/*
* Copyright (c) 2011-2017 Pivotal Software Inc, All Rights Reserved.
*
* 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 reactor.core.publisher;
import java.util.Objects;
import java.util.function.Function;
import org.reactivestreams.Subscriber;
import org.reactivestreams.Subscription;
import reactor.core.Fuseable.ConditionalSubscriber;
/**
* Filters out subsequent and repeated elements.
*
* @param <T> the value type
* @param <K> the key type used for comparing subsequent elements
* @see <a href="https://github.com/reactor/reactive-streams-commons">Reactive-Streams-Commons</a>
*/
final class FluxDistinctUntilChanged<T, K> extends FluxSource<T, T> {
final Function<? super T, K> keyExtractor;
FluxDistinctUntilChanged(Flux<? extends T> source, Function<? super T, K> keyExtractor) {
super(source);
this.keyExtractor = Objects.requireNonNull(keyExtractor, "keyExtractor");
}
@Override
@SuppressWarnings("unchecked")
public void subscribe(Subscriber<? super T> s) {
if (s instanceof ConditionalSubscriber) {
source.subscribe(new DistinctUntilChangedConditionalSubscriber<>((ConditionalSubscriber<? super T>) s,
keyExtractor));
}
else {
source.subscribe(new DistinctUntilChangedSubscriber<>(s, keyExtractor));
}
}
static final class DistinctUntilChangedSubscriber<T, K>
implements ConditionalSubscriber<T>, InnerOperator<T, T> {
final Subscriber<? super T> actual;
final Function<? super T, K> keyExtractor;
Subscription s;
boolean done;
K lastKey;
DistinctUntilChangedSubscriber(Subscriber<? super T> actual,
Function<? super T, K> keyExtractor) {
this.actual = actual;
this.keyExtractor = keyExtractor;
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
if (!tryOnNext(t)) {
s.request(1);
}
}
@Override
public boolean tryOnNext(T t) {
if (done) {
Operators.onNextDropped(t);
return true;
}
K k;
try {
k = Objects.requireNonNull(keyExtractor.apply(t),
"The distinct extractor returned a null value.");
}
catch (Throwable e) {
onError(Operators.onOperatorError(s, e, t));
return true;
}
if (Objects.equals(lastKey, k)) {
lastKey = k;
return false;
}
lastKey = k;
actual.onNext(t);
return true;
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t);
return;
}
done = true;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
actual.onComplete();
}
@Override
public Object scan(Attr key) {
switch (key) {
case PARENT:
return s;
case TERMINATED:
return done;
}
return InnerOperator.super.scan(key);
}
@Override
public Subscriber<? super T> actual() {
return actual;
}
@Override
public void request(long n) {
s.request(n);
}
@Override
public void cancel() {
s.cancel();
}
}
static final class DistinctUntilChangedConditionalSubscriber<T, K>
implements ConditionalSubscriber<T>, InnerOperator<T, T> {
final ConditionalSubscriber<? super T> actual;
final Function<? super T, K> keyExtractor;
Subscription s;
boolean done;
K lastKey;
DistinctUntilChangedConditionalSubscriber(ConditionalSubscriber<? super T> actual,
Function<? super T, K> keyExtractor) {
this.actual = actual;
this.keyExtractor = keyExtractor;
}
@Override
public void onSubscribe(Subscription s) {
if (Operators.validate(this.s, s)) {
this.s = s;
actual.onSubscribe(this);
}
}
@Override
public void onNext(T t) {
if (!tryOnNext(t)) {
s.request(1);
}
}
@Override
public boolean tryOnNext(T t) {
if (done) {
Operators.onNextDropped(t);
return true;
}
K k;
try {
k = Objects.requireNonNull(keyExtractor.apply(t),
"The distinct extractor returned a null value.");
}
catch (Throwable e) {
onError(Operators.onOperatorError(s, e, t));
return true;
}
if (Objects.equals(lastKey, k)) {
lastKey = k;
return false;
}
lastKey = k;
return actual.tryOnNext(t);
}
@Override
public void onError(Throwable t) {
if (done) {
Operators.onErrorDropped(t);
return;
}
done = true;
actual.onError(t);
}
@Override
public void onComplete() {
if (done) {
return;
}
done = true;
actual.onComplete();
}
@Override
public Object scan(Attr key) {
switch (key) {
case PARENT:
return s;
case TERMINATED:
return done;
}
return InnerOperator.super.scan(key);
}
@Override
public Subscriber<? super T> actual() {
return actual;
}
@Override
public void request(long n) {
s.request(n);
}
@Override
public void cancel() {
s.cancel();
}
}
}