module Data.Hashable ( Hashable(..)
, combine
) where
import Data.Bits
import Data.Int
import Data.Word
import Data.List (foldl')
import qualified Data.ByteString as B
import qualified Data.ByteString.Internal as BInt
import qualified Data.ByteString.Unsafe as BInt
import qualified Data.ByteString.Lazy as BL
import qualified Data.ByteString.Lazy.Internal as BLInt
import Foreign.C
class Hashable a where
hash :: a -> Int
combine :: Int -> Int -> Int
combine h1 h2 = (h1 + h1 `shiftL` 5) `xor` h2
hashAndCombine :: Hashable h => Int -> h -> Int
hashAndCombine acc h = acc `combine` hash h
instance Hashable () where hash _ = 0
instance Hashable Bool where hash x = case x of { True -> 1; False -> 0 }
instance Hashable Int where hash = id
instance Hashable Int8 where hash = fromIntegral
instance Hashable Int16 where hash = fromIntegral
instance Hashable Int32 where hash = fromIntegral
instance Hashable Int64 where hash = fromIntegral
instance Hashable Word where hash = fromIntegral
instance Hashable Word8 where hash = fromIntegral
instance Hashable Word16 where hash = fromIntegral
instance Hashable Word32 where hash = fromIntegral
instance Hashable Word64 where hash = fromIntegral
instance Hashable Char where hash = fromEnum
instance Hashable a => Hashable (Maybe a) where
hash Nothing = 0
hash (Just a) = 42 `combine` hash a
instance (Hashable a1, Hashable a2) => Hashable (a1, a2) where
hash (a1, a2) = hash a1 `combine` hash a2
instance (Hashable a1, Hashable a2, Hashable a3) => Hashable (a1, a2, a3) where
hash (a1, a2, a3) = hash a1 `combine` hash a2 `combine` hash a3
instance (Hashable a1, Hashable a2, Hashable a3, Hashable a4) => Hashable (a1, a2, a3, a4) where
hash (a1, a2, a3, a4) = hash a1 `combine` hash a2 `combine` hash a3 `combine` hash a4
instance (Hashable a1, Hashable a2, Hashable a3, Hashable a4, Hashable a5)
=> Hashable (a1, a2, a3, a4, a5) where
hash (a1, a2, a3, a4, a5) =
hash a1 `combine` hash a2 `combine` hash a3 `combine` hash a4 `combine` hash a5
instance (Hashable a1, Hashable a2, Hashable a3, Hashable a4, Hashable a5, Hashable a6)
=> Hashable (a1, a2, a3, a4, a5, a6) where
hash (a1, a2, a3, a4, a5, a6) =
hash a1 `combine` hash a2 `combine` hash a3 `combine` hash a4 `combine` hash a5 `combine` hash a6
instance (Hashable a1, Hashable a2, Hashable a3, Hashable a4, Hashable a5, Hashable a6, Hashable a7)
=> Hashable (a1, a2, a3, a4, a5, a6, a7) where
hash (a1, a2, a3, a4, a5, a6, a7) =
hash a1 `combine` hash a2 `combine` hash a3 `combine` hash a4 `combine` hash a5 `combine` hash a6 `combine` hash a7
instance Hashable a => Hashable [a] where
hash = foldl' hashAndCombine 0
foreign import ccall unsafe hashByteString :: CString -> CInt -> IO CInt
instance Hashable B.ByteString where
hash bstr = fromIntegral $ BInt.inlinePerformIO $ BInt.unsafeUseAsCStringLen bstr $
\(str, len) -> hashByteString str (fromIntegral len)
instance Hashable BL.ByteString where hash = BLInt.foldlChunks hashAndCombine 0