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Implemented LastOrDefault Operator #159

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Merged
benjchristensen merged 1 commit into from
Feb 28, 2013
Merged

Implemented LastOrDefault Operator #159

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12 changes: 12 additions & 0 deletions language-adaptors/rxjava-groovy/src/test/groovy/rx/lang/groovy/ObservableTests.groovy
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Original file line number Diff line number Diff line change
Expand Up @@ -233,6 +233,18 @@ def class ObservableTests {
}
}

@Test
public void testLastOrDefault() {
def val = Observable.toObservable("one", "two").lastOrDefault("default", { x -> x.length() == 3})
assertEquals("two", val)
}

@Test
public void testLastOrDefault2() {
def val = Observable.toObservable("one", "two").lastOrDefault("default", { x -> x.length() > 3})
assertEquals("default", val)
}

def class AsyncObservable implements Func1<Observer<Integer>, Subscription> {

public Subscription call(final Observer<Integer> observer) {
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136 changes: 136 additions & 0 deletions rxjava-core/src/main/java/rx/Observable.java
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Original file line number Diff line number Diff line change
Expand Up @@ -685,6 +685,61 @@ public static <T> Observable<T> last(final Observable<T> that) {
return _create(OperationLast.last(that));
}

/**
* Returns the last element of an observable sequence, or a default value if no value is found.
* @param source the source observable.
* @param defaultValue a default value that would be returned if observable is empty.
* @param <T> the type of source.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public static <T> T lastOrDefault(Observable<T> source, T defaultValue) {
boolean found = false;
T result = null;

for (T value : source.toIterable()) {
found = true;
result = value;
}

if (!found) {
return defaultValue;
}

return result;
}

/**
* Returns the last element of an observable sequence that matches the predicate, or a default value if no value is found.
* @param source the source observable.
* @param defaultValue a default value that would be returned if observable is empty.
* @param predicate a predicate function to evaluate for elements in the sequence.
* @param <T> the type of source.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public static <T> T lastOrDefault(Observable<T> source, T defaultValue, Func1<T, Boolean> predicate) {
return lastOrDefault(source.filter(predicate), defaultValue);
}

/**
* Returns the last element of an observable sequence that matches the predicate, or a default value if no value is found.
* @param source the source observable.
* @param defaultValue a default value that would be returned if observable is empty.
* @param predicate a predicate function to evaluate for elements in the sequence.
* @param <T> the type of source.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public static <T> T lastOrDefault(Observable<T> source, T defaultValue, Object predicate){
@SuppressWarnings("rawtypes")
final FuncN _f = Functions.from(predicate);

return lastOrDefault(source, defaultValue, new Func1<T, Boolean>() {
@Override
public Boolean call(T args) {
return (Boolean) _f.call(args);
}
});
}

/**
* Applies a function of your choosing to every notification emitted by an Observable, and returns
* this transformation as a new Observable sequence.
Expand Down Expand Up @@ -2030,6 +2085,38 @@ public Observable<T> last() {
return last(this);
}

/**
* Returns the last element, or a default value if no value is found.
*
* @param defaultValue a default value that would be returned if observable is empty.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public T lastOrDefault(T defaultValue) {
return lastOrDefault(this, defaultValue);
}

/**
* Returns the last element that matches the predicate, or a default value if no value is found.
*
* @param defaultValue a default value that would be returned if observable is empty.
* @param predicate a predicate function to evaluate for elements in the sequence.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public T lastOrDefault(T defaultValue, Func1<T, Boolean> predicate) {
return lastOrDefault(this, defaultValue, predicate);
}

/**
* Returns the last element that matches the predicate, or a default value if no value is found.
*
* @param defaultValue a default value that would be returned if observable is empty.
* @param predicate a predicate function to evaluate for elements in the sequence.
* @return the last element of an observable sequence that matches the predicate, or a default value if no value is found.
*/
public T lastOrDefault(T defaultValue, Object predicate) {
return lastOrDefault(this, defaultValue, predicate);
}

/**
* Applies a function of your choosing to every item emitted by an Observable, and returns this
* transformation as a new Observable sequence.
Expand Down Expand Up @@ -2743,6 +2830,55 @@ public Subscription call(Observer<String> observer) {

}

@Test
public void testLastOrDefault1() {
Observable<String> observable = toObservable("one", "two", "three");
assertEquals("three", observable.lastOrDefault("default"));
}

@Test
public void testLastOrDefault2() {
Observable<String> observable = toObservable();
assertEquals("default", observable.lastOrDefault("default"));
}

@Test
public void testLastOrDefault() {
Observable<Integer> observable = toObservable(1, 0, -1);
int last = observable.lastOrDefault(-100, new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer args) {
return args >= 0;
}
});
assertEquals(0, last);
}

@Test
public void testLastOrDefaultWrongPredicate() {
Observable<Integer> observable = toObservable(-1, -2, -3);
int last = observable.lastOrDefault(0, new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer args) {
return args >= 0;
}
});
assertEquals(0, last);
}

@Test
public void testLastOrDefaultWithPredicate() {
Observable<Integer> observable = toObservable(1, 0, -1);
int last = observable.lastOrDefault(0, new Func1<Integer, Boolean>() {
@Override
public Boolean call(Integer args) {
return args < 0;
}
});

assertEquals(-1, last);
}

private static class TestException extends RuntimeException {

}
Expand Down