view src/samer/core_/Viewable.java @ 0:bf79fb79ee13

Initial Mercurial check in.

/*
 *	Viewable.java	
 *
 *	Copyright (c) 2000, Samer Abdallah, King's College London.
 *	All rights reserved.
 *
 *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
 *	without even the implied warranty of MERCHANTABILITY or 
 *	FITNESS FOR A PARTICULAR PURPOSE.
 */

package	samer.core;
import	java.util.*;


/**
		<p>
		A Viewable is a named Observable object, for which
		can be created a Viewer. A Viewer is meant to allow user
		interaction with the object. The name is managed
		by a Node object, so they can form a heirarchy.
		A Viewable can also have an associated Agent, so that
		Viewers can automatically expose commands
		for the Agent.
  */


public class Viewable extends Observable
{
	/** sent to Obervable.update() when Viewable is
	  * being disposed of.
	  */
	public final static Object DISPOSING = new Object();

	public final Node getNode() { return node; }
	public final void setNode(Node n) { node=n; }
	public Agent getAgent() { return agent; }
	public void setAgent(Agent a) { agent=a; }
	public void addAgent(Agent a) { setAgent(new CompoundAgent(agent,a)); }

	public String getLabel() {
		String str = Shell.getString(node.fullNameFor("label"),null);
		return str==null ? node.fullName().substring(1)	: str;
	}

	/**	<p>Should leave the Viewable in such a state that the
	  *	garbage collector can get it as soon as any direct
	  *	references go out of scope. In particular, any attached
	  *	Viewers or Observers should drop their references to
	  *	this Viewable, and if necessary, dispose of themselves.
	  *	<p>
	  *	The default implementation deregisters the Viewable,
	  *	notifies Obervers and detaches the node.
	  */

	public void dispose()
	{
		Shell.deregisterViewable(this);
		changed(DISPOSING);
	}

	/** This should return a suitable Viewer for this object.
		Default implementation asks the <code>samer.core.Registry</code>
		to create one. */
	public Viewer  getViewer() { return Registry.createViewer(this); }

	protected Viewable(String nm) { node = new Node(nm); }
	protected Viewable(Node nd) { node = nd; }
	protected Viewable() {}

	protected Node		node;
	protected Agent		agent=null;
	// protected Vector	agents=new Vector();

	public String toString() {
		return Node.lastPart(getClass().getName())+":"+getLabel();
	}
	
	public void finalize() { Shell.trace("Viewable finalizing: "+toString()); }

	/* ------- override implementation of Observable here -----------*/
	
	private static class Vector extends java.util.Vector {
		public Object[] getArray() { return elementData; }
	}

	private Vector observers=new Vector();

	public synchronized void addObserver(Observer o) {
		if (!observers.contains(o)) observers.addElement(o);
   }

	public synchronized void deleteObserver(Observer o) {
		observers.removeElement(o);
	}

	public synchronized void deleteObservers() {
		observers.removeAllElements();
	}

	public  void notifyObservers(Object arg)
	{
		Object [] arr=observers.getArray();

		for (int i=observers.size()-1; i>=0; i--) {
			((Observer)arr[i]).update(this, arg);
		}
	}

	/** This will notify all observers that this object may have changed
		The second argument to Observer.update() will be null */
	public final void changed() { notifyObservers(null); }

	/** This will notify all observers that this object may have changed.
		The second argument to Observer.update() will be the given object */
	public final void changed(Object o)	{ notifyObservers(o); }
}