IfThen.java example

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ptii-master
/* A polymorphic IfThenElse actor.
 Copyright (c) 2009 The Regents of the University of California.
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY
 */
package ptolemy.domains.sequence.lib;

import ptolemy.actor.TypedIOPort;
import ptolemy.data.BooleanToken;
import ptolemy.data.type.BaseType;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.StringAttribute;

//////////////////////////////////////////////////////////////////////////
//// IfThenElse

/**
 A type polymorphic If-Then-Else actor. 
 <p>In an iteration, if an input token is available at the <i>If</i> input,
 that token is read.
 The <i>Then</i> output is set to true, if then <i>If</i> input is true.
 The <i>Else</i> output is set to true, if then <i>If</i> input is false.
 The <i>If</i> port may only receive Tokens of type Boolean. The output 
 ports are also of type boolean.</p>
 
 <p>IfThen is a ControlActor, meaning that it keeps a list of
 enabled output ports.</p>

 @author Elizabeth Latronico (Bosch)
 @version $Id$
 @since Ptolemy II 8.1
 @Pt.ProposedRating Red (beth)
 @Pt.AcceptedRating Red (beth)
 */
public class IfThen extends ControlActor {
    /** Construct an actor in the specified container with the specified
     *  name.
     *  @param container The container.
     *  @param name The name of this actor within the container.
     *  @exception IllegalActionException If the actor cannot be contained
     *   by the proposed container.
     *  @exception NameDuplicationException If the name coincides with
     *   an actor already in the container.
     */
    public IfThen(CompositeEntity container, String name)
            throws IllegalActionException, NameDuplicationException {
        super(container, name);

        // set name to invisible
        StringAttribute hideName = new StringAttribute(this, "_hideName");
        hideName.setExpression("true");
        
        // create inports
        ifInput = new TypedIOPort(this, "If", true, false);

        // create outports
        thenOutput = new TypedIOPort(this, "Then", false, true);

        // set portnames to visible
        StringAttribute ifShowName = new StringAttribute(ifInput, "_showName");
        ifShowName.setExpression("false");
        StringAttribute thenShowName = new StringAttribute(thenOutput, "_showName");
        thenShowName.setExpression("false");

        // set direction of ports
        StringAttribute ifCardinal = new StringAttribute(ifInput, "_cardinal");
        ifCardinal.setExpression("WEST");
        StringAttribute thenCardinal = new StringAttribute(thenOutput, "_cardinal");
        thenCardinal.setExpression("EAST");

        // set type constraints for ports        
        ifInput.setTypeEquals(BaseType.BOOLEAN);
        thenOutput.setTypeEquals(BaseType.BOOLEAN);
    }

    ///////////////////////////////////////////////////////////////////
    ////                     ports and parameters                  ////

    /** The input port.  The type can only be BOOLEAN.
     */
    public TypedIOPort ifInput;

    /** Same as Input.
     */
    public TypedIOPort thenOutput;

    ///////////////////////////////////////////////////////////////////
    ////                         public methods                    ////

    /** Read a token from the input port.  
     *  This actor is used for control flow by only sending true token
     *  to the output when the input receives a true token.
     *
     *  @exception IllegalActionException If there is no director.
     */
    public void fire() throws IllegalActionException {
        super.fire();
        
        if (ifInput.hasToken(0)) {
            BooleanToken token = (BooleanToken) ifInput.get(0);

            // Set the enabled output ports accordingly
            clearEnabledOutports();
            
            // Beth - changed 02/06/09 - use the .equals() function instead of ==
            if (token.equals(BooleanToken.TRUE)) {
                addEnabledOutport(thenOutput);
                
                thenOutput.send(0, BooleanToken.TRUE);
            } else {
                thenOutput.send(0, BooleanToken.FALSE);                
            }
        }
    }
}