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