package net.fortytwo.ripple.libs.logic;
import net.fortytwo.flow.Sink;
import net.fortytwo.ripple.RippleException;
import net.fortytwo.ripple.libs.stack.StackLibrary;
import net.fortytwo.ripple.model.ModelConnection;
import net.fortytwo.ripple.model.PrimitiveStackMapping;
import net.fortytwo.ripple.model.RippleList;
import net.fortytwo.ripple.model.RippleValue;
import net.fortytwo.ripple.model.StackMapping;
/**
* A primitive which consumes two Boolean values and produces the result of
* their exclusive logical disjunction.
*
* @author Joshua Shinavier (http://fortytwo.net)
*/
public class Xor extends PrimitiveStackMapping {
private static final String[] IDENTIFIERS = {
LogicLibrary.NS_2013_03 + "xor",
LogicLibrary.NS_2008_08 + "xor",
StackLibrary.NS_2007_08 + "xor",
StackLibrary.NS_2007_05 + "xor"};
private final StackMapping self = this;
public String[] getIdentifiers() {
return IDENTIFIERS;
}
public Xor()
throws RippleException {
super();
}
public Parameter[] getParameters() {
return new Parameter[]{
new Parameter("x", "a boolean value (xsd:true or xsd:false)", true),
new Parameter("y", "a boolean value (xsd:true or xsd:false)", true)};
}
public String getComment() {
return "x y => z -- where z is the logical exclusive disjunction of truth values x and y";
}
public void apply(final RippleList arg,
final Sink<RippleList> solutions,
final ModelConnection mc) throws RippleException {
RippleList stack = arg;
boolean x, y;
x = mc.toBoolean(stack.getFirst());
stack = stack.getRest();
y = mc.toBoolean(stack.getFirst());
stack = stack.getRest();
RippleValue result = mc.valueOf((x && !y) || (!x && y));
solutions.put(
stack.push(result));
}
@Override
public StackMapping getInverse() {
return new StackMapping() {
public int arity() {
return 1;
}
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;
boolean x;
x = mc.toBoolean(stack.getFirst());
stack = stack.getRest();
if (x) {
RippleValue t = mc.valueOf(true);
RippleValue f = mc.valueOf(false);
solutions.put(stack.push(t).push(f));
solutions.put(stack.push(f).push(t));
} else {
RippleValue f = mc.valueOf(false);
solutions.put(stack.push(f).push(f));
}
}
};
}
}