class Rack::MediaType

def params(content_type)

{ 'charset' => 'utf-8' }
this method responds with the following Hash:
provided. e.g., when the CONTENT_TYPE is "text/plain;charset=utf-8",
an empty Hash if no CONTENT_TYPE or media-type parameters were
The media type parameters provided in CONTENT_TYPE as a Hash, or 
def params(content_type)
  return {} if content_type.nil?
  content_type.split(SPLIT_PATTERN)[1..-1].each_with_object({}) do |s, hsh|
    k, v = s.split('=', 2)
    hsh[k.tap(&:downcase!)] = strip_doublequotes(v)
  end
end

def strip_doublequotes(str) 

def strip_doublequotes(str)
  (str.start_with?('"') && str.end_with?('"')) ? str[1..-2] : str
end

def type(content_type)

http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.7
For more information on the use of media types in HTTP, see:

"text/plain;charset=utf-8", the media-type is "text/plain".
without any media type parameters. e.g., when CONTENT_TYPE is
The media type (type/subtype) portion of the CONTENT_TYPE header 
def type(content_type)
  return nil unless content_type
  content_type.split(SPLIT_PATTERN, 2).first.tap &:downcase!
end