cancellation_slot.hpp

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#ifndef NEFORCE_CORE_ASYNC_CANCELLATION_SLOT_HPP__
#define NEFORCE_CORE_ASYNC_CANCELLATION_SLOT_HPP__

 
#include "NeForce/core/async/stop_token.hpp"
#include "NeForce/core/exception/error_code.hpp"
#include "NeForce/core/functional/function.hpp"
#include "NeForce/core/memory/shared_ptr.hpp"
NEFORCE_BEGIN_NAMESPACE__


inline error_code make_operation_aborted() noexcept {
    return error_code(static_cast<int>(errc::operation_canceled), error_category::system());
}

class cancellation_slot {
private:
    stop_token token_;          
    shared_ptr<void> callback_; 
 
public:
    using cancel_handler = function<void()>;

    cancellation_slot() = default;

    explicit cancellation_slot(stop_token token) :
    token_(move(token)) {}

    NEFORCE_NODISCARD bool is_cancelled() const noexcept { return token_.stop_requested(); }

    template <typename Handler>
    bool assign(Handler&& handler) {
        if (is_cancelled()) {
            forward<Handler>(handler)();
            return false;
        }
        if (!token_.stop_possible()) {
            return false;
        }
        callback_ = make_shared<stop_callback<Handler>>(token_, forward<Handler>(handler));
        return true;
    }

    NEFORCE_NODISCARD const stop_token& get_token() const noexcept { return token_; }

    NEFORCE_NODISCARD bool has_slot() const noexcept { return token_.stop_possible(); }
};
 // Cancellation
 
NEFORCE_END_NAMESPACE__
#endif // NEFORCE_CORE_ASYNC_CANCELLATION_SLOT_HPP__