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.Transformer;
023    import org.apache.commons.collections.collection.TransformedCollection;
024    import org.apache.commons.collections.set.TransformedSet;
025    
026    /**
027     * Decorates another <code>Bag</code> to transform objects that are added.
028     * <p>
029     * The add methods are affected by this class.
030     * Thus objects must be removed or searched for using their transformed form.
031     * For example, if the transformation converts Strings to Integers, you must
032     * use the Integer form to remove objects.
033     * <p>
034     * This class is Serializable from Commons Collections 3.1.
035     *
036     * @since Commons Collections 3.0
037     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
038     * 
039     * @author Stephen Colebourne
040     */
041    public class TransformedBag
042            extends TransformedCollection implements Bag {
043    
044        /** Serialization version */
045        private static final long serialVersionUID = 5421170911299074185L;
046    
047        /**
048         * Factory method to create a transforming bag.
049         * <p>
050         * If there are any elements already in the bag being decorated, they
051         * are NOT transformed.
052         * 
053         * @param bag  the bag to decorate, must not be null
054         * @param transformer  the transformer to use for conversion, must not be null
055         * @return a new transformed Bag
056         * @throws IllegalArgumentException if bag or transformer is null
057         */
058        public static Bag decorate(Bag bag, Transformer transformer) {
059            return new TransformedBag(bag, transformer);
060        }
061        
062        //-----------------------------------------------------------------------
063        /**
064         * Constructor that wraps (not copies).
065         * <p>
066         * If there are any elements already in the bag being decorated, they
067         * are NOT transformed.
068         * 
069         * @param bag  the bag to decorate, must not be null
070         * @param transformer  the transformer to use for conversion, must not be null
071         * @throws IllegalArgumentException if bag or transformer is null
072         */
073        protected TransformedBag(Bag bag, Transformer transformer) {
074            super(bag, transformer);
075        }
076    
077        /**
078         * Gets the decorated bag.
079         * 
080         * @return the decorated bag
081         */
082        protected Bag getBag() {
083            return (Bag) collection;
084        }
085    
086        //-----------------------------------------------------------------------
087        public int getCount(Object object) {
088            return getBag().getCount(object);
089        }
090    
091        public boolean remove(Object object, int nCopies) {
092            return getBag().remove(object, nCopies);
093        }
094    
095        //-----------------------------------------------------------------------
096        public boolean add(Object object, int nCopies) {
097            object = transform(object);
098            return getBag().add(object, nCopies);
099        }
100    
101        public Set uniqueSet() {
102            Set set = getBag().uniqueSet();
103            return TransformedSet.decorate(set, transformer);
104        }
105    
106    }