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Drop read thread #172

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efd0f64
Drop read thread
bgamari Sep 26, 2022
a1345a3
Factor out surrogate pair predicate
bgamari Sep 26, 2022
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14 changes: 9 additions & 5 deletions System/Console/Haskeline/Backend/Win32.hsc
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Original file line number Diff line number Diff line change
Expand Up @@ -66,19 +66,23 @@ eventReader :: HANDLE -> IO [Event]
eventReader h = do
let waitTime = 500 -- milliseconds
ret <- c_WaitForSingleObject h waitTime
yield -- otherwise, the above foreign call causes the loop to never
-- respond to the killThread
if ret /= (#const WAIT_OBJECT_0)
then eventReader h
else do
es <- readEvents h
return $ combineSurrogatePairs $ mapMaybe processEvent es

isSurrogatePair :: Char -> Char -> Maybe Char
isSurrogatePair c1 c2
| 0xD800 <= ord c1 && ord c1 < 0xDC00 && 0xDC00 <= ord c2 && ord c2 < 0xE000
= Just $ (((ord c1 .&. 0x3FF) `shiftL` 10) .|. (ord c2 .&. 0x3FF)) + 0x10000
| otherwise
= Nothing

combineSurrogatePairs :: [Event] -> [Event]
combineSurrogatePairs (KeyInput [Key m1 (KeyChar c1)] : KeyInput [Key _ (KeyChar c2)] : es)
| 0xD800 <= ord c1 && ord c1 < 0xDC00 && 0xDC00 <= ord c2 && ord c2 < 0xE000
= let c = (((ord c1 .&. 0x3FF) `shiftL` 10) .|. (ord c2 .&. 0x3FF)) + 0x10000
in KeyInput [Key m1 (KeyChar (chr c))] : combineSurrogatePairs es
| Just c <- isSurrogatePair c1 c2
= KeyInput [Key m1 (KeyChar (chr c))] : combineSurrogatePairs es
combineSurrogatePairs (e:es) = e : combineSurrogatePairs es
combineSurrogatePairs [] = []

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17 changes: 8 additions & 9 deletions System/Console/Haskeline/Term.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -138,18 +138,17 @@ keyEventLoop readEvents eventChan = do
isEmpty <- atomically $ isEmptyTChan eventChan
if not isEmpty
then atomically $ readTChan eventChan
else do
tid <- forkIO $ handleErrorEvent readerLoop
atomically (readTChan eventChan) `finally` killThread tid
else handleErrorEvent readerLoop
where
readerLoop :: IO Event
readerLoop = do
es <- readEvents
if null es
then readerLoop
else atomically $ mapM_ (writeTChan eventChan) es
handleErrorEvent = handle $ \e -> case fromException e of
Just ThreadKilled -> return ()
_ -> atomically $ writeTChan eventChan (ErrorEvent e)
case es of
[] -> readerLoop
e : rest -> do atomically $ mapM_ (writeTChan eventChan) rest
return e

handleErrorEvent = handle $ \e -> return (ErrorEvent e)

saveKeys :: TChan Event -> [Key] -> IO ()
saveKeys ch = atomically . writeTChan ch . KeyInput
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