1 /*
2 * $Header: /home/cvs/jakarta-commons/primitives/src/java/org/apache/commons/collections/primitives/adapters/io/ReaderCharIterator.java,v 1.2 2003/10/29 18:28:20 rwaldhoff Exp $
3 * ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2003 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution, if
22 * any, must include the following acknowledgement:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgement may appear in the software itself,
26 * if and wherever such third-party acknowledgements normally appear.
27 *
28 * 4. The names "The Jakarta Project", "Commons", and "Apache Software
29 * Foundation" must not be used to endorse or promote products derived
30 * from this software without prior written permission. For written
31 * permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache"
34 * nor may "Apache" appear in their names without prior written
35 * permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 *
56 */
57
58 package org.apache.commons.collections.primitives.adapters.io;
59
60 import java.io.IOException;
61 import java.io.Reader;
62 import java.util.NoSuchElementException;
63
64 import org.apache.commons.collections.primitives.CharIterator;
65
66 /**
67 * Adapts a {@link Reader} to the {@link CharIterator} interface.
68 *
69 * @version $Revision: 1.2 $ $Date: 2003/10/29 18:28:20 $
70 * @author Rodney Waldhoff
71 */
72 public class ReaderCharIterator implements CharIterator {
73
74 public ReaderCharIterator(Reader in) {
75 this.reader = in;
76 }
77
78 public static CharIterator adapt(Reader in) {
79 return null == in ? null : new ReaderCharIterator(in);
80 }
81
82 public boolean hasNext() {
83 ensureNextAvailable();
84 return (-1 != next);
85 }
86
87 public char next() {
88 if(!hasNext()) {
89 throw new NoSuchElementException("No next element");
90 } else {
91 nextAvailable = false;
92 return (char)next;
93 }
94 }
95
96 /**
97 * Not supported.
98 * @throws UnsupportedOperationException
99 */
100 public void remove() throws UnsupportedOperationException {
101 throw new UnsupportedOperationException("remove() is not supported here");
102 }
103
104 private void ensureNextAvailable() {
105 if(!nextAvailable) {
106 readNext();
107 }
108 }
109
110 private void readNext() {
111 try {
112 next = reader.read();
113 nextAvailable = true;
114 } catch(IOException e) {
115 // TODO: Use a tunnelled exception instead?
116 // See http://radio.weblogs.com/0122027/2003/04/01.html#a7, for example
117 throw new RuntimeException(e.toString());
118 }
119 }
120
121 private Reader reader = null;
122 private boolean nextAvailable = false;
123 private int next;
124
125 }
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