6a6be9d · streamly · git.iko.soy

git.iko.soy/streamly

Initialize parser only if the stream is not empty

In parseMany on the next parse if we find that the stream has ended then the parse may fail on extraction, so we initialize the parser only if we see at least one element in the stream.

commit6a6be9dfca925949615387bb77586e9cc7357fcd authorHarendra Kumar <harendra@composewell.com> dateWed 2 Sep 2020, 13:17 (6 years ago) parentfbb1c84

1 file changed+9−4

compare with master

unifiedsplit

src/Streamly/Internal/Data/Stream/StreamD.hs+9−4

src/Streamly/Internal/Data/Stream/StreamD.hs+9−4

@@ -1038,9 +1038,14 @@ parseMany (PRD.Parser pstep initial extract) (Stream step state) =

10381038 where

10391039

10401040 {-# INLINE_LATE stepOuter #-}

1041− -- Buffer is empty, go to stream processing loop

1042− stepOuter _ (ParseChunksInit [] st) = do

1043− initial >>= return . Skip . ParseChunksStream st []

1041+ -- Buffer is empty, get the first element from the stream, initialize the

1042+ -- fold and then go to stream processing loop.

1043+ stepOuter gst (ParseChunksInit [] st) = do

1044+ r <- step (adaptState gst) st

1045+ case r of

1046+ Yield x s -> initial >>= return . Skip . ParseChunksBuf [x] s []

1047+ Skip s -> return $ Skip $ ParseChunksInit [] s

1048+ Stop -> return Stop

10441049

10451050 -- Buffer is not empty, go to buffered processing loop

10461051 stepOuter _ (ParseChunksInit src st) = do

@@ -1049,7 +1054,7 @@ parseMany (PRD.Parser pstep initial extract) (Stream step state) =

10491054 -- XXX we just discard any leftover input at the end

10501055 stepOuter _ (ParseChunksInitLeftOver _) = return Stop

10511056

1052− -- Buffer is empty process elements from the stream

1057+ -- Buffer is empty, process elements from the stream

10531058 stepOuter gst (ParseChunksStream st buf pst) = do

10541059 r <- step (adaptState gst) st

10551060 case r of