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.mavibot.btree;
21
22
23 import java.util.Arrays;
24 import java.util.Comparator;
25
26
27 /**
28 * A comparator for the RevisionOffset class
29 *
30 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
31 */
32 /* no qualifier*/class RevisionOffsetComparator implements Comparator<RevisionOffset>
33 {
34 /** A static instance of a RevisionOffsetComparator */
35 public static final RevisionOffsetComparator INSTANCE = new RevisionOffsetComparator();
36
37 public static final RevisionOffsetComparator INSTANCE_DESC_ORDER = new RevisionOffsetComparator( true );
38
39 private boolean desc;
40
41 /**
42 * A private constructor of the RevisionOffsetComparator class
43 */
44 private RevisionOffsetComparator()
45 {
46 }
47
48
49 private RevisionOffsetComparator( boolean desc )
50 {
51 this.desc = desc;
52 }
53
54
55 /**
56 * {@inheritDoc}
57 */
58 public int compare( RevisionOffset rn1, RevisionOffset rn2 )
59 {
60 if ( rn1 == rn2 )
61 {
62 return 0;
63 }
64
65 // the RevisionOffset will never be used as a key
66
67 // First compare the revisions
68 if ( rn1.getRevision() < rn2.getRevision() )
69 {
70 return desc ? 1 : -1;
71 }
72 else if ( rn1.getRevision() > rn2.getRevision() )
73 {
74 return desc ? -1 : 1;
75 }
76
77 // ignore the offsets
78 return 0;
79 }
80 }