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


1 /* (c) Copyright 2001, 2002, 2003, 2004, 2005 Hewlett-Packard Development Company, LP
2      [See end of file]
3
4      $Id: NullIterator.java,v 1.7 2005/02/21 12:19:16 andy_seaborne Exp $
5  */
6
7 package com.hp.hpl.jena.util.iterator;
8
9 /**
10      An empty iterator. The specialised versions of andThen() eliminate left operands
11      that are empty iterators from cascaded sequences.
12 */
13 public class NullIterator extends NiceIterator
14     {
15     public static NullIterator instance = new NullIterator();
16     
17     public ExtendedIterator andThen( ClosableIterator it )
18         {
19         return it instanceof ExtendedIterator
20             ? (ExtendedIterator) it
21             : super.andThen( it )
22             ;
23         }
24     }
25
26
27 /*
28      (c) Copyright 2001, 2002, 2003, 2004, 2005 Hewlett-Packard Development Company, LP
29      All rights reserved.
30      
31      Redistribution and use in source and binary forms, with or without
32      modification, are permitted provided that the following conditions
33      are met:
34      1. Redistributions of source code must retain the above copyright
35         notice, this list of conditions and the following disclaimer.
36      2. Redistributions in binary form must reproduce the above copyright
37         notice, this list of conditions and the following disclaimer in the
38         documentation and/or other materials provided with the distribution.
39      3. The name of the author may not be used to endorse or promote products
40         derived from this software without specific prior written permission.
41      
42      THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
43      IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
44      OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
45      IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
46      INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
47      NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
48      DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
49      THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
50      (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
51      THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
52  */
53
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