/**
* 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 <T> the source value type
* @param <R> the element type of the Iterable
*/
public final class
MaybeFlatMapIterableFlowable<T, R> extends
Flowable<R> {
final
MaybeSource<T>
source;
final
Function<? super T, ? extends
Iterable<? extends R>>
mapper;
public
MaybeFlatMapIterableFlowable(
MaybeSource<T>
source,
Function<? super T, ? extends
Iterable<? extends R>>
mapper) {
this.
source =
source;
this.
mapper =
mapper;
}
@
Override
protected void
subscribeActual(
Subscriber<? super R>
s) {
source.
subscribe(new
FlatMapIterableObserver<T, R>(
s,
mapper));
}
static final class
FlatMapIterableObserver<T, R>
extends
BasicIntQueueSubscription<R>
implements
MaybeObserver<T> {
private static final long
serialVersionUID = -8938804753851907758L;
final
Subscriber<? super R>
downstream;
final
Function<? super T, ? extends
Iterable<? extends R>>
mapper;
final
AtomicLong requested;
Disposable upstream;
volatile
Iterator<? extends R>
it;
volatile boolean
cancelled;
boolean
outputFused;
FlatMapIterableObserver(
Subscriber<? super R>
actual,
Function<? super T, ? extends
Iterable<? extends R>>
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<? extends R>
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<? super R>
a,
Iterator<? extends R>
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<? super R>
a =
downstream;
Iterator<? extends R>
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<? extends R>
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;
}
}
}