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Java > Open Source Codes > net > sf > jga > util > FindAllIterator


1 // ============================================================================
2 // $Id: FindAllIterator.java,v 1.6 2006/10/19 01:43:44 davidahall Exp $
3 // Copyright (c) 2004-2005 David A. Hall
4 // ============================================================================
5 // The contents of this file are subject to the Common Development and
6 // Distribution License (CDDL), Version 1.0 (the License); you may not use this
7 // file except in compliance with the License. You should have received a copy
8 // of the the License along with this file: if not, a copy of the License is
9 // available from Sun Microsystems, Inc.
10 //
11 // http://www.sun.com/cddl/cddl.html
12 //
13 // From time to time, the license steward (initially Sun Microsystems, Inc.) may
14 // publish revised and/or new versions of the License. You may not use,
15 // distribute, or otherwise make this file available under subsequent versions
16 // of the License.
17 //
18 // Alternatively, the contents of this file may be used under the terms of the
19 // GNU Lesser General Public License Version 2.1 or later (the "LGPL"), in which
20 // case the provisions of the LGPL are applicable instead of those above. If you
21 // wish to allow use of your version of this file only under the terms of the
22 // LGPL, and not to allow others to use your version of this file under the
23 // terms of the CDDL, indicate your decision by deleting the provisions above
24 // and replace them with the notice and other provisions required by the LGPL.
25 // If you do not delete the provisions above, a recipient may use your version
26 // of this file under the terms of either the CDDL or the LGPL.
27 //
28 // This library is distributed in the hope that it will be useful,
29 // but WITHOUT ANY WARRANTY; without even the implied warranty of
30 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
31 // ============================================================================
32
33 package net.sf.jga.util;
34
35 import java.util.Iterator JavaDoc;
36 import java.util.NoSuchElementException JavaDoc;
37 import net.sf.jga.fn.UnaryFunctor;
38
39 /**
40  * Iterator that applies one of the FindX functors as many times as possible.
41  * Formally, this iterator uses a functor that takes one iterator and returns
42  * an iterator, and repeatedly applies it to a given iterator until the result
43  * iterator's <code>hasNext()</code> method is false.
44  * <p>
45  * Copyright &copy; 2004-2005 David A. Hall
46  *
47  * @author <a HREF="mailto:davidahall@users.sourceforge.net">David A. Hall</a>
48  **/
49
50 public class FindAllIterator<T>
51     implements Iterable JavaDoc<Iterator JavaDoc<? extends T>>, Iterator JavaDoc<Iterator JavaDoc<? extends T>>
52 {
53
54     // the base iterator
55 private Iterator JavaDoc<? extends T> _iter;
56
57     // the functor
58 private UnaryFunctor<Iterator JavaDoc<? extends T>, ? extends Iterator JavaDoc<T>> _fn;
59
60     // three state flag indicating that the test was done and its results
61 private Boolean JavaDoc _tested;
62     
63     /**
64      * Builds a FindAllIterator that will apply the given functor to the given
65      * iterator.
66      */
67     public FindAllIterator(Iterator JavaDoc<? extends T> it,
68                            UnaryFunctor<Iterator JavaDoc<? extends T>,? extends Iterator JavaDoc<T>> fn)
69     {
70         _iter = it;
71         _fn = fn;
72     }
73  
74     // - - - - - - - - - - -
75 // Iterable<T> interface
76 // - - - - - - - - - - -
77
78     public Iterator JavaDoc<Iterator JavaDoc<? extends T>> iterator() { return this; }
79     
80     // - - - - - - - - - - -
81 // Iterator<T> interface
82 // - - - - - - - - - - -
83
84     public boolean hasNext() {
85         _iter = _fn.fn(_iter);
86         _tested = Boolean.valueOf(_iter.hasNext());
87         return _tested;
88     }
89
90     public Iterator JavaDoc<? extends T> next() {
91         if (_tested == null)
92             hasNext();
93
94         if (!_tested)
95             throw new NoSuchElementException JavaDoc();
96         
97         _tested = null;
98         return /*(Iterator<T>)*/ _iter;
99     }
100
101     public void remove() {
102         _iter.remove();
103     }
104 }
105
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