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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.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.HashSet;
	import java.util.LinkedList;
	import java.util.List;
	import java.util.Queue;
	import java.util.Set;

	import org.apache.commons.collections4.Bag;
	import org.apache.commons.collections4.MultiSet;
	import org.apache.commons.collections4.Predicate;
	import org.apache.commons.collections4.bag.HashBag;
	import org.apache.commons.collections4.bag.PredicatedBag;
	import org.apache.commons.collections4.functors.NotNullPredicate;
	import org.apache.commons.collections4.list.PredicatedList;
	import org.apache.commons.collections4.multiset.HashMultiSet;
	import org.apache.commons.collections4.multiset.PredicatedMultiSet;
	import org.apache.commons.collections4.queue.PredicatedQueue;
	import org.apache.commons.collections4.set.PredicatedSet;

	/**
	* Decorates another {@link Collection} to validate that additions
	* match a specified predicate.
	* <p>
	* This collection exists to provide validation for the decorated collection.
	* It is normally created to decorate an empty collection.
	* If an object cannot be added to the collection, an IllegalArgumentException is thrown.
	* </p>
	* <p>
	* One usage would be to ensure that no null entries are added to the collection:
	* </p>
	* <pre>
	* Collection coll = PredicatedCollection.predicatedCollection(new ArrayList(), NotNullPredicate.INSTANCE);
	* </pre>
	* <p>
	* This class is Serializable from Commons Collections 3.1.
	* </p>
	*
	* @param <E> the type of the elements in the collection
	* @since 3.0
	*/
	public class PredicatedCollection<E> extends AbstractCollectionDecorator<E> {

	/** Serialization version */
	private static final long serialVersionUID = -5259182142076705162L;

	/** The predicate to use */
	protected final Predicate<? super E> predicate;

	/**
	* Returns a Builder with the given predicate.
	*
	* @param <E> the element type
	* @param predicate the predicate to use
	* @return a new Builder for predicated collections
	* @since 4.1
	*/
	public static <E> Builder<E> builder(final Predicate<? super E> predicate) {
	return new Builder<>(predicate);
	}

	/**
	* Returns a Builder with a NotNullPredicate.
	*
	* @param <E> the element type
	* @return a new Builder for predicated collections that ignores null values.
	* @since 4.1
	*/
	public static <E> Builder<E> notNullBuilder() {
	return new Builder<>(NotNullPredicate.<E>notNullPredicate());
	}

	/**
	* Factory method to create a predicated (validating) collection.
	* <p>
	* If there are any elements already in the collection being decorated, they
	* are validated.
	*
	* @param <T> the type of the elements in the collection
	* @param coll the collection to decorate, must not be null
	* @param predicate the predicate to use for validation, must not be null
	* @return a new predicated collection
	* @throws NullPointerException if collection or predicate is null
	* @throws IllegalArgumentException if the collection contains invalid elements
	* @since 4.0
	*/
	public static <T> PredicatedCollection<T> predicatedCollection(final Collection<T> coll,
	final Predicate<? super T> predicate) {
	return new PredicatedCollection<>(coll, predicate);
	}

	//-----------------------------------------------------------------------
	/**
	* Constructor that wraps (not copies).
	* <p>
	* If there are any elements already in the collection being decorated, they
	* are validated.
	*
	* @param coll the collection to decorate, must not be null
	* @param predicate the predicate to use for validation, must not be null
	* @throws NullPointerException if collection or predicate is null
	* @throws IllegalArgumentException if the collection contains invalid elements
	*/
	protected PredicatedCollection(final Collection<E> coll, final Predicate<? super E> predicate) {
	super(coll);
	if (predicate == null) {
	throw new NullPointerException("Predicate must not be null.");
	}
	this.predicate = predicate;
	for (final E item : coll) {
	validate(item);
	}
	}

	/**
	* Validates the object being added to ensure it matches the predicate.
	* <p>
	* The predicate itself should not throw an exception, but return false to
	* indicate that the object cannot be added.
	*
	* @param object the object being added
	* @throws IllegalArgumentException if the add is invalid
	*/
	protected void validate(final E object) {
	if (predicate.evaluate(object) == false) {
	throw new IllegalArgumentException("Cannot add Object '" + object + "' - Predicate '" +
	predicate + "' rejected it");
	}
	}

	//-----------------------------------------------------------------------
	/**
	* Override to validate the object being added to ensure it matches
	* the predicate.
	*
	* @param object the object being added
	* @return the result of adding to the underlying collection
	* @throws IllegalArgumentException if the add is invalid
	*/
	@Override
	public boolean add(final E object) {
	validate(object);
	return decorated().add(object);
	}

	/**
	* Override to validate the objects being added to ensure they match
	* the predicate. If any one fails, no update is made to the underlying
	* collection.
	*
	* @param coll the collection being added
	* @return the result of adding to the underlying collection
	* @throws IllegalArgumentException if the add is invalid
	*/
	@Override
	public boolean addAll(final Collection<? extends E> coll) {
	for (final E item : coll) {
	validate(item);
	}
	return decorated().addAll(coll);
	}

	/**
	* Builder for creating predicated collections.
	* <p>
	* Create a Builder with a predicate to validate elements against, then add any elements
	* to the builder. Elements that fail the predicate will be added to a rejected list.
	* Finally create or decorate a collection using the createPredicated[List,Set,Bag,Queue] methods.
	* <p>
	* An example:
	* <pre>
	* Predicate<String> predicate = NotNullPredicate.notNullPredicate();
	* PredicatedCollectionBuilder<String> builder = PredicatedCollection.builder(predicate);
	* builder.add("item1");
	* builder.add(null);
	* builder.add("item2");
	* List<String> predicatedList = builder.createPredicatedList();
	* </pre>
	* <p>
	* At the end of the code fragment above predicatedList is protected by the predicate supplied
	* to the builder and it contains item1 and item2.
	* <p>
	* More elements can be added to the builder once a predicated collection has been created,
	* but these elements will not be reflected in already created collections.
	*
	* @param <E> the element type
	* @since 4.1
	*/
	public static class Builder<E> {

	/** The predicate to use. */
	private final Predicate<? super E> predicate;

	/** The buffer containing valid elements. */
	private final List<E> accepted = new ArrayList<>();

	/** The buffer containing rejected elements. */
	private final List<E> rejected = new ArrayList<>();

	// -----------------------------------------------------------------------
	/**
	* Constructs a PredicatedCollectionBuilder with the specified Predicate.
	*
	* @param predicate the predicate to use
	* @throws NullPointerException if predicate is null
	*/
	public Builder(final Predicate<? super E> predicate) {
	if (predicate == null) {
	throw new NullPointerException("Predicate must not be null");
	}
	this.predicate = predicate;
	}

	/**
	* Adds the item to the builder.
	* <p>
	* If the predicate is true, it is added to the list of accepted elements,
	* otherwise it is added to the rejected list.
	*
	* @param item the element to add
	* @return the PredicatedCollectionBuilder.
	*/
	public Builder<E> add(final E item) {
	if (predicate.evaluate(item)) {
	accepted.add(item);
	} else {
	rejected.add(item);
	}
	return this;
	}

	/**
	* Adds all elements from the given collection to the builder.
	* <p>
	* All elements for which the predicate evaluates to true will be added to the
	* list of accepted elements, otherwise they are added to the rejected list.
	*
	* @param items the elements to add to the builder
	* @return the PredicatedCollectionBuilder.
	*/
	public Builder<E> addAll(final Collection<? extends E> items) {
	if (items != null) {
	for (final E item : items) {
	add(item);
	}
	}
	return this;
	}

	/**
	* Create a new predicated list filled with the accepted elements.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned list.
	*
	* @return a new predicated list.
	*/
	public List<E> createPredicatedList() {
	return createPredicatedList(new ArrayList<E>());
	}

	/**
	* Decorates the given list with validating behavior using the predicate. All accepted elements
	* are appended to the list. If the list already contains elements, they are validated.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned list.
	*
	* @param list the List to decorate, must not be null
	* @return the decorated list.
	* @throws NullPointerException if list is null
	* @throws IllegalArgumentException if list contains invalid elements
	*/
	public List<E> createPredicatedList(final List<E> list) {
	if (list == null) {
	throw new NullPointerException("List must not be null.");
	}
	final List<E> predicatedList = PredicatedList.predicatedList(list, predicate);
	predicatedList.addAll(accepted);
	return predicatedList;
	}

	/**
	* Create a new predicated set filled with the accepted elements.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned set.
	*
	* @return a new predicated set.
	*/
	public Set<E> createPredicatedSet() {
	return createPredicatedSet(new HashSet<E>());
	}

	/**
	* Decorates the given list with validating behavior using the predicate. All accepted elements
	* are appended to the set. If the set already contains elements, they are validated.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned set.
	*
	* @param set the set to decorate, must not be null
	* @return the decorated set.
	* @throws NullPointerException if set is null
	* @throws IllegalArgumentException if set contains invalid elements
	*/
	public Set<E> createPredicatedSet(final Set<E> set) {
	if (set == null) {
	throw new NullPointerException("Set must not be null.");
	}
	final PredicatedSet<E> predicatedSet = PredicatedSet.predicatedSet(set, predicate);
	predicatedSet.addAll(accepted);
	return predicatedSet;
	}

	/**
	* Create a new predicated multiset filled with the accepted elements.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned multiset.
	*
	* @return a new predicated multiset.
	*/
	public MultiSet<E> createPredicatedMultiSet() {
	return createPredicatedMultiSet(new HashMultiSet<E>());
	}

	/**
	* Decorates the given multiset with validating behavior using the predicate. All accepted elements
	* are appended to the multiset. If the multiset already contains elements, they are validated.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned multiset.
	*
	* @param multiset the multiset to decorate, must not be null
	* @return the decorated multiset.
	* @throws NullPointerException if multiset is null
	* @throws IllegalArgumentException if multiset contains invalid elements
	*/
	public MultiSet<E> createPredicatedMultiSet(final MultiSet<E> multiset) {
	if (multiset == null) {
	throw new NullPointerException("MultiSet must not be null.");
	}
	final PredicatedMultiSet<E> predicatedMultiSet =
	PredicatedMultiSet.predicatedMultiSet(multiset, predicate);
	predicatedMultiSet.addAll(accepted);
	return predicatedMultiSet;
	}

	/**
	* Create a new predicated bag filled with the accepted elements.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned bag.
	*
	* @return a new predicated bag.
	*/
	public Bag<E> createPredicatedBag() {
	return createPredicatedBag(new HashBag<E>());
	}

	/**
	* Decorates the given bag with validating behavior using the predicate. All accepted elements
	* are appended to the bag. If the bag already contains elements, they are validated.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned bag.
	*
	* @param bag the bag to decorate, must not be null
	* @return the decorated bag.
	* @throws NullPointerException if bag is null
	* @throws IllegalArgumentException if bag contains invalid elements
	*/
	public Bag<E> createPredicatedBag(final Bag<E> bag) {
	if (bag == null) {
	throw new NullPointerException("Bag must not be null.");
	}
	final PredicatedBag<E> predicatedBag = PredicatedBag.predicatedBag(bag, predicate);
	predicatedBag.addAll(accepted);
	return predicatedBag;
	}

	/**
	* Create a new predicated queue filled with the accepted elements.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned queue.
	*
	* @return a new predicated queue.
	*/
	public Queue<E> createPredicatedQueue() {
	return createPredicatedQueue(new LinkedList<E>());
	}

	/**
	* Decorates the given queue with validating behavior using the predicate. All accepted elements
	* are appended to the queue. If the queue already contains elements, they are validated.
	* <p>
	* The builder is not modified by this method, so it is possible to create more collections
	* or add more elements afterwards. Further changes will not propagate to the returned queue.
	*
	* @param queue the queue to decorate, must not be null
	* @return the decorated queue.
	* @throws NullPointerException if queue is null
	* @throws IllegalArgumentException if queue contains invalid elements
	*/
	public Queue<E> createPredicatedQueue(final Queue<E> queue) {
	if (queue == null) {
	throw new NullPointerException("queue must not be null");
	}
	final PredicatedQueue<E> predicatedQueue = PredicatedQueue.predicatedQueue(queue, predicate);
	predicatedQueue.addAll(accepted);
	return predicatedQueue;
	}

	/**
	* Returns an unmodifiable collection containing all rejected elements.
	*
	* @return an unmodifiable collection
	*/
	public Collection<E> rejectedElements() {
	return Collections.unmodifiableCollection(rejected);
	}

	}

	}

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