// Copyright (c) 1995, 1996 Regents of the University of California.
// All rights reserved.
//
// This software was developed by the Arcadia project
// at the University of California, Irvine.
//
// Redistribution and use in source and binary forms are permitted
// provided that the above copyright notice and this paragraph are
// duplicated in all such forms and that any documentation,
// advertising materials, and other materials related to such
// distribution and use acknowledge that the software was developed
// by the University of California, Irvine.  The name of the
// University may not be used to endorse or promote products derived
// from this software without specific prior written permission.
// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
// WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

// File: Action.java
// Classes: Action
// Original Author: Jason Robbins
// Modifications : Kedar Patankar
// Date : 11 Feb 1997

package uci.graphedit;

import java.util.Properties;


/**
 * Abstract class for all editor actions. The editor serves as a
 * command shell for executing actions in much the same way that a
 * DOS or UNIX commmand command shell executes programs. Each action
 * can have a Hashtable of "command-line" arguments and also look at
 * global variables (its environment). Once an instance of an Action
 * is made, it can be sent the doIt() and undoIt() messages to perform
 * that action. <p>
 * needs-more-work: canDoIt, canUndoIt predicates control graying. <p>
 * needs-more-work: Editor will keep a history of recent actions for
 * undo. <p>
 * @see Editor
 * @see Document
 * @see UmlPalette
 */
public abstract class Action 
{
	/** Attributes */
	protected Properties _args;
	protected Editor _editor;
	protected Document _document;

	/** Constructors*/
	public Action(Properties args) { _args = args; }
	public Action(Editor editor) 
	{
		this(new Properties());
		_editor=editor;
		_document=null;
	}
	public Action(Document document) 
	{
		this(new Properties());
		_document=document;
		_editor=null;
	}
	public Action(Editor editor,Document document)
	{
		this(new Properties());
		_document=document;
		_editor=editor;
	}

	/** Return a name for this action suitable for display to the user */
	public abstract String name();

	/** Perform whatever action this Action is meant to do. Subclasses
	* should override this to do whatever is intended. When the action
	* executes, it should store enough information to undo itself later
	* if needed.
	*/

	public abstract void doIt();

	/** Undo the action using information stored during its
	* execution. <p>
	* needs-more-work: This is not currently implemented.
	*/
	public abstract void undoIt();

  // needs-more-work: do I need a separate redo()? Should doIt() take
  // flag to indicate if this is the first time the action is being
  // done, or it it is actually being redone? What information does
  // undoIt() need to store to support redo?

  
} /* end class Action */