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 }