/**
* This method is invoked when the builtin is called in a rule body.
*
* @param args the array of argument values for the builtin, this is an array of Nodes, some of
* which may be Node_RuleVariables.
* @param length the length of the argument list, may be less than the length of the args array
* for some rule engines
* @param context an execution context giving access to other relevant data
* @return return true if the buildin predicate is deemed to have succeeded in the current
* environment
*/
public boolean bodyCall(Node[] args, int length, RuleContext context) {
checkArgs(length, context);
BindingEnvironment env = context.getEnv();
Node n1 = getArg(0, args, context);
Node n2 = getArg(1, args, context);
if (n1.isLiteral() && n2.isLiteral()) {
Object v1 = n1.getLiteralValue();
Object v2 = n2.getLiteralValue();
Node sum = null;
if (v1 instanceof Number && v2 instanceof Number) {
Number nv1 = (Number) v1;
Number nv2 = (Number) v2;
if (v1 instanceof Float
|| v1 instanceof Double
|| v2 instanceof Float
|| v2 instanceof Double) {
sum = Util.makeDoubleNode(nv1.doubleValue() - nv2.doubleValue());
} else {
sum = Util.makeLongNode(nv1.longValue() - nv2.longValue());
}
return env.bind(args[2], sum);
}
}
// Doesn't (yet) handle partially bound cases
return false;
}
private long getIntegralValueInRange(long min, Number n, long max) {
long result = n.longValue();
if (min <= result && result <= max) return result;
throw new IllegalArgumentException("byte value required: " + result);
}