1 /**
2 * JDBM LICENSE v1.00
3 *
4 * Redistribution and use of this software and associated documentation
5 * ("Software"), with or without modification, are permitted provided
6 * that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain copyright
9 * statements and notices. Redistributions must also contain a
10 * copy of this document.
11 *
12 * 2. Redistributions in binary form must reproduce the
13 * above copyright notice, this list of conditions and the
14 * following disclaimer in the documentation and/or other
15 * materials provided with the distribution.
16 *
17 * 3. The name "JDBM" must not be used to endorse or promote
18 * products derived from this Software without prior written
19 * permission of Cees de Groot. For written permission,
20 * please contact cg@cdegroot.com.
21 *
22 * 4. Products derived from this Software may not be called "JDBM"
23 * nor may "JDBM" appear in their names without prior written
24 * permission of Cees de Groot.
25 *
26 * 5. Due credit should be given to the JDBM Project
27 * (http://jdbm.sourceforge.net/).
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
30 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
31 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
32 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
33 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
34 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
35 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
36 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
38 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
39 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
40 * OF THE POSSIBILITY OF SUCH DAMAGE.
41 *
42 * Copyright 2001 (C) Alex Boisvert. All Rights Reserved.
43 * Contributions are Copyright (C) 2001 by their associated contributors.
44 *
45 */
46
47 package jdbm.helper;
48
49 import java.io.IOException;
50 import java.io.Serializable;
51 import java.util.Comparator;
52
53 /**
54 * Comparator for objects which have been serialized into byte arrays.
55 * In effect, it wraps another Comparator which compares object and provides
56 * transparent deserialization from byte array to object.
57 *
58 * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a>
59 * @version $Id: ObjectBAComparator.java,v 1.1 2002/05/31 06:33:20 boisvert Exp $
60 */
61 public final class ObjectBAComparator
62 implements Comparator, Serializable
63 {
64
65 /**
66 * Version id for serialization.
67 */
68 final static long serialVersionUID = 1L;
69
70
71 /**
72 * Wrapped comparator.
73 */
74 private Comparator _comparator;
75
76
77 /**
78 * Construct an ObjectByteArrayComparator which wraps an Object Comparator.
79 *
80 * @param comparator Object comparator.
81 */
82 public ObjectBAComparator( Comparator comparator )
83 {
84 if ( comparator == null ) {
85 throw new IllegalArgumentException( "Argument 'comparator' is null" );
86 }
87
88 _comparator = comparator;
89 }
90
91
92 /**
93 * Compare two objects.
94 *
95 * @param obj1 First object
96 * @param obj2 Second object
97 * @return 1 if obj1 > obj2, 0 if obj1 == obj2, -1 if obj1 < obj2
98 */
99 public int compare( Object obj1, Object obj2 )
100 {
101 if ( obj1 == null ) {
102 throw new IllegalArgumentException( "Argument 'obj1' is null" );
103 }
104
105 if ( obj2 == null ) {
106 throw new IllegalArgumentException( "Argument 'obj2' is null" );
107 }
108
109 try {
110 obj1 = Serialization.deserialize( (byte[]) obj1 );
111 obj2 = Serialization.deserialize( (byte[]) obj2 );
112
113 return _comparator.compare( obj1, obj2 );
114 } catch ( IOException except ) {
115 throw new WrappedRuntimeException( except );
116 } catch ( ClassNotFoundException except ) {
117 throw new WrappedRuntimeException( except );
118 }
119 }
120
121
122 /**
123 * Compare two byte arrays.
124 */
125 public static int compareByteArray( byte[] thisKey, byte[] otherKey )
126 {
127 int len = Math.min( thisKey.length, otherKey.length );
128
129 // compare the byte arrays
130 for ( int i=0; i<len; i++ ) {
131 if ( thisKey[i] >= 0 ) {
132 if ( otherKey[i] >= 0 ) {
133 // both positive
134 if ( thisKey[i] < otherKey[i] ) {
135 return -1;
136 } else if ( thisKey[i] > otherKey[i] ) {
137 return 1;
138 }
139 } else {
140 // otherKey is negative => greater (because MSB is 1)
141 return -1;
142 }
143 } else {
144 if ( otherKey[i] >= 0 ) {
145 // thisKey is negative => greater (because MSB is 1)
146 return 1;
147 } else {
148 // both negative
149 if ( thisKey[i] < otherKey[i] ) {
150 return -1;
151 } else if ( thisKey[i] > otherKey[i] ) {
152 return 1;
153 }
154 }
155 }
156 }
157 if ( thisKey.length == otherKey.length) {
158 return 0;
159 }
160 if ( thisKey.length < otherKey.length ) {
161 return -1;
162 }
163 return 1;
164 }
165
166 }