01: /*
02: * (c) Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 Hewlett-Packard Development Company, LP
03: * All rights reserved.
04: *
05: * Redistribution and use in source and binary forms, with or without
06: * modification, are permitted provided that the following conditions
07: * are met:
08: * 1. Redistributions of source code must retain the above copyright
09: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. The name of the author may not be used to endorse or promote products
14: * derived from this software without specific prior written permission.
15:
16: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26: *
27: * $Id: IteratorIterator.java,v 1.7 2008/01/02 12:07:36 andy_seaborne Exp $
28: *
29: */
30:
31: package com.hp.hpl.jena.util.iterator;
32:
33: import java.util.Iterator;
34: import java.util.NoSuchElementException;
35:
36: /** Given an Iterator that returns Iterator's, this creates an
37: * Iterator over the next level values.
38: * Similar to list splicing in lisp.
39: * @author jjc
40: * @version Release='$Name: $' Revision='$Revision: 1.7 $' Date='$Date: 2008/01/02 12:07:36 $'
41: */
42: public class IteratorIterator implements Iterator {
43: private Iterator top;
44: private Iterator currentMember;
45:
46: /** The first element of this Iterator is the first element of the
47: * first non-empty element of <code>e</code>.
48: * @param e An Iterator all of whose members are themselves Iterator's.
49: */
50: public IteratorIterator(Iterator e) {
51: top = e;
52: currentMember = null;
53: }
54:
55: /** Is there another element in one of the Iterator's
56: * still to consider.
57: */
58: public boolean hasNext() {
59: while (currentMember == null || !currentMember.hasNext()) {
60: if (!top.hasNext())
61: return false;
62: currentMember = (Iterator) top.next();
63: }
64: return true;
65: }
66:
67: public Object next() {
68: hasNext();
69: if (currentMember == null)
70: throw new NoSuchElementException();
71: return currentMember.next();
72: }
73:
74: /** remove's the element from the underlying Iterator
75: * in which it is a member.
76: */
77: public void remove() {
78: if (currentMember == null)
79: throw new IllegalStateException();
80: currentMember.remove();
81: }
82: }
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