import "dart:isolate";
import "dart:async";

abstract class Worker<I, O> {
  final I input;

  Worker(this.input);

  O doWork();

  void run(SendPort port) {
    new Future.value(doWork()).then((value) {
      port.send(value);
    });
  }

  Future<O> spawn() {
    var receiver = new ReceivePort();
    return Isolate.spawn(doStuff, new WorkerMessage(this, receiver.sendPort)).then((isolate) {
      return receiver.first;
    }).then((value) {
      receiver.close();
      return value;
    });
  }
}

class WorkerMessage {
  final Worker worker;
  final SendPort sendPort;

  WorkerMessage(this.worker, this.sendPort);

  void doWork() {
    worker.run(sendPort);
  }
}

doStuff(WorkerMessage message) {
  message.doWork();
}