com.groupbyinc.common.apache.commons.collections4.queue.TransformedQueue Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 org.apache.commons.collections4.queue;
import java.util.Queue;
import org.apache.commons.collections4.Transformer;
import org.apache.commons.collections4.collection.TransformedCollection;
/**
* Decorates another {@link Queue} to transform objects that are added.
*
* The add/offer methods are affected by this class.
* Thus objects must be removed or searched for using their transformed form.
* For example, if the transformation converts Strings to Integers, you must
* use the Integer form to remove objects.
*
* @since 4.0
* @version $Id: TransformedQueue.java 1686855 2015-06-22 13:00:27Z tn $
*/
public class TransformedQueue extends TransformedCollection implements Queue {
/** Serialization version */
private static final long serialVersionUID = -7901091318986132033L;
/**
* Factory method to create a transforming queue.
*
* If there are any elements already in the queue being decorated, they
* are NOT transformed.
* Contrast this with {@link #transformedQueue(Queue, Transformer)}.
*
* @param the type of the elements in the queue
* @param queue the queue to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @return a new transformed Queue
* @throws NullPointerException if queue or transformer is null
*/
public static TransformedQueue transformingQueue(final Queue queue,
final Transformer transformer) {
return new TransformedQueue(queue, transformer);
}
/**
* Factory method to create a transforming queue that will transform
* existing contents of the specified queue.
*
* If there are any elements already in the queue being decorated, they
* will be transformed by this method.
* Contrast this with {@link #transformingQueue(Queue, Transformer)}.
*
* @param the type of the elements in the queue
* @param queue the queue to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @return a new transformed Queue
* @throws NullPointerException if queue or transformer is null
* @since 4.0
*/
public static TransformedQueue transformedQueue(final Queue queue,
final Transformer transformer) {
// throws IAE if queue or transformer is null
final TransformedQueue decorated = new TransformedQueue(queue, transformer);
if (queue.size() > 0) {
@SuppressWarnings("unchecked") // queue is type
final E[] values = (E[]) queue.toArray(); // NOPMD - false positive for generics
queue.clear();
for (final E value : values) {
decorated.decorated().add(transformer.transform(value));
}
}
return decorated;
}
//-----------------------------------------------------------------------
/**
* Constructor that wraps (not copies).
*
* If there are any elements already in the queue being decorated, they
* are NOT transformed.
*
* @param queue the queue to decorate, must not be null
* @param transformer the transformer to use for conversion, must not be null
* @throws NullPointerException if queue or transformer is null
*/
protected TransformedQueue(final Queue queue, final Transformer transformer) {
super(queue, transformer);
}
/**
* Gets the decorated queue.
*
* @return the decorated queue
*/
protected Queue getQueue() {
return (Queue) decorated();
}
//-----------------------------------------------------------------------
public boolean offer(final E obj) {
return getQueue().offer(transform(obj));
}
public E poll() {
return getQueue().poll();
}
public E peek() {
return getQueue().peek();
}
public E element() {
return getQueue().element();
}
public E remove() {
return getQueue().remove();
}
}