src/Graphics/Text/Width.hs · vty

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2{-# OPTIONS_GHC -D_XOPEN_SOURCE #-}

3{-# LANGUAGE ForeignFunctionInterface #-}

4module Graphics.Text.Width ( wcwidth

5 , wcswidth

6 , safeWcwidth

7 , safeWcswidth

8 )

9 where

11foreign import ccall unsafe "vty_mk_wcwidth" wcwidth :: Char -> Int

13wcswidth :: String -> Int

14wcswidth = sum . map wcwidth

16-- XXX: Characters with unknown widths occupy 1 column?

17--

18-- Not sure if this is actually correct. I presume there is a replacement character that is output

19-- by the terminal instead of the character and this replacement character is 1 column wide. If this

20-- is not true for all terminals then a per-terminal replacement character width needs to be

21-- implemented.

23-- | Returns the display width of a character. Assumes all characters with unknown widths are 0 width

24safeWcwidth :: Char -> Int

25safeWcwidth c = case wcwidth c of

26 i | i < 0 -> 0

27 | otherwise -> i

29-- | Returns the display width of a string. Assumes all characters with unknown widths are 0 width

30safeWcswidth :: String -> Int

31safeWcswidth str = case wcswidth str of

32 i | i < 0 -> 0

33 | otherwise -> i