-- |

module Data.Text.PureScript (spanUpTo) where

import Prelude

import Data.Text.Internal (Text(..), text)

import Data.Text.Unsafe (Iter(..), iter)

-- | /O(n)/ 'spanUpTo', applied to a number @n@, predicate @p@, and text @t@,

{-# INLINE spanUpTo #-}

spanUpTo :: Int -> (Char -> Bool) -> Text -> (Text, Text)

spanUpTo n p t@(Text arr off len) = (hd, tl)

where hd = text arr off k

tl = text arr (off + k) (len - k)

!k = loop n 0

loop !n' !i | n' > 0 && i < len && p c = loop (n' - 1) (i + d)

| otherwise = i

where Iter c d = iter t i