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- /*
- * Copyright (c) 2006-2012 DMDirc Developers
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- */
-
- package com.dmdirc.util.collections;
-
- import java.util.Iterator;
- import java.util.LinkedHashSet;
- import java.util.NoSuchElementException;
- import java.util.Queue;
-
- /**
- * A LinkedHashSet with a Queue implementation added, also supports readding
- * unique items to the head of the queue.
- *
- * @param <E> the type of elements held in this collection
- */
- public class QueuedLinkedHashSet<E> extends LinkedHashSet<E>
- implements Queue<E> {
-
- /**
- * A version number for this class. It should be changed whenever the class
- * structure is changed (or anything else that would prevent serialized
- * objects being unserialized with the new class).
- */
- private static final long serialVersionUID = 1;
-
- /** {@inheritDoc} */
- @Override
- public boolean offer(final E e) {
- return add(e);
- }
-
- /** {@inheritDoc} */
- @Override
- public E remove() {
- if (isEmpty()) {
- throw new NoSuchElementException("Queue is empty.");
- }
- return poll();
- }
-
- /** {@inheritDoc} */
- @Override
- public E poll() {
- final E object = peek();
- if (object != null) {
- remove(object);
- }
- return object;
- }
-
- /** {@inheritDoc} */
- @Override
- public E element() {
- if (isEmpty()) {
- throw new NoSuchElementException("Queue is empty.");
- }
- return peek();
- }
-
- /** {@inheritDoc} */
- @Override
- public E peek() {
- if (isEmpty()) {
- return null;
- }
- final Iterator<E> iterator = iterator();
- E object = null;
- while (iterator.hasNext()) {
- object = iterator.next();
- }
- return object;
- }
-
- /**
- * Offers an item to this queue, if the item exists in the queue it removes
- * it and re-adds it to the queue.
- *
- * @param e Object to add
- *
- * @return true iif the item was added
- */
- public boolean offerAndMove(final E e) {
- if (contains(e)) {
- remove(e);
- }
- return offer(e);
- }
- }
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