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Java > Open Source Codes > com > db4o > foundation > CompositeIterator4


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.foundation;
22
23
24 public class CompositeIterator4 implements Iterator4 {
25
26     private final Iterator4 _iterators;
27
28     private Iterator4 _currentIterator;
29     
30     public CompositeIterator4(Iterator4[] iterators) {
31         this(new ArrayIterator4(iterators));
32     }
33
34     public CompositeIterator4(Iterator4 iterators) {
35         if (null == iterators) {
36             throw new ArgumentNullException();
37         }
38         _iterators = iterators;
39     }
40
41     public boolean moveNext() {
42         if (null == _currentIterator) {
43             if (!_iterators.moveNext()) {
44                 return false;
45             }
46             _currentIterator = nextIterator(_iterators.current());
47         }
48         if (!_currentIterator.moveNext()) {
49             _currentIterator = null;
50             return moveNext();
51         }
52         return true;
53     }
54     
55     public void reset() {
56         resetIterators();
57         _currentIterator = null;
58         _iterators.reset();
59     }
60
61     private void resetIterators() {
62         _iterators.reset();
63         while (_iterators.moveNext()) {
64             nextIterator(_iterators.current()).reset();
65         }
66     }
67     
68     public Iterator4 currentIterator() {
69         return _currentIterator;
70     }
71
72     public Object JavaDoc current() {
73         return _currentIterator.current();
74     }
75     
76     protected Iterator4 nextIterator(final Object JavaDoc current) {
77         return (Iterator4)current;
78     }
79 }
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