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 2000 (C) Cees de Groot. All Rights Reserved.
043: * Contributions are Copyright (C) 2000 by their associated contributors.
044: *
045: * $Id: Location.java,v 1.2 2003/11/01 14:17:21 dranatunga Exp $
046: */package jdbm.recman;
047:
048: /**
049: * This class represents a location within a file. Both physical and
050: * logical rowids are based on locations internally - this version is
051: * used when there is no file block to back the location's data.
052: */
053: final class Location {
054: private long block;
055: private short offset;
056:
057: /**
058: * Creates a location from a (block, offset) tuple.
059: */
060: Location(long block, short offset) {
061: this .block = block;
062: this .offset = offset;
063: }
064:
065: /**
066: * Creates a location from a combined block/offset long, as
067: * used in the external representation of logical rowids.
068: *
069: * @see #toLong()
070: */
071: Location(long blockOffset) {
072: this .offset = (short) (blockOffset & 0xffff);
073: this .block = blockOffset >> 16;
074: }
075:
076: /**
077: * Creates a location based on the data of the physical rowid.
078: */
079: Location(PhysicalRowId src) {
080: block = src.getBlock();
081: offset = src.getOffset();
082: }
083:
084: /**
085: * Returns the file block of the location
086: */
087: long getBlock() {
088: return block;
089: }
090:
091: /**
092: * Returns the offset within the block of the location
093: */
094: short getOffset() {
095: return offset;
096: }
097:
098: /**
099: * Returns the external representation of a location when used
100: * as a logical rowid, which combines the block and the offset
101: * in a single long.
102: */
103: long toLong() {
104: return (block << 16) + (long) offset;
105: }
106:
107: // overrides of java.lang.Object
108:
109: public boolean equals(Object o) {
110: if (o == null || !(o instanceof Location))
111: return false;
112: Location ol = (Location) o;
113: return ol.block == block && ol.offset == offset;
114: }
115:
116: public String toString() {
117: return "PL(" + block + ":" + offset + ")";
118: }
119: }
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