base-4.4.0.0: Basic libraries

Portabilitynon-portable (GHC Extensions)
Stabilityinternal
Maintainer[email protected]

GHC.IO.Buffer

Contents

Description

Buffers used in the IO system

Synopsis

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 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.

Constructors

Buffer 

Fields

bufRaw :: !(RawBuffer e)
 
bufState :: BufferState
 
bufSize :: !Int
 
bufL :: !Int
 
bufR :: !Int
 

data BufferState Source

Constructors

ReadBuffer 
WriteBuffer 

Instances

Creation

Insertion/removal

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

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 aSource

withRawBuffer :: RawBuffer e -> (Ptr e -> IO a) -> IO aSource

Assertions

Raw buffers