module Data.Conduit.Codec.Util
( CodecDecodeException(..)
, encodeI
, decodeI
, decodeII
, encodeII
) where
import Data.Typeable (Typeable)
import Control.Exception (Exception)
import Data.ByteString as BS (ByteString, append, null)
import Data.Conduit (Conduit, await, yield)
import Data.Maybe (fromJust)
import Control.Monad (unless, void)
import Control.Monad.Catch (MonadThrow, throwM)
type EncFunc = ByteString -> ByteString
type EncFuncPart = ByteString -> (ByteString, ByteString)
type EncFuncFinal = ByteString -> Maybe ByteString
type DecFunc = ByteString -> Either (ByteString, ByteString) (ByteString, ByteString)
type DecFuncFinal = ByteString -> Maybe ByteString
data CodecDecodeException = CodecDecodeException ByteString
deriving (Typeable, Show)
instance Exception CodecDecodeException
encodeI :: (Monad m) => EncFuncPart -> EncFuncFinal -> ByteString -> Conduit ByteString m ByteString
encodeI enc_part enc_final i = do
clear <- await
case clear of
Nothing -> void (yield $ fromJust $ enc_final i)
Just s -> let
(a, b) = enc_part (i `append` s)
in do
unless (BS.null a) $ yield a
encodeI enc_part enc_final b
decodeI :: (Monad m, MonadThrow m) => DecFunc -> DecFuncFinal -> ByteString -> Conduit ByteString m ByteString
decodeI dec_part dec_final i = do
enc <- await
case enc of
Nothing ->
case dec_final i of
Nothing -> throwM (CodecDecodeException i)
Just s -> void (yield s)
Just s ->
case dec_part (i `append` s) of
Left (a, b) -> do
unless (BS.null a) $ yield a
throwM (CodecDecodeException b)
Right (a, b) -> do
unless (BS.null a) $ yield a
decodeI dec_part dec_final b
encodeII :: (Monad m) => EncFunc -> Conduit ByteString m ByteString
encodeII enc = do
clear <- await
case clear of
Nothing -> return ()
Just s -> do
yield $ enc s
encodeII enc
decodeII :: (Monad m, MonadThrow m) => DecFunc -> ByteString -> Conduit ByteString m ByteString
decodeII dec i = do
enc <- await
case enc of
Nothing -> unless (BS.null i) (throwM $ CodecDecodeException i)
Just s -> case dec $ i `append` s of
Left (c, b) -> do
unless (BS.null c) $ yield c
throwM $ CodecDecodeException b
Right (c, r) -> do
unless (BS.null c) $ yield c
decodeII dec r