package net.fortytwo.ripple.libs.math;
import net.fortytwo.flow.Sink;
import net.fortytwo.ripple.RippleException;
import net.fortytwo.ripple.model.ModelConnection;
import net.fortytwo.ripple.model.NumericValue;
import net.fortytwo.ripple.model.PrimitiveStackMapping;
import net.fortytwo.ripple.model.RippleList;
/**
* A primitive which consumes a number and produces its sign. This has three
* possible values: -1 if the number is less than 0, 0 if the number is equal to
* 0, and 1 if the number is greater than 0.
*
* @author Joshua Shinavier (http://fortytwo.net)
*/
public class Sign extends PrimitiveStackMapping {
private static final String[] IDENTIFIERS = {
MathLibrary.NS_2013_03 + "sign",
MathLibrary.NS_2008_08 + "sign",
MathLibrary.NS_2007_08 + "signum",
MathLibrary.NS_2007_05 + "sign"};
public String[] getIdentifiers() {
return IDENTIFIERS;
}
public Sign()
throws RippleException {
super();
}
public Parameter[] getParameters() {
return new Parameter[]{
new Parameter("x", null, true)};
}
public String getComment() {
return "x => sign of x (-1, 0, or +1)";
}
public void apply(final RippleList arg,
final Sink<RippleList> solutions,
final ModelConnection mc) throws RippleException {
RippleList stack = arg;
NumericValue a, result;
a = mc.toNumericValue(stack.getFirst());
stack = stack.getRest();
result = mc.valueOf(a.sign());
solutions.put(
stack.push(result));
}
}