/**
* 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.observable;
import io.reactivex.*;
import io.reactivex.disposables.
Disposable;
import io.reactivex.internal.disposables.
DisposableHelper;
import io.reactivex.plugins.
RxJavaPlugins;
import java.util.
NoSuchElementException;
public final class
ObservableSingleSingle<T> extends
Single<T> {
final
ObservableSource<? extends T>
source;
final T
defaultValue;
public
ObservableSingleSingle(
ObservableSource<? extends T>
source, T
defaultValue) {
this.
source =
source;
this.
defaultValue =
defaultValue;
}
@
Override
public void
subscribeActual(
SingleObserver<? super T>
t) {
source.
subscribe(new
SingleElementObserver<T>(
t,
defaultValue));
}
static final class
SingleElementObserver<T> implements
Observer<T>,
Disposable {
final
SingleObserver<? super T>
downstream;
final T
defaultValue;
Disposable upstream;
T
value;
boolean
done;
SingleElementObserver(
SingleObserver<? super T>
actual, T
defaultValue) {
this.
downstream =
actual;
this.
defaultValue =
defaultValue;
}
@
Override
public void
onSubscribe(
Disposable d) {
if (
DisposableHelper.
validate(this.
upstream,
d)) {
this.
upstream =
d;
downstream.
onSubscribe(this);
}
}
@
Override
public void
dispose() {
upstream.
dispose();
}
@
Override
public boolean
isDisposed() {
return
upstream.
isDisposed();
}
@
Override
public void
onNext(T
t) {
if (
done) {
return;
}
if (
value != null) {
done = true;
upstream.
dispose();
downstream.
onError(new
IllegalArgumentException("Sequence contains more than one element!"));
return;
}
value =
t;
}
@
Override
public void
onError(
Throwable t) {
if (
done) {
RxJavaPlugins.
onError(
t);
return;
}
done = true;
downstream.
onError(
t);
}
@
Override
public void
onComplete() {
if (
done) {
return;
}
done = true;
T
v =
value;
value = null;
if (
v == null) {
v =
defaultValue;
}
if (
v != null) {
downstream.
onSuccess(
v);
} else {
downstream.
onError(new
NoSuchElementException());
}
}
}
}