hws-1.1.0.1: src/MimeTypes.hs

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-- Copyright 2002, Simon Marlow.
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module MimeTypes (
       MimeType(..),
       initMimeTypes,	-- :: IO ()
       mimeTypeOf,	-- :: String -> MimeType
       ) where

import Data.Map hiding(map, null)
import IO
import Foreign
import Data.IORef
import Text.Regex

data MimeType = MimeType String String
instance Show MimeType where
   showsPrec _ (MimeType part1 part2) = showString (part1 ++ '/':part2)

mime_types_ref :: IORef (Map String MimeType)
mime_types_ref = unsafePerformIO (newIORef (error "no mime types"))

mimeTypeOf :: String -> Maybe MimeType
mimeTypeOf filename = unsafePerformIO (do
  mime_types <- readIORef mime_types_ref
  let ext = extension filename
  if null ext 
     then return Nothing 
     else return (Data.Map.lookup ext mime_types)
  )

extension :: String -> String
extension fn = go (reverse fn) ""
  where go []      _   = ""
	go ('.':_) ext = ext
	go (x:s)   ext = go s (x:ext)

initMimeTypes :: String -> IO ()
initMimeTypes mime_types_file = do
   h <- openFile mime_types_file ReadMode
   stuff <- hGetContents h
   let mime_types = fromList (parseMimeTypes stuff)
   writeIORef mime_types_ref mime_types

parseMimeTypes file =
  [ (ext,val) 
  | Just (val,exts) <- map (parseMimeLine . takeWhile (/= '#')) (lines file)
  , ext <- exts
  ]

mimeRegex = mkRegex "^([^/]+)/([^ \t]+)[ \t]+(.*)$"

parseMimeLine l = 
  case matchRegex mimeRegex l of
      Just (part1:part2:extns:_) -> Just (MimeType part1 part2, words extns)
      _ -> Nothing