public RandomAccessFilter buildRandomAccessOrFilter(String[] vals, Properties prop, boolean isNot)
      throws IOException {
    RandomAccessFilter filter = null;
    if (vals.length > 0) {
      filter = new CompactMultiValueFacetFilter(this, vals);
    } else {
      filter = EmptyFilter.getInstance();
    }
    if (isNot) {
      filter = new RandomAccessNotFilter(filter);