# File lib/html/sgml-parser.rb, line 193
     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
       src_length = match + matched_length - i
       set_range(i, i + src_length)
       handle_comment(rawdata[i+4..(j-1)])
       return src_length
     end