Add the cast operator to Single. (#5332)

* Add the cast operator to Single.

Signed-off-by: Mike Burns <[email protected]>

* Create a separate operator for Single.cast and test it.

Signed-off-by: Inferno23 <[email protected]>

* Update spacing and javadoc.

Signed-off-by: Inferno23 <[email protected]>

* Add missing @experimental annotation.

Signed-off-by: Inferno23 <[email protected]>

* Fix the copyrights.

Signed-off-by: Inferno23 <[email protected]>

* Remove extra verify call.

Signed-off-by: Inferno23 <[email protected]>

Author: inferno23

src/main/java/rx/Single.java

@@ -210,6 +210,23 @@ private static <T> Observable<T> asObservable(Single<T> t) {
      * *********************************************************************************************************
      */
 
+    /**
+     * Casts the success value of the current Single into the target type or signals a
+     * ClassCastException if not compatible.
+     * <dl>
+     * <dt><b>Scheduler:</b></dt>
+     * <dd>{@code cast} does not operate by default on a particular {@link Scheduler}.</dd>
+     * </dl>
+     * @param <R> the target type
+     * @param klass the type token to use for casting the success result from the current Single
+     * @return the new Single instance
+     * @since 1.3.1 - experimental
+     */
+    @Experimental
+    public final <R> Single<R> cast(final Class<R> klass) {
+        return map(new SingleOperatorCast<T, R>(klass));
+    }
+
     /**
      * Returns an Observable that emits the items emitted by two Singles, one after the other.
      * <p>

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

@@ -0,0 +1,37 @@
+/**
+ * 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.internal.operators;
+
+import rx.functions.Func1;
+
+/**
+ * Converts the element of a Single to the specified type.
+ * @param <T> the input value type
+ * @param <R> the output value type
+ */
+public class SingleOperatorCast<T, R> implements Func1<T, R> {
+
+    final Class<R> castClass;
+
+    public SingleOperatorCast(Class<R> castClass) {
+        this.castClass = castClass;
+    }
+
+    @Override
+    public R call(T t) {
+        return castClass.cast(t);
+    }
+}

src/test/java/rx/internal/operators/SingleOperatorCastTest.java

@@ -0,0 +1,51 @@
+/**
+ * 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.internal.operators;
+;
+import org.junit.Test;
+import rx.Observer;
+import rx.Single;
+
+import static org.mockito.Mockito.*;
+
+public class SingleOperatorCastTest {
+
+    @Test
+    public void testSingleCast() {
+        Single<?> source = Single.just(1);
+        Single<Integer> single = source.cast(Integer.class);
+
+        @SuppressWarnings("unchecked")
+        Observer<Integer> observer = mock(Observer.class);
+        single.subscribe(observer);
+        verify(observer, times(1)).onNext(1);
+        verify(observer, never()).onError(
+            org.mockito.Matchers.any(Throwable.class));
+        verify(observer, times(1)).onCompleted();
+    }
+
+    @Test
+    public void testSingleCastWithWrongType() {
+        Single<?> source = Single.just(1);
+        Single<Boolean> single = source.cast(Boolean.class);
+
+        @SuppressWarnings("unchecked")
+        Observer<Boolean> observer = mock(Observer.class);
+        single.subscribe(observer);
+        verify(observer, times(1)).onError(
+            org.mockito.Matchers.any(ClassCastException.class));
+    }
+}