001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one
003     *  or more contributor license agreements.  See the NOTICE file
004     *  distributed with this work for additional information
005     *  regarding copyright ownership.  The ASF licenses this file
006     *  to you under the Apache License, Version 2.0 (the
007     *  "License"); you may not use this file except in compliance
008     *  with the License.  You may obtain a copy of the License at
009     *  
010     *    http://www.apache.org/licenses/LICENSE-2.0
011     *  
012     *  Unless required by applicable law or agreed to in writing,
013     *  software distributed under the License is distributed on an
014     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015     *  KIND, either express or implied.  See the License for the
016     *  specific language governing permissions and limitations
017     *  under the License. 
018     *  
019     */
020    package org.apache.directory.shared.ldap.schema.comparators;
021    
022    
023    import java.util.Comparator;
024    import javax.naming.NamingException;
025    
026    import org.apache.directory.shared.ldap.entry.Value;
027    import org.apache.directory.shared.ldap.schema.Normalizer;
028    import org.slf4j.Logger;
029    import org.slf4j.LoggerFactory;
030    
031    
032    /**
033     * A comparator which normalizes a value first before using a subordinate
034     * comparator to compare them.
035     * 
036     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
037     * @version $Rev: 798550 $
038     */
039    public class NormalizingComparator implements Comparator
040    {
041        private static final Logger log = LoggerFactory.getLogger( NormalizingComparator.class );
042    
043        /** the Normalizer to normalize values with before comparing */
044        private Normalizer normalizer;
045    
046        /** the underlying comparator to use for comparisons */
047        private Comparator<Object> comparator;
048    
049    
050        /**
051         * A comparator which normalizes a value first before comparing them.
052         * 
053         * @param normalizer the Normalizer to normalize values with before comparing
054         * @param comparator the underlying comparator to use for comparisons
055         */
056        public NormalizingComparator( Normalizer normalizer, Comparator<Object> comparator )
057        {
058            this.normalizer = normalizer;
059            this.comparator = comparator;
060        }
061    
062    
063        /**
064         * If any normalization attempt fails we compare using the unnormalized
065         * object.
066         * 
067         * @see Comparator#compare(Object, Object)
068         */
069        public int compare( Object o1, Object o2 )
070        {
071            Object n1;
072            Object n2;
073    
074            try
075            {
076                n1 = normalizer.normalize( (String)o1 );
077            }
078            catch ( NamingException e )
079            {
080                log.warn( "Failed to normalize: " + o1, e );
081                n1 = o1;
082            }
083    
084            try
085            {
086                n2 = normalizer.normalize( (String)o2 );
087            }
088            catch ( NamingException e )
089            {
090                log.warn( "Failed to normalize: " + o2, e );
091                n2 = o2;
092            }
093    
094            return comparator.compare( n1, n2 );
095        }
096    }