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     *      http://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     */
017    package org.apache.commons.collections.bag;
018    
019    import java.util.Set;
020    
021    import org.apache.commons.collections.Bag;
022    import org.apache.commons.collections.Predicate;
023    import org.apache.commons.collections.collection.PredicatedCollection;
024    
025    /**
026     * Decorates another <code>Bag</code> to validate that additions
027     * match a specified predicate.
028     * <p>
029     * This bag exists to provide validation for the decorated bag.
030     * It is normally created to decorate an empty bag.
031     * If an object cannot be added to the bag, an IllegalArgumentException is thrown.
032     * <p>
033     * One usage would be to ensure that no null entries are added to the bag.
034     * <pre>Bag bag = PredicatedBag.decorate(new HashBag(), NotNullPredicate.INSTANCE);</pre>
035     * <p>
036     * This class is Serializable from Commons Collections 3.1.
037     *
038     * @since Commons Collections 3.0
039     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
040     * 
041     * @author Stephen Colebourne
042     * @author Paul Jack
043     */
044    public class PredicatedBag
045            extends PredicatedCollection implements Bag {
046    
047        /** Serialization version */
048        private static final long serialVersionUID = -2575833140344736876L;
049    
050        /**
051         * Factory method to create a predicated (validating) bag.
052         * <p>
053         * If there are any elements already in the bag being decorated, they
054         * are validated.
055         * 
056         * @param bag  the bag to decorate, must not be null
057         * @param predicate  the predicate to use for validation, must not be null
058         * @return a new predicated Bag
059         * @throws IllegalArgumentException if bag or predicate is null
060         * @throws IllegalArgumentException if the bag contains invalid elements
061         */
062        public static Bag decorate(Bag bag, Predicate predicate) {
063            return new PredicatedBag(bag, predicate);
064        }
065    
066        //-----------------------------------------------------------------------
067        /**
068         * Constructor that wraps (not copies).
069         * <p>
070         * If there are any elements already in the bag being decorated, they
071         * are validated.
072         * 
073         * @param bag  the bag to decorate, must not be null
074         * @param predicate  the predicate to use for validation, must not be null
075         * @throws IllegalArgumentException if bag or predicate is null
076         * @throws IllegalArgumentException if the bag contains invalid elements
077         */
078        protected PredicatedBag(Bag bag, Predicate predicate) {
079            super(bag, predicate);
080        }
081    
082        /**
083         * Gets the decorated bag.
084         * 
085         * @return the decorated bag
086         */
087        protected Bag getBag() {
088            return (Bag) getCollection();
089        }
090        
091        //-----------------------------------------------------------------------
092        public boolean add(Object object, int count) {
093            validate(object);
094            return getBag().add(object, count);
095        }
096    
097        public boolean remove(Object object, int count) {
098            return getBag().remove(object, count);
099        }
100    
101        public Set uniqueSet() {
102            return getBag().uniqueSet();
103        }
104    
105        public int getCount(Object object) {
106            return getBag().getCount(object);
107        }
108    
109    }