presto-local-file/src/main/java/io/prestosql/plugin/localfile/LocalFileRecordCursor.java/FilesReader/readFields
class FilesReader:        public List<String> readFields()
                throws IOException
        {
            List<String> fields = null;
            boolean newReader = false;

            while (fields == null) {
                if (reader == null) {
                    return null;
                }
                String line = reader.readLine();
                if (line != null) {
                    fields = LINE_SPLITTER.splitToList(line);
                    if (!newReader || meetsPredicate(fields)) {
                        return fields;
                    }
                }
                reader.close();
                reader = createNextReader();
                newReader = true;
            }
            return fields;
        }