Copyright	(c) The University of Glasgow 2008
License	see libraries/base/LICENSE
Maintainer	cvs-ghc@haskell.org
Stability	internal
Portability	non-portable (GHC Extensions)
Safe Haskell	Trustworthy
Language	Haskell2010

GHC.IO.Buffer

Contents

Buffers of any element
Raw buffers

Description

Buffers used in the IO system

Synopsis

data Buffer e = Buffer {
- bufRaw :: !(RawBuffer e)
- bufState :: BufferState
- bufSize :: !Int
- bufL :: !Int
- bufR :: !Int
}
data BufferState
- = ReadBuffer
- | WriteBuffer
type CharBuffer = Buffer Char
type CharBufElem = Char
newByteBuffer :: Int -> BufferState -> IO (Buffer Word8)
newCharBuffer :: Int -> BufferState -> IO CharBuffer
newBuffer :: Int -> Int -> BufferState -> IO (Buffer e)
emptyBuffer :: RawBuffer e -> Int -> BufferState -> Buffer e
bufferRemove :: Int -> Buffer e -> Buffer e
bufferAdd :: Int -> Buffer e -> Buffer e
slideContents :: Buffer Word8 -> IO (Buffer Word8)
bufferAdjustL :: Int -> Buffer e -> Buffer e
isEmptyBuffer :: Buffer e -> Bool
isFullBuffer :: Buffer e -> Bool
isFullCharBuffer :: Buffer e -> Bool
isWriteBuffer :: Buffer e -> Bool
bufferElems :: Buffer e -> Int
bufferAvailable :: Buffer e -> Int
summaryBuffer :: Buffer a -> String
withBuffer :: Buffer e -> (Ptr e -> IO a) -> IO a
withRawBuffer :: RawBuffer e -> (Ptr e -> IO a) -> IO a
checkBuffer :: Buffer a -> IO ()
type RawBuffer e = ForeignPtr e
readWord8Buf :: RawBuffer Word8 -> Int -> IO Word8
writeWord8Buf :: RawBuffer Word8 -> Int -> Word8 -> IO ()
type RawCharBuffer = RawBuffer CharBufElem
peekCharBuf :: RawCharBuffer -> Int -> IO Char
readCharBuf :: RawCharBuffer -> Int -> IO (Char, Int)
writeCharBuf :: RawCharBuffer -> Int -> Char -> IO Int
readCharBufPtr :: Ptr CharBufElem -> Int -> IO (Char, Int)
writeCharBufPtr :: Ptr CharBufElem -> Int -> Char -> IO Int
charSize :: Int

Buffers of any element

data Buffer e Source #

A mutable array of bytes that can be passed to foreign functions.

The buffer is represented by a record, where the record contains the raw buffer and the start/end points of the filled portion. The buffer contents itself is mutable, but the rest of the record is immutable. This is a slightly odd mix, but it turns out to be quite practical: by making all the buffer metadata immutable, we can have operations on buffer metadata outside of the IO monad.

The "live" elements of the buffer are those between the bufL and bufR offsets. In an empty buffer, bufL is equal to bufR, but they might not be zero: for example, the buffer might correspond to a memory-mapped file and in which case bufL will point to the next location to be written, which is not necessarily the beginning of the file.

Constructors

Buffer
Fields bufRaw :: !(RawBuffer e) bufState :: BufferState bufSize :: !Int bufL :: !Int bufR :: !Int

data BufferState Source #

Constructors

ReadBuffer
WriteBuffer

Instances

Instances details

Eq BufferState Source #	Since: base-4.2.0.0
Instance details Defined in GHC.IO.Buffer Methods (==) :: BufferState -> BufferState -> Bool Source # (/=) :: BufferState -> BufferState -> Bool Source #