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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.rxjava3.internal.jdk8;
import java.util.Iterator;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.Stream;
import org.reactivestreams.Subscriber;
import io.reactivex.rxjava3.annotations.*;
import io.reactivex.rxjava3.core.Flowable;
import io.reactivex.rxjava3.exceptions.Exceptions;
import io.reactivex.rxjava3.internal.subscriptions.*;
import io.reactivex.rxjava3.internal.util.BackpressureHelper;
import io.reactivex.rxjava3.operators.ConditionalSubscriber;
import io.reactivex.rxjava3.operators.QueueSubscription;
import io.reactivex.rxjava3.plugins.RxJavaPlugins;
/**
* Wraps a {@link Stream} and emits its values as a Flowable sequence.
* @param the element type of the Stream
* @since 3.0.0
*/
public final class FlowableFromStream extends Flowable {
final Stream stream;
public FlowableFromStream(Stream stream) {
this.stream = stream;
}
@Override
protected void subscribeActual(Subscriber s) {
subscribeStream(s, stream);
}
/**
* Subscribes to the Stream by picking the normal or conditional stream Subscription implementation.
* @param the element type of the flow
* @param s the subscriber to drive
* @param stream the sequence to consume
*/
public static void subscribeStream(Subscriber s, Stream stream) {
Iterator iterator;
try {
iterator = stream.iterator();
if (!iterator.hasNext()) {
EmptySubscription.complete(s);
closeSafely(stream);
return;
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
EmptySubscription.error(ex, s);
closeSafely(stream);
return;
}
if (s instanceof ConditionalSubscriber) {
s.onSubscribe(new StreamConditionalSubscription<>((ConditionalSubscriber)s, iterator, stream));
} else {
s.onSubscribe(new StreamSubscription<>(s, iterator, stream));
}
}
static void closeSafely(AutoCloseable c) {
try {
c.close();
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
RxJavaPlugins.onError(ex);
}
}
abstract static class AbstractStreamSubscription extends AtomicLong implements QueueSubscription {
private static final long serialVersionUID = -9082954702547571853L;
Iterator iterator;
AutoCloseable closeable;
volatile boolean cancelled;
boolean once;
AbstractStreamSubscription(Iterator iterator, AutoCloseable closeable) {
this.iterator = iterator;
this.closeable = closeable;
}
@Override
public void request(long n) {
if (SubscriptionHelper.validate(n)) {
if (BackpressureHelper.add(this, n) == 0L) {
run(n);
}
}
}
abstract void run(long n);
@Override
public void cancel() {
cancelled = true;
request(1L);
}
@Override
public int requestFusion(int mode) {
if ((mode & SYNC) != 0) {
lazySet(Long.MAX_VALUE);
return SYNC;
}
return NONE;
}
@Override
public boolean offer(@NonNull T value) {
throw new UnsupportedOperationException();
}
@Override
public boolean offer(@NonNull T v1, @NonNull T v2) {
throw new UnsupportedOperationException();
}
@Nullable
@Override
public T poll() {
if (iterator == null) {
return null;
}
if (!once) {
once = true;
} else {
if (!iterator.hasNext()) {
clear();
return null;
}
}
return Objects.requireNonNull(iterator.next(), "The Stream's Iterator.next() returned a null value");
}
@Override
public boolean isEmpty() {
Iterator it = iterator;
if (it != null) {
if (!once || it.hasNext()) {
return false;
}
clear();
}
return true;
}
@Override
public void clear() {
iterator = null;
AutoCloseable c = closeable;
closeable = null;
if (c != null) {
closeSafely(c);
}
}
}
static final class StreamSubscription extends AbstractStreamSubscription {
private static final long serialVersionUID = -9082954702547571853L;
final Subscriber downstream;
StreamSubscription(Subscriber downstream, Iterator iterator, AutoCloseable closeable) {
super(iterator, closeable);
this.downstream = downstream;
}
@Override
public void run(long n) {
long emitted = 0L;
Iterator iterator = this.iterator;
Subscriber downstream = this.downstream;
for (;;) {
if (cancelled) {
clear();
break;
} else {
T next;
try {
next = Objects.requireNonNull(iterator.next(), "The Stream's Iterator returned a null value");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
downstream.onError(ex);
cancelled = true;
continue;
}
downstream.onNext(next);
if (cancelled) {
continue;
}
try {
if (!iterator.hasNext()) {
downstream.onComplete();
cancelled = true;
continue;
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
downstream.onError(ex);
cancelled = true;
continue;
}
if (++emitted != n) {
continue;
}
}
n = get();
if (emitted == n) {
if (compareAndSet(n, 0L)) {
break;
}
n = get();
}
}
}
}
static final class StreamConditionalSubscription extends AbstractStreamSubscription {
private static final long serialVersionUID = -9082954702547571853L;
final ConditionalSubscriber downstream;
StreamConditionalSubscription(ConditionalSubscriber downstream, Iterator iterator, AutoCloseable closeable) {
super(iterator, closeable);
this.downstream = downstream;
}
@Override
public void run(long n) {
long emitted = 0L;
Iterator iterator = this.iterator;
ConditionalSubscriber downstream = this.downstream;
for (;;) {
if (cancelled) {
clear();
break;
} else {
T next;
try {
next = Objects.requireNonNull(iterator.next(), "The Stream's Iterator returned a null value");
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
downstream.onError(ex);
cancelled = true;
continue;
}
if (downstream.tryOnNext(next)) {
emitted++;
}
if (cancelled) {
continue;
}
try {
if (!iterator.hasNext()) {
downstream.onComplete();
cancelled = true;
continue;
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
downstream.onError(ex);
cancelled = true;
continue;
}
if (emitted != n) {
continue;
}
}
n = get();
if (emitted == n) {
if (compareAndSet(n, 0L)) {
break;
}
n = get();
}
}
}
}
}
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