src/Graphics/Text/Width.hs · vty

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vty/src/Graphics/Text/Width.hs

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2{-# OPTIONS_GHC -D_XOPEN_SOURCE #-}

3{-# LANGUAGE ForeignFunctionInterface #-}

4module Graphics.Text.Width

5 ( wcwidth

6 , wcswidth

7 , wctwidth

8 , wctlwidth

9 , safeWcwidth

10 , safeWcswidth

11 , safeWctwidth

12 , safeWctlwidth

13 )

14where

16import Data.List (foldl')

17import qualified Data.Text as T

18import qualified Data.Text.Lazy as TL

20foreign import ccall unsafe "vty_mk_wcwidth" wcwidth :: Char -> Int

22wcswidth :: String -> Int

23wcswidth = foldl' (\l c -> wcwidth c + l) 0

24{-# INLINE [1] wcswidth #-}

26wctwidth :: T.Text -> Int

27wctwidth = T.foldl' (\l c -> wcwidth c + l) 0

29wctlwidth :: TL.Text -> Int

30wctlwidth = TL.foldl' (\l c -> wcwidth c + l) 0

32{-# RULES

33"wcswidth/unpack" forall x. wcswidth (T.unpack x) = wctwidth x

34"wcswidth/lazy-unpack" forall x. wcswidth (TL.unpack x) = wctlwidth x

35 #-}

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

38--

39-- Not sure if this is actually correct. I presume there is a

40-- replacement character that is output by the terminal instead of the

41-- character and this replacement character is 1 column wide. If this is

42-- not true for all terminals then a per-terminal replacement character

43-- width needs to be implemented.

45-- | Returns the display width of a character. Assumes all characters

46-- with unknown widths are 0 width.

47safeWcwidth :: Char -> Int

48safeWcwidth = max 0 . wcwidth

50-- | Returns the display width of a string. Assumes all characters with

51-- unknown widths are 0 width.

52safeWcswidth :: String -> Int

53safeWcswidth = foldl' (\l c -> safeWcwidth c + l) 0

55-- | Returns the display width of a text. Assumes all characters with

56-- unknown widths are 0 width.

57safeWctwidth :: T.Text -> Int

58safeWctwidth = T.foldl' (\l c -> safeWcwidth c + l) 0

60-- | Returns the display width of a lazy text. Assumes all characters

61-- with unknown widths are 0 width.

62safeWctlwidth :: TL.Text -> Int

63safeWctlwidth = TL.foldl' (\l c -> safeWcwidth c + l) 0