protected TermsEnum filter(Terms terms, AtomicReader reader) throws IOException { TermsEnum iterator = terms.iterator(null); if (iterator == null) { return null; } if (iterator != null && frequency != null) { iterator = FrequencyFilter.filter(iterator, terms, reader, frequency); } if (iterator != null && regex != null) { iterator = RegexFilter.filter(iterator, terms, reader, regex); } return iterator; }