Flat.Decoder

Strict Decoder

Documentation

strictDecoder :: Get a -> ByteString -> Int -> Either DecodeException a

Given a decoder and an input buffer returns either the decoded value or an error (if the input buffer is not fully consumed)

listTDecoder :: Get a -> ByteString -> IO (ListT IO a)

Decode a list of values, one value at a time.

Useful in case that the decoded values takes a lot more memory than the encoded ones.

See ../test/Big.hs for a test and an example of use.

See also Flat.AsBin.

Since: 0.5

type Decoded a = Either DecodeException a

A decoded value

data DecodeException

An exception during decoding

Constructors

NotEnoughSpace Env

TooMuchSpace Env

BadEncoding Env String

BadOp String

Instances

Exception DecodeException

Defined in Flat.Decoder.Types

Methods

toException :: DecodeException -> SomeException

fromException :: SomeException -> Maybe DecodeException

displayException :: DecodeException -> String

Show DecodeException

Defined in Flat.Decoder.Types

Methods

showsPrec :: Int -> DecodeException -> ShowS

show :: DecodeException -> String

showList :: [DecodeException] -> ShowS

Eq DecodeException

Defined in Flat.Decoder.Types

Methods

(==) :: DecodeException -> DecodeException -> Bool

(/=) :: DecodeException -> DecodeException -> Bool

Ord DecodeException

Defined in Flat.Decoder.Types

Methods

compare :: DecodeException -> DecodeException -> Ordering

(<) :: DecodeException -> DecodeException -> Bool

(<=) :: DecodeException -> DecodeException -> Bool

(>) :: DecodeException -> DecodeException -> Bool

(>=) :: DecodeException -> DecodeException -> Bool

max :: DecodeException -> DecodeException -> DecodeException

min :: DecodeException -> DecodeException -> DecodeException

data Get a

A decoder.

Given:

• end of input buffer
• current position in input buffer

Returns:

• decoded value
• new position in input buffer

Instances

MonadFail Get

Defined in Flat.Decoder.Types

Methods

fail :: String -> Get a

Applicative Get

Defined in Flat.Decoder.Types

Methods

pure :: a -> Get a

(<*>) :: Get (a -> b) -> Get a -> Get b

liftA2 :: (a -> b -> c) -> Get a -> Get b -> Get c

(*>) :: Get a -> Get b -> Get b

(<*) :: Get a -> Get b -> Get a

Functor Get

Defined in Flat.Decoder.Types

Methods

fmap :: (a -> b) -> Get a -> Get b

(<$) :: a -> Get b -> Get a

Monad Get

Defined in Flat.Decoder.Types

Methods

(>>=) :: Get a -> (a -> Get b) -> Get b

(>>) :: Get a -> Get b -> Get b

return :: a -> Get a

Show (Get a)

Defined in Flat.Decoder.Types

Methods

showsPrec :: Int -> Get a -> ShowS

show :: Get a -> String

showList :: [Get a] -> ShowS

NFData (Get a)

Defined in Flat.Decoder.Types

Methods

rnf :: Get a -> ()

dByteString :: Get ByteString

dLazyByteString :: Get ByteString

dShortByteString :: Get ShortByteString

dShortByteString_ :: Get ShortByteString

dUTF16 :: Get Text

dUTF8 :: Get Text

decodeArrayWith :: Get a -> Get [a]

decodeListWith :: Get a -> Get [a]

dFloat :: Get Float

Decode a Float

dDouble :: Get Double

Decode a Double

dInteger :: Get Integer

dNatural :: Get Natural

dChar :: Get Char

dBool :: Get Bool

Decode a boolean

dWord8 :: Get Word8

Return the 8 most significant bits (same as dBE8)

dWord16 :: Get Word16

dWord32 :: Get Word32

dWord64 :: Get Word64

dWord :: Get Word

dInt8 :: Get Int8

dInt16 :: Get Int16

dInt32 :: Get Int32

dInt64 :: Get Int64

dInt :: Get Int

dBE8 :: Get Word8

Return the 8 most significant bits

dBE16 :: Get Word16

Return the 16 most significant bits

dBE32 :: Get Word32

Return the 32 most significant bits

dBE64 :: Get Word64

Return the 64 most significant bits

dBEBits8 :: Int -> Get Word8

Return the n most significant bits (up to maximum of 8)

The bits are returned right shifted:

>>> unflatWith (dBEBits8 3) [0b11100001::Word8] == Right 0b00000111
True

>>> unflatWith (dBEBits8 9) [0b11100001::Word8,0b11111111]
Left (BadOp "read8: cannot read 9 bits")

dBEBits16 :: Int -> Get Word16

Return the n most significant bits (up to maximum of 16)

The bits are returned right shifted:

>>> pPrint . asBits <$> unflatWith (dBEBits16 11) [0b10110111::Word8,0b11100001]
Right 00000101 10111111

If more than 16 bits are requested, only the last 16 are returned:

>>> pPrint . asBits <$> unflatWith (dBEBits16 19) [0b00000000::Word8,0b11111111,0b11100001]
Right 00000111 11111111

dBEBits32 :: Int -> Get Word32

Return the n most significant bits (up to maximum of 32) The bits are returned right shifted.

dBEBits64 :: Int -> Get Word64

Return the n most significant bits (up to maximum of 64) The bits are returned right shifted.

dropBits :: Int -> Get ()

Drop the specified number of bits

data ConsState

A special state, optimised for constructor decoding.

It consists of:

• The bits to parse, the top bit being the first to parse (could use a Word16 instead, no difference in performance)
• The number of decoded bits

Supports up to 512 constructors (9 bits).

Constructors

ConsState !Word !Int

consOpen :: Get ConsState

Switch to constructor decoding {-# INLINE consOpen #-}

consClose :: Int -> Get ()

Switch back to normal decoding {-# NOINLINE consClose #-}

consBool :: ConsState -> (ConsState, Bool)

Decode a single bit

consBits :: ConsState -> Int -> (ConsState, Word)

Decode from 1 to 3 bits

It could read more bits that are available, but it doesn't matter, errors will be checked in consClose.