/**
* Copyright 2014 Netflix, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package rx.internal.operators;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import rx.Notification;
import rx.Observable;
import rx.Subscriber;
import rx.exceptions.Exceptions;
/**
* Returns an Iterator that iterates over all items emitted by a specified Observable.
* <p>
* <img width="640" src="https://github.com/Netflix/RxJava/wiki/images/rx-operators/B.toIterator.png" alt="">
* <p>
*
* @see <a href="https://github.com/Netflix/RxJava/issues/50">Issue #50</a>
*/
public class BlockingOperatorToIterator {
/**
* Returns an iterator that iterates all values of the observable.
*
* @param <T>
* the type of source.
* @return the iterator that could be used to iterate over the elements of the observable.
*/
public static <T> Iterator<T> toIterator(Observable<? extends T> source) {
final BlockingQueue<Notification<? extends T>> notifications = new LinkedBlockingQueue<Notification<? extends T>>();
// using subscribe instead of unsafeSubscribe since this is a BlockingObservable "final subscribe"
source.materialize().subscribe(new Subscriber<Notification<? extends T>>() {
@Override
public void onCompleted() {
// ignore
}
@Override
public void onError(Throwable e) {
notifications.offer(Notification.<T>createOnError(e));
}
@Override
public void onNext(Notification<? extends T> args) {
notifications.offer(args);
}
});
return new Iterator<T>() {
private Notification<? extends T> buf;
@Override
public boolean hasNext() {
if (buf == null) {
buf = take();
}
if (buf.isOnError()) {
throw Exceptions.propagate(buf.getThrowable());
}
return !buf.isOnCompleted();
}
@Override
public T next() {
if (hasNext()) {
T result = buf.getValue();
buf = null;
return result;
}
throw new NoSuchElementException();
}
private Notification<? extends T> take() {
try {
// TODO remove this timeout and logging before final release of 0.20
Notification<? extends T> n = notifications.poll(10000, TimeUnit.MILLISECONDS);
if(n == null) {
System.err.println("Timed out waiting for value. File a bug at github.com/Netflix/RxJava");
throw new RuntimeException("Timed out waiting for value. File a bug at github.com/Netflix/RxJava");
} else {
return n;
}
} catch (InterruptedException e) {
throw Exceptions.propagate(e);
}
}
@Override
public void remove() {
throw new UnsupportedOperationException("Read-only iterator");
}
};
}
}