src/Graphics/Text/Width.hs · vty

git.iko.soy/vty

on c384656 help sign in

vty/src/Graphics/Text/Width.hs

65 lines 2.0 kB history raw

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

28{-# INLINE [1] wctwidth #-}

30wctlwidth :: TL.Text -> Int

31wctlwidth = TL.foldl' (\l c -> wcwidth c + l) 0

32{-# INLINE [1] wctlwidth #-}

34{-# RULES

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

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

37 #-}

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

40--

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

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

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

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

45-- width needs to be implemented.

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

48-- with unknown widths are 0 width.

49safeWcwidth :: Char -> Int

50safeWcwidth = max 0 . wcwidth

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

53-- unknown widths are 0 width.

54safeWcswidth :: String -> Int

55safeWcswidth = foldl' (\l c -> safeWcwidth c + l) 0

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

58-- unknown widths are 0 width.

59safeWctwidth :: T.Text -> Int

60safeWctwidth = T.foldl' (\l c -> safeWcwidth c + l) 0

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

63-- with unknown widths are 0 width.

64safeWctlwidth :: TL.Text -> Int

65safeWctlwidth = TL.foldl' (\l c -> safeWcwidth c + l) 0