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.set;
018    
019    import java.util.Comparator;
020    import java.util.SortedSet;
021    
022    import org.apache.commons.collections.Transformer;
023    
024    /**
025     * Decorates another <code>SortedSet</code> to transform objects that are added.
026     * <p>
027     * The add methods are affected by this class.
028     * Thus objects must be removed or searched for using their transformed form.
029     * For example, if the transformation converts Strings to Integers, you must
030     * use the Integer form to remove objects.
031     * <p>
032     * This class is Serializable from Commons Collections 3.1.
033     * 
034     * @since Commons Collections 3.0
035     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
036     * 
037     * @author Stephen Colebourne
038     */
039    public class TransformedSortedSet extends TransformedSet implements SortedSet {
040    
041        /** Serialization version */
042        private static final long serialVersionUID = -1675486811351124386L;
043    
044        /**
045         * Factory method to create a transforming sorted set.
046         * <p>
047         * If there are any elements already in the set being decorated, they
048         * are NOT transformed.
049         * 
050         * @param set  the set to decorate, must not be null
051         * @param transformer  the transformer to use for conversion, must not be null
052         * @throws IllegalArgumentException if set or transformer is null
053         */
054        public static SortedSet decorate(SortedSet set, Transformer transformer) {
055            return new TransformedSortedSet(set, transformer);
056        }
057        
058        //-----------------------------------------------------------------------
059        /**
060         * Constructor that wraps (not copies).
061         * <p>
062         * If there are any elements already in the set being decorated, they
063         * are NOT transformed.
064         * 
065         * @param set  the set to decorate, must not be null
066         * @param transformer  the transformer to use for conversion, must not be null
067         * @throws IllegalArgumentException if set or transformer is null
068         */
069        protected TransformedSortedSet(SortedSet set, Transformer transformer) {
070            super(set, transformer);
071        }
072    
073        /**
074         * Gets the decorated set.
075         * 
076         * @return the decorated set
077         */
078        protected SortedSet getSortedSet() {
079            return (SortedSet) collection;
080        }
081    
082        //-----------------------------------------------------------------------
083        public Object first() {
084            return getSortedSet().first();
085        }
086    
087        public Object last() {
088            return getSortedSet().last();
089        }
090    
091        public Comparator comparator() {
092            return getSortedSet().comparator();
093        }
094    
095        //-----------------------------------------------------------------------
096        public SortedSet subSet(Object fromElement, Object toElement) {
097            SortedSet set = getSortedSet().subSet(fromElement, toElement);
098            return new TransformedSortedSet(set, transformer);
099        }
100    
101        public SortedSet headSet(Object toElement) {
102            SortedSet set = getSortedSet().headSet(toElement);
103            return new TransformedSortedSet(set, transformer);
104        }
105    
106        public SortedSet tailSet(Object fromElement) {
107            SortedSet set = getSortedSet().tailSet(fromElement);
108            return new TransformedSortedSet(set, transformer);
109        }
110    
111    }