001: /*
002: * $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 $
003: * ====================================================================
004: * The Apache Software License, Version 1.1
005: *
006: * Copyright (c) 2003 The Apache Software Foundation. All rights
007: * reserved.
008: *
009: * Redistribution and use in source and binary forms, with or without
010: * modification, are permitted provided that the following conditions
011: * are met:
012: *
013: * 1. Redistributions of source code must retain the above copyright
014: * notice, this list of conditions and the following disclaimer.
015: *
016: * 2. Redistributions in binary form must reproduce the above copyright
017: * notice, this list of conditions and the following disclaimer in
018: * the documentation and/or other materials provided with the
019: * distribution.
020: *
021: * 3. The end-user documentation included with the redistribution, if
022: * any, must include the following acknowledgement:
023: * "This product includes software developed by the
024: * Apache Software Foundation (http://www.apache.org/)."
025: * Alternately, this acknowledgement may appear in the software itself,
026: * if and wherever such third-party acknowledgements normally appear.
027: *
028: * 4. The names "The Jakarta Project", "Commons", and "Apache Software
029: * Foundation" must not be used to endorse or promote products derived
030: * from this software without prior written permission. For written
031: * permission, please contact apache@apache.org.
032: *
033: * 5. Products derived from this software may not be called "Apache"
034: * nor may "Apache" appear in their names without prior written
035: * permission of the Apache Software Foundation.
036: *
037: * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
038: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
039: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
040: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
041: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
042: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
043: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
044: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
045: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
046: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
047: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
048: * SUCH DAMAGE.
049: * ====================================================================
050: *
051: * This software consists of voluntary contributions made by many
052: * individuals on behalf of the Apache Software Foundation. For more
053: * information on the Apache Software Foundation, please see
054: * <http://www.apache.org/>.
055: *
056: */
057:
058: package org.apache.commons.collections.primitives.adapters.io;
059:
060: import java.io.IOException;
061: import java.io.Reader;
062: import java.util.NoSuchElementException;
063:
064: import org.apache.commons.collections.primitives.CharIterator;
065:
066: /**
067: * Adapts a {@link Reader} to the {@link CharIterator} interface.
068: *
069: * @version $Revision: 1.2 $ $Date: 2003/10/29 18:28:20 $
070: * @author Rodney Waldhoff
071: */
072: public class ReaderCharIterator implements CharIterator {
073:
074: public ReaderCharIterator(Reader in) {
075: this .reader = in;
076: }
077:
078: public static CharIterator adapt(Reader in) {
079: return null == in ? null : new ReaderCharIterator(in);
080: }
081:
082: public boolean hasNext() {
083: ensureNextAvailable();
084: return (-1 != next);
085: }
086:
087: public char next() {
088: if (!hasNext()) {
089: throw new NoSuchElementException("No next element");
090: } else {
091: nextAvailable = false;
092: return (char) next;
093: }
094: }
095:
096: /**
097: * Not supported.
098: * @throws UnsupportedOperationException
099: */
100: public void remove() throws UnsupportedOperationException {
101: throw new UnsupportedOperationException(
102: "remove() is not supported here");
103: }
104:
105: private void ensureNextAvailable() {
106: if (!nextAvailable) {
107: readNext();
108: }
109: }
110:
111: private void readNext() {
112: try {
113: next = reader.read();
114: nextAvailable = true;
115: } catch (IOException e) {
116: // TODO: Use a tunnelled exception instead?
117: // See http://radio.weblogs.com/0122027/2003/04/01.html#a7, for example
118: throw new RuntimeException(e.toString());
119: }
120: }
121:
122: private Reader reader = null;
123: private boolean nextAvailable = false;
124: private int next;
125:
126: }
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