/**
* 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 io.reactivex.*;
import io.reactivex.disposables.
Disposable;
import io.reactivex.internal.disposables.
DisposableHelper;
import io.reactivex.internal.fuseable.
HasUpstreamMaybeSource;
import java.util.concurrent.atomic.
AtomicReference;
/**
* Subscribes to the other source if the main source is empty.
*
* @param <T> the value type
*/
public final class
MaybeSwitchIfEmptySingle<T> extends
Single<T> implements
HasUpstreamMaybeSource<T> {
final
MaybeSource<T>
source;
final
SingleSource<? extends T>
other;
public
MaybeSwitchIfEmptySingle(
MaybeSource<T>
source,
SingleSource<? extends T>
other) {
this.
source =
source;
this.
other =
other;
}
@
Override
public
MaybeSource<T>
source() {
return
source;
}
@
Override
protected void
subscribeActual(
SingleObserver<? super T>
observer) {
source.
subscribe(new
SwitchIfEmptyMaybeObserver<T>(
observer,
other));
}
static final class
SwitchIfEmptyMaybeObserver<T>
extends
AtomicReference<
Disposable>
implements
MaybeObserver<T>,
Disposable {
private static final long
serialVersionUID = 4603919676453758899L;
final
SingleObserver<? super T>
downstream;
final
SingleSource<? extends T>
other;
SwitchIfEmptyMaybeObserver(
SingleObserver<? super T>
actual,
SingleSource<? extends T>
other) {
this.
downstream =
actual;
this.
other =
other;
}
@
Override
public void
dispose() {
DisposableHelper.
dispose(this);
}
@
Override
public boolean
isDisposed() {
return
DisposableHelper.
isDisposed(
get());
}
@
Override
public void
onSubscribe(
Disposable d) {
if (
DisposableHelper.
setOnce(this,
d)) {
downstream.
onSubscribe(this);
}
}
@
Override
public void
onSuccess(T
value) {
downstream.
onSuccess(
value);
}
@
Override
public void
onError(
Throwable e) {
downstream.
onError(
e);
}
@
Override
public void
onComplete() {
Disposable d =
get();
if (
d !=
DisposableHelper.
DISPOSED) {
if (
compareAndSet(
d, null)) {
other.
subscribe(new
OtherSingleObserver<T>(
downstream, this));
}
}
}
static final class
OtherSingleObserver<T> implements
SingleObserver<T> {
final
SingleObserver<? super T>
downstream;
final
AtomicReference<
Disposable>
parent;
OtherSingleObserver(
SingleObserver<? super T>
actual,
AtomicReference<
Disposable>
parent) {
this.
downstream =
actual;
this.
parent =
parent;
}
@
Override
public void
onSubscribe(
Disposable d) {
DisposableHelper.
setOnce(
parent,
d);
}
@
Override
public void
onSuccess(T
value) {
downstream.
onSuccess(
value);
}
@
Override
public void
onError(
Throwable e) {
downstream.
onError(
e);
}
}
}
}