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.slots;
22:
23: import com.db4o.foundation.Tree;
24: import com.db4o.internal.*;
25:
26: /**
27: * @exclude
28: */
29: public class ReferencedSlot extends TreeInt {
30:
31: private Slot _slot;
32:
33: private int _references;
34:
35: public ReferencedSlot(int a_key) {
36: super (a_key);
37: }
38:
39: public Object shallowClone() {
40: ReferencedSlot rs = new ReferencedSlot(_key);
41: rs._slot = _slot;
42: rs._references = _references;
43: return super .shallowCloneInternal(rs);
44: }
45:
46: public void pointTo(Slot slot) {
47: _slot = slot;
48: }
49:
50: public Tree free(LocalObjectContainer file, Tree treeRoot, Slot slot) {
51: file.free(_slot.address(), _slot.length());
52: if (removeReferenceIsLast()) {
53: if (treeRoot != null) {
54: return treeRoot.removeNode(this );
55: }
56: }
57: pointTo(slot);
58: return treeRoot;
59: }
60:
61: public boolean addReferenceIsFirst() {
62: _references++;
63: return (_references == 1);
64: }
65:
66: public boolean removeReferenceIsLast() {
67: _references--;
68: return _references < 1;
69: }
70:
71: public Slot slot() {
72: return _slot;
73: }
74:
75: }
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