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Java > Open Source Codes > com > hp > hpl > jena > util > iterator > IteratorIterator


1 /*
2  * (c) Copyright 2000, 2001, 2002, 2003, 2004, 2005 Hewlett-Packard Development Company, LP
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * 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 1.4 2005/02/21 12:19:15 andy_seaborne Exp $
28  *
29  */
30
31 package com.hp.hpl.jena.util.iterator;
32
33 import java.util.Iterator JavaDoc;
34 import java.util.NoSuchElementException JavaDoc;
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: 1.4 $' Date='$Date: 2005/02/21 12:19:15 $'
41  */
42 public class IteratorIterator implements Iterator JavaDoc
43 {
44     private Iterator JavaDoc top;
45     private Iterator JavaDoc currentMember;
46
47 /** The first element of this Iterator is the first element of the
48  * first non-empty element of <code>e</code>.
49  * @param e An Iterator all of whose members are themselves Iterator's.
50  */
51     public IteratorIterator(Iterator JavaDoc e) {
52         top = e;
53         currentMember = null;
54     }
55
56 /** Is there another element in one of the Iterator's
57  * still to consider.
58  */
59     public boolean hasNext() {
60         while ( currentMember == null || !currentMember.hasNext() ) {
61             if (!top.hasNext())
62                 return false;
63             currentMember = (Iterator JavaDoc)top.next();
64         }
65         return true;
66     }
67
68     public Object JavaDoc next() {
69         hasNext();
70         if (currentMember == null)
71             throw new NoSuchElementException JavaDoc();
72         return currentMember.next();
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 JavaDoc();
80           currentMember.remove();
81         }
82 }
83
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