001    /*
002     * Copyright (C) 2008-2010 by Holger Arndt
003     *
004     * This file is part of the Universal Java Matrix Package (UJMP).
005     * See the NOTICE file distributed with this work for additional
006     * information regarding copyright ownership and licensing.
007     *
008     * UJMP is free software; you can redistribute it and/or modify
009     * it under the terms of the GNU Lesser General Public License as
010     * published by the Free Software Foundation; either version 2
011     * of the License, or (at your option) any later version.
012     *
013     * UJMP is distributed in the hope that it will be useful,
014     * but WITHOUT ANY WARRANTY; without even the implied warranty of
015     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
016     * GNU Lesser General Public License for more details.
017     *
018     * You should have received a copy of the GNU Lesser General Public
019     * License along with UJMP; if not, write to the
020     * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
021     * Boston, MA  02110-1301  USA
022     */
023    
024    package org.ujmp.core.util.io;
025    
026    import java.io.IOException;
027    import java.io.OutputStream;
028    
029    public class RingBufferOutputStream extends OutputStream {
030    
031            private int start = -1;
032    
033            private int end = -1;
034    
035            private final byte values[];
036    
037            public RingBufferOutputStream() {
038                    this(10);
039            }
040    
041            public RingBufferOutputStream(int maximumSize) {
042                    values = new byte[maximumSize];
043            }
044    
045            public int maxSize() {
046                    return values.length;
047            }
048    
049            public boolean add(byte a) {
050                    if (end >= 0) {
051                            end++;
052                            if (end >= values.length) {
053                                    end = 0;
054                            }
055                            if (end == start) {
056                                    start++;
057                            }
058                            if (start >= values.length) {
059                                    start = 0;
060                            }
061                    } else {
062                            start = 0;
063                            end = 0;
064                    }
065                    values[end] = a;
066                    return true;
067            }
068    
069            public int size() {
070                    if (end < 0) {
071                            return 0;
072                    }
073                    return end < start ? values.length : end - start + 1;
074            }
075    
076            
077            public String toString() {
078                    StringBuilder s = new StringBuilder();
079                    for (int i = 0; i < size(); i++) {
080                            s.append((char) get(i));
081                    }
082                    return s.toString();
083            }
084    
085            public byte get(int index) {
086                    return values[(start + index) % values.length];
087            }
088    
089            public byte set(int index, byte a) {
090                    byte old = values[(start + index) % values.length];
091                    values[(start + index) % values.length] = a;
092                    return old;
093            }
094    
095            public void clear() {
096                    start = -1;
097                    end = -1;
098            }
099    
100            public void add(int index, char element) {
101                    new Exception("not implemented").printStackTrace();
102            }
103    
104            public boolean isEmpty() {
105                    return size() == 0;
106            }
107    
108            
109            public void write(int b) throws IOException {
110                    add((byte) b);
111            }
112    
113    }