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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 java.util.HashMap;
import java.util.Map;
import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import rx.Observable;
import rx.Observer;
import rx.Subscription;
import rx.util.functions.Func1;
public final class OperationMap {
/**
* Accepts a sequence and a transformation function. Returns a sequence that is the result of
* applying the transformation function to each item in the sequence.
*
* @param sequence
* the input sequence.
* @param func
* a function to apply to each item in the sequence.
* @param <T>
* the type of the input sequence.
* @param <R>
* the type of the output sequence.
* @return a sequence that is the result of applying the transformation function to each item in the input sequence.
*/
public static <T, R> Func1<Observer<R>, Subscription> map(Observable<T> sequence, Func1<T, R> func) {
return new MapObservable<T, R>(sequence, func);
}
/**
* Accepts a sequence of observable sequences and a transformation function. Returns a flattened sequence that is the result of
* applying the transformation function to each item in the sequence of each observable sequence.
* <p>
* The closure should return an Observable which will then be merged.
*
* @param sequence
* the input sequence.
* @param func
* a function to apply to each item in the sequence.
* @param <T>
* the type of the input sequence.
* @param <R>
* the type of the output sequence.
* @return a sequence that is the result of applying the transformation function to each item in the input sequence.
*/
public static <T, R> Func1<Observer<R>, Subscription> mapMany(Observable<T> sequence, Func1<T, Observable<R>> func) {
return OperationMerge.merge(Observable.create(map(sequence, func)));
}
/**
* An observable sequence that is the result of applying a transformation to each item in an input sequence.
*
* @param <T>
* the type of the input sequence.
* @param <R>
* the type of the output sequence.
*/
private static class MapObservable<T, R> implements Func1<Observer<R>, Subscription> {
public MapObservable(Observable<T> sequence, Func1<T, R> func) {
this.sequence = sequence;
this.func = func;
}
private Observable<T> sequence;
private Func1<T, R> func;
public Subscription call(Observer<R> observer) {
return sequence.subscribe(new MapObserver<T, R>(observer, func));
}
}
/**
* An observer that applies a transformation function to each item and forwards the result to an inner observer.
*
* @param <T>
* the type of the observer items.
* @param <R>
* the type of the inner observer items.
*/
private static class MapObserver<T, R> implements Observer<T> {
public MapObserver(Observer<R> observer, Func1<T, R> func) {
this.observer = observer;
this.func = func;
}
Observer<R> observer;
Func1<T, R> func;
public void onNext(T value) {
try {
observer.onNext(func.call(value));
} catch (Exception ex) {
observer.onError(ex);
}
}
public void onError(Exception ex) {
observer.onError(ex);
}
public void onCompleted() {
observer.onCompleted();
}
}
public static class UnitTest {
@Mock
Observer<String> stringObserver;
@Before
public void before() {
MockitoAnnotations.initMocks(this);
}
@Test
public void testMap() {
Map<String, String> m1 = getMap("One");
Map<String, String> m2 = getMap("Two");
@SuppressWarnings("unchecked")
Observable<Map<String, String>> observable = Observable.toObservable(m1, m2);
Observable<String> m = Observable.create(map(observable, new Func1<Map<String, String>, String>() {
@Override
public String call(Map<String, String> map) {
return map.get("firstName");
}
}));
m.subscribe(stringObserver);
verify(stringObserver, never()).onError(any(Exception.class));
verify(stringObserver, times(1)).onNext("OneFirst");
verify(stringObserver, times(1)).onNext("TwoFirst");
verify(stringObserver, times(1)).onCompleted();
}
@Test
public void testMapMany() {
/* simulate a top-level async call which returns IDs */
Observable<Integer> ids = Observable.toObservable(1, 2);
/* now simulate the behavior to take those IDs and perform nested async calls based on them */
Observable<String> m = Observable.create(mapMany(ids, new Func1<Integer, Observable<String>>() {
@SuppressWarnings("unchecked")
@Override
public Observable<String> call(Integer id) {
/* simulate making a nested async call which creates another Observable */
Observable<Map<String, String>> subObservable = null;
if (id == 1) {
Map<String, String> m1 = getMap("One");
Map<String, String> m2 = getMap("Two");
subObservable = Observable.toObservable(m1, m2);
} else {
Map<String, String> m3 = getMap("Three");
Map<String, String> m4 = getMap("Four");
subObservable = Observable.toObservable(m3, m4);
}
/* simulate kicking off the async call and performing a select on it to transform the data */
return Observable.create(map(subObservable, new Func1<Map<String, String>, String>() {
@Override
public String call(Map<String, String> map) {
return map.get("firstName");
}
}));
}
}));
m.subscribe(stringObserver);
verify(stringObserver, never()).onError(any(Exception.class));
verify(stringObserver, times(1)).onNext("OneFirst");
verify(stringObserver, times(1)).onNext("TwoFirst");
verify(stringObserver, times(1)).onNext("ThreeFirst");
verify(stringObserver, times(1)).onNext("FourFirst");
verify(stringObserver, times(1)).onCompleted();
}
@Test
public void testMapMany2() {
Map<String, String> m1 = getMap("One");
Map<String, String> m2 = getMap("Two");
@SuppressWarnings("unchecked")
Observable<Map<String, String>> observable1 = Observable.toObservable(m1, m2);
Map<String, String> m3 = getMap("Three");
Map<String, String> m4 = getMap("Four");
@SuppressWarnings("unchecked")
Observable<Map<String, String>> observable2 = Observable.toObservable(m3, m4);
@SuppressWarnings("unchecked")
Observable<Observable<Map<String, String>>> observable = Observable.toObservable(observable1, observable2);
Observable<String> m = Observable.create(mapMany(observable, new Func1<Observable<Map<String, String>>, Observable<String>>() {
@Override
public Observable<String> call(Observable<Map<String, String>> o) {
return Observable.create(map(o, new Func1<Map<String, String>, String>() {
@Override
public String call(Map<String, String> map) {
return map.get("firstName");
}
}));
}
}));
m.subscribe(stringObserver);
verify(stringObserver, never()).onError(any(Exception.class));
verify(stringObserver, times(1)).onNext("OneFirst");
verify(stringObserver, times(1)).onNext("TwoFirst");
verify(stringObserver, times(1)).onNext("ThreeFirst");
verify(stringObserver, times(1)).onNext("FourFirst");
verify(stringObserver, times(1)).onCompleted();
}
private Map<String, String> getMap(String prefix) {
Map<String, String> m = new HashMap<String, String>();
m.put("firstName", prefix + "First");
m.put("lastName", prefix + "Last");
return m;
}
}
}