git.iko.soy/vty
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vty/src/Graphics/Text/Width.hs
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1-- Copyright 2009 Corey O'Connor
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
25wctwidth :: T.Text -> Int
26wctwidth = T.foldl' (\l c -> wcwidth c + l) 0
28wctlwidth :: TL.Text -> Int
29wctlwidth = TL.foldl' (\l c -> wcwidth c + l) 0
31-- XXX: Characters with unknown widths occupy 1 column?
32--
33-- Not sure if this is actually correct. I presume there is a
34-- replacement character that is output by the terminal instead of the
35-- character and this replacement character is 1 column wide. If this is
36-- not true for all terminals then a per-terminal replacement character
37-- width needs to be implemented.
39-- | Returns the display width of a character. Assumes all characters
40-- with unknown widths are 0 width.
41safeWcwidth :: Char -> Int
42safeWcwidth = max 0 . wcwidth
44-- | Returns the display width of a string. Assumes all characters with
45-- unknown widths are 0 width.
46safeWcswidth :: String -> Int
47safeWcswidth = foldl' (\l c -> safeWcwidth c + l) 0
49-- | Returns the display width of a text. Assumes all characters with
50-- unknown widths are 0 width.
51safeWctwidth :: T.Text -> Int
52safeWctwidth = T.foldl' (\l c -> safeWcwidth c + l) 0
54-- | Returns the display width of a lazy text. Assumes all characters
55-- with unknown widths are 0 width.
56safeWctlwidth :: TL.Text -> Int
57safeWctlwidth = TL.foldl' (\l c -> safeWcwidth c + l) 0