Copyright | (c) Duncan Coutts 2015-2017 |
---|---|
License | BSD3-style (see LICENSE.txt) |
Maintainer | duncan@community.haskell.org |
Stability | experimental |
Portability | non-portable (GHC extensions) |
Safe Haskell | Safe-Inferred |
Language | Haskell2010 |
High level API for decoding values that were encoded with the
Codec.CBOR.Encoding module, using a Monad
based interface.
Synopsis
- data Decoder s a
- data DecodeAction s a
- = ConsumeWord (Word# -> ST s (DecodeAction s a))
- | ConsumeWord8 (Word# -> ST s (DecodeAction s a))
- | ConsumeWord16 (Word# -> ST s (DecodeAction s a))
- | ConsumeWord32 (Word# -> ST s (DecodeAction s a))
- | ConsumeNegWord (Word# -> ST s (DecodeAction s a))
- | ConsumeInt (Int# -> ST s (DecodeAction s a))
- | ConsumeInt8 (Int# -> ST s (DecodeAction s a))
- | ConsumeInt16 (Int# -> ST s (DecodeAction s a))
- | ConsumeInt32 (Int# -> ST s (DecodeAction s a))
- | ConsumeListLen (Int# -> ST s (DecodeAction s a))
- | ConsumeMapLen (Int# -> ST s (DecodeAction s a))
- | ConsumeTag (Word# -> ST s (DecodeAction s a))
- | ConsumeInteger (Integer -> ST s (DecodeAction s a))
- | ConsumeFloat (Float# -> ST s (DecodeAction s a))
- | ConsumeDouble (Double# -> ST s (DecodeAction s a))
- | ConsumeBytes (ByteString -> ST s (DecodeAction s a))
- | ConsumeByteArray (ByteArray -> ST s (DecodeAction s a))
- | ConsumeString (Text -> ST s (DecodeAction s a))
- | ConsumeUtf8ByteArray (ByteArray -> ST s (DecodeAction s a))
- | ConsumeBool (Bool -> ST s (DecodeAction s a))
- | ConsumeSimple (Word# -> ST s (DecodeAction s a))
- | ConsumeBytesIndef (ST s (DecodeAction s a))
- | ConsumeStringIndef (ST s (DecodeAction s a))
- | ConsumeListLenIndef (ST s (DecodeAction s a))
- | ConsumeMapLenIndef (ST s (DecodeAction s a))
- | ConsumeNull (ST s (DecodeAction s a))
- | ConsumeListLenOrIndef (Int# -> ST s (DecodeAction s a))
- | ConsumeMapLenOrIndef (Int# -> ST s (DecodeAction s a))
- | ConsumeBreakOr (Bool -> ST s (DecodeAction s a))
- | PeekTokenType (TokenType -> ST s (DecodeAction s a))
- | PeekAvailable (Int# -> ST s (DecodeAction s a))
- | PeekByteOffset (Int# -> ST s (DecodeAction s a))
- | ConsumeWordCanonical (Word# -> ST s (DecodeAction s a))
- | ConsumeWord8Canonical (Word# -> ST s (DecodeAction s a))
- | ConsumeWord16Canonical (Word# -> ST s (DecodeAction s a))
- | ConsumeWord32Canonical (Word# -> ST s (DecodeAction s a))
- | ConsumeNegWordCanonical (Word# -> ST s (DecodeAction s a))
- | ConsumeIntCanonical (Int# -> ST s (DecodeAction s a))
- | ConsumeInt8Canonical (Int# -> ST s (DecodeAction s a))
- | ConsumeInt16Canonical (Int# -> ST s (DecodeAction s a))
- | ConsumeInt32Canonical (Int# -> ST s (DecodeAction s a))
- | ConsumeListLenCanonical (Int# -> ST s (DecodeAction s a))
- | ConsumeMapLenCanonical (Int# -> ST s (DecodeAction s a))
- | ConsumeTagCanonical (Word# -> ST s (DecodeAction s a))
- | ConsumeIntegerCanonical (Integer -> ST s (DecodeAction s a))
- | ConsumeFloat16Canonical (Float# -> ST s (DecodeAction s a))
- | ConsumeFloatCanonical (Float# -> ST s (DecodeAction s a))
- | ConsumeDoubleCanonical (Double# -> ST s (DecodeAction s a))
- | ConsumeBytesCanonical (ByteString -> ST s (DecodeAction s a))
- | ConsumeByteArrayCanonical (ByteArray -> ST s (DecodeAction s a))
- | ConsumeStringCanonical (Text -> ST s (DecodeAction s a))
- | ConsumeUtf8ByteArrayCanonical (ByteArray -> ST s (DecodeAction s a))
- | ConsumeSimpleCanonical (Word# -> ST s (DecodeAction s a))
- | Fail String
- | Done a
- liftST :: ST s a -> Decoder s a
- getDecodeAction :: Decoder s a -> ST s (DecodeAction s a)
- decodeWord :: Decoder s Word
- decodeWord8 :: Decoder s Word8
- decodeWord16 :: Decoder s Word16
- decodeWord32 :: Decoder s Word32
- decodeWord64 :: Decoder s Word64
- decodeNegWord :: Decoder s Word
- decodeNegWord64 :: Decoder s Word64
- decodeInt :: Decoder s Int
- decodeInt8 :: Decoder s Int8
- decodeInt16 :: Decoder s Int16
- decodeInt32 :: Decoder s Int32
- decodeInt64 :: Decoder s Int64
- decodeInteger :: Decoder s Integer
- decodeFloat :: Decoder s Float
- decodeDouble :: Decoder s Double
- decodeBytes :: Decoder s ByteString
- decodeBytesIndef :: Decoder s ()
- decodeByteArray :: Decoder s ByteArray
- decodeString :: Decoder s Text
- decodeStringIndef :: Decoder s ()
- decodeUtf8ByteArray :: Decoder s ByteArray
- decodeListLen :: Decoder s Int
- decodeListLenIndef :: Decoder s ()
- decodeMapLen :: Decoder s Int
- decodeMapLenIndef :: Decoder s ()
- decodeTag :: Decoder s Word
- decodeTag64 :: Decoder s Word64
- decodeBool :: Decoder s Bool
- decodeNull :: Decoder s ()
- decodeSimple :: Decoder s Word8
- decodeWordOf :: Word -> Decoder s ()
- decodeListLenOf :: Int -> Decoder s ()
- decodeListLenOrIndef :: Decoder s (Maybe Int)
- decodeMapLenOrIndef :: Decoder s (Maybe Int)
- decodeBreakOr :: Decoder s Bool
- peekTokenType :: Decoder s TokenType
- data TokenType
- = TypeUInt
- | TypeUInt64
- | TypeNInt
- | TypeNInt64
- | TypeInteger
- | TypeFloat16
- | TypeFloat32
- | TypeFloat64
- | TypeBytes
- | TypeBytesIndef
- | TypeString
- | TypeStringIndef
- | TypeListLen
- | TypeListLen64
- | TypeListLenIndef
- | TypeMapLen
- | TypeMapLen64
- | TypeMapLenIndef
- | TypeTag
- | TypeTag64
- | TypeBool
- | TypeNull
- | TypeSimple
- | TypeBreak
- | TypeInvalid
- peekAvailable :: Decoder s Int
- type ByteOffset = Int64
- peekByteOffset :: Decoder s ByteOffset
- decodeWithByteSpan :: Decoder s a -> Decoder s (a, ByteOffset, ByteOffset)
- decodeWordCanonical :: Decoder s Word
- decodeWord8Canonical :: Decoder s Word8
- decodeWord16Canonical :: Decoder s Word16
- decodeWord32Canonical :: Decoder s Word32
- decodeWord64Canonical :: Decoder s Word64
- decodeNegWordCanonical :: Decoder s Word
- decodeNegWord64Canonical :: Decoder s Word64
- decodeIntCanonical :: Decoder s Int
- decodeInt8Canonical :: Decoder s Int8
- decodeInt16Canonical :: Decoder s Int16
- decodeInt32Canonical :: Decoder s Int32
- decodeInt64Canonical :: Decoder s Int64
- decodeBytesCanonical :: Decoder s ByteString
- decodeByteArrayCanonical :: Decoder s ByteArray
- decodeStringCanonical :: Decoder s Text
- decodeUtf8ByteArrayCanonical :: Decoder s ByteArray
- decodeListLenCanonical :: Decoder s Int
- decodeMapLenCanonical :: Decoder s Int
- decodeTagCanonical :: Decoder s Word
- decodeTag64Canonical :: Decoder s Word64
- decodeIntegerCanonical :: Decoder s Integer
- decodeFloat16Canonical :: Decoder s Float
- decodeFloatCanonical :: Decoder s Float
- decodeDoubleCanonical :: Decoder s Double
- decodeSimpleCanonical :: Decoder s Word8
- decodeWordCanonicalOf :: Word -> Decoder s ()
- decodeListLenCanonicalOf :: Int -> Decoder s ()
- decodeSequenceLenIndef :: (r -> a -> r) -> r -> (r -> r') -> Decoder s a -> Decoder s r'
- decodeSequenceLenN :: (r -> a -> r) -> r -> (r -> r') -> Int -> Decoder s a -> Decoder s r'
Decode primitive operations
A continuation-based decoder, used for decoding values that were
previously encoded using the Codec.CBOR.Encoding
module. As Decoder
has a Monad
instance, you can easily
write Decoder
s monadically for building your deserialisation
logic.
Since: 0.2.0.0
data DecodeAction s a Source #
An action, representing a step for a decoder to taken and a continuation to invoke with the expected value.
Since: 0.2.0.0
liftST :: ST s a -> Decoder s a Source #
Lift an ST
action into a Decoder
. Useful for, e.g., leveraging
in-place mutation to efficiently build a deserialised value.
Since: 0.2.0.0
getDecodeAction :: Decoder s a -> ST s (DecodeAction s a) Source #
Given a Decoder
, give us the DecodeAction
Since: 0.2.0.0
Read input tokens
decodeBytes :: Decoder s ByteString Source #
Decode a string of bytes as a ByteString
.
Since: 0.2.0.0
decodeBytesIndef :: Decoder s () Source #
Decode a token marking the beginning of an indefinite length set of bytes.
Since: 0.2.0.0
decodeStringIndef :: Decoder s () Source #
Decode a token marking the beginning of an indefinite length string.
Since: 0.2.0.0
decodeListLen :: Decoder s Int Source #
Decode the length of a list.
Since: 0.2.0.0
decodeListLenIndef :: Decoder s () Source #
Decode a token marking the beginning of a list of indefinite length.
Since: 0.2.0.0
decodeMapLen :: Decoder s Int Source #
Decode the length of a map.
Since: 0.2.0.0
decodeMapLenIndef :: Decoder s () Source #
Decode a token marking the beginning of a map of indefinite length.
Since: 0.2.0.0
decodeTag64 :: Decoder s Word64 Source #
Decode an arbitrary 64-bit tag and return it as a Word64
.
Since: 0.2.0.0
decodeBool :: Decoder s Bool Source #
Decode a bool.
Since: 0.2.0.0
decodeNull :: Decoder s () Source #
Decode a nullary value, and return a unit value.
Since: 0.2.0.0
decodeSimple :: Decoder s Word8 Source #
Decode a simple
CBOR value and give back a Word8
. You
probably don't ever need to use this.
Since: 0.2.0.0
Specialised Read input token operations
Attempt to decode a word with decodeWord
, and ensure the word
is exactly as expected, or fail.
Since: 0.2.0.0
decodeListLenOf :: Int -> Decoder s () Source #
Attempt to decode a list length using decodeListLen
, and
ensure it is exactly the specified length, or fail.
Since: 0.2.0.0
Branching operations
decodeBreakOr :: Decoder s Bool Source #
Inspecting the token type
peekTokenType :: Decoder s TokenType Source #
Peek at the current token we're about to decode, and return a
TokenType
specifying what it is.
Since: 0.2.0.0
The type of a token, which a decoder can ask for at an arbitrary time.
Since: 0.2.0.0
Instances
Bounded TokenType Source # | |
Enum TokenType Source # | |
Defined in Codec.CBOR.Decoding succ :: TokenType -> TokenType # pred :: TokenType -> TokenType # fromEnum :: TokenType -> Int # enumFrom :: TokenType -> [TokenType] # enumFromThen :: TokenType -> TokenType -> [TokenType] # enumFromTo :: TokenType -> TokenType -> [TokenType] # enumFromThenTo :: TokenType -> TokenType -> TokenType -> [TokenType] # | |
Show TokenType Source # | |
Eq TokenType Source # | |
Ord TokenType Source # | |
Defined in Codec.CBOR.Decoding |
Special operations
peekAvailable :: Decoder s Int Source #
Peek and return the length of the current buffer that we're running our decoder on.
Since: 0.2.0.0
type ByteOffset = Int64 Source #
peekByteOffset :: Decoder s ByteOffset Source #
Get the current ByteOffset
in the input byte sequence of the Decoder
.
The Decoder
does not provide any facility to get at the input data
directly (since that is tricky with an incremental decoder). The next best
is this primitive which can be used to keep track of the offset within the
input bytes that makes up the encoded form of a term.
By keeping track of the byte offsets before and after decoding a subterm
(a pattern captured by decodeWithByteSpan
) and if the overall input data
is retained then this is enables later retrieving the span of bytes for the
subterm.
Since: 0.2.2.0
decodeWithByteSpan :: Decoder s a -> Decoder s (a, ByteOffset, ByteOffset) Source #
This captures the pattern of getting the byte offsets before and after decoding a subterm.
!before <- peekByteOffset x <- decode !after <- peekByteOffset
Canonical CBOR
https://tools.ietf.org/html/rfc7049#section-3.9
In general in CBOR there can be multiple representations for the same value,
for example the integer 0
can be represented in 8, 16, 32 or 64 bits. This
library always encoded values in the shortest representation but on
decoding allows any valid encoding. For some applications it is useful or
important to only decode the canonical encoding. The decoder primitives here
are to allow applications to implement canonical decoding.
It is important to note that achieving a canonical representation is not
simply about using these primitives. For example consider a typical CBOR
encoding of a Haskell Set
data type. This will be encoded as a CBOR list
of the set elements. A typical implementation might be:
encodeSet = encodeList . Set.toList decodeSet = fmap Set.fromList . decodeList
This does not enforce a canonical encoding. The decoder above will allow
set elements in any order. The use of Set.fromList
forgets the order.
To enforce that the decoder only accepts the canonical encoding it will
have to check that the elements in the list are strictly increasing.
Similar issues arise in many other data types, wherever there is redundancy
in the external representation.
The decoder primitives in this section are not much more expensive than their normal counterparts. If checking the canonical encoding property is critical then a technique that is more expensive but easier to implement and test is to decode normally, re-encode and check the serialised bytes are the same.
decodeWordCanonical :: Decoder s Word Source #
Decode canonical representation of a Word
.
Since: 0.2.0.0
decodeWord8Canonical :: Decoder s Word8 Source #
Decode canonical representation of a Word8
.
Since: 0.2.0.0
decodeWord16Canonical :: Decoder s Word16 Source #
Decode canonical representation of a Word16
.
Since: 0.2.0.0
decodeWord32Canonical :: Decoder s Word32 Source #
Decode canonical representation of a Word32
.
Since: 0.2.0.0
decodeWord64Canonical :: Decoder s Word64 Source #
Decode canonical representation of a Word64
.
Since: 0.2.0.0
decodeNegWordCanonical :: Decoder s Word Source #
Decode canonical representation of a negative Word
.
Since: 0.2.0.0
decodeNegWord64Canonical :: Decoder s Word64 Source #
Decode canonical representation of a negative Word64
.
Since: 0.2.0.0
decodeIntCanonical :: Decoder s Int Source #
Decode canonical representation of an Int
.
Since: 0.2.0.0
decodeInt8Canonical :: Decoder s Int8 Source #
Decode canonical representation of an Int8
.
Since: 0.2.0.0
decodeInt16Canonical :: Decoder s Int16 Source #
Decode canonical representation of an Int16
.
Since: 0.2.0.0
decodeInt32Canonical :: Decoder s Int32 Source #
Decode canonical representation of an Int32
.
Since: 0.2.0.0
decodeInt64Canonical :: Decoder s Int64 Source #
Decode canonical representation of an Int64
.
Since: 0.2.0.0
decodeBytesCanonical :: Decoder s ByteString Source #
Decode canonical representation of a string of bytes as a ByteString
.
Since: 0.2.1.0
decodeStringCanonical :: Decoder s Text Source #
Decode canonical representation of a textual string as a piece of Text
.
Since: 0.2.1.0
decodeUtf8ByteArrayCanonical :: Decoder s ByteArray Source #
Decode canonical representation of a textual string as UTF-8 encoded
ByteArray
. Note that the result is not validated to be well-formed UTF-8.
Also note that this will eagerly copy the content out of the input
to ensure that the input does not leak in the event that the ByteArray
is
live but not forced.
Since: 0.2.1.0
decodeListLenCanonical :: Decoder s Int Source #
Decode canonical representation of the length of a list.
Since: 0.2.0.0
decodeMapLenCanonical :: Decoder s Int Source #
Decode canonical representation of the length of a map.
Since: 0.2.0.0
decodeTagCanonical :: Decoder s Word Source #
Decode canonical representation of an arbitrary tag and return it as a
Word
.
Since: 0.2.0.0
decodeTag64Canonical :: Decoder s Word64 Source #
Decode canonical representation of an arbitrary 64-bit tag and return it as
a Word64
.
Since: 0.2.0.0
decodeIntegerCanonical :: Decoder s Integer Source #
Decode canonical representation of an Integer
.
Since: 0.2.0.0
decodeFloat16Canonical :: Decoder s Float Source #
Decode canonical representation of a half-precision Float
.
Since: 0.2.0.0
decodeFloatCanonical :: Decoder s Float Source #
Decode canonical representation of a Float
.
Since: 0.2.0.0
decodeDoubleCanonical :: Decoder s Double Source #
Decode canonical representation of a Double
.
Since: 0.2.0.0
decodeSimpleCanonical :: Decoder s Word8 Source #
Decode canonical representation of a simple
CBOR value and give back a
Word8
. You probably don't ever need to use this.
Since: 0.2.0.0
decodeWordCanonicalOf Source #
Attempt to decode canonical representation of a word with decodeWordCanonical
,
and ensure the word is exactly as expected, or fail.
Since: 0.2.0.0
decodeListLenCanonicalOf :: Int -> Decoder s () Source #
Attempt to decode canonical representation of a list length using
decodeListLenCanonical
, and ensure it is exactly the specified length, or
fail.
Since: 0.2.0.0
Sequence operations
decodeSequenceLenIndef :: (r -> a -> r) -> r -> (r -> r') -> Decoder s a -> Decoder s r' Source #
Decode an indefinite sequence length.
Since: 0.2.0.0