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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.*;
import io.reactivex.rxjava3.core.Observable;
import io.reactivex.rxjava3.core.Observer;
import io.reactivex.rxjava3.functions.Function;
import io.reactivex.rxjava3.internal.observers.BasicFuseableObserver;
/**
* Map the upstream values into an Optional and emit its value if any.
* @param the upstream element type
* @param the output element type
* @since 3.0.0
*/
public final class ObservableMapOptional extends Observable {
final Observable source;
final Function super T, Optional extends R>> mapper;
public ObservableMapOptional(Observable source, Function super T, Optional extends R>> mapper) {
this.source = source;
this.mapper = mapper;
}
@Override
protected void subscribeActual(Observer super R> observer) {
source.subscribe(new MapOptionalObserver<>(observer, mapper));
}
static final class MapOptionalObserver extends BasicFuseableObserver {
final Function super T, Optional extends R>> mapper;
MapOptionalObserver(Observer super R> downstream, Function super T, Optional extends R>> mapper) {
super(downstream);
this.mapper = mapper;
}
@Override
public void onNext(T t) {
if (done) {
return;
}
if (sourceMode != NONE) {
downstream.onNext(null);
return;
}
Optional extends R> result;
try {
result = Objects.requireNonNull(mapper.apply(t), "The mapper returned a null Optional");
} catch (Throwable ex) {
fail(ex);
return;
}
if (result.isPresent()) {
downstream.onNext(result.get());
}
}
@Override
public int requestFusion(int mode) {
return transitiveBoundaryFusion(mode);
}
@Override
public R poll() throws Throwable {
for (;;) {
T item = qd.poll();
if (item == null) {
return null;
}
Optional extends R> result = Objects.requireNonNull(mapper.apply(item), "The mapper returned a null Optional");
if (result.isPresent()) {
return result.get();
}
}
}
}
}
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