/**
* 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.ArrayDeque;
import java.util.Deque;
import rx.Observable.Operator;
import rx.Subscriber;
/**
* Bypasses a specified number of elements at the end of an observable sequence.
*/
public class OperatorSkipLast<T> implements Operator<T, T> {
private final int count;
public OperatorSkipLast(int count) {
if (count < 0) {
throw new IndexOutOfBoundsException("count could not be negative");
}
this.count = count;
}
@Override
public Subscriber<? super T> call(final Subscriber<? super T> subscriber) {
return new Subscriber<T>(subscriber) {
private final NotificationLite<T> on = NotificationLite.instance();
/**
* Store the last count elements until now.
*/
private final Deque<Object> deque = new ArrayDeque<Object>();
@Override
public void onCompleted() {
subscriber.onCompleted();
}
@Override
public void onError(Throwable e) {
subscriber.onError(e);
}
@Override
public void onNext(T value) {
if (count == 0) {
// If count == 0, we do not need to put value into deque
// and remove it at once. We can emit the value
// directly.
subscriber.onNext(value);
return;
}
if (deque.size() == count) {
subscriber.onNext(on.getValue(deque.removeFirst()));
} else {
request(1);
}
deque.offerLast(on.next(value));
}
};
}
}