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/*
* 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 io.microsphere.collection;
import io.microsphere.util.BaseUtils;
import java.io.Serializable;
import java.util.Collection;
import java.util.Deque;
import java.util.Iterator;
import java.util.Queue;
import java.util.Spliterator;
import java.util.function.Consumer;
import java.util.function.Predicate;
import java.util.stream.Stream;
import static io.microsphere.collection.CollectionUtils.singletonIterator;
import static io.microsphere.collection.CollectionUtils.unmodifiableIterator;
import static java.util.Collections.emptyIterator;
/**
* The utilities class for Java {@link Queue}
*
* @author Mercy
* @see Queue
* @since 1.0.0
*/
public abstract class QueueUtils extends BaseUtils {
private static final Deque EMPTY_DEQUE = new EmptyDeque();
public static boolean isQueue(Iterable values) {
return values instanceof Queue;
}
public static boolean isDeque(Iterable values) {
return values instanceof Deque;
}
public static Queue emptyQueue() {
return (Queue) EMPTY_DEQUE;
}
public static Deque emptyDeque() {
return (Deque) EMPTY_DEQUE;
}
public static Queue unmodifiableQueue(Queue queue) {
return new UnmodifiableQueue(queue);
}
public static Queue singletonQueue(E element) {
return new SingletonDeque<>(element);
}
public static Deque singletonDeque(E element) {
return new SingletonDeque<>(element);
}
static class EmptyDeque extends AbstractDeque implements Serializable {
private static final long serialVersionUID = -1L;
@Override
public Iterator iterator() {
return emptyIterator();
}
@Override
public Iterator descendingIterator() {
return emptyIterator();
}
@Override
public boolean offerFirst(E e) {
throw new UnsupportedOperationException();
}
@Override
public boolean offerLast(E e) {
throw new UnsupportedOperationException();
}
@Override
public E pollFirst() {
throw new UnsupportedOperationException();
}
@Override
public E pollLast() {
throw new UnsupportedOperationException();
}
@Override
public E getFirst() {
throw new UnsupportedOperationException();
}
@Override
public E getLast() {
throw new UnsupportedOperationException();
}
@Override
public boolean removeLastOccurrence(Object o) {
return false;
}
@Override
public int size() {
return 0;
}
}
static class UnmodifiableQueue implements Queue, Serializable {
private static final long serialVersionUID = -1L;
private final Queue delegate;
UnmodifiableQueue(Queue queue) {
this.delegate = queue;
}
@Override
public int size() {
return delegate.size();
}
@Override
public boolean isEmpty() {
return delegate.isEmpty();
}
@Override
public boolean contains(Object o) {
return delegate.contains(o);
}
@Override
public Iterator iterator() {
return unmodifiableIterator(delegate.iterator());
}
@Override
public Object[] toArray() {
return delegate.toArray();
}
@Override
public T[] toArray(T[] a) {
return delegate.toArray(a);
}
@Override
public boolean add(E e) {
throw new UnsupportedOperationException();
}
@Override
public boolean remove(Object o) {
throw new UnsupportedOperationException();
}
@Override
public boolean offer(E e) {
throw new UnsupportedOperationException();
}
@Override
public E remove() {
throw new UnsupportedOperationException();
}
@Override
public E poll() {
throw new UnsupportedOperationException();
}
@Override
public E element() {
return delegate.element();
}
@Override
public E peek() {
return delegate.peek();
}
@Override
public boolean containsAll(Collection c) {
return delegate.containsAll(c);
}
@Override
public boolean addAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeIf(Predicate filter) {
throw new UnsupportedOperationException();
}
@Override
public boolean retainAll(Collection c) {
throw new UnsupportedOperationException();
}
@Override
public void clear() {
throw new UnsupportedOperationException();
}
@Override
public boolean equals(Object o) {
return delegate.equals(o);
}
@Override
public int hashCode() {
return delegate.hashCode();
}
@Override
public Spliterator spliterator() {
return delegate.spliterator();
}
@Override
public Stream stream() {
return delegate.stream();
}
@Override
public Stream parallelStream() {
return delegate.parallelStream();
}
@Override
public void forEach(Consumer action) {
delegate.forEach(action);
}
}
static class UnmodifiableDeque extends UnmodifiableQueue implements Deque, Serializable {
private final Deque delegate;
UnmodifiableDeque(Deque deque) {
super(deque);
this.delegate = deque;
}
@Override
public void addFirst(E e) {
throw new UnsupportedOperationException();
}
@Override
public void addLast(E e) {
throw new UnsupportedOperationException();
}
@Override
public boolean offerFirst(E e) {
throw new UnsupportedOperationException();
}
@Override
public boolean offerLast(E e) {
throw new UnsupportedOperationException();
}
@Override
public E removeFirst() {
throw new UnsupportedOperationException();
}
@Override
public E removeLast() {
throw new UnsupportedOperationException();
}
@Override
public E pollFirst() {
throw new UnsupportedOperationException();
}
@Override
public E pollLast() {
throw new UnsupportedOperationException();
}
@Override
public E getFirst() {
return delegate.getFirst();
}
@Override
public E getLast() {
return delegate.getLast();
}
@Override
public E peekFirst() {
return getFirst();
}
@Override
public E peekLast() {
return getLast();
}
@Override
public boolean removeFirstOccurrence(Object o) {
throw new UnsupportedOperationException();
}
@Override
public boolean removeLastOccurrence(Object o) {
throw new UnsupportedOperationException();
}
@Override
public void push(E e) {
throw new UnsupportedOperationException();
}
@Override
public E pop() {
throw new UnsupportedOperationException();
}
@Override
public Iterator descendingIterator() {
return unmodifiableIterator(delegate.descendingIterator());
}
}
static class SingletonDeque extends AbstractDeque implements Serializable {
private static final long serialVersionUID = -1L;
private final E element;
private final Iterator iterator;
SingletonDeque(E element) {
this.element = element;
this.iterator = singletonIterator(element);
}
@Override
public Iterator iterator() {
return iterator;
}
@Override
public Iterator descendingIterator() {
return iterator;
}
@Override
public boolean offerFirst(E e) {
return false;
}
@Override
public boolean offerLast(E e) {
return false;
}
@Override
public E pollFirst() {
throw new UnsupportedOperationException();
}
@Override
public E pollLast() {
throw new UnsupportedOperationException();
}
@Override
public E getFirst() {
return element;
}
@Override
public E getLast() {
return element;
}
@Override
public boolean removeLastOccurrence(Object o) {
throw new UnsupportedOperationException();
}
@Override
public int size() {
return 1;
}
}
}