2 -- (c) The University of Glasgow 2002-2006
6 {-# LANGUAGE ScopedTypeVariables #-}
8 -- * Main Serialized data type
12 -- * Going into and out of 'Serialized'
13 toSerialized, fromSerialized,
15 -- * Handy serialization functions
16 serializeWithData, deserializeWithData,
25 import Data.Word ( Word8 )
30 -- | Represents a serialized value of a particular type. Attempts can be made to deserialize it at certain types
31 data Serialized = Serialized TypeRep [Word8]
33 instance Outputable Serialized where
34 ppr (Serialized the_type bytes) = int (length bytes) <+> ptext (sLit "of type") <+> text (show the_type)
36 instance Binary Serialized where
37 put_ bh (Serialized the_type bytes) = do
43 return (Serialized the_type bytes)
45 -- | Put a Typeable value that we are able to actually turn into bytes into a 'Serialized' value ready for deserialization later
46 toSerialized :: Typeable a => (a -> [Word8]) -> a -> Serialized
47 toSerialized serialize what = Serialized (typeOf what) (serialize what)
49 -- | If the 'Serialized' value contains something of the given type, then use the specified deserializer to return @Just@ that.
50 -- Otherwise return @Nothing@.
51 fromSerialized :: forall a. Typeable a => ([Word8] -> a) -> Serialized -> Maybe a
52 fromSerialized deserialize (Serialized the_type bytes)
53 | the_type == typeOf (undefined :: a) = Just (deserialize bytes)
56 -- | Force the contents of the Serialized value so weknow it doesn't contain any bottoms
57 seqSerialized :: Serialized -> ()
58 seqSerialized (Serialized the_type bytes) = the_type `seq` bytes `seqList` ()
61 -- | Use a 'Data' instance to implement a serialization scheme dual to that of 'deserializeWithData'
62 serializeWithData :: Data a => a -> [Word8]
63 serializeWithData what = serializeWithData' what []
65 serializeWithData' :: Data a => a -> [Word8] -> [Word8]
66 serializeWithData' what = fst $ gfoldl (\(before, a_to_b) a -> (before . serializeWithData' a, a_to_b a))
67 (\x -> (serializeConstr (constrRep (toConstr what)), x))
70 -- | Use a 'Data' instance to implement a deserialization scheme dual to that of 'serializeWithData'
71 deserializeWithData :: Data a => [Word8] -> a
72 deserializeWithData = snd . deserializeWithData'
74 deserializeWithData' :: forall a. Data a => [Word8] -> ([Word8], a)
75 deserializeWithData' bytes = deserializeConstr bytes $ \constr_rep bytes ->
76 gunfold (\(bytes, b_to_r) -> let (bytes', b) = deserializeWithData' bytes in (bytes', b_to_r b))
78 (repConstr (dataTypeOf (undefined :: a)) constr_rep)
81 serializeConstr :: ConstrRep -> [Word8] -> [Word8]
82 serializeConstr (AlgConstr ix) = serializeWord8 1 . serializeInt ix
83 serializeConstr (IntConstr i) = serializeWord8 2 . serializeInteger i
84 serializeConstr (FloatConstr r) = serializeWord8 3 . serializeRational r
85 serializeConstr (CharConstr c) = serializeWord8 4 . serializeChar c
88 deserializeConstr :: [Word8] -> (ConstrRep -> [Word8] -> a) -> a
89 deserializeConstr bytes k = deserializeWord8 bytes $ \constr_ix bytes ->
91 1 -> deserializeInt bytes $ \ix -> k (AlgConstr ix)
92 2 -> deserializeInteger bytes $ \i -> k (IntConstr i)
93 3 -> deserializeRational bytes $ \r -> k (FloatConstr r)
94 4 -> deserializeChar bytes $ \c -> k (CharConstr c)
95 x -> error $ "deserializeConstr: unrecognised serialized constructor type " ++ show x ++ " in context " ++ show bytes
98 serializeFixedWidthNum :: forall a. (Num a, Integral a, Bits a) => a -> [Word8] -> [Word8]
99 serializeFixedWidthNum what = go (bitSize what) what
101 go :: Int -> a -> [Word8] -> [Word8]
104 | otherwise = fromIntegral (current .&. 255) : go (size - 8) (current `shiftR` 8) rest
106 deserializeFixedWidthNum :: forall a b. (Num a, Integral a, Bits a) => [Word8] -> (a -> [Word8] -> b) -> b
107 deserializeFixedWidthNum bytes k = go (bitSize (undefined :: a)) bytes k
109 go :: Int -> [Word8] -> (a -> [Word8] -> b) -> b
111 | size <= 0 = k 0 bytes
112 | otherwise = case bytes of
113 (byte:bytes) -> go (size - 8) bytes (\x -> k ((x `shiftL` 8) .|. fromIntegral byte))
114 [] -> error "deserializeFixedWidthNum: unexpected end of stream"
117 serializeEnum :: (Enum a) => a -> [Word8] -> [Word8]
118 serializeEnum = serializeInt . fromEnum
120 deserializeEnum :: Enum a => [Word8] -> (a -> [Word8] -> b) -> b
121 deserializeEnum bytes k = deserializeInt bytes (k . toEnum)
124 serializeWord8 :: Word8 -> [Word8] -> [Word8]
125 serializeWord8 x = (x:)
127 deserializeWord8 :: [Word8] -> (Word8 -> [Word8] -> a) -> a
128 deserializeWord8 (byte:bytes) k = k byte bytes
129 deserializeWord8 [] _ = error "deserializeWord8: unexpected end of stream"
132 serializeInt :: Int -> [Word8] -> [Word8]
133 serializeInt = serializeFixedWidthNum
135 deserializeInt :: [Word8] -> (Int -> [Word8] -> a) -> a
136 deserializeInt = deserializeFixedWidthNum
139 serializeRational :: (Real a) => a -> [Word8] -> [Word8]
140 serializeRational = serializeString . show . toRational
142 deserializeRational :: (Fractional a) => [Word8] -> (a -> [Word8] -> b) -> b
143 deserializeRational bytes k = deserializeString bytes (k . fromRational . read)
146 serializeInteger :: Integer -> [Word8] -> [Word8]
147 serializeInteger = serializeString . show
149 deserializeInteger :: [Word8] -> (Integer -> [Word8] -> a) -> a
150 deserializeInteger bytes k = deserializeString bytes (k . read)
153 serializeChar :: Char -> [Word8] -> [Word8]
154 serializeChar = serializeString . show
156 deserializeChar :: [Word8] -> (Char -> [Word8] -> a) -> a
157 deserializeChar bytes k = deserializeString bytes (k . read)
160 serializeString :: String -> [Word8] -> [Word8]
161 serializeString = serializeList serializeEnum
163 deserializeString :: [Word8] -> (String -> [Word8] -> a) -> a
164 deserializeString = deserializeList deserializeEnum
167 serializeList :: (a -> [Word8] -> [Word8]) -> [a] -> [Word8] -> [Word8]
168 serializeList serialize_element xs = serializeInt (length xs) . foldr (.) id (map serialize_element xs)
170 deserializeList :: forall a b. (forall c. [Word8] -> (a -> [Word8] -> c) -> c)
171 -> [Word8] -> ([a] -> [Word8] -> b) -> b
172 deserializeList deserialize_element bytes k = deserializeInt bytes $ \len bytes -> go len bytes k
174 go :: Int -> [Word8] -> ([a] -> [Word8] -> b) -> b
176 | len <= 0 = k [] bytes
177 | otherwise = deserialize_element bytes (\elt bytes -> go (len - 1) bytes (k . (elt:)))