mohws-0.1: src/MimeTypes.hs

-- -----------------------------------------------------------------------------
-- Copyright 2002, Simon Marlow.
-- Copyright 2006, Bjorn Bringert.
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module MimeTypes (
                  MimeTypes,
                  MimeType(..),
                  initMimeTypes,
                  mimeTypeOf,
                  pMimeType
                 ) where

import Parse

import Data.Map (Map)
import qualified Data.Map as Map hiding (Map)
import Text.ParserCombinators.Parsec

type MimeTypes = Map String MimeType

data MimeType = MimeType String String

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

mimeTypeOf :: MimeTypes -> FilePath -> Maybe MimeType
mimeTypeOf mime_types filename =
    do let ext = extension filename
       if null ext
         then Nothing
         else 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 :: FilePath -> IO MimeTypes
initMimeTypes mime_types_file =
    do stuff <- readFile mime_types_file
       return $ Map.fromList (parseMimeTypes stuff)

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

parseMimeLine :: String -> Maybe (MimeType, [String])
parseMimeLine l = case parse pMimeLine "MIME line" l of
                    Left _  -> Nothing
                    Right m -> Just m

pMimeLine :: Parser (MimeType, [String])
pMimeLine = do t <- pMimeType
               es <- (spaces >> sepBy pToken spaces)
               return (t, es)

pMimeType :: Parser MimeType
pMimeType = do part1 <- pToken
               char '/'
               part2 <- pToken
               return $ MimeType part1 part2