asyncExpand<E> method

@override Stream<E> asyncExpand<E>(Stream<E>? convert(SupabaseStreamEvent event))

Transforms each element into a sequence of asynchronous events.

Returns a new stream and for each event of this stream, do the following:

• If the event is an error event or a done event, it is emitted directly by the returned stream.
• Otherwise it is an element. Then the convert function is called with the element as argument to produce a convert-stream for the element.
• If that call throws, the error is emitted on the returned stream.
• If the call returns null, no further action is taken for the elements.
• Otherwise, this stream is paused and convert-stream is listened to. Every data and error event of the convert-stream is emitted on the returned stream in the order it is produced. When the convert-stream ends, this stream is resumed.

The returned stream is a broadcast stream if this stream is.

Implementation

@override
Stream<E> asyncExpand<E>(
    Stream<E>? Function(SupabaseStreamEvent event) convert) {
  //Copied from [Stream.asyncExpand]
  final controller = BehaviorSubject<E>();
  controller.onListen = () {
    StreamSubscription<SupabaseStreamEvent> subscription = listen(null,
        onError: controller.addError, // Avoid Zone error replacement.
        onDone: controller.close);
    subscription.onData((SupabaseStreamEvent event) {
      Stream<E>? newStream;
      try {
        newStream = convert(event);
      } catch (e, s) {
        controller.addError(e, s);
        return;
      }
      if (newStream != null) {
        subscription.pause();
        controller.addStream(newStream).whenComplete(subscription.resume);
      }
    });
    controller.onCancel = subscription.cancel;
    if (!isBroadcast) {
      controller
        ..onPause = subscription.pause
        ..onResume = subscription.resume;
    }
  };
  return controller.stream;
}