module Foreign.Codec
(
ForeignContext, ForeignCodec, ForeignCodec'
, peekWith, pokeWith, storable, field
, cast, cBool
, codecFor
) where
import Control.Monad.Reader
import Foreign
import Data.Codec.Codec
type ForeignContext a = ReaderT (Ptr a) IO
type ForeignCodec' p a = Codec (ForeignContext p) (ForeignContext p) a
type ForeignCodec a = ForeignCodec' a a
peekWith :: ForeignCodec' p a -> Ptr p -> IO a
peekWith (Codec r _)
= runReaderT r
pokeWith :: ForeignCodec' p a -> Ptr p -> a -> IO ()
pokeWith (Codec _ w) ptr x
= runReaderT (w x) ptr
field :: Int -> ForeignCodec' f a -> ForeignCodec' p a
field off cd = Codec
{ parse = inField $ parse cd
, produce = inField . produce cd
} where inField = withReaderT (`plusPtr` off)
storable :: Storable a => ForeignCodec a
storable = Codec (ReaderT peek) (\x -> ReaderT (`poke`x))
castContext :: ForeignCodec' c a -> ForeignCodec' c' a
castContext = mapCodecF castc castc
where castc = withReaderT castPtr
cast :: (Integral c, Storable c, Integral a) => ForeignCodec' c a
cast = mapCodec fromIntegral fromIntegral storable
cBool :: Integral c => ForeignCodec' c Bool
cBool = castContext storable
codecFor :: c -> ForeignCodec' c a -> ForeignCodec' c a
codecFor _ = id