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/**
* Copyright 2015 David Karnok and 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 hu.akarnokd.rxjava2.subjects;
import org.reactivestreams.*;
import hu.akarnokd.rxjava2.Observable;
/**
* Represents a Subscriber and an Observable (Publisher) at the same time, allowing
* multicasting events from a single source to multiple child Subscribers.
* All methods except the onSubscribe, onNext, onError and onComplete are thread-safe.
* Use {@link #toSerialized()} to make these methods thread-safe as well.
*
* @param the source value type
* @param the emission value type
*/
public abstract class Subject extends Observable implements Processor {
protected Subject(Publisher onSubscribe) {
super(onSubscribe);
}
/**
* Returns true if the subject has subscribers.
* The method is thread-safe.
* @return true if the subject has subscribers
*/
public abstract boolean hasSubscribers();
/**
* Returns true if the subject has reached a terminal state through an error event.
*
The method is thread-safe.
* @return true if the subject has reached a terminal state through an error event
* @see #getThrowable()
* @see #hasComplete()
*/
public boolean hasThrowable() {
throw new UnsupportedOperationException();
}
/**
* Returns true if the subject has reached a terminal state through a complete event.
*
The method is thread-safe.
* @return true if the subject has reached a terminal state through a complete event
* @see #hasThrowable()
*/
public boolean hasComplete() {
throw new UnsupportedOperationException();
}
/**
* Returns true if the subject has any value.
*
The method is thread-safe.
* @return true if the subject has any value
*/
public boolean hasValue() {
throw new UnsupportedOperationException();
}
/**
* Returns the error that caused the Subject to terminate or null if the Subject
* hasn't terminated yet.
*
The method is thread-safe.
* @return the error that caused the Subject to terminate or null if the Subject
* hasn't terminated yet
*/
public Throwable getThrowable() {
throw new UnsupportedOperationException();
}
/**
* Returns a single value the Subject currently has or null if no such value exists.
*
The method is thread-safe.
* @return a single value the Subject currently has or null if no such value exists
*/
public R getValue() {
throw new UnsupportedOperationException();
}
/**
* Wraps this Subject and serializes the calls to the onSubscribe, onNext, onError and
* onComplete methods, making them thread-safe.
*
The method is thread-safe.
* @return the wrapped and serialized subject
*/
public final Subject toSerialized() {
if (this instanceof SerializedSubject) {
return this;
}
return new SerializedSubject(this);
}
/** An empty array to avoid allocation in getValues(). */
private static final Object[] EMPTY = new Object[0];
/**
* Returns an Object array containing snapshot all values of the Subject.
* The method is thread-safe.
* @return the array containing the snapshot of all values of the Subject
*/
public Object[] getValues() {
@SuppressWarnings("unchecked")
R[] a = (R[])EMPTY;
R[] b = getValues(a);
if (b == EMPTY) {
return new Object[0];
}
return b;
}
/**
* Returns a typed array containing a snapshot of all values of the Subject.
*
The method follows the conventions of Collection.toArray by setting the array element
* after the last value to null (if the capacity permits).
*
The method is thread-safe.
* @param array the target array to copy values into if it fits
* @return the given array if the values fit into it or a new array containing all values
*/
public R[] getValues(R[] array) {
throw new UnsupportedOperationException();
}
}