blaze-builder- Efficient buffered output.

Portabilitytested on GHC only
MaintainerSimon Meier <>
Safe HaskellNone




Execution of the Put monad and hence also Builders with respect to buffers.



data Buffer Source

A buffer Buffer fpbuf p0 op ope describes a buffer with the underlying byte array fpbuf..ope, the currently written slice p0..op and the free space op..ope.

Status information

freeSize :: Buffer -> IntSource

The size of the free space of the buffer.

sliceSize :: Buffer -> IntSource

The size of the written slice in the buffer.

bufferSize :: Buffer -> IntSource

The size of the whole byte array underlying the buffer.

Creation and modification

allocBuffer :: Int -> IO BufferSource

allocBuffer size allocates a new buffer of size size.

reuseBuffer :: Buffer -> BufferSource

Resets the beginning of the next slice and the next free byte such that the whole buffer can be filled again.

nextSlice :: Int -> Buffer -> Maybe BufferSource

Move the beginning of the slice to the next free byte such that the remaining free space of the buffer can be filled further. This operation is safe and can be used to fill the remaining part of the buffer after a direct insertion of a bytestring or a flush.

updateEndOfSlice :: Buffer -> Ptr Word8 -> BufferSource

Update the end of slice pointer.

execBuildStep :: BuildStep a -> Buffer -> IO (BuildSignal a)Source

Execute a build step on the given buffer.

Conversion to bytestings

unsafeFreezeBuffer :: Buffer -> ByteStringSource

Convert the buffer to a bytestring. This operation is unsafe in the sense that created bytestring shares the underlying byte array with the buffer. Hence, depending on the later use of this buffer (e.g., if it gets reset and filled again) referential transparency may be lost.

unsafeFreezeNonEmptyBuffer :: Buffer -> Maybe ByteStringSource

Convert a buffer to a non-empty bytestring. See unsafeFreezeBuffer for the explanation of why this operation may be unsafe.

Buffer allocation strategies

type BufferAllocStrategy = (IO Buffer, Int -> Buffer -> IO (IO Buffer))Source

A buffer allocation strategy (buf0, nextBuf) specifies the initial buffer to use and how to compute a new buffer nextBuf minSize buf with at least size minSize from a filled buffer buf. The double nesting of the IO monad helps to ensure that the reference to the filled buffer buf is lost as soon as possible, but the new buffer doesn't have to be allocated too early.

allNewBuffersStrategy :: Int -> BufferAllocStrategySource

The simplest buffer allocation strategy: whenever a buffer is requested, allocate a new one that is big enough for the next build step to execute.

NOTE that this allocation strategy may spill quite some memory upon direct insertion of a bytestring by the builder. Thats no problem for garbage collection, but it may lead to unreasonably high memory consumption in special circumstances.

reuseBufferStrategy :: IO Buffer -> BufferAllocStrategySource

An unsafe, but possibly more efficient buffer allocation strategy: reuse the buffer, if it is big enough for the next build step to execute.

Executing puts respect to some monad

runPut :: Monad m => (IO (BuildSignal a) -> m (BuildSignal a)) -> (Int -> Buffer -> m Buffer) -> (ByteString -> m ()) -> Put a -> Buffer -> m (a, Buffer)Source

Execute a put on a buffer.

TODO: Generalize over buffer allocation strategy.