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Java > Open Source Codes > com > caucho > db > index > StringKeyCompare


1 /*
2  * Copyright (c) 1998-2006 Caucho Technology -- all rights reserved
3  *
4  * This file is part of Resin(R) Open Source
5  *
6  * Each copy or derived work must preserve the copyright notice and this
7  * notice unmodified.
8  *
9  * Resin Open Source is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License as published by
11  * the Free Software Foundation; either version 2 of the License, or
12  * (at your option) any later version.
13  *
14  * Resin Open Source is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, or any warranty
17  * of NON-INFRINGEMENT. See the GNU General Public License for more
18  * details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with Resin Open Source; if not, write to the
22  *
23  * Free Software Foundation, Inc.
24  * 59 Temple Place, Suite 330
25  * Boston, MA 02111-1307 USA
26  *
27  * @author Scott Ferguson
28  */
29
30 package com.caucho.db.index;
31
32 /**
33  * Compares two keys.
34  */
35 public class StringKeyCompare extends KeyCompare {
36   /**
37    * Compares the key to the block data.
38    */
39   public int compare(byte []keyBuffer, int keyOffset,
40              byte []block, int offset, int length)
41   {
42     int keyLen = keyBuffer[keyOffset];
43     int blockLen = block[offset];
44
45     int keySize = 2 * keyLen;
46     int blockSize = 2 * blockLen;
47     
48     int end = keySize;
49     if (blockSize < end)
50       end = blockSize;
51     
52     for (int i = 1; i <= end; i++) {
53       int ch1 = keyBuffer[keyOffset + i] & 0xff;
54       int ch2 = block[offset + i] & 0xff;
55
56       if (ch1 < ch2)
57     return -1;
58       else if (ch2 < ch1)
59     return 1;
60     }
61
62     if (keyLen < blockLen)
63       return -1;
64     else if (blockLen < keyLen)
65       return 1;
66     else
67       return 0;
68   }
69
70   public String JavaDoc toString(byte []buffer, int offset, int length)
71   {
72     StringBuilder JavaDoc sb = new StringBuilder JavaDoc();
73     
74     int keyLen = buffer[offset];
75
76     for (int j = 0; j < keyLen; j++) {
77       int ch1 = buffer[offset + 1 + 2 * j] & 0xff;
78       int ch2 = buffer[offset + 1 + 2 * j + 1] & 0xff;
79
80       int ch = (ch1 << 8) + ch2;
81
82       if (ch == 0)
83     break;
84       
85       sb.append((char) ch);
86     }
87
88     return sb.toString();
89   }
90 }
91
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