Future? add()

in lib/src/stream_group.dart [140:157]

• 13 lines of code
• 4 McCabe index (conditional complexity)

  Future<void>? add(Stream<T> stream) {
    if (_closed) {
      throw StateError("Can't add a Stream to a closed StreamGroup.");
    }

    if (_state == _StreamGroupState.dormant) {
      _subscriptions.putIfAbsent(stream, () => null);
    } else if (_state == _StreamGroupState.canceled) {
      // Listen to the stream and cancel it immediately so that no one else can
      // listen, for consistency. If the stream has an onCancel listener this
      // will also fire that, which may help it clean up resources.
      return stream.listen(null).cancel();
    } else {
      _subscriptions.putIfAbsent(stream, () => _listenToStream(stream));
    }

    return null;
  }