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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.schema;
21  
22  
23  import java.io.Serializable;
24  import java.util.Comparator;
25  
26  import javax.naming.NamingException;
27  
28  import org.apache.directory.server.schema.registries.ComparatorRegistry;
29  
30  
31  /**
32   * A serializable wrapper around a Comparator which uses delayed initialization
33   * of the underlying wrapped comparator which is JIT resolved from a static
34   * global registry.
35   *
36   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
37   * @version $Rev: 610243 $
38   */
39  public class SerializableComparator<E> implements Comparator<E>, Serializable
40  {
41      private static final long serialVersionUID = 3257566226288162870L;
42  
43      /** the system global Comparator registry */
44      private static ComparatorRegistry registry;
45      /** the OID of the matchingRule for this comparator */
46      private String matchingRuleOid;
47      /** the transient wrapped comparator */
48      private transient Comparator<E> wrapped;
49  
50  
51      // ------------------------------------------------------------------------
52      // S T A T I C   M E T H O D S
53      // ------------------------------------------------------------------------
54  
55      /**
56       * Sets the global Comparator registry for comparator lookups.
57       *
58       * @param registry the comparator registry to use for Comparator lookups
59       */
60      public static void setRegistry( ComparatorRegistry registry )
61      {
62          SerializableComparator.registry = registry;
63      }
64  
65  
66      // ------------------------------------------------------------------------
67      // C O N T R U C T O R S
68      // ------------------------------------------------------------------------
69  
70  
71      public SerializableComparator( String matchingRuleOid )
72      {
73          this.matchingRuleOid = matchingRuleOid;
74      }
75  
76  
77      // ------------------------------------------------------------------------
78      // C O M P A R A T O R   I M P L E M E N T A T I O N S
79      // ------------------------------------------------------------------------
80  
81      /**
82       * @see java.util.Comparator#compare(java.lang.Object, java.lang.Object)
83       */
84      @SuppressWarnings("unchecked")
85      public int compare( E o1, E o2 )
86      {
87          if ( wrapped == null )
88          {
89              try
90              {
91                  wrapped = registry.lookup( matchingRuleOid );
92              }
93              catch ( NamingException e )
94              {
95                  throw new RuntimeException( "Matching rule not found: " + matchingRuleOid );
96              }
97          }
98  
99          return wrapped.compare( o1, o2 );
100     }
101 }