001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      https://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.collections4.bag;
018
019import java.io.IOException;
020import java.io.ObjectInputStream;
021import java.io.ObjectOutputStream;
022import java.util.Collection;
023import java.util.Iterator;
024
025import org.apache.commons.collections4.Bag;
026import org.apache.commons.collections4.MultiSet;
027
028/**
029 * Decorates another {@link Bag} to comply with the Collection contract.
030 * <p>
031 * By decorating an existing {@link Bag} instance with a {@link CollectionBag},
032 * it can be safely passed on to methods that require Collection types that
033 * are fully compliant with the Collection contract.
034 * </p>
035 * <p>
036 * The method Javadoc highlights the differences compared to the original Bag interface.
037 * </p>
038 *
039 * @see Bag
040 * @param <E> The type of elements in this bag
041 * @since 4.0
042 * @deprecated Since 4.6.0, no longer needed; a {@link MultiSet} already complies with the {@link Collection} contract.
043 */
044@Deprecated
045public final class CollectionBag<E> extends AbstractBagDecorator<E> {
046
047    /** Serialization version */
048    private static final long serialVersionUID = -2560033712679053143L;
049
050    /**
051     * Factory method to create a bag that complies to the Collection contract.
052     *
053     * @param <E> The type of the elements in the bag
054     * @param bag  The bag to decorate, must not be null
055     * @return A Bag that complies to the Collection contract
056     * @throws NullPointerException if bag is null
057     */
058    public static <E> Bag<E> collectionBag(final Bag<E> bag) {
059        return new CollectionBag<>(bag);
060    }
061
062    /**
063     * Constructor that wraps (not copies).
064     *
065     * @param bag  The bag to decorate, must not be null
066     * @throws NullPointerException if bag is null
067     */
068    public CollectionBag(final Bag<E> bag) {
069        super(bag);
070    }
071
072    /**
073     * <em>(Change)</em> Adds one copy of the specified object to the Bag.
074     * <p>
075     * Since this method always increases the size of the bag, it will always return {@code true}.
076     * </p>
077     *
078     * @param object The object to add
079     * @return {@code true}, always
080     * @throws ClassCastException if the class of the specified element prevents it from being added to this collection
081     */
082    @Override
083    public boolean add(final E object) {
084        return add(object, 1);
085    }
086
087    /**
088     * <em>(Change)</em>
089     * Adds {@code count} copies of the specified object to the Bag.
090     * <p>
091     * Since this method always increases the size of the bag, it
092     * will always return {@code true}.
093     *
094     * @param object  The object to add
095     * @param count  The number of copies to add
096     * @return {@code true}, always
097     * @throws ClassCastException if the class of the specified element prevents it from being added to this collection
098     */
099    @Override
100    public boolean add(final E object, final int count) {
101        decorated().add(object, count);
102        return true;
103    }
104
105    @Override
106    public boolean addAll(final Collection<? extends E> coll) {
107        boolean changed = false;
108        for (final E current : coll) {
109            final boolean added = add(current, 1);
110            changed = changed || added;
111        }
112        return changed;
113    }
114
115    /**
116     * <em>(Change)</em>
117     * Returns {@code true} if the bag contains all elements in
118     * the given collection, <strong>not</strong> respecting cardinality. That is,
119     * if the given collection {@code coll} contains at least one of
120     * every object contained in this object.
121     *
122     * @param coll  The collection to check against
123     * @return {@code true} if the Bag contains at least one of every object in the collection
124     */
125    @Override
126    public boolean containsAll(final Collection<?> coll) {
127        return coll.stream().allMatch(this::contains);
128    }
129
130    /**
131     * Reads the collection in using a custom routine.
132     *
133     * @param in  The input stream
134     * @throws IOException Thrown if an error occurs while reading from the stream
135     * @throws ClassNotFoundException if an object read from the stream cannot be loaded
136     * @throws ClassCastException if deserialized object has wrong type
137     */
138    @SuppressWarnings("unchecked") // will throw CCE, see Javadoc
139    private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException {
140        in.defaultReadObject();
141        setCollection((Collection<E>) in.readObject());
142    }
143
144    /**
145     * <em>(Change)</em>
146     * Removes the first occurrence of the given object from the bag.
147     * <p>
148     * This will also remove the object from the {@link #uniqueSet()} if the
149     * bag contains no occurrence anymore of the object after this operation.
150     * </p>
151     *
152     * @param object  The object to remove
153     * @return {@code true} if this call changed the collection
154     */
155    @Override
156    public boolean remove(final Object object) {
157        return remove(object, 1);
158    }
159
160    /**
161     * <em>(Change)</em>
162     * Remove all elements represented in the given collection,
163     * <strong>not</strong> respecting cardinality. That is, remove <em>all</em>
164     * occurrences of every object contained in the given collection.
165     *
166     * @param coll  The collection to remove
167     * @return {@code true} if this call changed the collection
168     */
169    @Override
170    public boolean removeAll(final Collection<?> coll) {
171        if (coll != null) {
172            boolean result = false;
173            for (final Object obj : coll) {
174                final boolean changed = remove(obj, getCount(obj));
175                result = result || changed;
176            }
177            return result;
178        }
179        // let the decorated bag handle the case of null argument
180        return decorated().removeAll(null);
181    }
182
183    /**
184     * <em>(Change)</em>
185     * Remove any members of the bag that are not in the given collection,
186     * <em>not</em> respecting cardinality. That is, any object in the given
187     * collection {@code coll} will be retained in the bag with the same
188     * number of copies prior to this operation. All other objects will be
189     * completely removed from this bag.
190     * <p>
191     * This implementation iterates over the elements of this bag, checking
192     * each element in turn to see if it's contained in {@code coll}.
193     * If it's not contained, it's removed from this bag. As a consequence,
194     * it is advised to use a collection type for {@code coll} that provides
195     * a fast (for example O(1)) implementation of {@link Collection#contains(Object)}.
196     * </p>
197     *
198     * @param coll  The collection to retain
199     * @return {@code true} if this call changed the collection
200     */
201    @Override
202    public boolean retainAll(final Collection<?> coll) {
203        if (coll != null) {
204            boolean modified = false;
205            final Iterator<E> e = iterator();
206            while (e.hasNext()) {
207                if (!coll.contains(e.next())) {
208                    e.remove();
209                    modified = true;
210                }
211            }
212            return modified;
213        }
214        // let the decorated bag handle the case of null argument
215        return decorated().retainAll(null);
216    }
217
218    /**
219     * Writes the collection out using a custom routine.
220     *
221     * @param out  The output stream
222     * @throws IOException Thrown if an error occurs while writing to the stream
223     */
224    private void writeObject(final ObjectOutputStream out) throws IOException {
225        out.defaultWriteObject();
226        out.writeObject(decorated());
227    }
228
229}