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|
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE ImportQualifiedPost #-}
{-# LANGUAGE MultiWayIf #-}
{-# LANGUAGE PatternGuards #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Blessings.String.WCWidth
( module Blessings
) where
import Blessings
import Blessings.Internal
import Data.Char.WCWidth qualified as WCWidth
import Data.List qualified as List
instance Blessable String where
length = length'
drop = drop'
take = take'
splitAt = splitAt'
intercalate = List.intercalate
fromWord8 = show
length' :: String -> Int
length' = foldr ((+) . wcwidth') 0
drop' :: Int -> String -> String
drop' k t =
if k <= 0
then t
else
case t of
c : t' ->
drop' (k - wcwidth' c) t'
[] -> mempty
take' :: Int -> String -> String
take' k0 =
rec k0
where
rec k t =
if | (c : t') <- t, nc <- wcwidth' c, nc <= k ->
c : rec (k - nc) t'
| otherwise ->
[]
splitAt' :: Int -> String -> (String, String)
splitAt' k0 =
rec k0 []
where
rec k a t =
if | (c : t') <- t, nc <- wcwidth' c, nc <= k ->
rec (k - nc) (c : a) t'
| otherwise ->
(reverse a, t)
-- TODO this breaks when WCWidth.wcwidth returns -1, which happens for
-- non-printable characters like '\n'.
-- Following wcwidth' isn't entirely correct because WCWidth.wcwidth '\0' == 0
wcwidth' :: Char -> Int
wcwidth' = max 1 . WCWidth.wcwidth
|
