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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.api.ldap.model.schema.comparators;
21  
22  
23  import java.io.Serializable;
24  
25  import org.apache.directory.api.ldap.model.schema.LdapComparator;
26  import org.slf4j.Logger;
27  import org.slf4j.LoggerFactory;
28  
29  
30  /**
31   * A comparator for Strings.
32   * 
33   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
34   */
35  public class StringComparator extends LdapComparator<String> implements Serializable
36  {
37      /** The serial version UID */
38      private static final long serialVersionUID = 2L;
39  
40      /** A logger for this class */
41      private static final Logger LOG = LoggerFactory.getLogger( StringComparator.class );
42  
43  
44      /**
45       * The StringComparator constructor. Its OID is the StringMatch matching
46       * rule OID.
47       * 
48       * @param oid The Comparator's OID
49       */
50      public StringComparator( String oid )
51      {
52          super( oid );
53      }
54  
55  
56      /**
57       * {@inheritDoc}
58       */
59      public int compare( String s1, String s2 )
60      {
61          LOG.debug( "comparing String objects '{}' with '{}'", s1, s2 );
62  
63          if ( s1 == s2 )
64          {
65              return 0;
66          }
67  
68          // -------------------------------------------------------------------
69          // Handle some basis cases
70          // -------------------------------------------------------------------
71          if ( s1 == null )
72          {
73              return -1;
74          }
75  
76          if ( s2 == null )
77          {
78              return 1;
79          }
80  
81          return s1.compareTo( s2 );
82      }
83  }