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1   /*
2    *   Copyright 2004 The Apache Software Foundation
3    *
4    *   Licensed under the Apache License, Version 2.0 (the "License");
5    *   you may not use this file except in compliance with the License.
6    *   You may obtain a copy of the License at
7    *
8    *       http://www.apache.org/licenses/LICENSE-2.0
9    *
10   *   Unless required by applicable law or agreed to in writing, software
11   *   distributed under the License is distributed on an "AS IS" BASIS,
12   *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   *   See the License for the specific language governing permissions and
14   *   limitations under the License.
15   *
16   */
17  package org.apache.ldap.server.partition.impl.btree;
18  
19  
20  import org.apache.ldap.common.util.BigIntegerComparator;
21  import org.apache.ldap.server.schema.SerializableComparator;
22  
23  
24  /***
25   * TupleComparator for index records.
26   *
27   * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
28   * @version $Rev: 264732 $
29   */
30  public class IndexComparator implements TupleComparator
31  {
32      private static final long serialVersionUID = 3257283621751633459L;
33  
34      private static final SerializableComparator BIG_INTEGER_COMPARATOR = 
35          new SerializableComparator( "1.2.6.1.4.1.18060.1.1.1.2.2" )
36          {
37              private static final long serialVersionUID = 3690478030414165816L;
38  
39              public int compare( Object o1, Object o2 )
40              {
41                  return BigIntegerComparator.INSTANCE.compare( o1, o2 );
42              }
43          };
44      /*** Whether or not the key/value is swapped */
45      private final boolean isForwardMap;
46      /*** The key comparison to use */
47      private final SerializableComparator keyComp;
48  
49  
50      /***
51       * Creates an IndexComparator.
52       *
53       * @param keyComp the table comparator to use for keys
54       * @param isForwardMap whether or not the comparator should swap the 
55       * key value pair while conducting comparisons.
56       */
57      public IndexComparator( SerializableComparator keyComp, boolean isForwardMap )
58      {
59          this.keyComp = keyComp;
60          this.isForwardMap = isForwardMap;
61      }
62  
63  
64      /***
65       * Gets the comparator used to compare keys.  May be null in which
66       * case the compareKey method will throw an UnsupportedOperationException.
67       *
68       * @return the comparator for comparing keys.
69       */
70      public SerializableComparator getKeyComparator()
71      {
72          if ( isForwardMap ) 
73          {
74              return keyComp;
75          }
76  
77          return BIG_INTEGER_COMPARATOR;
78      }
79  
80  
81      /***
82       * Gets the binary comparator used to compare valuess.  May be null in which
83       * case the compareValue method will throw an UnsupportedOperationException.
84       *
85       * @return the binary comparator for comparing values.
86       */
87      public SerializableComparator getValueComparator()
88      {
89          if ( isForwardMap ) 
90          {
91              return BIG_INTEGER_COMPARATOR;
92          }
93  
94          return keyComp;
95      }
96  
97  
98      /***
99       * Compares key Object to determine their sorting order returning a
100      * value = to, < or > than 0.
101      *
102      * @param key1 the first key to compare
103      * @param key2 the other key to compare to the first
104      * @return 0 if both are equal, a negative value less than 0 if the first
105      * is less than the second, or a postive value if the first is greater than
106      * the second byte array.
107      */
108     public int compareKey( Object key1, Object key2 )
109     {
110         return getKeyComparator().compare( key1, key2 );
111     }
112 
113 
114     /***
115      * Comparse value Objects to determine their sorting order returning a
116      * value = to, < or > than 0.
117      *
118      * @param value1 the first value to compare
119      * @param value2 the other value to compare to the first
120      * @return 0 if both are equal, a negative value less than 0 if the first
121      * is less than the second, or a postive value if the first is greater than
122      * the second Object.
123      */
124     public int compareValue( Object value1, Object value2 )
125     {
126         return getValueComparator().compare( value1, value2 );
127     }
128 }