module Data.Conduit.Zlib (
compress, decompress, gzip, ungzip,
WindowBits (..), defaultWindowBits
) where
import Codec.Zlib
import Data.Conduit
import Data.ByteString (ByteString)
import qualified Data.ByteString as S
import Control.Monad.Trans.Resource
import Control.Monad.Trans.Class
gzip :: ResourceUnsafeIO m => Conduit ByteString m ByteString
gzip = compress 1 (WindowBits 31)
ungzip :: ResourceUnsafeIO m => Conduit ByteString m ByteString
ungzip = decompress (WindowBits 31)
decompress
:: ResourceUnsafeIO m
=> WindowBits
-> Conduit ByteString m ByteString
decompress config = Conduit $ do
inf <- lift $ unsafeFromIO $ initInflate config
return $ PreparedConduit (push inf) (close inf)
where
push inf x = do
chunks <- lift $ unsafeFromIO $ withInflateInput inf x callback
return $ Producing chunks
close inf = do
chunk <- lift $ unsafeFromIO $ finishInflate inf
return $ if S.null chunk then [] else [chunk]
compress
:: ResourceUnsafeIO m
=> Int
-> WindowBits
-> Conduit ByteString m ByteString
compress level config = Conduit $ do
def <- lift $ unsafeFromIO $ initDeflate level config
return $ PreparedConduit (push def) (close def)
where
push def x = do
chunks <- lift $ unsafeFromIO $ withDeflateInput def x callback
return $ Producing chunks
close def = do
chunks <- lift $ unsafeFromIO $ finishDeflate def callback
return chunks
callback :: Monad m => m (Maybe a) -> m [a]
callback pop = go id where
go front = do
x <- pop
case x of
Nothing -> return $ front []
Just y -> go (front . (:) y)