/**
* 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.subscriptions;
import java.util.concurrent.
Future;
import rx.
Subscription;
import rx.functions.
Action0;
/**
* Helper methods and utilities for creating and working with {@link Subscription} objects
*/
public final class
Subscriptions {
/**
* A {@link Subscription} that does nothing when its unsubscribe method is called.
*/
private static final
Unsubscribed UNSUBSCRIBED = new
Unsubscribed();
private
Subscriptions() {
throw new
IllegalStateException("No instances!");
}
/**
* Returns a {@link Subscription} to which {@code unsubscribe} does nothing except to change
* {@code isUnsubscribed} to {@code true}. It's stateful and {@code isUnsubscribed} indicates if
* {@code unsubscribe} is called, which is different from {@link #unsubscribed()}.
*
* <pre><code>
* Subscription empty = Subscriptions.empty();
* System.out.println(empty.isUnsubscribed()); // false
* empty.unsubscribe();
* System.out.println(empty.isUnsubscribed()); // true
* </code></pre>
*
* @return a {@link Subscription} to which {@code unsubscribe} does nothing except to change
* {@code isUnsubscribed} to {@code true}
*/
public static
Subscription empty() {
return
BooleanSubscription.
create();
}
/**
* Returns a {@link Subscription} to which {@code unsubscribe} does nothing, as it is already unsubscribed.
* Its {@code isUnsubscribed} always returns {@code true}, which is different from {@link #empty()}.
*
* <pre><code>
* Subscription unsubscribed = Subscriptions.unsubscribed();
* System.out.println(unsubscribed.isUnsubscribed()); // true
* </code></pre>
*
* @return a {@link Subscription} to which {@code unsubscribe} does nothing, as it is already unsubscribed
* @since 1.1.0
*/
public static
Subscription unsubscribed() {
return
UNSUBSCRIBED;
}
/**
* Creates and returns a {@link Subscription} that invokes the given {@link Action0} when unsubscribed.
*
* @param unsubscribe
* Action to invoke on unsubscribe.
* @return {@link Subscription}
*/
public static
Subscription create(final
Action0 unsubscribe) {
return
BooleanSubscription.
create(
unsubscribe);
}
/**
* Converts a {@link Future} into a {@link Subscription} and cancels it when unsubscribed.
*
* @param f
* the {@link Future} to convert
* @return a {@link Subscription} that wraps {@code f}
*/
public static
Subscription from(final
Future<?>
f) {
return new
FutureSubscription(
f);
}
/** Naming classes helps with debugging. */
static final class
FutureSubscription implements
Subscription {
final
Future<?>
f;
public
FutureSubscription(
Future<?>
f) {
this.
f =
f;
}
@
Override
public void
unsubscribe() {
f.
cancel(true);
}
@
Override
public boolean
isUnsubscribed() {
return
f.
isCancelled();
}
}
/**
* Converts a set of {@link Subscription}s into a {@link CompositeSubscription} that groups the multiple
* Subscriptions together and unsubscribes from all of them together.
*
* @param subscriptions
* the Subscriptions to group together
* @return a {@link CompositeSubscription} representing the {@code subscriptions} set
*/
public static
CompositeSubscription from(
Subscription...
subscriptions) {
return new
CompositeSubscription(
subscriptions);
}
/** Naming classes helps with debugging. */
static final class
Unsubscribed implements
Subscription {
@
Override
public void
unsubscribe() {
// deliberately ignored
}
@
Override
public boolean
isUnsubscribed() {
return true;
}
}
}