return new IntItem(buf);
            } else if (buf.length() <= MAX_LONGITEM_LENGTH) {
                // lower than 2^63
                return new LongItem(buf);
            }
            return new BigIntegerItem(buf);
        }
        return new StringItem(buf, false);
    }

    private static String stripLeadingZeroes(String buf) {
        if (buf == null || buf.isEmpty()) {
            return "0";

        } else {
            StringBuilder buf = new StringBuilder();
            for (Iterator<Restriction> i = restrictions.iterator(); i.hasNext(); ) {
                Restriction r = i.next();

                buf.append(r.toString());

                if (i.hasNext()) {
                    buf.append(',');
                }
            }
            return buf.toString();
        }
    }