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toMultimap - prevent post-terminal-emissions (ReactiveX#4270)
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-197
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4 files changed

+362
-197
lines changed

‎src/main/java/rx/Observable.java‎

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -11239,7 +11239,7 @@ public final <K, V> Observable<Map<K, V>> toMap(Func1<? super T, ? extends K> ke
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* @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
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*/
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public final <K> Observable<Map<K, Collection<T>>> toMultimap(Func1<? super T, ? extends K> keySelector) {
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return lift(new OperatorToMultimap<T, K, T>(keySelector, UtilityFunctions.<T>identity()));
11242+
return create(new OnSubscribeToMultimap<T, K, T>(this, keySelector, UtilityFunctions.<T>identity()));
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}
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/**
@@ -11267,7 +11267,7 @@ public final <K> Observable<Map<K, Collection<T>>> toMultimap(Func1<? super T, ?
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* @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
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*/
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public final <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T, ? extends K> keySelector, Func1<? super T, ? extends V> valueSelector) {
11270-
return lift(new OperatorToMultimap<T, K, V>(keySelector, valueSelector));
11270+
return create(new OnSubscribeToMultimap<T, K, V>(this, keySelector, valueSelector));
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}
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/**
@@ -11297,7 +11297,7 @@ public final <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T
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* @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
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*/
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public final <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T, ? extends K> keySelector, Func1<? super T, ? extends V> valueSelector, Func0<? extends Map<K, Collection<V>>> mapFactory) {
11300-
return lift(new OperatorToMultimap<T, K, V>(keySelector, valueSelector, mapFactory));
11300+
return create(new OnSubscribeToMultimap<T, K, V>(this, keySelector, valueSelector, mapFactory));
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}
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/**
@@ -11329,7 +11329,7 @@ public final <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T
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* @see <a href="http://reactivex.io/documentation/operators/to.html">ReactiveX operators documentation: To</a>
1133011330
*/
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public final <K, V> Observable<Map<K, Collection<V>>> toMultimap(Func1<? super T, ? extends K> keySelector, Func1<? super T, ? extends V> valueSelector, Func0<? extends Map<K, Collection<V>>> mapFactory, Func1<? super K, ? extends Collection<V>> collectionFactory) {
11332-
return lift(new OperatorToMultimap<T, K, V>(keySelector, valueSelector, mapFactory, collectionFactory));
11332+
return create(new OnSubscribeToMultimap<T, K, V>(this, keySelector, valueSelector, mapFactory, collectionFactory));
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}
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/**

‎src/main/java/rx/internal/operators/OnSubscribeToMultimap.java‎

Lines changed: 204 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,204 @@
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/**
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* Copyright one 2014 Netflix, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package rx.internal.operators;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.HashMap;
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import java.util.Map;
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import rx.Observable;
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import rx.Observable.OnSubscribe;
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import rx.Subscriber;
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import rx.exceptions.Exceptions;
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import rx.functions.Func0;
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import rx.functions.Func1;
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/**
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* Maps the elements of the source observable into a multimap
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* (Map&lt;K, Collection&lt;V>>) where each
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* key entry has a collection of the source's values.
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*
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* @see <a href="https://github.com/ReactiveX/RxJava/issues/97">Issue #97</a>
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* @param <T> the value type of the input
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* @param <K> the multimap-key type
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* @param <V> the multimap-value type
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*/
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public final class OnSubscribeToMultimap<T, K, V> implements OnSubscribe<Map<K, Collection<V>>>, Func0<Map<K, Collection<V>>> {
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private final Func1<? super T, ? extends K> keySelector;
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private final Func1<? super T, ? extends V> valueSelector;
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private final Func0<? extends Map<K, Collection<V>>> mapFactory;
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private final Func1<? super K, ? extends Collection<V>> collectionFactory;
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private final Observable<T> source;
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/**
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* ToMultimap with key selector, custom value selector,
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* default HashMap factory and default ArrayList collection factory.
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* @param keySelector the function extracting the map-key from the main value
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* @param valueSelector the function extracting the map-value from the main value
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*/
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public OnSubscribeToMultimap(
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Observable<T> source,
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Func1<? super T, ? extends K> keySelector,
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Func1<? super T, ? extends V> valueSelector) {
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this(source, keySelector, valueSelector,
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null,
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DefaultMultimapCollectionFactory.<K, V>instance());
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}
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/**
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* ToMultimap with key selector, custom value selector,
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* custom Map factory and default ArrayList collection factory.
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* @param the observable source
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* @param keySelector the function extracting the map-key from the main value
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* @param valueSelector the function extracting the map-value from the main value
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* @param mapFactory function that returns a Map instance to store keys and values into
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*/
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public OnSubscribeToMultimap(
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Observable<T> source,
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Func1<? super T, ? extends K> keySelector,
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Func1<? super T, ? extends V> valueSelector,
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Func0<? extends Map<K, Collection<V>>> mapFactory) {
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this(source, keySelector, valueSelector,
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mapFactory,
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DefaultMultimapCollectionFactory.<K, V>instance());
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}
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/**
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* ToMultimap with key selector, custom value selector,
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* custom Map factory and custom collection factory.
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* @param source the observable source
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* @param keySelector the function extracting the map-key from the main value
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* @param valueSelector the function extracting the map-value from the main value
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* @param mapFactory function that returns a Map instance to store keys and values into
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* @param collectionFactory function that returns a Collection for a particular key to store values into
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*/
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public OnSubscribeToMultimap(
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Observable<T> source,
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Func1<? super T, ? extends K> keySelector,
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Func1<? super T, ? extends V> valueSelector,
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Func0<? extends Map<K, Collection<V>>> mapFactory,
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Func1<? super K, ? extends Collection<V>> collectionFactory) {
97+
this.source = source;
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this.keySelector = keySelector;
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this.valueSelector = valueSelector;
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if (mapFactory == null) {
101+
this.mapFactory = this;
102+
} else {
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this.mapFactory = mapFactory;
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}
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this.collectionFactory = collectionFactory;
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}
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// default map factory
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@Override
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public Map<K, Collection<V>> call() {
111+
return new HashMap<K, Collection<V>>();
112+
}
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@Override
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public void call(final Subscriber<? super Map<K, Collection<V>>> subscriber) {
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117+
Map<K, Collection<V>> map;
118+
try {
119+
map = mapFactory.call();
120+
} catch (Throwable ex) {
121+
Exceptions.throwIfFatal(ex);
122+
subscriber.onError(ex);
123+
return;
124+
}
125+
new ToMultimapSubscriber<T, K, V>(
126+
subscriber, map, keySelector, valueSelector, collectionFactory)
127+
.subscribeTo(source);
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}
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private static final class ToMultimapSubscriber<T, K, V>
131+
extends DeferredScalarSubscriberSafe<T,Map<K, Collection<V>>> {
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private final Func1<? super T, ? extends K> keySelector;
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private final Func1<? super T, ? extends V> valueSelector;
135+
private final Func1<? super K, ? extends Collection<V>> collectionFactory;
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ToMultimapSubscriber(
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Subscriber<? super Map<K, Collection<V>>> subscriber,
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Map<K, Collection<V>> map,
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Func1<? super T, ? extends K> keySelector, Func1<? super T, ? extends V> valueSelector,
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Func1<? super K, ? extends Collection<V>> collectionFactory) {
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super(subscriber);
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this.value = map;
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this.hasValue = true;
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this.keySelector = keySelector;
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this.valueSelector = valueSelector;
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this.collectionFactory = collectionFactory;
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}
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@Override
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public void onStart() {
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request(Long.MAX_VALUE);
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}
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@Override
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public void onNext(T t) {
157+
if (done){
158+
return;
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}
160+
try {
161+
// any interaction with keySelector, valueSelector, collectionFactory, collection or value
162+
// may fail unexpectedly because their behaviour is customisable by the user. For this
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// reason we wrap their calls in try-catch block.
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K key = keySelector.call(t);
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V v = valueSelector.call(t);
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Collection<V> collection = value.get(key);
168+
if (collection == null) {
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collection = collectionFactory.call(key);
170+
value.put(key, collection);
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}
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collection.add(v);
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} catch (Throwable ex) {
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Exceptions.throwIfFatal(ex);
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unsubscribe();
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onError(ex);
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}
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}
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}
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/**
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* The default collection factory for a key in the multimap returning
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* an ArrayList independent of the key.
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* @param <K> the key type
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* @param <V> the value type
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*/
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private static final class DefaultMultimapCollectionFactory<K, V>
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implements Func1<K, Collection<V>> {
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private static final DefaultMultimapCollectionFactory<Object,Object> INSTANCE = new DefaultMultimapCollectionFactory<Object, Object>();
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@SuppressWarnings("unchecked")
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static <K, V> DefaultMultimapCollectionFactory<K,V> instance() {
195+
return (DefaultMultimapCollectionFactory<K, V>) INSTANCE;
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}
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@Override
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public Collection<V> call(K t1) {
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return new ArrayList<V>();
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}
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}
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}

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