StreamSubscription listen()

in lib/src/stream_completer.dart [120:137]

• 16 lines of code
• 5 McCabe index (conditional complexity)

  StreamSubscription<T> listen(void Function(T)? onData,
      {Function? onError, void Function()? onDone, bool? cancelOnError}) {
    if (_controller == null) {
      var sourceStream = _sourceStream;
      if (sourceStream != null && !sourceStream.isBroadcast) {
        // If the source stream is itself single subscription,
        // just listen to it directly instead of creating a controller.
        return sourceStream.listen(onData,
            onError: onError, onDone: onDone, cancelOnError: cancelOnError);
      }
      _ensureController();
      if (_sourceStream != null) {
        _linkStreamToController();
      }
    }
    return _controller!.stream.listen(onData,
        onError: onError, onDone: onDone, cancelOnError: cancelOnError);
  }