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 2000 (C) Cees de Groot. All Rights Reserved.
43 * Contributions are Copyright (C) 2000 by their associated contributors.
44 *
45 * $Id: Location.java,v 1.2 2003/11/01 14:17:21 dranatunga Exp $
46 */
47
48 package jdbm.recman;
49
50 /**
51 * This class represents a location within a file. Both physical and
52 * logical rowids are based on locations internally - this version is
53 * used when there is no file block to back the location's data.
54 */
55 final class Location {
56 private long block;
57 private short offset;
58
59 /**
60 * Creates a location from a (block, offset) tuple.
61 */
62 Location(long block, short offset) {
63 this.block = block;
64 this.offset = offset;
65 }
66
67 /**
68 * Creates a location from a combined block/offset long, as
69 * used in the external representation of logical rowids.
70 *
71 * @see #toLong()
72 */
73 Location(long blockOffset) {
74 this.offset = (short) (blockOffset & 0xffff);
75 this.block = blockOffset >> 16;
76 }
77
78 /**
79 * Creates a location based on the data of the physical rowid.
80 */
81 Location(PhysicalRowId src) {
82 block = src.getBlock();
83 offset = src.getOffset();
84 }
85
86 /**
87 * Returns the file block of the location
88 */
89 long getBlock() {
90 return block;
91 }
92
93 /**
94 * Returns the offset within the block of the location
95 */
96 short getOffset() {
97 return offset;
98 }
99
100 /**
101 * Returns the external representation of a location when used
102 * as a logical rowid, which combines the block and the offset
103 * in a single long.
104 */
105 long toLong() {
106 return (block << 16) + (long) offset;
107 }
108
109 // overrides of java.lang.Object
110
111 public boolean equals(Object o) {
112 if (o == null || !(o instanceof Location))
113 return false;
114 Location ol = (Location) o;
115 return ol.block == block && ol.offset == offset;
116 }
117
118 public String toString() {
119 return "PL(" + block + ":" + offset + ")";
120 }
121 }