Standard library header <coroutine> (C++20)

 

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Language support <cfloat> <climits> <compare>(C++20) <contracts>(C++26) <coroutine>(C++20) <csetjmp> <csignal> <cstdarg> <cstddef> <cstdint>(C++11) <cstdlib> <exception> <initializer_list>(C++11)    <limits> <new> <source_location>(C++20) <stdfloat>(C++23) <typeinfo> <version>(C++20) Concepts <concepts>(C++20) Diagnostics <cassert> <cerrno> <debugging>(C++26) <stacktrace>(C++23) <stdexcept> <system_error>(C++11) Memory management <memory> <memory_resource>(C++17) <scoped_allocator>(C++11) Metaprogramming <type_traits>(C++11) <ratio>(C++11)

General utilities <any>(C++17) <bitset> <bit>(C++20) <charconv>(C++17) <expected>(C++23) <format>(C++20) <functional> <optional>(C++17) <stdbit.h>(C++26) <tuple>(C++11) <typeindex>(C++11) <utility> <variant>(C++17) Containers <array>(C++11) <deque> <flat_map>(C++23) <flat_set>(C++23) <forward_list>(C++11) <hive>(C++26) <inplace_vector>(C++26)    <list> <map> <mdspan>(C++23) <queue> <set> <span>(C++20) <stack> <unordered_map>(C++11) <unordered_set>(C++11) <vector> Iterators <iterator> Ranges <generator>(C++23) <ranges>(C++20)

Algorithms <algorithm> <numeric> Strings <cctype> <cstring> <cuchar>(C++11) <cwchar> <cwctype> <string_view>(C++17) <string> Text processing <clocale> <codecvt>(C++11/17/26*) <locale> <regex>(C++11) <text_encoding>(C++26)    Numerics <cfenv>(C++11) <cmath> <complex> <linalg>(C++26) <numbers>(C++20) <random>(C++11) <simd>(C++26) <stdckdint.h>(C++26) <valarray> Time <chrono>(C++11) <ctime> C compatibility <ccomplex>(C++11/17/20*) <ciso646>(until C++20) <cstdalign>(C++11/17/20*) <cstdbool>(C++11/17/20*) <ctgmath>(C++11/17/20*)

Input/output <cinttypes>(C++11) <cstdio> <filesystem>(C++17) <fstream> <iomanip> <iosfwd> <iostream> <ios> <istream> <ostream> <print>(C++23) <spanstream>(C++23) <sstream> <streambuf> <strstream>(C++98/26*) <syncstream>(C++20) Concurrency support <atomic>(C++11) <barrier>(C++20) <condition_variable>(C++11) <future>(C++11) <hazard_pointer>(C++26) <latch>(C++20) <mutex>(C++11) <rcu>(C++26) <semaphore>(C++20) <shared_mutex>(C++14) <stdatomic.h>(C++23) <stop_token>(C++20) <thread>(C++11) Execution support <execution>(C++17)

 

This header is part of the language support library.

Includes
<compare> (C++20)	Three-way comparison operator support
Classes
coroutine_traits (C++20)	trait type for discovering coroutine promise types (class template)
coroutine_handle (C++20)	used to refer to a suspended or executing coroutine (class template)
std::hash<std::coroutine_handle> (C++20)	hash support for std::coroutine_handle (class template specialization)
No-op Coroutines
noop_coroutine_promise (C++20)	used for coroutines with no observable effects (class)
noop_coroutine_handle (C++20)	std::coroutine_handle<std::noop_coroutine_promise>, intended to refer to a no-op coroutine (typedef)
Trivial Awaitables
suspend_never (C++20)	indicates that an await-expression should never suspend (class)
suspend_always (C++20)	indicates that an await-expression should always suspend (class)
Functions
operator==operator<=> (C++20)	compares two coroutine_handle objects (function)
No-op Coroutines
noop_coroutine (C++20)	creates a coroutine handle that has no observable effects when resumed or destroyed (function)

Synopsis

#include <compare>   namespace std {// coroutine traitstemplate<class R, class... ArgTypes>struct coroutine_traits;   // coroutine handletemplate<class Promise =void>struct coroutine_handle;   // comparison operatorsconstexprbool operator==(coroutine_handle<> x, coroutine_handle<> y)noexcept;constexpr strong_ordering operator<=>(coroutine_handle<> x, coroutine_handle<> y)noexcept;   // hash supporttemplate<class T>struct hash;template<class P>struct hash<coroutine_handle<P>>;   // no-op coroutinesstruct noop_coroutine_promise;   template<>struct coroutine_handle<noop_coroutine_promise>;using noop_coroutine_handle = coroutine_handle<noop_coroutine_promise>;   noop_coroutine_handle noop_coroutine()noexcept;   // trivial awaitablesstruct suspend_never;struct suspend_always;}

Class template std::coroutine_handle

namespace std {template<>struct coroutine_handle<void>{// construct/resetconstexpr coroutine_handle()noexcept;constexpr coroutine_handle(nullptr_t)noexcept; coroutine_handle& operator=(nullptr_t)noexcept;   // export/importconstexprvoid* address()constnoexcept;staticconstexpr coroutine_handle from_address(void* addr);   // observersconstexprexplicit operator bool()constnoexcept;bool done()const;   // resumptionvoid operator()()const;void resume()const;void destroy()const;   private:void* ptr;// exposition only};   template<class Promise>struct coroutine_handle {// construct/resetconstexpr coroutine_handle()noexcept;constexpr coroutine_handle(nullptr_t)noexcept;static coroutine_handle from_promise(Promise&); coroutine_handle& operator=(nullptr_t)noexcept;   // export/importconstexprvoid* address()constnoexcept;staticconstexpr coroutine_handle from_address(void* addr);   // conversionconstexpr operator coroutine_handle<>()constnoexcept;   // observersconstexprexplicit operator bool()constnoexcept;bool done()const;   // resumptionvoid operator()()const;void resume()const;void destroy()const;   // promise access Promise& promise()const;   private:void* ptr;// exposition only };}

Class std::noop_coroutine_promise

namespace std {struct noop_coroutine_promise {};}

Class std::coroutine_handle<std::noop_coroutine_promise>

namespace std {template<>struct coroutine_handle<noop_coroutine_promise>{// conversionconstexpr operator coroutine_handle<>()constnoexcept;   // observersconstexprexplicit operator bool()constnoexcept;constexprbool done()constnoexcept;   // resumptionconstexprvoid operator()()constnoexcept;constexprvoid resume()constnoexcept;constexprvoid destroy()constnoexcept;   // promise access noop_coroutine_promise& promise()constnoexcept;   // addressconstexprvoid* address()constnoexcept;private: coroutine_handle(/* unspecified */);void* ptr;// exposition only };}

Class std::suspend_never

namespace std {struct suspend_never {constexprbool await_ready()constnoexcept{returntrue;}constexprvoid await_suspend(coroutine_handle<>)constnoexcept{}constexprvoid await_resume()constnoexcept{}};}

Class std::suspend_always

namespace std {struct suspend_always {constexprbool await_ready()constnoexcept{returnfalse;}constexprvoid await_suspend(coroutine_handle<>)constnoexcept{}constexprvoid await_resume()constnoexcept{}};}