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: /**
24: * Adapts Iterable4/Iterator4 iteration model (moveNext, current) to the old db4o
25: * and jdk model (hasNext, next).
26: *
27: * @exclude
28: */
29: public class Iterable4Adaptor {
30:
31: private static final Object EOF = new Object();
32: private static final Object MOVE_NEXT = new Object();
33:
34: private final Iterable4 _delegate;
35:
36: private Iterator4 _iterator;
37:
38: private Object _current = MOVE_NEXT;
39:
40: public Iterable4Adaptor(Iterable4 delegate_) {
41: _delegate = delegate_;
42: }
43:
44: public boolean hasNext() {
45: if (_current == MOVE_NEXT) {
46: return moveNext();
47: }
48: return _current != EOF;
49: }
50:
51: public Object next() {
52: if (!hasNext()) {
53: throw new IllegalStateException();
54: }
55: Object returnValue = _current;
56: _current = MOVE_NEXT;
57: return returnValue;
58: }
59:
60: private boolean moveNext() {
61: if (null == _iterator) {
62: _iterator = _delegate.iterator();
63: }
64: if (_iterator.moveNext()) {
65: _current = _iterator.current();
66: return true;
67: }
68: _current = EOF;
69: return false;
70: }
71:
72: public void reset() {
73: _iterator = null;
74: _current = MOVE_NEXT;
75: }
76: }
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