| Copyright | (c) The University of Glasgow 2008 |
|---|---|
| License | (c) The University of Glasgow 2008 |
| Maintainer | cvs-ghc@haskell.org |
| Stability | internal |
| Portability | non-portable (GHC Extensions) |
| Safe Haskell | Trustworthy |
GHC.IO.BufferedIO
Description
Class of buffered IO devices
- class BufferedIO dev where
- newBuffer :: dev -> BufferState -> IO (Buffer Word8)
- fillReadBuffer :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)
- fillReadBuffer0 :: dev -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)
- emptyWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)
- flushWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)
- flushWriteBuffer0 :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)
- readBuf :: RawIO dev => dev -> Buffer Word8 -> IO (Int, Buffer Word8)
- readBufNonBlocking :: RawIO dev => dev -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)
- writeBuf :: RawIO dev => dev -> Buffer Word8 -> IO (Buffer Word8)
- writeBufNonBlocking :: RawIO dev => dev -> Buffer Word8 -> IO (Int, Buffer Word8)
Documentation
class BufferedIO dev whereSource
The purpose of BufferedIO is to provide a common interface for I/O
devices that can read and write data through a buffer. Devices that
implement BufferedIO include ordinary files, memory-mapped files,
and bytestrings. The underlying device implementing a Handle must
provide BufferedIO.
Methods
newBuffer :: dev -> BufferState -> IO (Buffer Word8)Source
allocate a new buffer. The size of the buffer is at the discretion of the device; e.g. for a memory-mapped file the buffer will probably cover the entire file.
fillReadBuffer :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)Source
reads bytes into the buffer, blocking if there are no bytes available. Returns the number of bytes read (zero indicates end-of-file), and the new buffer.
fillReadBuffer0 :: dev -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)Source
reads bytes into the buffer without blocking. Returns the number of bytes read (Nothing indicates end-of-file), and the new buffer.
emptyWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)Source
Prepares an empty write buffer. This lets the device decide how to set up a write buffer: the buffer may need to point to a specific location in memory, for example. This is typically used by the client when switching from reading to writing on a buffered read/write device.
There is no corresponding operation for read buffers, because before
reading the client will always call fillReadBuffer.
flushWriteBuffer :: dev -> Buffer Word8 -> IO (Buffer Word8)Source
Flush all the data from the supplied write buffer out to the device. The returned buffer should be empty, and ready for writing.
flushWriteBuffer0 :: dev -> Buffer Word8 -> IO (Int, Buffer Word8)Source
Flush data from the supplied write buffer out to the device without blocking. Returns the number of bytes written and the remaining buffer.