package graph;

/**
 * An action that is applied to a graph.
 * 
 * @see Graph
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
public interface Action {
	/**
	 * Perform the action on the graph from start to finish.
	 * Calls the functions init(), step() (possibly multiple times),
	 * and finish().
	 *
	 * @see Action
	 */
	public void apply(Graph g);
	
	/**
	 * A one-time initialization so
	 * that apply() can be called repeatedly
	 * without re-executing redundant work.
	 *
	 * @see Action#apply
	 */
	public void init(Graph g);
	
	/**
	 * Perform a single pass of a multi-pass
	 * operation, or the entire operation of
	 * a non-iterative action.
	 *
	 * @see Action#apply
	 */
	public void step(Graph g);
	

	/**
	 * A one-time cleanup after the action
	 * is finished executing
	 *
	 * @see Action#apply
	 */
	public void finish(Graph g);
	
	//XXX the certainty with which the action
	//XXX was successful.
	//XXX public float certainty();
}