public boolean matchIgnoreCase(String s) {
      int lc = low.compareToIgnoreCase(s);
      if (high != null) {
        int hc = high.compareToIgnoreCase(s);
        return (lc * hc < 0 || (low.closed && lc == 0) || (high.closed && hc == 0));
      } else {
        return lc == 0;
      }
    }