GHC.IO.Buffer (original) (raw)
Contents
Description
Buffers used in the IO system
Synopsis
- 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 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](GHC-IO-Buffer.html#v:bufL) and[bufR](GHC-IO-Buffer.html#v:bufR) offsets. In an empty buffer, [bufL](GHC-IO-Buffer.html#v:bufL) is equal to [bufR](GHC-IO-Buffer.html#v:bufR), but they might not be zero: for exmaple, the buffer might correspond to a memory-mapped file and in which case [bufL](GHC-IO-Buffer.html#v:bufL) will point to the next location to be written, which is not necessarily the beginning of the file.