VirtualChannel virtualChannel()

in lib/src/multi_channel.dart [173:215]

• 30 lines of code
• 6 McCabe index (conditional complexity)

  VirtualChannel<T> virtualChannel([int? id]) {
    int inputId;
    int outputId;
    if (id != null) {
      // Since the user is passing in an id, we're connected to a remote
      // VirtualChannel. This means messages they send over this channel will
      // have the original odd id, but our replies will have an even id.
      inputId = id;
      outputId = id + 1;
    } else {
      // Since we're generating an id, we originated this VirtualChannel. This
      // means messages we send over this channel will have the original odd id,
      // but the remote channel's replies will have an even id.
      inputId = _nextId + 1;
      outputId = _nextId;
      _nextId += 2;
    }

    // If the inner channel has already closed, create new virtual channels in a
    // closed state.
    if (_inner == null) {
      return VirtualChannel._(this, inputId, Stream.empty(), NullStreamSink());
    }

    late StreamChannelController<T> controller;
    if (_pendingIds.remove(inputId)) {
      // If we've already received messages for this channel, use the controller
      // where those messages are buffered.
      controller = _controllers[inputId]!;
    } else if (_controllers.containsKey(inputId) ||
        _closedIds.contains(inputId)) {
      throw ArgumentError('A virtual channel with id $id already exists.');
    } else {
      controller = StreamChannelController(sync: true);
      _controllers[inputId] = controller;
    }

    controller.local.stream.listen(
        (message) => _inner!.sink.add(<Object?>[outputId, message]),
        onDone: () => _closeChannel(inputId, outputId));
    return VirtualChannel._(
        this, outputId, controller.foreign.stream, controller.foreign.sink);
  }