01: /* Copyright (C) 2004 - 2007 db4objects Inc. http://www.db4o.com
02:
03: This file is part of the db4o open source object database.
04:
05: db4o is free software; you can redistribute it and/or modify it under
06: the terms of version 2 of the GNU General Public License as published
07: by the Free Software Foundation and as clarified by db4objects' GPL
08: interpretation policy, available at
09: http://www.db4o.com/about/company/legalpolicies/gplinterpretation/
10: Alternatively you can write to db4objects, Inc., 1900 S Norfolk Street,
11: Suite 350, San Mateo, CA 94403, USA.
12:
13: db4o is distributed in the hope that it will be useful, but WITHOUT ANY
14: WARRANTY; without even the implied warranty of MERCHANTABILITY or
15: FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16: for more details.
17:
18: You should have received a copy of the GNU General Public License along
19: with this program; if not, write to the Free Software Foundation, Inc.,
20: 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
21: package com.db4o.internal;
22:
23: /**
24: * @exclude
25: */
26: public class Null implements Indexable4 {
27:
28: public static final Indexable4 INSTANCE = new Null();
29:
30: public int compareTo(Object a_obj) {
31: if (a_obj == null) {
32: return 0;
33: }
34: return -1;
35: }
36:
37: public int linkLength() {
38: return 0;
39: }
40:
41: public Comparable4 prepareComparison(Object obj) {
42: // do nothing
43: return this ;
44: }
45:
46: public Object readIndexEntry(Buffer a_reader) {
47: return null;
48: }
49:
50: public void writeIndexEntry(Buffer a_writer, Object a_object) {
51: // do nothing
52: }
53:
54: public void defragIndexEntry(BufferPair readers) {
55: // do nothing
56: }
57: }
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