protected static Value grind(RCvalue args, Operation op) throws EvalException {
for (int i = 0; i < args.size(); i++)
if (!(args.value(i) instanceof PolygonValue))
throw new EvalException(
op.name() + "(): all operands must polgons." + "Operand " + (i + 1) + "is not.");
return (grind(args, op, 0, args.size()));
}
// value(lo) to value(hi-1)
protected static Value grind(RCvalue args, Operation op, int lo, int hi) throws EvalException {
switch (hi - lo) {
case 0:
return new PolygonValue(
(RCvalue) (RCvalue.factory().create(new Value[] {}, true))); // empty
case 1:
return args.value(lo); // one
case 2:
Value result = op.op((PolygonValue) (args.value(lo)), (PolygonValue) (args.value(hi - 1)));
return result; // two
default:
int mid = (lo + hi + 1) / 2; // split
Value v0 = grind(args, op, lo, mid);
Value v1 = grind(args, op, mid, hi);
result = op.op((PolygonValue) (v0), (PolygonValue) (v1));
return result;
}
}