3.x: Add Single.mergeArray & mergeArrayDelayError (#6882)

* 3.x: Add Single.mergeArray & mergeArrayDelayError

* Remove unnecessary shortcut

Author: akarnokd

src/main/java/io/reactivex/rxjava3/core/Maybe.java

@@ -1415,7 +1415,7 @@ public static <T> Flowable<T> merge(
     }
 
     /**
-     * Merges an array sequence of {@link MaybeSource} instances into a single {@link Flowable} sequence,
+     * Merges an array of {@link MaybeSource} instances into a single {@link Flowable} sequence,
      * running all {@code MaybeSource}s at once.
      * <p>
      * <img width="640" height="272" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Maybe.mergeArray.png" alt="">
@@ -1470,10 +1470,10 @@ public static <T> Flowable<T> mergeArray(MaybeSource<? extends T>... sources) {
      * <img width="640" height="422" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Maybe.mergeArrayDelayError.png" alt="">
      * <p>
      * This behaves like {@link #merge(Publisher)} except that if any of the merged {@code MaybeSource}s notify of an
-     * error via {@link Subscriber#onError onError}, {@code mergeDelayError} will refrain from propagating that
+     * error via {@link Subscriber#onError onError}, {@code mergeArrayDelayError} will refrain from propagating that
      * error notification until all of the merged {@code MaybeSource}s have finished emitting items.
      * <p>
-     * Even if multiple merged {@code MaybeSource}s send {@code onError} notifications, {@code mergeDelayError} will only
+     * Even if multiple merged {@code MaybeSource}s send {@code onError} notifications, {@code mergeArrayDelayError} will only
      * invoke the {@code onError} method of its subscribers once.
      * <dl>
      *  <dt><b>Backpressure:</b></dt>

src/main/java/io/reactivex/rxjava3/core/Single.java

@@ -17,7 +17,7 @@
 import java.util.concurrent.*;
 import java.util.stream.*;
 
-import org.reactivestreams.Publisher;
+import org.reactivestreams.*;
 
 import io.reactivex.rxjava3.annotations.*;
 import io.reactivex.rxjava3.disposables.Disposable;
@@ -1323,6 +1323,81 @@ public static <T> Flowable<T> merge(
         return merge(Flowable.fromArray(source1, source2, source3, source4));
     }
 
+    /**
+     * Merges an array of {@link SingleSource} instances into a single {@link Flowable} sequence,
+     * running all {@code SingleSource}s at once.
+     * <p>
+     * <img width="640" height="272" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Single.mergeArray.png" alt="">
+     * <dl>
+     *  <dt><b>Backpressure:</b></dt>
+     *  <dd>The operator honors backpressure from downstream.</dd>
+     * <dt><b>Scheduler:</b></dt>
+     * <dd>{@code mergeArray} does not operate by default on a particular {@link Scheduler}.</dd>
+     *  <dt><b>Error handling:</b></dt>
+     *  <dd>If any of the source {@code SingleSource}s signal a {@link Throwable} via {@code onError}, the resulting
+     *  {@code Flowable} terminates with that {@code Throwable} and all other source {@code SingleSource}s are disposed.
+     *  If more than one {@code SingleSource} signals an error, the resulting {@code Flowable} may terminate with the
+     *  first one's error or, depending on the concurrency of the sources, may terminate with a
+     *  {@link CompositeException} containing two or more of the various error signals.
+     *  {@code Throwable}s that didn't make into the composite will be sent (individually) to the global error handler via
+     *  {@link RxJavaPlugins#onError(Throwable)} method as {@link UndeliverableException} errors. Similarly, {@code Throwable}s
+     *  signaled by source(s) after the returned {@code Flowable} has been cancelled or terminated with a
+     *  (composite) error will be sent to the same global error handler.
+     *  Use {@link #mergeArrayDelayError(SingleSource...)} to merge sources and terminate only when all source {@code SingleSource}s
+     *  have completed or failed with an error.
+     *  </dd>
+     * </dl>
+     * @param <T> the common and resulting value type
+     * @param sources the array sequence of {@code SingleSource} sources
+     * @return the new {@code Flowable} instance
+     * @throws NullPointerException if {@code sources} is {@code null}
+     * @see #mergeArrayDelayError(SingleSource...)
+     */
+    @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
+    @NonNull
+    @SchedulerSupport(SchedulerSupport.NONE)
+    @SafeVarargs
+    public static <T> Flowable<T> mergeArray(SingleSource<? extends T>... sources) {
+        return Flowable.fromArray(sources).flatMapSingle(Functions.identity(), false, sources.length);
+    }
+
+    /**
+     * Flattens an array of {@link SingleSource}s into one {@link Flowable}, in a way that allows a subscriber to receive all
+     * successfully emitted items from each of the source {@code SingleSource}s without being interrupted by an error
+     * notification from one of them.
+     * <p>
+     * <img width="640" height="422" src="https://raw.github.com/wiki/ReactiveX/RxJava/images/rx-operators/Single.mergeArrayDelayError.png" alt="">
+     * <p>
+     * This behaves like {@link #merge(Publisher)} except that if any of the merged {@code SingleSource}s notify of an
+     * error via {@link Subscriber#onError onError}, {@code mergeArrayDelayError} will refrain from propagating that
+     * error notification until all of the merged {@code SingleSource}s have finished emitting items.
+     * <p>
+     * Even if multiple merged {@code SingleSource}s send {@code onError} notifications, {@code mergeArrayDelayError} will only
+     * invoke the {@code onError} method of its subscribers once.
+     * <dl>
+     *  <dt><b>Backpressure:</b></dt>
+     *  <dd>The operator honors backpressure from downstream.</dd>
+     *  <dt><b>Scheduler:</b></dt>
+     *  <dd>{@code mergeArrayDelayError} does not operate by default on a particular {@link Scheduler}.</dd>
+     * </dl>
+     *
+     * @param <T> the common element base type
+     * @param sources
+     *            the array of {@code SingleSource}s
+     * @return the new {@code Flowable} instance
+     * @throws NullPointerException if {@code sources} is {@code null}
+     * @see <a href="http://reactivex.io/documentation/operators/merge.html">ReactiveX operators documentation: Merge</a>
+     */
+    @BackpressureSupport(BackpressureKind.FULL)
+    @CheckReturnValue
+    @SchedulerSupport(SchedulerSupport.NONE)
+    @SafeVarargs
+    @NonNull
+    public static <T> Flowable<T> mergeArrayDelayError(@NonNull SingleSource<? extends T>... sources) {
+        return Flowable.fromArray(sources).flatMapSingle(Functions.identity(), true, sources.length);
+    }
+
     /**
      * Merges an {@link Iterable} sequence of {@link SingleSource} instances into one {@link Flowable} sequence,
      * running all {@code SingleSource}s at once and delaying any error(s) until all sources succeed or fail.

src/test/java/io/reactivex/rxjava3/internal/fuseable/CancellableQueueFuseableTest.java

@@ -57,7 +57,7 @@ public void dispose() {
 
     @Test
     public void cancel2() {
-        AbstractEmptyQueueFuseable<Object> qs = new AbstractEmptyQueueFuseable<Object>() {};
+        AbstractEmptyQueueFuseable<Object> qs = new AbstractEmptyQueueFuseable<Object>() { };
 
         assertFalse(qs.isDisposed());
 
@@ -66,7 +66,7 @@ public void cancel2() {
 
     @Test
     public void dispose2() {
-        AbstractEmptyQueueFuseable<Object> qs = new AbstractEmptyQueueFuseable<Object>() {};
+        AbstractEmptyQueueFuseable<Object> qs = new AbstractEmptyQueueFuseable<Object>() { };
 
         assertFalse(qs.isDisposed());
 

src/test/java/io/reactivex/rxjava3/internal/operators/single/SingleMergeArrayTest.java

@@ -0,0 +1,50 @@
+/**
+ * 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.operators.single;
+
+import org.junit.Test;
+
+import io.reactivex.rxjava3.core.*;
+import io.reactivex.rxjava3.exceptions.TestException;
+
+public class SingleMergeArrayTest extends RxJavaTest {
+
+    @Test
+    public void normal() {
+        Single.mergeArray(Single.just(1), Single.just(2), Single.just(3))
+        .test()
+        .assertResult(1, 2, 3);
+    }
+
+    @Test
+    public void error() {
+        Single.mergeArray(Single.just(1), Single.error(new TestException()), Single.just(3))
+        .test()
+        .assertFailure(TestException.class, 1);
+    }
+
+    @Test
+    public void normalDelayError() {
+        Single.mergeArrayDelayError(Single.just(1), Single.just(2), Single.just(3))
+        .test()
+        .assertResult(1, 2, 3);
+    }
+
+    @Test
+    public void errorDelayError() {
+        Single.mergeArrayDelayError(Single.just(1), Single.error(new TestException()), Single.just(3))
+        .test()
+        .assertFailure(TestException.class, 1, 3);
+    }
+}