1 /* ====================================================================
2 * The Apache Software License, Version 1.1
3 *
4 * Copyright (c) 2000 The Apache Software Foundation. All rights
5 * reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 *
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in
16 * the documentation and/or other materials provided with the
17 * distribution.
18 *
19 * 3. The end-user documentation included with the redistribution,
20 * if any, must include the following acknowledgment:
21 * "This product includes software developed by the
22 * Apache Software Foundation (http://www.apache.org/)."
23 * Alternately, this acknowledgment may appear in the software itself,
24 * if and wherever such third-party acknowledgments normally appear.
25 *
26 * 4. The names "Apache" and "Apache Software Foundation" must
27 * not be used to endorse or promote products derived from this
28 * software without prior written permission. For written
29 * permission, please contact apache@apache.org.
30 *
31 * 5. Products derived from this software may not be called "Apache",
32 * nor may "Apache" appear in their name, without prior written
33 * permission of the Apache Software Foundation.
34 *
35 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
36 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
37 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
38 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
39 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
40 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
41 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
42 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
43 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
44 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
45 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
46 * SUCH DAMAGE.
47 * ====================================================================
48 *
49 * This software consists of voluntary contributions made by many
50 * individuals on behalf of the Apache Software Foundation. For more
51 * information on the Apache Software Foundation, please see
52 * <http://www.apache.org/>;.
53 *
54 * Portions of this software are based upon public domain software
55 * originally written at the National Center for Supercomputing Applications,
56 * University of Illinois, Urbana-Champaign.
57 */
58
59 package net.sourceforge.jane.util;
60
61 import java.util.Enumeration;
62 import java.util.NoSuchElementException;
63
64 import org.apache.commons.collections.Predicate;
65
66 /***
67 * An extended enumeration base class with predicate and reset support.
68 */
69 abstract public class ExtendedEnumeration implements Enumeration
70 {
71
72 protected Predicate predicate;
73
74 /***
75 * Create a new <code>ExtendedEnumeration</code>.
76 */
77 public ExtendedEnumeration()
78 {
79 this(null);
80 }
81
82 /***
83 * Create a new <code>ExtendedEnumeration</code>.
84 */
85 public ExtendedEnumeration(Predicate aPredicate)
86 {
87 predicate = aPredicate;
88 reset();
89 }
90
91 /***
92 * Returns <code>true</code> if there are more elements.
93 */
94 public boolean hasMoreElements()
95 {
96 while (doCheckSize()) {
97 if (doEvaluate()) {
98 return true;
99 }
100 doNext();
101 }
102 return false;
103 }
104
105 /***
106 * Returns the next element.
107 */
108 public Object nextElement()
109 {
110 while (doCheckSize()) {
111 if (doEvaluate()) {
112 Object cur = getCurrent();
113 doNext();
114 return cur;
115 }
116 doNext();
117 }
118 throw new NoSuchElementException("No more elements");
119 }
120
121 /***
122 * Reset this enumeration to the beginning.
123 */
124 abstract public void reset();
125
126 /***
127 * Returns <code>true</code> if there are not more elements in the
128 * current series.
129 */
130 abstract protected boolean doCheckSize();
131
132 /***
133 * Returns the current element.
134 */
135 abstract protected Object getCurrent();
136
137 /***
138 * Go to the next element.
139 */
140 abstract protected void doNext();
141
142 /***
143 * Evaluate the current element.
144 */
145 protected boolean doEvaluate()
146 {
147 if (predicate == null)
148 return true;
149 return predicate.evaluate(getCurrent());
150 }
151
152 }
153
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