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.server.core.partition.impl.btree;
021    
022    
023    import java.io.Serializable;
024    
025    import org.apache.directory.shared.ldap.schema.comparators.SerializableComparator;
026    
027    
028    /**
029     * A TupleComparator that compares keys only.
030     * 
031     * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
032     * @version $Rev: 917231 $
033     */
034    public class KeyOnlyComparator<K, V> implements TupleComparator<K, V>, Serializable
035    {
036        private static final long serialVersionUID = 3544956549803161397L;
037    
038        private SerializableComparator<K> keyComparator;
039    
040    
041        public KeyOnlyComparator( SerializableComparator<K> comparator )
042        {
043            keyComparator = comparator;
044        }
045    
046    
047        /**
048         * Gets the comparator used to compare keys.  May be null in which
049         * case the compareKey method will throw an UnsupportedOperationException.
050         *
051         * @return the comparator for comparing keys.
052         */
053        public SerializableComparator<K> getKeyComparator()
054        {
055            return keyComparator;
056        }
057    
058    
059        /**
060         * Will throw an UnsupportedOperationException every time.
061         */
062        public SerializableComparator<V> getValueComparator()
063        {
064            throw new UnsupportedOperationException();
065        }
066    
067    
068        /**
069         * Compares key Object to determine their sorting order returning a
070         * value = to, < or > than 0.
071         *
072         * @param key1 the first key to compare
073         * @param key2 the other key to compare to the first
074         * @return 0 if both are equal, a negative value less than 0 if the first
075         * is less than the second, or a postive value if the first is greater than
076         * the second byte array.
077         */
078        public int compareKey( K key1, K key2 )
079        {
080            return keyComparator.compare( key1, key2 );
081        }
082    
083    
084        /**
085         * Comparse value Objects to determine their sorting order returning a
086         * value = to, < or > than 0.
087         *
088         * @param value1 the first value to compare
089         * @param value2 the other value to compare to the first
090         * @return 0 if both are equal, a negative value less than 0 if the first
091         * is less than the second, or a postive value if the first is greater than
092         * the second Object.
093         */
094        public int compareValue( V value1, V value2 )
095        {
096            throw new UnsupportedOperationException();
097        }
098    }