/**
* Copyright 2014 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.observables;
import rx.Observable;
import rx.Subscriber;
import rx.functions.Func1;
/**
* An {@link Observable} that has been grouped by key, the value of which can be obtained with
* {@link #getKey()}.
* <p>
* <em>Note:</em> A {@link GroupedObservable} will cache the items it is to emit until such time as it
* is subscribed to. For this reason, in order to avoid memory leaks, you should not simply ignore those
* {@code GroupedObservable}s that do not concern you. Instead, you can signal to them that they may
* discard their buffers by applying an operator like {@link Observable#take}{@code (0)} to them.
*
* @param <K>
* the type of the key
* @param <T>
* the type of the items emitted by the {@code GroupedObservable}
* @see Observable#groupBy(Func1)
* @see <a href="https://github.com/Netflix/RxJava/wiki/Transforming-Observables#groupby-and-groupbyuntil">RxJava Wiki: groupBy() and groupByUntil()</a>
*/
public class GroupedObservable<K, T> extends Observable<T> {
private final K key;
/**
* Converts an {@link Observable} into a {@code GroupedObservable} with a particular key.
*
* @param key
* the key to identify the group of items emitted by this {@code GroupedObservable}
* @param o
* the {@link Observable} to convert
* @return a {@code GroupedObservable} representation of {@code o}, with key {@code key}
*/
public static <K, T> GroupedObservable<K, T> from(K key, final Observable<T> o) {
return new GroupedObservable<K, T>(key, new OnSubscribe<T>() {
@Override
public void call(Subscriber<? super T> s) {
o.unsafeSubscribe(s);
}
});
}
public GroupedObservable(K key, OnSubscribe<T> onSubscribe) {
super(onSubscribe);
this.key = key;
}
/**
* Returns the key that identifies the group of items emited by this {@code GroupedObservable}
*
* @return the key that the items emitted by this {@code GroupedObservable} were grouped by
*/
public K getKey() {
return key;
}
}