src/Codec/Binary/UTF8/Width.hs · vty

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2{-# OPTIONS_GHC -D_XOPEN_SOURCE -fno-cse #-}

3{-# LANGUAGE ForeignFunctionInterface #-}

4{-# INCLUDE <wchar.h> #-}

5module Codec.Binary.UTF8.Width ( wcwidth

6 , wcswidth

7 )

8 where

10import Foreign.C.Types

11import Foreign.C.String

12import Foreign.Storable

14import Numeric ( showHex )

16import System.IO.Unsafe

18wcwidth :: Char -> Int

19wcwidth c = unsafePerformIO (withCWString [c] $ \ws -> do

20 wc <- peek ws

21 putStr $ "wcwidth(0x" ++ showHex (fromEnum wc) "" ++ ")"

22 w <- wcwidth' wc >>= return . fromIntegral

23 putStrLn $ " -> " ++ show w

24 return w

25 )

26{-# NOINLINE wcwidth #-}

28foreign import ccall "mk_wcwidth" wcwidth' :: CWchar -> IO CInt

30wcswidth :: String -> Int

31wcswidth str = sum $ map wcwidth str