close method

@override Future<void> close()

Closes the group, indicating that no more streams will be added.

If there are no streams in the group, stream is closed immediately. Otherwise, stream will close once all streams in the group close.

Returns a Future that completes once stream has actually been closed.

Implementation

@override
Future<void> close() {
  if (_closed) return _controller.done;

  _closed = true;

  if (_subscriptions.isEmpty) {
    _onIdleController?.close();
    _controller.close();
    return _controller.done;
  }

  if (_controller.stream.isBroadcast) {
    // For a broadcast group that's closed, we must listen to streams with
    // null subscriptions to detect when they complete. This ensures the
    // group itself can close once all its streams have closed.
    List<Stream<T>>? streamsToRemove;

    _subscriptions.updateAll((stream, subscription) {
      if (subscription != null) return subscription;

      try {
        return _listenToStream(stream);
      } on Object {
        (streamsToRemove ??= []).add(stream);
        return null;
      }
    });

    streamsToRemove?.forEach(_subscriptions.remove);
  }

  return _controller.done;
}