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{-# LANGUAGE BangPatterns #-}
-----------------------------------------------------------------------------
--
-- Fast write-buffered Handles
--
-- (c) The University of Glasgow 2005-2006
--
-- This is a simple abstraction over Handles that offers very fast write
-- buffering, but without the thread safety that Handles provide. It's used
-- to save time in Pretty.printDoc.
--
-----------------------------------------------------------------------------
module BufWrite (
BufHandle(..),
newBufHandle,
bPutChar,
bPutStr,
bPutFS,
bPutFZS,
bPutLitString,
bFlush,
) where
import GhcPrelude
import FastString
import FastMutInt
import Control.Monad ( when )
import Data.ByteString (ByteString)
import qualified Data.ByteString.Unsafe as BS
import Data.Char ( ord )
import Foreign
import Foreign.C.String
import System.IO
-- -----------------------------------------------------------------------------
data BufHandle = BufHandle {-#UNPACK#-}!(Ptr Word8)
{-#UNPACK#-}!FastMutInt
Handle
newBufHandle :: Handle -> IO BufHandle
newBufHandle hdl = do
ptr <- mallocBytes buf_size
r <- newFastMutInt
writeFastMutInt r 0
return (BufHandle ptr r hdl)
buf_size :: Int
buf_size = 8192
bPutChar :: BufHandle -> Char -> IO ()
bPutChar b@(BufHandle buf r hdl) !c = do
i <- readFastMutInt r
if (i >= buf_size)
then do hPutBuf hdl buf buf_size
writeFastMutInt r 0
bPutChar b c
else do pokeElemOff buf i (fromIntegral (ord c) :: Word8)
writeFastMutInt r (i+1)
bPutStr :: BufHandle -> String -> IO ()
bPutStr (BufHandle buf r hdl) !str = do
i <- readFastMutInt r
loop str i
where loop "" !i = do writeFastMutInt r i; return ()
loop (c:cs) !i
| i >= buf_size = do
hPutBuf hdl buf buf_size
loop (c:cs) 0
| otherwise = do
pokeElemOff buf i (fromIntegral (ord c))
loop cs (i+1)
bPutFS :: BufHandle -> FastString -> IO ()
bPutFS b fs = bPutBS b $ fastStringToByteString fs
bPutFZS :: BufHandle -> FastZString -> IO ()
bPutFZS b fs = bPutBS b $ fastZStringToByteString fs
bPutBS :: BufHandle -> ByteString -> IO ()
bPutBS b bs = BS.unsafeUseAsCStringLen bs $ bPutCStringLen b
bPutCStringLen :: BufHandle -> CStringLen -> IO ()
bPutCStringLen b@(BufHandle buf r hdl) cstr@(ptr, len) = do
i <- readFastMutInt r
if (i + len) >= buf_size
then do hPutBuf hdl buf i
writeFastMutInt r 0
if (len >= buf_size)
then hPutBuf hdl ptr len
else bPutCStringLen b cstr
else do
copyBytes (buf `plusPtr` i) ptr len
writeFastMutInt r (i + len)
bPutLitString :: BufHandle -> LitString -> Int -> IO ()
bPutLitString b@(BufHandle buf r hdl) a len = a `seq` do
i <- readFastMutInt r
if (i+len) >= buf_size
then do hPutBuf hdl buf i
writeFastMutInt r 0
if (len >= buf_size)
then hPutBuf hdl a len
else bPutLitString b a len
else do
copyBytes (buf `plusPtr` i) a len
writeFastMutInt r (i+len)
bFlush :: BufHandle -> IO ()
bFlush (BufHandle buf r hdl) = do
i <- readFastMutInt r
when (i > 0) $ hPutBuf hdl buf i
free buf
return ()
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