33 Concurrency support library [thread]

33.3 Stop tokens [thread.stoptoken]

33.3.4 Class stop_token [stoptoken]

33.3.4.1 General [stoptoken.general]

The class stop_token models the concept stoppable_token.
It shares ownership of its stop state, if any, with its associated stop_source object ([stopsource]) and any stop_token objects to which it compares equal.
namespace std { class stop_token { public: template<class CallbackFn> using callback_type = stop_callback<CallbackFn>; stop_token() noexcept = default; // [stoptoken.mem], member functions void swap(stop_token&) noexcept; bool stop_requested() const noexcept; bool stop_possible() const noexcept; bool operator==(const stop_token& rhs) noexcept = default; private: shared_ptr<unspecified> stop-state; // exposition only }; }
stop-state refers to the stop_token's associated stop state.
A stop_token object is disengaged when stop-state is empty.

33.3.4.2 Member functions [stoptoken.mem]

void swap(stop_token& rhs) noexcept;
Effects: Equivalent to: stop-state.swap(rhs.stop-state);
bool stop_requested() const noexcept;
Returns: true if stop-state refers to a stop state that has received a stop request; otherwise, false.
bool stop_possible() const noexcept;
Returns: false if
  • *this is disengaged, or
  • a stop request was not made and there are no associated stop_source objects;
otherwise, true.