module Sprockets::Mime

def encoding_for_mime_type(type)

back on the default external encoding, if it exists.
Returns the correct encoding for a given mime type, while falling 
def encoding_for_mime_type(type)
  encoding = Encoding::BINARY if type =~ %r{^(image|audio|video)/}
  encoding ||= default_external_encoding if respond_to?(:default_external_encoding)
  encoding
end

def extension_for_mime_type(type) 

def extension_for_mime_type(type)
  mime_types.key(type)
end

def extension_for_mime_type(type) 

def extension_for_mime_type(type)
  mime_types.index(type)
end

def mime_types(ext = nil)

If an `ext` is given, it will lookup the mime type for that extension.

environment and those part of `Rack::Mime`.
Returns a `Hash` of registered mime types registered on the 
def mime_types(ext = nil)
  if ext.nil?
    Rack::Mime::MIME_TYPES.merge(@mime_types)
  else
    ext = Sprockets::Utils.normalize_extension(ext)
    @mime_types[ext] || Rack::Mime::MIME_TYPES[ext]
  end
end

def register_mime_type(mime_type, ext)

Register a new mime type. 
def register_mime_type(mime_type, ext)
  ext = Sprockets::Utils.normalize_extension(ext)
  @mime_types[ext] = mime_type
end