/* Interface for directors that use a super-dense model of time.

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 All rights reserved.
 Permission is hereby granted, without written agreement and without
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 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY

 */
package ptolemy.actor;

import ptolemy.kernel.util.IllegalActionException;

//////////////////////////////////////////////////////////////////////////
//// SuperdenseTimeDirector

/**
 This is an interface for directors that use a superdense model of time.
 Actors can determine the index, also called the microstep,
 of current time by calling getIndex().
 <p>
 Superdense time is defined by Haiyang Zheng as:
 <blockquote>
 <p>"The interactions between CT and DE subsystems and between DE
 subsystems themselves are captured by discontinuities in
 continuous-time signals and simultaneous discrete events in
 discrete-event signals."</p>

 <p>"In order to precisely represent them in compute execution
 results, a two-dimension domain, called "superdense time," is used
 as the domain for defining signals. This domain allows a signal to
 have multiple values at the same time point while keeping the values
 ordered."</p>
 </blockquote>
 <p>See: Haiyang Zheng. <a
href="http://chess.eecs.berkeley.edu/pubs/303.html#in_browser"><i>Operational Semantics of Hybrid Systems</i></a>, PhD thesis,
 University of California, Berkeley, May, 2007.</p>

 @author Edward A. Lee
 @version $Id: SuperdenseTimeDirector.java 61458 2011-07-11 19:54:07Z cxh $
 @since Ptolemy II 8.0
 @Pt.ProposedRating Yellow (eal)
 @Pt.AcceptedRating Red (eal)
 */
public interface SuperdenseTimeDirector {
    /** Return a superdense time index for the current time.
     *  @return A superdense time object.
     *  @see #setIndex(int)
     */
    public int getIndex();

    /** Set the superdense time index. This should only be
     *  called by an enclosing director.
     *  @param index The index of the superdense time object.
     *  Events that occur at the same time have different indicies.
     *  @exception IllegalActionException If the specified index is invalid.
     *  @see #getIndex()
     */
    public void setIndex(int index) throws IllegalActionException;
}