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Merge branch 'first-firstDefault' of git://github.com/jmhofer/RxJava …
…into operator-first-merge Conflicts: rxjava-core/src/test/java/rx/ObservableTests.java This merges pull request ReactiveX#357 Also aliased first with takeFirst to match takeLast.
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rxjava-core/src/main/java/rx/operators/OperationFirstOrDefault.java
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| /** | ||
| * Copyright 2013 Netflix, Inc. | ||
| * | ||
| * 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 rx.operators; | ||
|
|
||
| import static org.mockito.Matchers.*; | ||
| import static org.mockito.Mockito.*; | ||
| import static org.mockito.MockitoAnnotations.initMocks; | ||
| import static rx.Observable.create; | ||
| import static rx.Observable.empty; | ||
| import static rx.Observable.from; | ||
| import static rx.util.functions.Functions.alwaysTrue; | ||
|
|
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| import java.util.concurrent.atomic.AtomicBoolean; | ||
|
|
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| import org.junit.Before; | ||
| import org.junit.Test; | ||
| import org.mockito.Mock; | ||
|
|
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| import rx.Observable; | ||
| import rx.Observable.OnSubscribeFunc; | ||
| import rx.Observer; | ||
| import rx.Subscription; | ||
| import rx.subscriptions.Subscriptions; | ||
| import rx.util.functions.Action0; | ||
| import rx.util.functions.Func1; | ||
|
|
||
| /** | ||
| * Returns an Observable that emits the first item emitted by the source | ||
| * Observable, or a default value if the source emits nothing. | ||
| */ | ||
| public final class OperationFirstOrDefault { | ||
|
|
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| /** | ||
| * Returns an Observable that emits the first item emitted by the source | ||
| * Observable that satisfies the given condition, | ||
| * or a default value if the source emits no items that satisfy the given condition. | ||
| * | ||
| * @param source | ||
| * The source Observable to emit the first item for. | ||
| * @param predicate | ||
| * The condition the emitted source items have to satisfy. | ||
| * @param defaultValue | ||
| * The default value to use whenever the source Observable doesn't emit anything. | ||
| * @return A subscription function for creating the target Observable. | ||
| */ | ||
| public static <T> OnSubscribeFunc<T> firstOrDefault(Observable<? extends T> source, Func1<? super T, Boolean> predicate, T defaultValue) { | ||
| return new FirstOrElse<T>(source, predicate, defaultValue); | ||
| } | ||
|
|
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| /** | ||
| * Returns an Observable that emits the first item emitted by the source | ||
| * Observable, or a default value if the source emits nothing. | ||
| * | ||
| * @param source | ||
| * The source Observable to emit the first item for. | ||
| * @param defaultValue | ||
| * The default value to use whenever the source Observable doesn't emit anything. | ||
| * @return A subscription function for creating the target Observable. | ||
| */ | ||
| public static <T> OnSubscribeFunc<T> firstOrDefault(Observable<? extends T> source, T defaultValue) { | ||
| return new FirstOrElse<T>(source, alwaysTrue(), defaultValue); | ||
| } | ||
|
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| private static class FirstOrElse<T> implements OnSubscribeFunc<T> { | ||
| private final Observable<? extends T> source; | ||
| private final Func1<? super T, Boolean> predicate; | ||
| private final T defaultValue; | ||
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| private FirstOrElse(Observable<? extends T> source, Func1<? super T, Boolean> predicate, T defaultValue) { | ||
| this.source = source; | ||
| this.defaultValue = defaultValue; | ||
| this.predicate = predicate; | ||
| } | ||
|
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| @Override | ||
| public Subscription onSubscribe(final Observer<? super T> observer) { | ||
| final Subscription sourceSub = source.subscribe(new Observer<T>() { | ||
| private final AtomicBoolean hasEmitted = new AtomicBoolean(false); | ||
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| @Override | ||
| public void onCompleted() { | ||
| if (!hasEmitted.get()) { | ||
| observer.onNext(defaultValue); | ||
| observer.onCompleted(); | ||
| } | ||
| } | ||
|
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| @Override | ||
| public void onError(Throwable e) { | ||
| observer.onError(e); | ||
| } | ||
|
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| @Override | ||
| public void onNext(T next) { | ||
| try { | ||
| if (!hasEmitted.get() && predicate.call(next)) { | ||
| hasEmitted.set(true); | ||
| observer.onNext(next); | ||
| observer.onCompleted(); | ||
| } | ||
| } catch (Throwable t) { | ||
| // may happen within the predicate call (user code) | ||
| observer.onError(t); | ||
| } | ||
| } | ||
| }); | ||
|
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| return Subscriptions.create(new Action0() { | ||
| @Override | ||
| public void call() { | ||
| sourceSub.unsubscribe(); | ||
| } | ||
| }); | ||
| } | ||
| } | ||
|
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| public static class UnitTest { | ||
| @Mock | ||
| Observer<? super String> w; | ||
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| private static final Func1<String, Boolean> IS_D = new Func1<String, Boolean>() { | ||
| @Override | ||
| public Boolean call(String value) { | ||
| return "d".equals(value); | ||
| } | ||
| }; | ||
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| @Before | ||
| public void before() { | ||
| initMocks(this); | ||
| } | ||
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| @Test | ||
| public void testFirstOrElseOfNone() { | ||
| Observable<String> src = empty(); | ||
| create(firstOrDefault(src, "default")).subscribe(w); | ||
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| verify(w, times(1)).onNext(anyString()); | ||
| verify(w, times(1)).onNext("default"); | ||
| verify(w, never()).onError(any(Throwable.class)); | ||
| verify(w, times(1)).onCompleted(); | ||
| } | ||
|
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| @Test | ||
| public void testFirstOrElseOfSome() { | ||
| Observable<String> src = from("a", "b", "c"); | ||
| create(firstOrDefault(src, "default")).subscribe(w); | ||
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| verify(w, times(1)).onNext(anyString()); | ||
| verify(w, times(1)).onNext("a"); | ||
| verify(w, never()).onError(any(Throwable.class)); | ||
| verify(w, times(1)).onCompleted(); | ||
| } | ||
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| @Test | ||
| public void testFirstOrElseWithPredicateOfNoneMatchingThePredicate() { | ||
| Observable<String> src = from("a", "b", "c"); | ||
| create(firstOrDefault(src, IS_D, "default")).subscribe(w); | ||
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| verify(w, times(1)).onNext(anyString()); | ||
| verify(w, times(1)).onNext("default"); | ||
| verify(w, never()).onError(any(Throwable.class)); | ||
| verify(w, times(1)).onCompleted(); | ||
| } | ||
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| @Test | ||
| public void testFirstOrElseWithPredicateOfSome() { | ||
| Observable<String> src = from("a", "b", "c", "d", "e", "f"); | ||
| create(firstOrDefault(src, IS_D, "default")).subscribe(w); | ||
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| verify(w, times(1)).onNext(anyString()); | ||
| verify(w, times(1)).onNext("d"); | ||
| verify(w, never()).onError(any(Throwable.class)); | ||
| verify(w, times(1)).onCompleted(); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,40 @@ | ||
| /** | ||
| * Copyright 2013 Netflix, Inc. | ||
| * | ||
| * 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 rx.util.functions; | ||
|
|
||
| /** | ||
| * Implements the negation of a predicate. | ||
| * | ||
| * @param <T> The type of the single input parameter. | ||
| */ | ||
| public class Not<T> implements Func1<T, Boolean> { | ||
| private final Func1<? super T, Boolean> predicate; | ||
|
|
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| /** | ||
| * Constructs a predicate that returns true for each input that the source | ||
| * predicate returns false for and vice versa. | ||
| * | ||
| * @param predicate The source predicate to negate. | ||
| */ | ||
| public Not(Func1<? super T, Boolean> predicate) { | ||
| this.predicate = predicate; | ||
| } | ||
|
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| @Override | ||
| public Boolean call(T param) { | ||
| return !predicate.call(param); | ||
| } | ||
| } |
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