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Java/media/Scroll.java

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+/*   
+Scroll.java
+ *    
+ *    Copyright (c) 2000, Ted Nelson and Tuomas Lukka
+ *
+ *    You may use and distribute under the terms of either the GNU Lesser
+ *    General Public License, either version 2 of the license or,
+ *    at your choice, any later version. Alternatively, you may use and
+ *    distribute under the terms of the XPL.
+ *
+ *    See the LICENSE.lgpl and LICENSE.xpl files for the specific terms of 
+ *    the licenses.
+ *
+ *    This software is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the README
+ *    file for more details.
+ *
+ */
+/*
+ * Written by Tuomas Lukka
+ */
+package org.gzigzag;
+import java.util.*;
+import java.io.*;
+
+/** A pseudo-permanent stable media storage.
+ * If you put data in a scroll, it is guaranteed (well, in the development
+ * stage only theoretically) that the same address will be eternal for it.
+ * If you look for that particular address, you will get the data you stored
+ * at it or you will get an error (e.g. if you have expunged some region
+ * of a scroll) from it not being accessible.
+ */
+
+public abstract class Scroll {
+public static final String rcsid = "$Id: Scroll.java,v 1.5 2000/11/03 08:01:05 ajk Exp $";
+    public static boolean dbg = true;
+    static public final void p(String s) { if(dbg) System.out.println(s); }
+    static public final void pa(String s) { if(dbg) System.out.println(s); }
+
+    protected Scroll(String i) { id = i; }
+
+    String id;
+    public String getId() { return id; }
+
+
+    static Hashtable scrolls = new Hashtable();
+
+
+    public interface Creator {
+	    Scroll create(String id, File f);
+    }
+    static Hashtable scrolltypes = new Hashtable(); // full of creators
+
+    static public void register(String id, Creator c) {
+	    scrolltypes.put(id, c);
+    }
+
+    static public void register(String id, Scroll s) {
+	scrolls.put(id, s);
+    }
+
+    /** Get a scroll for the given identifier.
+     * This method encapsulates the way the system finds 
+     * scrolls and the implementation will change in the future.
+     * Currently it looks in the given ZZSpace for a file name.
+     */
+    static public Scroll obtain(ZZSpace e, String id) {
+
+
+	Scroll scr;
+	if((scr=(Scroll)scrolls.get(id))!=null)
+		return scr;
+
+	ZZCell c = e.getHomeCell();
+	c = ZZDefaultSpace.findScrollCell(c, id);
+	if(c==null) return null;
+	ZZCell cfn = c.s("d.2",1);
+	File f = new File(cfn.getText());
+	ZZCell typ = cfn.s("d.2",1);
+	String t = typ.getText();
+	if(t.equals("Byte")) {
+		scr = new ByteScroll(id, f, "r", "ISO8859_1", true);
+	} else if(t.equals("Sound")) {
+		ZZCell dur = typ.s("d.2", 1);
+		scr = new SoundScroll(id, f, Long.parseLong(dur.getText()));
+	} else {
+		Creator crea = (Creator)scrolltypes.get(t);
+		if(crea==null)
+			throw new ZZError("No such scroll type: "+t);
+		scr = crea.create(id, f);
+	}
+
+	scrolls.put(id, scr);
+	return scr;
+    }
+}