001 /**
002 * JDBM LICENSE v1.00
003 *
004 * Redistribution and use of this software and associated documentation
005 * ("Software"), with or without modification, are permitted provided
006 * that the following conditions are met:
007 *
008 * 1. Redistributions of source code must retain copyright
009 * statements and notices. Redistributions must also contain a
010 * copy of this document.
011 *
012 * 2. Redistributions in binary form must reproduce the
013 * above copyright notice, this list of conditions and the
014 * following disclaimer in the documentation and/or other
015 * materials provided with the distribution.
016 *
017 * 3. The name "JDBM" must not be used to endorse or promote
018 * products derived from this Software without prior written
019 * permission of Cees de Groot. For written permission,
020 * please contact cg@cdegroot.com.
021 *
022 * 4. Products derived from this Software may not be called "JDBM"
023 * nor may "JDBM" appear in their names without prior written
024 * permission of Cees de Groot.
025 *
026 * 5. Due credit should be given to the JDBM Project
027 * (http://jdbm.sourceforge.net/).
028 *
029 * THIS SOFTWARE IS PROVIDED BY THE JDBM PROJECT AND CONTRIBUTORS
030 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
031 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
032 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
033 * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
034 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
035 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
036 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
037 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
038 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
039 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
040 * OF THE POSSIBILITY OF SUCH DAMAGE.
041 *
042 * Copyright 2001 (C) Alex Boisvert. All Rights Reserved.
043 * Contributions are Copyright (C) 2001 by their associated contributors.
044 *
045 */
046
047 package jdbm.helper;
048
049 import java.io.IOException;
050 import java.io.Serializable;
051 import java.util.Comparator;
052
053 /**
054 * Comparator for objects which have been serialized into byte arrays.
055 * In effect, it wraps another Comparator which compares object and provides
056 * transparent deserialization from byte array to object.
057 *
058 * @author <a href="mailto:boisvert@intalio.com">Alex Boisvert</a>
059 * @version $Id: ObjectBAComparator.java,v 1.1 2002/05/31 06:33:20 boisvert Exp $
060 */
061 public final class ObjectBAComparator
062 implements Comparator, Serializable
063 {
064
065 /**
066 * Version id for serialization.
067 */
068 final static long serialVersionUID = 1L;
069
070
071 /**
072 * Wrapped comparator.
073 */
074 private Comparator _comparator;
075
076
077 /**
078 * Construct an ObjectByteArrayComparator which wraps an Object Comparator.
079 *
080 * @param comparator Object comparator.
081 */
082 public ObjectBAComparator( Comparator comparator )
083 {
084 if ( comparator == null ) {
085 throw new IllegalArgumentException( "Argument 'comparator' is null" );
086 }
087
088 _comparator = comparator;
089 }
090
091
092 /**
093 * Compare two objects.
094 *
095 * @param obj1 First object
096 * @param obj2 Second object
097 * @return 1 if obj1 > obj2, 0 if obj1 == obj2, -1 if obj1 < obj2
098 */
099 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 }