1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.directory.api.ldap.model.schema.comparators;
21
22
23 import org.apache.directory.api.ldap.model.entry.StringValue;
24 import org.apache.directory.api.ldap.model.schema.LdapComparator;
25 import org.slf4j.Logger;
26 import org.slf4j.LoggerFactory;
27
28
29 /**
30 * A comparator for CSN.
31 *
32 * The CSN are ordered depending on an evaluation of its component, in this order :
33 * - time,
34 * - changeCount,
35 * - sid
36 * - modifierNumber
37 *
38 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
39 */
40 public class CsnComparator extends LdapComparator<Object>
41 {
42 /** The serial version UID */
43 private static final long serialVersionUID = 2L;
44
45 /** A logger for this class */
46 private static final Logger LOG = LoggerFactory.getLogger( CsnComparator.class );
47
48
49 /**
50 * The CsnComparator constructor. Its OID is the CsnMatch matching
51 * rule OID.
52 */
53 public CsnComparator( String oid )
54 {
55 super( oid );
56 }
57
58
59 /**
60 * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
61 */
62 public int compare( Object csnObj1, Object csnObj2 )
63 {
64 LOG.debug( "comparing CSN objects '{}' with '{}'", csnObj1, csnObj2 );
65
66 if ( csnObj1 == csnObj2 )
67 {
68 return 0;
69 }
70
71 // -------------------------------------------------------------------
72 // Handle some basis cases
73 // -------------------------------------------------------------------
74 if ( csnObj1 == null )
75 {
76 return ( csnObj2 == null ) ? 0 : -1;
77 }
78
79 if ( csnObj2 == null )
80 {
81 return 1;
82 }
83
84 String csnStr1 = null;
85 String csnStr2 = null;
86
87 if ( csnObj1 instanceof StringValue )
88 {
89 csnStr1 = ( ( StringValue ) csnObj1 ).getValue();
90 }
91 else
92 {
93 csnStr1 = csnObj1.toString();
94 }
95
96 if ( csnObj2 instanceof StringValue )
97 {
98 csnStr2 = ( ( StringValue ) csnObj2 ).getValue();
99 }
100 else
101 {
102 csnStr2 = csnObj2.toString();
103 }
104
105 return csnStr1.compareTo( csnStr2 );
106 }
107 }