{

public:

/// Construct to a cancellation token that can't be cancelled.

cancellation_token() noexcept;

/// Copy another cancellation token.

///

/// New token will refer to the same underlying state.

cancellation_token(const cancellation_token& other) noexcept;

cancellation_token(cancellation_token&& other) noexcept;

~cancellation_token();

cancellation_token& operator=(const cancellation_token& other) noexcept;

cancellation_token& operator=(cancellation_token&& other) noexcept;

void swap(cancellation_token& other) noexcept;

/// Query if it is possible that this operation will be cancelled

/// or not.

///

/// Cancellable operations may be able to take more efficient code-paths

/// if they don't need to handle cancellation requests.

bool can_be_cancelled() const noexcept;

/// Query if some thread has requested cancellation on an associated

/// cancellation_source object.

bool is_cancellation_requested() const noexcept;

/// Throws cppcoro::operation_cancelled exception if cancellation

/// has been requested for the associated operation.

void throw_if_cancellation_requested() const;

private:

friend class cancellation_source;

friend class cancellation_registration;

cancellation_token(detail::cancellation_state* state) noexcept;

detail::cancellation_state* m_state;