base-4.12.0.0: Basic libraries

Copyright(c) The University of Glasgow 2008
Licensesee libraries/base/LICENSE
Maintainercvs-ghc@haskell.org
Stabilityinternal
Portabilitynon-portable (GHC Extensions)
Safe HaskellTrustworthy
LanguageHaskell2010

GHC.IO.Buffer

Contents

Description

Buffers used in the IO system

Synopsis

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 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

data BufferState #

Constructors

ReadBuffer 
WriteBuffer 
Instances
Eq BufferState #

Since: base-4.2.0.0

Instance details

Defined in GHC.IO.Buffer

Creation

Insertion/removal

bufferAdd :: Int -> Buffer e -> Buffer e #

slideContents :: Buffer Word8 -> IO (Buffer Word8) #

slides the contents of the buffer to the beginning

Inspecting

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