package net.fortytwo.ripple.libs.stack;
import net.fortytwo.flow.Sink;
import net.fortytwo.ripple.RippleException;
import net.fortytwo.ripple.model.ModelConnection;
import net.fortytwo.ripple.model.PrimitiveStackMapping;
import net.fortytwo.ripple.model.RippleList;
import net.fortytwo.ripple.model.RippleValue;
/**
* A primitive which pushes a copy of the second-to-topmost item on the stack to
* the head of the stack.
*
* @author Joshua Shinavier (http://fortytwo.net)
*/
public class Dupd extends PrimitiveStackMapping {
private static final String[] IDENTIFIERS = {
StackLibrary.NS_2013_03 + "dupd",
StackLibrary.NS_2008_08 + "dupd",
StackLibrary.NS_2007_08 + "dupd",
StackLibrary.NS_2007_05 + "dupd"};
public String[] getIdentifiers() {
return IDENTIFIERS;
}
public Dupd()
throws RippleException {
super();
}
public Parameter[] getParameters() {
return new Parameter[]{
new Parameter("x", null, true),
new Parameter("y", null, true)};
}
public String getComment() {
return "x y => x x y";
}
public void apply(final RippleList arg,
final Sink<RippleList> solutions,
final ModelConnection mc) throws RippleException {
RippleValue y, x;
RippleList stack = arg;
y = stack.getFirst();
stack = stack.getRest();
x = stack.getFirst();
stack = stack.getRest();
solutions.put(
stack.push(x).push(x).push(y));
}
}