class Mime::Type

def parse(accept_header)
  if accept_header !~ /,/
    [Mime::Type.lookup(accept_header)]
  else
    # keep track of creation order to keep the subsequent sort stable
    list = []
    accept_header.split(/,/).each_with_index do |header, index|
      params, q = header.split(/;\s*q=/)
      if params
        params.strip!
        list << AcceptItem.new(index, params, q) unless params.empty?
      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