/* A polymorphic switch with boolean select.
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This is similar to Switch and could be design/code reviewed at the same time.
*/
package ptolemy.actor.lib;
import ptolemy.actor.TypedAtomicActor;
import ptolemy.actor.TypedIOPort;
import ptolemy.data.BooleanToken;
import ptolemy.data.Token;
import ptolemy.data.type.BaseType;
import ptolemy.kernel.CompositeEntity;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.StringAttribute;
//////////////////////////////////////////////////////////////////////////
//// BooleanSwitch
/**
<p>A type polymorphic switch with boolean valued control. In an
iteration, if an input token is available at the <i>control</i> input,
that token is read, and its value is noted. Its value specifies the
input port that should be read next. If the <i>control</i> input is
true, then if an input token is available on the <i>input</i> port,
then it is is read and sent to the <i>trueOutput</i>. Likewise with a
false input and the <i>falseOutput</i> port. Because tokens are
immutable, the same Token is sent to the output, rather than a copy.
The <i>input</i> port may receive Tokens of any type.</p>
<p>If no token has ever been received on the <i>control</i> port, then
<i>falseOutput</i> is assumed to be the one to receive data.</p>
<p>Note that the this actor may be used in Synchronous Dataflow (SDF)
models, but only under certain circumstances. The problem is that
the number of tokens on the <i>trueOutput</i> or the <i>falseOutput</i>
can change while the model is running, which makes static scheduling
of the actor firings difficult.
@author Steve Neuendorffer
@version $Id: BooleanSwitch.java,v 1.29 2008/01/24 00:33:44 cxh Exp $
@since Ptolemy II 2.0
@Pt.ProposedRating Green (neuendor)
@Pt.AcceptedRating Red (neuendor)
*/
public class BooleanSwitch extends TypedAtomicActor {
/** 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 BooleanSwitch(CompositeEntity container, String name)
throws IllegalActionException, NameDuplicationException {
super(container, name);
input = new TypedIOPort(this, "input", true, false);
control = new TypedIOPort(this, "control", true, false);
control.setTypeEquals(BaseType.BOOLEAN);
trueOutput = new TypedIOPort(this, "trueOutput", false, true);
falseOutput = new TypedIOPort(this, "falseOutput", false, true);
trueOutput.setTypeAtLeast(input);
falseOutput.setTypeAtLeast(input);
// Put the control input on the bottom of the actor.
StringAttribute controlCardinal = new StringAttribute(control,
"_cardinal");
controlCardinal.setExpression("SOUTH");
}
///////////////////////////////////////////////////////////////////
//// ports and parameters ////
/** Input that selects one of the other input ports. The type is
* BooleanToken.
*/
public TypedIOPort control;
/** The input port. The type can be anything.
*/
public TypedIOPort input;
/** Output for tokens on the true path. The type is at least the
* type of the input.
*/
public TypedIOPort trueOutput;
/** Output for tokens on the false path. The type is at least the
* type of the input.
*/
public TypedIOPort falseOutput;
///////////////////////////////////////////////////////////////////
//// public methods ////
/** Read a token from each input port. If the token from the
* <i>control</i> input is true, then output the token consumed from the
* <i>input</i> port on the <i>trueOutput</i> port,
* otherwise output the token on the <i>falseOutput</i> port.
*
* @exception IllegalActionException If there is no director.
*/
public void fire() throws IllegalActionException {
super.fire();
if (control.hasToken(0)) {
_control = ((BooleanToken) control.get(0)).booleanValue();
}
if (input.hasToken(0)) {
Token token = input.get(0);
if (_control) {
trueOutput.send(0, token);
} else {
falseOutput.send(0, token);
}
}
}
/** Initialize this actor so that the <i>falseOutput</i> is written
* to until a token arrives on the <i>control</i> input.
* @exception IllegalActionException If the parent class throws it.
*/
public void initialize() throws IllegalActionException {
super.initialize();
_control = false;
}
///////////////////////////////////////////////////////////////////
//// private variables ////
// The most recently read control token.
private boolean _control = false;
}