# File lib/feedparser/sgml-parser.rb, line 160
    def parse_comment(i)
      rawdata = @rawdata
      if rawdata[i, 4] != '<!--'
        raise RuntimeError, 'unexpected call to handle_comment'
      end
      match = rawdata.index(Commentclose, i)
      return nil unless match
      matched_length = $&.length
      j = match
      handle_comment(rawdata[i+4..(j-1)])
      j = match + matched_length
      return j-i
    end