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;
import net.fortytwo.ripple.model.StackMapping;
/**
* A primitive which consumes two numbers x and y and produces the number x to
* the power of y.
*
* @author Joshua Shinavier (http://fortytwo.net)
*/
public class Pow extends PrimitiveStackMapping {
private static final String[] IDENTIFIERS = {
MathLibrary.NS_2013_03 + "pow",
MathLibrary.NS_2008_08 + "pow",
MathLibrary.NS_2007_08 + "pow",
MathLibrary.NS_2007_05 + "pow"};
private final StackMapping self = this;
public String[] getIdentifiers() {
return IDENTIFIERS;
}
public Pow()
throws RippleException {
super();
}
public Parameter[] getParameters() {
return new Parameter[]{
new Parameter("x", null, true),
new Parameter("p", null, true)};
}
public String getComment() {
return "x p => x^p";
}
public void apply(final RippleList arg,
final Sink<RippleList> solutions,
final ModelConnection mc) throws RippleException {
RippleList stack = arg;
NumericValue p, x, result;
p = mc.toNumericValue(stack.getFirst());
stack = stack.getRest();
x = mc.toNumericValue(stack.getFirst());
stack = stack.getRest();
result = x.pow(p);
solutions.put(
stack.push(result));
}
@Override
public StackMapping getInverse() {
return new StackMapping() {
public int arity() {
return 2;
}
public StackMapping getInverse() throws RippleException {
return self;
}
public boolean isTransparent() {
return true;
}
public void apply(final RippleList arg,
final Sink<RippleList> solutions,
final ModelConnection mc) throws RippleException {
RippleList stack = arg;
NumericValue a, c, result;
c = mc.toNumericValue(stack.getFirst());
stack = stack.getRest();
a = mc.toNumericValue(stack.getFirst());
stack = stack.getRest();
if (a.doubleValue() > 0 && c.doubleValue() > 0) {
result = mc.valueOf(Math.log(c.doubleValue()) / Math.log(a.doubleValue()));
solutions.put(stack.push(result));
}
}
};
}
}