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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 org.apache.commons.collections4.collection;

	import java.io.Serializable;
	import java.util.Collection;
	import java.util.Iterator;
	import java.util.function.Predicate;

	/**
	* Decorates another <code>Collection</code> to provide additional behaviour.
	* <p>
	* Each method call made on this <code>Collection</code> is forwarded to the
	* decorated <code>Collection</code>. This class is used as a framework on which
	* to build to extensions such as synchronized and unmodifiable behaviour. The
	* main advantage of decoration is that one decorator can wrap any implementation
	* of <code>Collection</code>, whereas sub-classing requires a new class to be
	* written for each implementation.
	* </p>
	* <p>
	* This implementation does not perform any special processing with
	* {@link #iterator()}. Instead it simply returns the value from the
	* wrapped collection. This may be undesirable, for example if you are trying
	* to write an unmodifiable implementation it might provide a loophole.
	* </p>
	* <p>
	* This implementation does not forward the hashCode and equals methods through
	* to the backing object, but relies on Object's implementation. This is necessary
	* to preserve the symmetry of equals. Custom definitions of equality are usually
	* based on an interface, such as Set or List, so that the implementation of equals
	* can cast the object being tested for equality to the custom interface.
	* AbstractCollectionDecorator does not implement such custom interfaces directly;
	* they are implemented only in subclasses. Therefore, forwarding equals would break
	* symmetry, as the forwarding object might consider itself equal to the object being
	* tested, but the reverse could not be true. This behavior is consistent with the
	* JDK's collection wrappers, such as {@link java.util.Collections#unmodifiableCollection(Collection)}.
	* Use an interface-specific subclass of AbstractCollectionDecorator, such as
	* AbstractListDecorator, to preserve equality behavior, or override equals directly.
	* </p>
	*
	* @param <E> the type of the elements in the collection
	* @since 3.0
	*/
	public abstract class AbstractCollectionDecorator<E>
	implements Collection<E>, Serializable {

	/** Serialization version */
	private static final long serialVersionUID = 6249888059822088500L;

	/** The collection being decorated */
	private Collection<E> collection;

	/**
	* Constructor only used in deserialization, do not use otherwise.
	* @since 3.1
	*/
	protected AbstractCollectionDecorator() {
	super();
	}

	/**
	* Constructor that wraps (not copies).
	*
	* @param coll the collection to decorate, must not be null
	* @throws NullPointerException if the collection is null
	*/
	protected AbstractCollectionDecorator(final Collection<E> coll) {
	if (coll == null) {
	throw new NullPointerException("Collection must not be null.");
	}
	this.collection = coll;
	}

	/**
	* Gets the collection being decorated.
	* All access to the decorated collection goes via this method.
	*
	* @return the decorated collection
	*/
	protected Collection<E> decorated() {
	return collection;
	}

	/**
	* Sets the collection being decorated.
	* <p>
	* <b>NOTE:</b> this method should only be used during deserialization
	*
	* @param coll the decorated collection
	*/
	protected void setCollection(final Collection<E> coll) {
	this.collection = coll;
	}

	//-----------------------------------------------------------------------

	@Override
	public boolean add(final E object) {
	return decorated().add(object);
	}

	@Override
	public boolean addAll(final Collection<? extends E> coll) {
	return decorated().addAll(coll);
	}

	@Override
	public void clear() {
	decorated().clear();
	}

	@Override
	public boolean contains(final Object object) {
	return decorated().contains(object);
	}

	@Override
	public boolean isEmpty() {
	return decorated().isEmpty();
	}

	@Override
	public Iterator<E> iterator() {
	return decorated().iterator();
	}

	@Override
	public boolean remove(final Object object) {
	return decorated().remove(object);
	}

	@Override
	public int size() {
	return decorated().size();
	}

	@Override
	public Object[] toArray() {
	return decorated().toArray();
	}

	@Override
	public <T> T[] toArray(final T[] object) {
	return decorated().toArray(object);
	}

	@Override
	public boolean containsAll(final Collection<?> coll) {
	return decorated().containsAll(coll);
	}

	/**
	* @since 4.4
	*/
	@Override
	public boolean removeIf(final Predicate<? super E> filter) {
	return decorated().removeIf(filter);
	}

	@Override
	public boolean removeAll(final Collection<?> coll) {
	return decorated().removeAll(coll);
	}

	@Override
	public boolean retainAll(final Collection<?> coll) {
	return decorated().retainAll(coll);
	}

	@Override
	public String toString() {
	return decorated().toString();
	}

	}

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