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.server.core.partition.impl.btree;
21
22
23 import org.apache.directory.api.ldap.model.schema.comparators.SerializableComparator;
24
25
26 /**
27 * TupleComparator for index records.
28 *
29 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
30 */
31 public class ReverseIndexComparator<V> implements TupleComparator<Long, V>
32 {
33 private static final long serialVersionUID = 3257283621751633459L;
34
35 /** The value comparison to use - keys are Longs */
36 private final SerializableComparator<V> valueComparator;
37
38
39 /**
40 * Creates an IndexComparator.
41 *
42 * @param valueComparator the table comparator to use for values
43 */
44 public ReverseIndexComparator( SerializableComparator<V> valueComparator )
45 {
46 this.valueComparator = valueComparator;
47 }
48
49
50 /**
51 * Gets the comparator used to compare keys.
52 *
53 * @return the comparator for comparing keys.
54 */
55 public SerializableComparator<Long> getKeyComparator()
56 {
57 return LongComparator.INSTANCE;
58 }
59
60
61 /**
62 * Gets the binary comparator used to compare values which are the values
63 * of attributes.
64 *
65 * @return the binary comparator for comparing values.
66 */
67 public SerializableComparator<V> getValueComparator()
68 {
69 return valueComparator;
70 }
71
72
73 /**
74 * Compares key Object to determine their sorting order returning a
75 * value = to, < or > than 0.
76 *
77 * @param l1 the first long key to compare
78 * @param l2 the other long key to compare to the first
79 * @return 0 if both are equal, a negative value less than 0 if the first
80 * is less than the second, or a positive value if the first is greater than
81 * the second byte array.
82 */
83 public int compareKey( Long l1, Long l2 )
84 {
85 return ( l1 < l2 ? -1 : ( l1.equals( l2 ) ? 0 : 1 ) );
86 }
87
88
89 /**
90 * Comparse value Objects to determine their sorting order returning a
91 * value = to, < or > than 0.
92 *
93 * @param v1 the first value to compare
94 * @param v2 the other value to compare to the first
95 * @return 0 if both are equal, a negative value less than 0 if the first
96 * is less than the second, or a positive value if the first is greater than
97 * the second Object.
98 */
99 public int compareValue( V v1, V v2 )
100 {
101 return valueComparator.compare( v1, v2 );
102 }
103 }