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Java/ZZCursor.java

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+/*   
+ZZCursor.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.*;
+
+/** A thing that points to a cell or to an offset at a cell.
+ * It is possible to have read-only ZZCursor objects which will
+ * throw Errors for the modification attempts.
+ */
+
+public abstract class ZZCursor {
+String rcsid = "$Id: ZZCursor.java,v 1.7 2000/11/25 00:36:33 tjl Exp $";
+    /** Get the cell the cursor is pointing to. 
+     */
+    public abstract ZZCell get();
+    /** Set the cursor to point to a cell.
+     */
+    public abstract void set(ZZCell c);
+    /** Get the offset of this cursor.
+     */
+    public abstract int getOffs();
+    /** Set the offset of this cursor.
+     */
+    public abstract void setOffs(int i);
+
+
+    /** Set the cursor and offset to the given cursor.
+     */
+    public void set(ZZCursor c) {
+	set(c.get());
+	setOffs(c.getOffs());
+    }
+
+    /** The constant to specify that there is no offset 
+     * for this cursor.
+     */
+    static public final int NO_OFFSET = -100;
+
+    public boolean equals(Object o) {
+	if(this == o) return true;
+	if(!(o instanceof ZZCursor)) return false;
+	ZZCursor oth = (ZZCursor) o;
+	return (oth.get() == get() && oth.getOffs() == getOffs());
+    }
+
+    public String toString() {
+	return "CURS: "+getOffs()+" of "+get()+"  Normal: "+super.toString();
+    }
+
+}