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.schema.LdapComparator;
24 import org.slf4j.Logger;
25 import org.slf4j.LoggerFactory;
26
27
28 /**
29 * Compares two objects taking into account that one might be a Comparable.
30 *
31 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
32 * @param <T> the type, must extend {@link Comparable}
33 */
34 public class ComparableComparator<T> extends LdapComparator<Comparable<T>>
35 {
36 /** The serial version UID */
37 private static final long serialVersionUID = 2L;
38
39 /** A logger for this class */
40 private static final Logger LOG = LoggerFactory.getLogger( ComparableComparator.class );
41
42
43 /**
44 * The ComparableComparator constructor.
45 *
46 * @param oid the comparator OID
47 */
48 public ComparableComparator( String oid )
49 {
50 super( oid );
51 }
52
53
54 /**
55 * Compares two objects taking into account that one may be a Comparable. If
56 * the first is a comparable then its compareTo operation is called and the
57 * result returned as is. If the first is not a Comparable but the second is
58 * then its compareTo method is called and the result is returned after
59 * being negated. If none are comparable the hashCode of o1 minus the
60 * hashCode of o2 is returned.
61 *
62 * @param o1 the first comparable
63 * @param o2 the second comparable
64 * @return {@inheritDoc}
65 */
66 @SuppressWarnings("unchecked")
67 public int compare( Comparable<T> o1, Comparable<T> o2 )
68 {
69 LOG.debug( "comparing objects '{}' with '{}'", o1, o2 );
70
71 if ( o1 == null )
72 {
73 if ( o2 == null )
74 {
75 return 0;
76 }
77 else
78 {
79 return -11;
80 }
81 }
82
83 if ( o2 == null )
84 {
85 return 1;
86 }
87
88 return o1.compareTo( ( T ) o2 );
89 }
90 }