MissingH-0.16.0: Contents Index

MissingH.IO.BlockIO Portability Haskell 2-pre Stability provisional Maintainer simons@cryp.to

Contents Static Buffer I/O BlockHandler and I/O Driver Handler Combinators I/O Exceptions Internal Helper Functions

Description

runLoop drives a BlockHandler with data read from the input stream until hIsEOF ensues. Everything else has to be done by the callback; runLoop just does the I/O. But it does it fast.

Synopsis

type ReadHandle = Handle type WriteHandle = Handle type ByteCount = Word16 type Capacity = Word16 data Buffer = Buf !Capacity !(Ptr Word8) !ByteCount withBuffer :: Capacity -> (Buffer -> IO a) -> IO a flush :: ByteCount -> Buffer -> IO Buffer slurp :: Timeout -> ReadHandle -> Buffer -> IO (Maybe Buffer) type BlockHandler st = Buffer -> st -> IO (Buffer, st) runLoopNB :: (st -> Timeout) -> (Exception -> st -> IO st) -> ReadHandle -> Capacity -> BlockHandler st -> st -> IO st runLoop :: ReadHandle -> Capacity -> BlockHandler st -> st -> IO st type StreamHandler st = [Word8] -> st -> IO (ByteCount, st) handleStream :: StreamHandler st -> BlockHandler st data BufferOverflow = BufferOverflow ReadHandle Buffer data ReadTimeout = ReadTimeout Timeout ReadHandle Buffer handleEOF :: IO a -> IO (Maybe a) strstr :: [Word8] -> [Word8] -> Maybe Int splitList :: Eq a => [a] -> [a] -> [[a]] (?) :: Bool -> (a, a) -> a

Static Buffer I/O

type ReadHandle = Handle

type WriteHandle = Handle

type ByteCount = Word16

type Capacity = Word16

data Buffer

Constructors Buf !Capacity !(Ptr Word8) !ByteCount Instances Eq Buffer Show Buffer Typeable Buffer

withBuffer :: Capacity -> (Buffer -> IO a) -> IO a

Run the given computation with an initialized, empty Buffer. The buffer is gone when the computation returns.

flush :: ByteCount -> Buffer -> IO Buffer

Drop the first n <= size octets from the buffer.

slurp :: Timeout -> ReadHandle -> Buffer -> IO (Maybe Buffer)

If there is space, read and append more octets; then return the modified buffer. In case of hIsEOF, Nothing is returned. If the buffer is full already, throwDyn a BufferOverflow exception. When the timeout exceeds, ReadTimeout is thrown.

BlockHandler and I/O Driver

type BlockHandler st = Buffer -> st -> IO (Buffer, st)

A callback function suitable for use with runLoop takes a buffer and a state, then returns a modified buffer and a modified state. Usually the callback will use slurp to remove data it has processed already.

runLoopNB

:: (st -> Timeout) user state provides timeout -> (Exception -> st -> IO st) user provides I/O error handler -> ReadHandle the input source -> Capacity I/O buffer size -> BlockHandler st callback -> st initial callback state -> IO st return final callback state Our main I/O driver.

runLoop :: ReadHandle -> Capacity -> BlockHandler st -> st -> IO st

A variant which won't time out and will just throw all exceptions.

Handler Combinators

type StreamHandler st = [Word8] -> st -> IO (ByteCount, st)

Signal how many bytes have been consumed from the front of the list; these octets will be dropped.

handleStream :: StreamHandler st -> BlockHandler st

I/O Exceptions

data BufferOverflow

Thrown by slurp. Constructors BufferOverflow ReadHandle Buffer Instances Show BufferOverflow Typeable BufferOverflow

data ReadTimeout

Thrown by slurp. Constructors ReadTimeout Timeout ReadHandle Buffer Instances Show ReadTimeout Typeable ReadTimeout

Internal Helper Functions

handleEOF :: IO a -> IO (Maybe a)

Return Nothing if the given computation throws an isEOFError exception. Used by slurp.

strstr :: [Word8] -> [Word8] -> Maybe Int

Our version of C's strstr(3).

splitList :: Eq a => [a] -> [a] -> [[a]]

Split a list by some delimiter. Will soon be provided by Data.List.

(?) :: Bool -> (a, a) -> a

Shorthand for if-then-else. Will soon by provided by Data.Bool.

Produced by Haddock version 0.8