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module Data.Conduit.Zstd
( compress
, decompress
) where
import qualified Data.Conduit as C
import qualified Data.ByteString as B
import qualified Codec.Compression.Zstd.Streaming as Z
import Control.Monad.IO.Class (MonadIO, liftIO)
import Control.Exception.Base (throwIO)
import System.IO.Error (userError)
import Data.Maybe (fromMaybe)
-- | compression conduit
compress :: MonadIO m =>
Int -- ^ compression level
-> C.ConduitT B.ByteString B.ByteString m ()
compress level = liftIO (Z.compress level) >>= go
-- | decompression conduit
decompress :: MonadIO m => C.ConduitT B.ByteString B.ByteString m ()
decompress = liftIO Z.decompress >>= go
go :: MonadIO m => Z.Result -> C.ConduitT B.ByteString B.ByteString m ()
go (Z.Produce r next) = do
C.yield r
liftIO next >>= go
go input@(Z.Consume f) = do
next <- C.await
case next of
Just chunk | B.null chunk ->
go input
_ ->
liftIO (f $ fromMaybe B.empty next) >>= go
go (Z.Error m e) = liftIO (throwIO $ userError ("ZStandard error :" ++ m ++ ": " ++ e))
go (Z.Done r) = C.yield r
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