KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > com > db4o > inside > btree > AbstractBTreeRangeIterator


1 /* Copyright (C) 2004 - 2006 db4objects Inc. http://www.db4o.com
2
3 This file is part of the db4o open source object database.
4
5 db4o is free software; you can redistribute it and/or modify it under
6 the terms of version 2 of the GNU General Public License as published
7 by the Free Software Foundation and as clarified by db4objects' GPL
8 interpretation policy, available at
9 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.inside.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 JavaDoc();
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 }
Popular Tags