| Portability | non-portable (GHC Extensions) |
|---|---|
| Stability | internal |
| Maintainer | cvs-ghc@haskell.org |
| Safe Haskell | Trustworthy |
GHC.IO.Buffer
Contents
Description
Buffers used in the IO system
- data Buffer e = Buffer {}
- data BufferState
- 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
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 exmaple, 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.
type CharBuffer = Buffer Char
type CharBufElem = Char
Creation
newByteBuffer :: Int -> BufferState -> IO (Buffer Word8)
newCharBuffer :: Int -> BufferState -> IO CharBuffer
emptyBuffer :: RawBuffer e -> Int -> BufferState -> Buffer e
Insertion/removal
bufferRemove :: Int -> Buffer e -> Buffer e
slideContents :: Buffer Word8 -> IO (Buffer Word8)
slides the contents of the buffer to the beginning
bufferAdjustL :: Int -> Buffer e -> Buffer e
Inspecting
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
Operating on the raw buffer as a Ptr
withBuffer :: Buffer e -> (Ptr e -> IO a) -> IO a
withRawBuffer :: RawBuffer e -> (Ptr e -> IO a) -> IO a
Assertions
checkBuffer :: Buffer a -> IO ()
Raw buffers
type RawBuffer e = ForeignPtr e
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