Class Continuation

future-java/src/main/java/io/trane/future/Promise.java:866–898

}

abstract class Continuation<T, R> extends Promise<R> implements WaitQueue<T> {

  @Override
  public final WaitQueue<T> add(final Continuation<T, ?> c) {
    return new WaitQueueHeadTail<>(c, this);
  }

  @Override
  public final void forward(final Promise<T> target) {
    target.continuation(this);
  }

  @SuppressWarnings("unchecked")
  @Override
  public final void flush(final Future<T> result) {
    Future<Object> r = (Future<Object>) result;
    WaitQueue<Object> q = (Continuation<Object, Object>) this;
    while (q instanceof Continuation) {
      final Continuation<Object, Object> c = (Continuation<Object, Object>) q;
      r = c.apply(r);
      q = c.safeFlush(r);
    }
    if (q != null)
      q.flush(r);
  }

  abstract Future<R> apply(Future<T> result);

  @Override
  protected String toStringPrefix() {
    return "Continuation";
  }
}

final class LinkedContinuation<T, R> {