Buffers for scanning string input stored in external arrays.
\begin{code}
+{-# LANGUAGE BangPatterns #-}
{-# OPTIONS_GHC -O -funbox-strict-fields #-}
-- We always optimise this, otherwise performance of a non-optimised
-- compiler is severely affected
instance Show StringBuffer where
showsPrec _ s = showString "<stringbuffer("
. shows (len s) . showString "," . shows (cur s)
- . showString ">"
+ . showString ")>"
-- -----------------------------------------------------------------------------
-- Creation / Destruction
calcLen sb = len sb - cur sb
size = sb1_len + sb2_len
-stringToStringBuffer :: String -> IO StringBuffer
-stringToStringBuffer str = do
+stringToStringBuffer :: String -> StringBuffer
+stringToStringBuffer str =
+ unsafePerformIO $ do
let size = utf8EncodedLength str
buf <- mallocForeignPtrArray (size+3)
withForeignPtr buf $ \ptr -> do
--LOL, in implementations where the indexing needs slow unsafePerformIO,
--this is less (not more) efficient than using the IO monad explicitly
--here.
- ptr' = pUnbox ptr
+ !ptr' = pUnbox ptr
byteOff i = cBox (indexWord8OffFastPtrAsFastChar ptr' (iUnbox (cur + i)))
go i x | i == len = x
| otherwise = case byteOff i of