cppdraft_translate/cppdraft/task/state.md

[task.state]

33 Execution control library [exec]

33.13 Coroutine utilities [exec.coro.util]

33.13.6 execution​::​task [exec.task]

33.13.6.4 Class template task​::​state [task.state]

namespace std::execution {template<class T, class Environment>template<receiver Rcvr>class task<T, Environment>::state { // exposition onlypublic:using operation_state_concept = operation_state_t; templatestate(coroutine_handle<promise_type> h, R&& rr); ~state(); void start() & noexcept; private:using own-env-t = see below; // exposition only coroutine_handle<promise_type> handle; // exposition only remove_cvref_t rcvr; // exposition only**own-env-t own-env; // exposition only Environment environment; // exposition only};}

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The type own-env-t is Environment​::​template env_type<decltype(get_env(​declval​(​)))​> if thatqualified-id is valid and denotes a type, env<> otherwise.

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template<class R> state(coroutine_handle<promise_type> h, R&& rr);

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Effects: Initializes

• (2.1)

  handle with std​::​move(h);

• (2.2)

  rcvr with std​::​forward(rr);

• (2.3)

  own-env with own-env-t(get_env(rcvr)) if that expression is valid and own-env-t() otherwise. If neither of these expressions is valid, the program is ill-formed.

• (2.4)

  environment withEnvironment(own-env) if that expression is valid, otherwise Environment(​get_env(rcvr)) if this expression is valid, otherwise Environment(). If neither of these expressions is valid, the program is ill-formed.

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~state();

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Effects: Equivalent to:if (handle)handle.destroy();

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void start() & noexcept;

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Effects: Let prom be the object handle.promise().

Associates STATE(prom), RCVR(prom), and SCHED(prom) with *this as follows:

• (4.1)

  STATE(prom) is *this.

• (4.2)

  RCVR(prom) is rcvr.

• (4.3)

  SCHED(prom) is the object initialized with scheduler_type(get_scheduler(get_env(rcvr))) if that expression is valid and scheduler_type() otherwise. If neither of these expressions is valid, the program is ill-formed.

Let st be get_stop_token(get_env(rcvr)).

Initializes prom.token andprom.source such that

• (4.4)

prom.token.stop_requested() returnsst.stop_requested();

• (4.5)

prom.token.stop_possible() returnsst.stop_possible(); and

• (4.6)

for types Fn and Init such that bothinvocable andconstructible_from<Fn, Init> are modeled,stop_token_type​::​callback_type modelsstoppable-callback-for<Fn,​ stop_token_type, Init>.

After that invokes handle.resume().