coro_promise (_M_fr_ptr, __alignof(_Promise), false); 240 return *static_cast<_Promise*>(__t); 241 } 242 243 private: 244 void* _M_fr_ptr = nullptr; 245 }; 246 247 /// [coroutine.noop] 248 struct noop_coroutine_promise 249 { 250 }; 251 252 // 17.12.4.1 Class noop_coroutine_promise 253 /// [coroutine.promise.noop] 254 template <> 255 struct coroutine_handle<noop_coroutine_promise> 256 { 257 // _GLIBCXX_RESOLVE_LIB_DEFECTS 258 // 3460. Unimplementable noop_coroutine_handle guarantees 259 // [coroutine.handle.noop.conv], conversion 260 constexpr operator coroutine_handle<>() const noexcept 261 { return coroutine_handle<>::from_address(address()); } 262 263 // [coroutine.handle.noop.observers], observers 264 constexpr explicit operator bool() const noexcept { return true; } 265 266 constexpr bool done() const noexcept { return false; } 267 268 // [coroutine.handle.noop.resumption], resumption 269 void operator()() const noexcept {} 270 271 void resume() const noexcept {} 272 273 void destroy() const noexcept {} 274 275 // [coroutine.handle.noop.promise], promise access 276 noop_coroutine_promise& promise() const noexcept 277 { return _S_fr.__p; } 278 279 // [coroutine.handle.noop.address], address 280 constexpr void* address() const noexcept { return _M_fr_ptr; } 281 282 private: 283 friend coroutine_handle noop_coroutine() noexcept; 284 285 struct __frame 286 { 287 static void __dummy_resume_destroy() { } 288 289 void (*__r)() = __dummy_resume_destroy; 290 void (*__d)() = __dummy_resume_destroy; 291 struct noop_coroutine_promise __p; 292 }; 293 294 static __frame _S_fr; 295 296 explicit coroutine_handle() noexcept = default; 297 298 void* _M_fr_ptr = &_S_fr; 299 }; 300 301 using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>; 302 303 inline noop_coroutine_handle::__frame 304 noop_coroutine_handle::_S_fr{}; 305 306 inline noop_coroutine_handle noop_coroutine() noexcept 307 { 308 return noop_coroutine_handle(); 309 } 310 311 // 17.12.5 Trivial awaitables 312 /// [coroutine.trivial.awaitables] 313 struct suspend_always 314 { 315 constexpr bool await_ready() const noexcept { return false; } 316 317 constexpr void await_suspend(coroutine_handle<>) const noexcept {} 318 319 constexpr void await_resume() const noexcept {} 320 }; 321 322 struct suspend_never 323 { 324 constexpr bool await_ready() const noexcept { return true; } 325 326 constexpr void await_suspend(coroutine_handle<>) const noexcept {} 327 328 constexpr void await_resume() const noexcept {} 329 }; 330 331 } // namespace __n4861 332 333#else 334#error "the coroutine header requires -fcoroutines" 335#endif 336 337 _GLIBCXX_END_NAMESPACE_VERSION 338} // namespace std 339 340#endif // C++14 (we are allowing use from at least this) 341 342#endif // _GLIBCXX_COROUTINE 343