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Reactive Extensions for Java
/**
* Copyright (c) 2016-present, RxJava Contributors.
*
* 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 io.reactivex.internal.operators.maybe;
import java.util.Iterator;
import java.util.concurrent.atomic.AtomicLong;
import io.reactivex.annotations.Nullable;
import org.reactivestreams.Subscriber;
import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.subscriptions.*;
import io.reactivex.internal.util.BackpressureHelper;
/**
* Maps a success value into an Iterable and streams it back as a Flowable.
*
* @param the source value type
* @param the element type of the Iterable
*/
public final class MaybeFlatMapIterableFlowable extends Flowable {
final MaybeSource source;
final Function> mapper;
public MaybeFlatMapIterableFlowable(MaybeSource source,
Function> mapper) {
this.source = source;
this.mapper = mapper;
}
@Override
protected void subscribeActual(Subscriber s) {
source.subscribe(new FlatMapIterableObserver(s, mapper));
}
static final class FlatMapIterableObserver
extends BasicIntQueueSubscription
implements MaybeObserver {
private static final long serialVersionUID = -8938804753851907758L;
final Subscriber downstream;
final Function> mapper;
final AtomicLong requested;
Disposable upstream;
volatile Iterator it;
volatile boolean cancelled;
boolean outputFused;
FlatMapIterableObserver(Subscriber actual,
Function> mapper) {
this.downstream = actual;
this.mapper = mapper;
this.requested = new AtomicLong();
}
@Override
public void onSubscribe(Disposable d) {
if (DisposableHelper.validate(this.upstream, d)) {
this.upstream = d;
downstream.onSubscribe(this);
}
}
@Override
public void onSuccess(T value) {
Iterator iterator;
boolean has;
try {
iterator = mapper.apply(value).iterator();
has = iterator.hasNext();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
downstream.onError(ex);
return;
}
if (!has) {
downstream.onComplete();
return;
}
this.it = iterator;
drain();
}
@Override
public void onError(Throwable e) {
upstream = DisposableHelper.DISPOSED;
downstream.onError(e);
}
@Override
public void onComplete() {
downstream.onComplete();
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
BackpressureHelper.add(requested, n);
drain();
}
}
@Override
public void cancel() {
cancelled = true;
upstream.dispose();
upstream = DisposableHelper.DISPOSED;
}
void fastPath(Subscriber a, Iterator iterator) {
for (;;) {
if (cancelled) {
return;
}
R v;
try {
v = iterator.next();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
a.onError(ex);
return;
}
a.onNext(v);
if (cancelled) {
return;
}
boolean b;
try {
b = iterator.hasNext();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
a.onError(ex);
return;
}
if (!b) {
a.onComplete();
return;
}
}
}
void drain() {
if (getAndIncrement() != 0) {
return;
}
Subscriber a = downstream;
Iterator iterator = this.it;
if (outputFused && iterator != null) {
a.onNext(null);
a.onComplete();
return;
}
int missed = 1;
for (;;) {
if (iterator != null) {
long r = requested.get();
if (r == Long.MAX_VALUE) {
fastPath(a, iterator);
return;
}
long e = 0L;
while (e != r) {
if (cancelled) {
return;
}
R v;
try {
v = ObjectHelper.requireNonNull(iterator.next(), "The iterator returned a null value");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
a.onError(ex);
return;
}
a.onNext(v);
if (cancelled) {
return;
}
e++;
boolean b;
try {
b = iterator.hasNext();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
a.onError(ex);
return;
}
if (!b) {
a.onComplete();
return;
}
}
if (e != 0L) {
BackpressureHelper.produced(requested, e);
}
}
missed = addAndGet(-missed);
if (missed == 0) {
break;
}
if (iterator == null) {
iterator = it;
}
}
}
@Override
public int requestFusion(int mode) {
if ((mode & ASYNC) != 0) {
outputFused = true;
return ASYNC;
}
return NONE;
}
@Override
public void clear() {
it = null;
}
@Override
public boolean isEmpty() {
return it == null;
}
@Nullable
@Override
public R poll() throws Exception {
Iterator iterator = it;
if (iterator != null) {
R v = ObjectHelper.requireNonNull(iterator.next(), "The iterator returned a null value");
if (!iterator.hasNext()) {
it = null;
}
return v;
}
return null;
}
}
}