base-4.2.0.1: Basic librariesSource codeContentsIndex
GHC.IO.BufferedIO
Portabilitynon-portable (GHC Extensions)
Stabilityinternal
Maintainercvs-ghc@haskell.org
Description
Class of buffered IO devices
Synopsis
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.
show/hide Instances
readBuf :: RawIO dev => dev -> Buffer Word8 -> IO (Int, Buffer Word8)Source
readBufNonBlocking :: RawIO dev => dev -> Buffer Word8 -> IO (Maybe Int, Buffer Word8)Source
writeBuf :: RawIO dev => dev -> Buffer Word8 -> IO (Buffer Word8)Source
writeBufNonBlocking :: RawIO dev => dev -> Buffer Word8 -> IO (Int, Buffer Word8)Source
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