1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.collections.primitives.adapters.io;
18
19 import java.io.IOException;
20 import java.io.Reader;
21 import java.util.NoSuchElementException;
22
23 import org.apache.commons.collections.primitives.CharIterator;
24
25 /**
26 * Adapts a {@link Reader} to the {@link CharIterator} interface.
27 *
28 * @version $Revision: 480462 $ $Date: 2006-11-29 03:15:00 -0500 (Wed, 29 Nov 2006) $
29 * @author Rodney Waldhoff
30 */
31 public class ReaderCharIterator implements CharIterator {
32
33 public ReaderCharIterator(Reader in) {
34 this.reader = in;
35 }
36
37 public static CharIterator adapt(Reader in) {
38 return null == in ? null : new ReaderCharIterator(in);
39 }
40
41 public boolean hasNext() {
42 ensureNextAvailable();
43 return (-1 != next);
44 }
45
46 public char next() {
47 if(!hasNext()) {
48 throw new NoSuchElementException("No next element");
49 } else {
50 nextAvailable = false;
51 return (char)next;
52 }
53 }
54
55 /**
56 * Not supported.
57 * @throws UnsupportedOperationException
58 */
59 public void remove() throws UnsupportedOperationException {
60 throw new UnsupportedOperationException("remove() is not supported here");
61 }
62
63 private void ensureNextAvailable() {
64 if(!nextAvailable) {
65 readNext();
66 }
67 }
68
69 private void readNext() {
70 try {
71 next = reader.read();
72 nextAvailable = true;
73 } catch(IOException e) {
74 // TODO: Use a tunnelled exception instead?
75 // See http://radio.weblogs.com/0122027/2003/04/01.html#a7, for example
76 throw new RuntimeException(e.toString());
77 }
78 }
79
80 private Reader reader = null;
81 private boolean nextAvailable = false;
82 private int next;
83
84 }