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.btree;
22:
23: import com.db4o.foundation.*;
24:
25: public abstract class AbstractBTreeRangeIterator implements Iterator4 {
26:
27: private final BTreeRangeSingle _range;
28: private BTreePointer _cursor;
29: private BTreePointer _current;
30:
31: public AbstractBTreeRangeIterator(BTreeRangeSingle range) {
32: _range = range;
33: _cursor = range.first();
34: }
35:
36: public boolean moveNext() {
37: if (reachedEnd(_cursor)) {
38: _current = null;
39: return false;
40: }
41: _current = _cursor;
42: _cursor = _cursor.next();
43: return true;
44: }
45:
46: public void reset() {
47: _cursor = _range.first();
48: }
49:
50: protected BTreePointer currentPointer() {
51: if (null == _current) {
52: throw new IllegalStateException();
53: }
54: return _current;
55: }
56:
57: private boolean reachedEnd(BTreePointer cursor) {
58: if (cursor == null) {
59: return true;
60: }
61: if (_range.end() == null) {
62: return false;
63: }
64: return _range.end().equals(cursor);
65: }
66: }
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