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
025
026 /**
027 * A comparator for UUID. We simply use the UUID compareTo method.
028 *
029 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
030 * @version $Rev$
031 */
032 public class UUIDComparator implements Comparator<byte[]>
033 {
034 /** A static instance of this comparator */
035 public static final Comparator<byte[]> INSTANCE = new UUIDComparator();
036
037
038 /**
039 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
040 */
041 public int compare( byte[] uuid1, byte[] uuid2 )
042 {
043 // -------------------------------------------------------------------
044 // Handle some basis cases
045 // -------------------------------------------------------------------
046 if ( uuid1 == null )
047 {
048 return ( uuid2 == null ) ? 0 : -1;
049 }
050
051 if ( uuid2 == null )
052 {
053 return 1;
054 }
055
056 if ( uuid1.length < uuid2.length )
057 {
058 return -1;
059 }
060 else if ( uuid1.length > uuid2.length )
061 {
062 return 1;
063 }
064
065 for ( int pos = 0; pos < uuid1.length; pos++ )
066 {
067 if ( uuid1[pos] == uuid2[pos ] )
068 {
069 continue;
070 }
071
072 if ( uuid1[pos] < uuid2[pos] )
073 {
074 return -1;
075 }
076 else
077 {
078 return 1;
079 }
080 }
081
082 return 0;
083 }
084 }