/**
* 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 rx.Observable.Operator;
import rx.Subscriber;
import rx.functions.Func1;
/**
* Returns an Observable that emits all sequentially distinct items emitted by the source.
* @param <T> the value type
* @param <U> the key type
*/
public final class OperatorDistinctUntilChanged<T, U> implements Operator<T, T> {
final Func1<? super T, ? extends U> keySelector;
public OperatorDistinctUntilChanged(Func1<? super T, ? extends U> keySelector) {
this.keySelector = keySelector;
}
@Override
public Subscriber<? super T> call(final Subscriber<? super T> child) {
return new Subscriber<T>(child) {
U previousKey;
boolean hasPrevious;
@Override
public void onNext(T t) {
U currentKey = previousKey;
U key = keySelector.call(t);
previousKey = key;
if (hasPrevious) {
if (!(currentKey == key || (key != null && key.equals(currentKey)))) {
child.onNext(t);
} else {
request(1);
}
} else {
hasPrevious = true;
child.onNext(t);
}
}
@Override
public void onError(Throwable e) {
child.onError(e);
}
@Override
public void onCompleted() {
child.onCompleted();
}
};
}
}