cereal-0.5.0.0: A binary serialization library

Copyright | Lennart Kolmodin, Galois Inc. 2009
License | BSD3-style (see LICENSE)
Maintainer | Trevor Elliott <trevor@galois.com>
Stability | Portability :
Safe Haskell | None
Language | Haskell2010

Data.Serialize.Get

Contents

- The Get type
  - Incremental interface
- Parsing
- Utility
- Parsing particular types
  - ByteStrings
  - Big-endian reads
  - Little-endian reads
  - Host-endian, unaligned reads
  - Containers

Description

The Get monad. A monad for efficiently building structures from strict ByteStrings

Synopsis

- data Get a
- runGet :: Get a -> ByteString -> Either String a
- runGetLazy :: Get a -> ByteString -> Either String a
- runGetState :: Get a -> ByteString -> Int -> Either String (a, ByteString)
- runGetLazyState :: Get a -> ByteString -> Either String (a, ByteString)
- data Result r
  - = Fail String ByteString
  - | Partial (ByteString -> Result r)
  - | Done r ByteString
- runGetPartial :: Get a -> ByteString -> Result a
- runGetChunk :: Get a -> Maybe Int -> ByteString -> Result a
- ensure :: Int -> Get ByteString
- isolate :: Int -> Get a -> Get a
- label :: String -> Get a -> Get a
- skip :: Int -> Get ()
- uncheckedSkip :: Int -> Get ()
- lookAhead :: Get a -> Get a
- lookAheadM :: Get (Maybe a) -> Get (Maybe a)
- lookAheadE :: Get (Either a b) -> Get (Either a b)
- uncheckedLookAhead :: Int -> Get ByteString
- getBytes :: Int -> Get ByteString
- remaining :: Get Int
- isEmpty :: Get Bool
- getWord8 :: Get Word8
- getInt8 :: Get Int8
- getByteString :: Int -> Get ByteString
- getLazyByteString :: Int64 -> Get ByteString
- getShortByteString :: Int -> Get ShortByteString
- getWord16be :: Get Word16
- getWord32be :: Get Word32
- getWord64be :: Get Word64
- getInt16be :: Get Int16
- getInt32be :: Get Int32
- getInt64be :: Get Int64
- getWord16le :: Get Word16
- getWord32le :: Get Word32
- getWord64le :: Get Word64
- getInt16le :: Get Int16
- getInt32le :: Get Int32
- getInt64le :: Get Int64
- getWordhost :: Get Word
- getWord16host :: Get Word16
- getWord32host :: Get Word32
- getWord64host :: Get Word64
- getTwoOf :: Get a -> Get b -> Get (a, b)
- getListOf :: Get a -> Get [a]
- getIArrayOf :: (Ix i, IArray a e) => Get i -> Get e -> Get (a i e)
- getTreeOf :: Get a -> Get (Tree a)
- getSeqOf :: Get a -> Get (Seq a)
- getMapOf :: Ord k => Get k -> Get a -> Get (Map k a)
- getIntMapOf :: Get Int -> Get a -> Get (IntMap a)
- getSetOf :: Ord a => Get a -> Get (Set a)
- getIntSetOf :: Get Int -> Get IntSet
- getMaybeOf :: Get a -> Get (Maybe a)
- getEitherOf :: Get a -> Get b -> Get (Either a b)
- getNested :: Get Int -> Get a -> Get a

# The Get type

data Get a

The Get monad is an Exception and State monad.

Instances

Monad Get |
Functor Get |
Applicative Get |
Alternative Get |
MonadPlus Get |

runGet :: Get a -> ByteString -> Either String a

Run the Get monad applies a `get`-based parser on the input ByteString

runGetLazy :: Get a -> ByteString -> Either String a

Run the Get monad over a Lazy ByteString. Note that this will not run the Get parser lazily, but will operate on lazy ByteStrings.

runGetState :: Get a -> ByteString -> Int -> Either String (a, ByteString)

Run the Get monad applies a `get`-based parser on the input ByteString. Additional to the result of get it returns the number of consumed bytes and the rest of the input.

runGetLazyState :: Get a -> ByteString -> Either String (a, ByteString)

Run the Get monad over a Lazy ByteString. Note that this does not run the Get parser lazily, but will operate on lazy ByteStrings.

## Incremental interface

data Result r

The result of a parse.

Constructors

Fail String ByteString | The parse failed. The `String` is the message describing the error, if any.
Partial (ByteString -> Result r) | Supply this continuation with more input so that the parser can resume. To indicate that no more input is available, use an `empty` string.
Done r ByteString | The parse succeeded. The `ByteString` is the input that had not yet been consumed (if any) when the parse succeeded.

Instances

Functor Result |
Show r => Show (Result r) |

runGetPartial :: Get a -> ByteString -> Result a

Run the Get monad applies a `get`-based parser on the input ByteString

runGetChunk :: Get a -> Maybe Int -> ByteString -> Result a

Run the get monad on a single chunk, providing an optional length for the remaining, unseen input, with Nothing indicating that it's not clear how much input is left. For example, with a lazy ByteString, the optional length represents the sum of the lengths of all remaining chunks.

# Parsing

ensure :: Int -> Get ByteString

If at least `n` bytes of input are available, return the current input, otherwise fail.

isolate :: Int -> Get a -> Get a

Isolate an action to operating within a fixed block of bytes. The action is required to consume all the bytes that it is isolated to.

label :: String -> Get a -> Get a

skip :: Int -> Get ()

Skip ahead `n` bytes. Fails if fewer than `n` bytes are available.

uncheckedSkip :: Int -> Get ()

Skip ahead `n` bytes. No error if there isn't enough bytes.

lookAhead :: Get a -> Get a

Run `ga`, but return without consuming its input. Fails if `ga` fails.

lookAheadM :: Get (Maybe a) -> Get (Maybe a)

Like `lookAhead`, but consume the input if `gma` returns 'Just _'. Fails if `gma` fails.

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

Like `lookAhead`, but consume the input if `gea` returns 'Right _'. Fails if `gea` fails.

uncheckedLookAhead :: Int -> Get ByteString

Get the next up to `n` bytes as a ByteString, without consuming them.

# Utility

getBytes :: Int -> Get ByteString

Pull `n` bytes from the input, as a strict ByteString.

remaining :: Get Int

Get the number of remaining unparsed bytes. Useful for checking whether all input has been consumed.

WARNING: when run with `runGetPartial`, remaining will only return the number of bytes that are remaining in the current input.

isEmpty :: Get Bool

Test whether all input has been consumed.

WARNING: when run with `runGetPartial`, isEmpty will only tell you if you're at the end of the current chunk.

# Parsing particular types

getWord8 :: Get Word8

Read a Word8 from the monad state

getInt8 :: Get Int8

Read a Int8 from the monad state

## ByteStrings

getByteString :: Int -> Get ByteString

An efficient `get` method for strict ByteStrings. Fails if fewer than `n` bytes are left in the input. This function creates a fresh copy of the underlying bytes.

getLazyByteString :: Int64 -> Get ByteString

getShortByteString :: Int -> Get ShortByteString

## Big-endian reads

getWord16be :: Get Word16

Read a Word16 in big endian format

getWord32be :: Get Word32

Read a Word32 in big endian format

getWord64be :: Get Word64

Read a Word64 in big endian format

getInt16be :: Get Int16

Read a Int16 in big endian format

getInt32be :: Get Int32

Read a Int32 in big endian format

getInt64be :: Get Int64

Read a Int64 in big endian format

## Little-endian reads

getWord16le :: Get Word16

Read a Word16 in little endian format

getWord32le :: Get Word32

Read a Word32 in little endian format

getWord64le :: Get Word64

Read a Word64 in little endian format

getInt16le :: Get Int16

Read a Int16 in little endian format

getInt32le :: Get Int32

Read a Int32 in little endian format

getInt64le :: Get Int64

Read a Int64 in little endian format

## Host-endian, unaligned reads

getWordhost :: Get Word

O(1). Read a single native machine word. The word is read in host order, host endian form, for the machine you're on. On a 64 bit machine the Word is an 8 byte value, on a 32 bit machine, 4 bytes.

getWord16host :: Get Word16

O(1). Read a 2 byte Word16 in native host order and host endianness.

getWord32host :: Get Word32

O(1). Read a Word32 in native host order and host endianness.

getWord64host :: Get Word64

O(1). Read a Word64 in native host order and host endianess.

## Containers

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

getListOf :: Get a -> Get [a]

Get a list in the following format: Word64 (big endian format) element 1 ... element n

getIArrayOf :: (Ix i, IArray a e) => Get i -> Get e -> Get (a i e)

Get an IArray in the following format: index (lower bound) index (upper bound) Word64 (big endian format) element 1 ... element n

getTreeOf :: Get a -> Get (Tree a)

Read as a list of lists.

getSeqOf :: Get a -> Get (Seq a)

Get a sequence in the following format: Word64 (big endian format) element 1 ... element n

getMapOf :: Ord k => Get k -> Get a -> Get (Map k a)

Read as a list of pairs of key and element.

getIntMapOf :: Get Int -> Get a -> Get (IntMap a)

Read as a list of pairs of int and element.

getSetOf :: Ord a => Get a -> Get (Set a)

Read as a list of elements.

getIntSetOf :: Get Int -> Get IntSet

Read as a list of ints.

getMaybeOf :: Get a -> Get (Maybe a)

Read in a Maybe in the following format: Word8 (0 for Nothing, anything else for Just) element (when Just)

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

Read an Either, in the following format: Word8 (0 for Left, anything else for Right) element a when 0, element b otherwise

getNested :: Get Int -> Get a -> Get a

Read in a length and then read a nested structure of that length.