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Java > Open Source Codes > org > netbeans > lib > jmi > query > FilterQuery


1 /*
2  * The contents of this file are subject to the terms of the Common Development
3  * and Distribution License (the License). You may not use this file except in
4  * compliance with the License.
5  *
6  * You can obtain a copy of the License at http://www.netbeans.org/cddl.html
7  * or http://www.netbeans.org/cddl.txt.
8  *
9  * When distributing Covered Code, include this CDDL Header Notice in each file
10  * and include the License file at http://www.netbeans.org/cddl.txt.
11  * If applicable, add the following below the CDDL Header, with the fields
12  * enclosed by brackets [] replaced by your own identifying information:
13  * "Portions Copyrighted [year] [name of copyright owner]"
14  *
15  * The Original Software is NetBeans. The Initial Developer of the Original
16  * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
17  * Microsystems, Inc. All Rights Reserved.
18  */
19 package org.netbeans.lib.jmi.query;
20
21 import java.util.Iterator JavaDoc;
22 import java.util.NoSuchElementException JavaDoc;
23
24 /** Abstract class for creating filter queries.
25  *
26  * @author Petr Hrebejk
27  */
28 public abstract class FilterQuery implements Query {
29
30     private final Query QUERY;
31
32     public FilterQuery( Query query ) {
33         this.QUERY = query;
34     }
35
36     public Iterator JavaDoc iterator() {
37         return new FilterIterator();
38     }
39
40     public boolean contains( Object JavaDoc object ) {
41         return accept( object ) ? QUERY.contains( object ) : false;
42     }
43     
44     abstract protected boolean accept( Object JavaDoc object );
45     
46     
47     // Inner classes -----------------------------------------------------------
48
49     private class FilterIterator extends QueryIterator.Delegate {
50         
51         /** The object which will be returned as next */
52         private Object JavaDoc next = null;
53         
54         FilterIterator() {
55             super ( QUERY.iterator() );
56         }
57         
58         public boolean hasNext() {
59             if ( !ITERATOR.hasNext() ) {
60                 return false;
61             }
62             else {
63                 return findNext();
64             }
65         }
66         
67         public Object JavaDoc next() {
68             if ( next != null ) {
69                 return next;
70             }
71             else if ( findNext() ) {
72                 return next;
73             }
74             else {
75                 throw new NoSuchElementException JavaDoc();
76             }
77         }
78         
79         /** Finds next accepted element
80         */
81         private boolean findNext() {
82             while( ITERATOR.hasNext() ) {
83                 Object JavaDoc object = ITERATOR.next();
84                 if ( accept( object ) ) {
85                     next = object;
86                     return true;
87                 }
88             }
89             
90             next = null;
91             return false;
92         }
93     }
94 }
95
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