33 Execution control library [exec]

33.14 Execution scope utilities [exec.scope]

33.14.2 Counting Scopes [exec.counting.scopes]

33.14.2.2 Simple Counting Scope [exec.scope.simple.counting]

33.14.2.2.3 Members [exec.simple.counting.mem]

token get_token() noexcept;

Returns: An object t of type simple_counting_scope::token such that t.scope == this is true.

void close() noexcept;

Effects: If state is

(2.1)
unused, then changes state to unused-and-closed;
(2.2)
open, then changes state to closed;
(2.3)
open-and-joining, then changes state to closed-and-joining;
(2.4)
otherwise, no effects.

Postconditions: Any subsequent call to try-associate() on *this returns false.

sender auto join() noexcept;

Returns: make-sender(scope-join-t(), this).

bool try-associate() noexcept;

Effects: If count is equal to max_associations, then no effects.

Otherwise, if state is

(5.1)
unused, then increments count and changes state to open;
(5.2)
open or open-and-joining, then increments count;
(5.3)
otherwise, no effects.

Returns: true if count was incremented, false otherwise.

void disassociate() noexcept;

Preconditions: count is greater than zero.

Effects: Decrements count.

If count is zero after decrementing and state is open-and-joining or closed-and-joining, changes state to joined and calls complete() on all objects registered with *this.

[Note 1:

Calling complete() on any registered object can cause *this to be destroyed.

— end note]

template<class State>
  bool start-join-sender(State& st) noexcept;

Effects: If state is

(9.1)
unused, unused-and-closed, or joined, then changes state to joined and returns true;
(9.2)
open or open-and-joining, then changes state to open-and-joining, registers st with *this and returns false;
(9.3)
closed or closed-and-joining, then changes state to closed-and-joining, registers st with *this and returns false.