io.reactivex.internal.operators.mixed.ScalarXMapZHelper Maven / Gradle / Ivy
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/**
* 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.mixed;
import java.util.concurrent.Callable;
import io.reactivex.*;
import io.reactivex.exceptions.Exceptions;
import io.reactivex.functions.Function;
import io.reactivex.internal.disposables.EmptyDisposable;
import io.reactivex.internal.functions.ObjectHelper;
import io.reactivex.internal.operators.maybe.MaybeToObservable;
import io.reactivex.internal.operators.single.SingleToObservable;
/**
* Utility class to extract a value from a scalar source reactive type,
* map it to a 0-1 type then subscribe the output type's consumer to it,
* saving on the overhead of the regular subscription channel.
* History: 2.1.11 - experimental
* @since 2.2
*/
final class ScalarXMapZHelper {
private ScalarXMapZHelper() {
throw new IllegalStateException("No instances!");
}
/**
* Try subscribing to a {@link CompletableSource} mapped from
* a scalar source (which implements {@link Callable}).
* @param the upstream value type
* @param source the source reactive type ({@code Flowable} or {@code Observable})
* possibly implementing {@link Callable}.
* @param mapper the function that turns the scalar upstream value into a
* {@link CompletableSource}
* @param observer the consumer to subscribe to the mapped {@link CompletableSource}
* @return true if a subscription did happen and the regular path should be skipped
*/
static boolean tryAsCompletable(Object source,
Function mapper,
CompletableObserver observer) {
if (source instanceof Callable) {
@SuppressWarnings("unchecked")
Callable call = (Callable) source;
CompletableSource cs = null;
try {
T item = call.call();
if (item != null) {
cs = ObjectHelper.requireNonNull(mapper.apply(item), "The mapper returned a null CompletableSource");
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
EmptyDisposable.error(ex, observer);
return true;
}
if (cs == null) {
EmptyDisposable.complete(observer);
} else {
cs.subscribe(observer);
}
return true;
}
return false;
}
/**
* Try subscribing to a {@link MaybeSource} mapped from
* a scalar source (which implements {@link Callable}).
* @param the upstream value type
* @param source the source reactive type ({@code Flowable} or {@code Observable})
* possibly implementing {@link Callable}.
* @param mapper the function that turns the scalar upstream value into a
* {@link MaybeSource}
* @param observer the consumer to subscribe to the mapped {@link MaybeSource}
* @return true if a subscription did happen and the regular path should be skipped
*/
static boolean tryAsMaybe(Object source,
Function> mapper,
Observer observer) {
if (source instanceof Callable) {
@SuppressWarnings("unchecked")
Callable call = (Callable) source;
MaybeSource cs = null;
try {
T item = call.call();
if (item != null) {
cs = ObjectHelper.requireNonNull(mapper.apply(item), "The mapper returned a null MaybeSource");
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
EmptyDisposable.error(ex, observer);
return true;
}
if (cs == null) {
EmptyDisposable.complete(observer);
} else {
cs.subscribe(MaybeToObservable.create(observer));
}
return true;
}
return false;
}
/**
* Try subscribing to a {@link SingleSource} mapped from
* a scalar source (which implements {@link Callable}).
* @param the upstream value type
* @param source the source reactive type ({@code Flowable} or {@code Observable})
* possibly implementing {@link Callable}.
* @param mapper the function that turns the scalar upstream value into a
* {@link SingleSource}
* @param observer the consumer to subscribe to the mapped {@link SingleSource}
* @return true if a subscription did happen and the regular path should be skipped
*/
static boolean tryAsSingle(Object source,
Function> mapper,
Observer observer) {
if (source instanceof Callable) {
@SuppressWarnings("unchecked")
Callable call = (Callable) source;
SingleSource cs = null;
try {
T item = call.call();
if (item != null) {
cs = ObjectHelper.requireNonNull(mapper.apply(item), "The mapper returned a null SingleSource");
}
} catch (Throwable ex) {
Exceptions.throwIfFatal(ex);
EmptyDisposable.error(ex, observer);
return true;
}
if (cs == null) {
EmptyDisposable.complete(observer);
} else {
cs.subscribe(SingleToObservable.create(observer));
}
return true;
}
return false;
}
}