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: import java.util.*;
24:
25: public class Iterator4JdkIterator implements Iterator {
26:
27: private static final Object BEFORE_START = new Object();
28:
29: private static final Object BEYOND_END = new Object();
30:
31: private final Iterator4 _delegate;
32:
33: private Object _current;
34:
35: public Iterator4JdkIterator(Iterator4 i) {
36: _delegate = i;
37: _current = BEFORE_START;
38: }
39:
40: public boolean hasNext() {
41: checkBeforeStart();
42: return _current != BEYOND_END;
43: }
44:
45: public Object next() {
46: checkBeforeStart();
47: if (_current == BEYOND_END) {
48: throw new NoSuchElementException();
49: }
50: Object result = _current;
51: if (_delegate.moveNext()) {
52: _current = _delegate.current();
53: } else {
54: _current = BEYOND_END;
55: }
56: return result;
57: }
58:
59: private void checkBeforeStart() {
60: if (_current != BEFORE_START) {
61: return;
62: }
63: if (_delegate.moveNext()) {
64: _current = _delegate.current();
65: } else {
66: _current = BEYOND_END;
67: }
68: }
69:
70: public void remove() {
71: throw new UnsupportedOperationException();
72: }
73:
74: }
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