BigDecimal tmp;
for (int i = 0; i < input.length; i++) {
Object o = input[i];
if (o instanceof BigDecimal) {
s.push(o);
} else if (o instanceof String) {
switch (((String)o).charAt(0)) {
// + and * are commutative, order doesn't matter
case '+":
s.push(((BigDecimal)s.pop()).add((BigDecimal)s.pop()));
break;
case '*":
s.push(((BigDecimal)s.pop()).multiply((BigDecimal)s.pop()));
break;
// - and /, order *does* matter
case '-":
tmp = (BigDecimal)s.pop();
s.push(((BigDecimal)s.pop()).subtract(tmp));
break;
case '/":
tmp = (BigDecimal)s.pop();
s.push(((BigDecimal)s.pop()).divide(tmp,
BigDecimal.ROUND_UP));
break;
default:
throw new IllegalStateException("Unknown OPERATOR popped");
}
} else {
throw new IllegalArgumentException("Syntax error in input");
}
}
return (BigDecimal)s.pop();
