parse

# File actionpack/lib/action_dispatch/http/mime_type.rb, line 109
      def parse(accept_header)
        if accept_header !~ /,/
          if accept_header =~ TRAILING_STAR_REGEXP
            parse_data_with_trailing_star($1)
          else
            [Mime::Type.lookup(accept_header)]
          end
        else
          # keep track of creation order to keep the subsequent sort stable
          list, index = [], 0
          accept_header.split(/,/).each do |header|
            params, q = header.split(/;\s*q=/)
            if params.present?
              params.strip!

              if params =~ TRAILING_STAR_REGEXP
                parse_data_with_trailing_star($1).each do |m|
                  list << AcceptItem.new(index, m.to_s, q)
                  index += 1
                end
              else
                list << AcceptItem.new(index, params, q)
                index += 1
              end
            end
          end
          list.sort!

          # Take care of the broken text/xml entry by renaming or deleting it
          text_xml = list.index("text/xml")
          app_xml = list.index(Mime::XML.to_s)

          if text_xml && app_xml
            # set the q value to the max of the two
            list[app_xml].q = [list[text_xml].q, list[app_xml].q].max

            # make sure app_xml is ahead of text_xml in the list
            if app_xml > text_xml
              list[app_xml], list[text_xml] = list[text_xml], list[app_xml]
              app_xml, text_xml = text_xml, app_xml
            end

            # delete text_xml from the list
            list.delete_at(text_xml)

          elsif text_xml
            list[text_xml].name = Mime::XML.to_s
          end

          # Look for more specific XML-based types and sort them ahead of app/xml

          if app_xml
            idx = app_xml
            app_xml_type = list[app_xml]

            while(idx < list.length)
              type = list[idx]
              break if type.q < app_xml_type.q
              if type.name =~ /\+xml$/
                list[app_xml], list[idx] = list[idx], list[app_xml]
                app_xml = idx
              end
              idx += 1
            end
          end

          list.map! { |i| Mime::Type.lookup(i.name) }.uniq!
          list
        end
      end