17 Language support library [support]

17.12 Coroutines [support.coroutine]

17.12.4 Class template coroutine_­handle [coroutine.handle]

17.12.4.1 General [coroutine.handle.general]

namespace std { template<> struct coroutine_handle<void> { // [coroutine.handle.con], construct/reset constexpr coroutine_handle() noexcept; constexpr coroutine_handle(nullptr_t) noexcept; coroutine_handle& operator=(nullptr_t) noexcept; // [coroutine.handle.export.import], export/import constexpr void* address() const noexcept; static constexpr coroutine_handle from_address(void* addr); // [coroutine.handle.observers], observers constexpr explicit operator bool() const noexcept; bool done() const; // [coroutine.handle.resumption], resumption void operator()() const; void resume() const; void destroy() const; private: void* ptr; // exposition only }; template<class Promise> struct coroutine_handle : coroutine_handle<> { // [coroutine.handle.con], construct/reset using coroutine_handle<>::coroutine_handle; static coroutine_handle from_promise(Promise&); coroutine_handle& operator=(nullptr_t) noexcept; // [coroutine.handle.export.import], export/import static constexpr coroutine_handle from_address(void* addr); // [coroutine.handle.promise], promise access Promise& promise() const; }; }
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An object of type coroutine_­handle<T> is called a coroutine handle and can be used to refer to a suspended or executing coroutine.
A default-constructed coroutine_­handle object does not refer to any coroutine.
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If a program declares an explicit or partial specialization of coroutine_­handle, the behavior is undefined.