samer@0: /*
samer@0:  *	Viewable.java	
samer@0:  *
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
samer@0:  *	without even the implied warranty of MERCHANTABILITY or 
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package	samer.core;
samer@0: import	java.util.*;
samer@0: 
samer@0: 
samer@0: /**
samer@0: 		<p>
samer@0: 		A Viewable is a named Observable object, for which
samer@0: 		can be created a Viewer. A Viewer is meant to allow user
samer@0: 		interaction with the object. The name is managed
samer@0: 		by a Node object, so they can form a heirarchy.
samer@0: 		A Viewable can also have an associated Agent, so that
samer@0: 		Viewers can automatically expose commands
samer@0: 		for the Agent.
samer@0:   */
samer@0: 
samer@0: 
samer@0: public class Viewable extends Observable
samer@0: {
samer@0: 	/** sent to Obervable.update() when Viewable is
samer@0: 	  * being disposed of.
samer@0: 	  */
samer@0: 	public final static Object DISPOSING = new Object();
samer@0: 
samer@0: 	public final Node getNode() { return node; }
samer@0: 	public final void setNode(Node n) { node=n; }
samer@0: 	public Agent getAgent() { return agent; }
samer@0: 	public void setAgent(Agent a) { agent=a; }
samer@0: 	public void addAgent(Agent a) { setAgent(new CompoundAgent(agent,a)); }
samer@0: 
samer@0: 	public String getLabel() {
samer@0: 		String str = Shell.getString(node.fullNameFor("label"),null);
samer@0: 		return str==null ? node.fullName().substring(1)	: str;
samer@0: 	}
samer@0: 
samer@0: 	/**	<p>Should leave the Viewable in such a state that the
samer@0: 	  *	garbage collector can get it as soon as any direct
samer@0: 	  *	references go out of scope. In particular, any attached
samer@0: 	  *	Viewers or Observers should drop their references to
samer@0: 	  *	this Viewable, and if necessary, dispose of themselves.
samer@0: 	  *	<p>
samer@0: 	  *	The default implementation deregisters the Viewable,
samer@0: 	  *	notifies Obervers and detaches the node.
samer@0: 	  */
samer@0: 
samer@0: 	public void dispose()
samer@0: 	{
samer@0: 		Shell.deregisterViewable(this);
samer@0: 		changed(DISPOSING);
samer@0: 	}
samer@0: 
samer@0: 	/** This should return a suitable Viewer for this object.
samer@0: 		Default implementation asks the <code>samer.core.Registry</code>
samer@0: 		to create one. */
samer@0: 	public Viewer  getViewer() { return Registry.createViewer(this); }
samer@0: 
samer@0: 	protected Viewable(String nm) { node = new Node(nm); }
samer@0: 	protected Viewable(Node nd) { node = nd; }
samer@0: 	protected Viewable() {}
samer@0: 
samer@0: 	protected Node		node;
samer@0: 	protected Agent		agent=null;
samer@0: 	// protected Vector	agents=new Vector();
samer@0: 
samer@0: 	public String toString() {
samer@0: 		return Node.lastPart(getClass().getName())+":"+getLabel();
samer@0: 	}
samer@0: 	
samer@0: 	public void finalize() { Shell.trace("Viewable finalizing: "+toString()); }
samer@0: 
samer@0: 	/* ------- override implementation of Observable here -----------*/
samer@0: 	
samer@0: 	private static class Vector extends java.util.Vector {
samer@0: 		public Object[] getArray() { return elementData; }
samer@0: 	}
samer@0: 
samer@0: 	private Vector observers=new Vector();
samer@0: 
samer@0: 	public synchronized void addObserver(Observer o) {
samer@0: 		if (!observers.contains(o)) observers.addElement(o);
samer@0:    }
samer@0: 
samer@0: 	public synchronized void deleteObserver(Observer o) {
samer@0: 		observers.removeElement(o);
samer@0: 	}
samer@0: 
samer@0: 	public synchronized void deleteObservers() {
samer@0: 		observers.removeAllElements();
samer@0: 	}
samer@0: 
samer@0: 	public  void notifyObservers(Object arg)
samer@0: 	{
samer@0: 		Object [] arr=observers.getArray();
samer@0: 
samer@0: 		for (int i=observers.size()-1; i>=0; i--) {
samer@0: 			((Observer)arr[i]).update(this, arg);
samer@0: 		}
samer@0: 	}
samer@0: 
samer@0: 	/** This will notify all observers that this object may have changed
samer@0: 		The second argument to Observer.update() will be null */
samer@0: 	public final void changed() { notifyObservers(null); }
samer@0: 
samer@0: 	/** This will notify all observers that this object may have changed.
samer@0: 		The second argument to Observer.update() will be the given object */
samer@0: 	public final void changed(Object o)	{ notifyObservers(o); }
samer@0: }
samer@0: