100 lines
2.4 KiB
Java
100 lines
2.4 KiB
Java
/*
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ByteScroll.java
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*
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* Copyright (c) 1999, Ted Nelson and Tuomas Lukka
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*
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* You may use and distribute under the terms of either the GNU Lesser
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* General Public License, either version 2 of the license or,
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* at your choice, any later version. Alternatively, you may use and
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* distribute under the terms of the XPL.
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*
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* See the LICENSE.lgpl and LICENSE.xpl files for the specific terms of
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* the licenses.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the README
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* file for more details.
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*
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*/
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/*
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* Written by Tuomas Lukka
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*/
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package org.gzigzag;
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import java.util.*;
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import java.io.*;
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/** A scroll of bytes. May later have holes etc. from expunging,
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* but basically the point is that the address to content mapping
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* is stable and will not change whatever is done.
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*/
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public class ByteScroll extends Scroll{
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public static final String rcsid = "$Id: ByteScroll.java,v 1.4 2000/09/19 10:32:00 ajk Exp $";
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// Cheat: it's just a file
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private RandomAccessFile f;
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private String encoding;
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private boolean readonly;
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public ByteScroll(String id, File fn, String mode, String encoding,
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boolean ro) {
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super(id);
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this.encoding = encoding;
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this.readonly = ro;
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try {
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f = new RandomAccessFile(fn, mode);
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} catch(Exception e) {
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ZZLogger.exc(e);
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throw new NullPointerException("Can't get");
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}
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}
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public synchronized byte[] get(long start, int n) {
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try {
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f.seek(start);
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byte[] ret = new byte[n];
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int r = f.read(ret);
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if(r!=n)
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throw new NullPointerException("NOT ENOUGH!");
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return ret;
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} catch(Exception e) {
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ZZLogger.exc(e);
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throw new NullPointerException("Can't get");
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}
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}
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// XXX ENCODING
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public String getString(long start, int n) {
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byte[] b = get(start,n);
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try {
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return new String(b, "ISO8859_1");
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} catch(Exception e) {
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ZZLogger.exc(e);
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throw new NullPointerException("Can't get");
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}
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}
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public long curEnd() { try { return f.length();
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} catch(Exception e) {
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ZZLogger.exc(e);
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throw new NullPointerException("Can't get");
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}
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}
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public synchronized long append(byte[] bytes) {
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if(readonly) throw new ZZError("Can't append to readonly scroll");
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try {
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long offs = curEnd();
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f.seek(offs);
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f.write(bytes);
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return offs;
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} catch(Exception e) {
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ZZLogger.exc(e);
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throw new NullPointerException("Can't get");
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}
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}
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}
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