content: --
  -- Copyright (c) 2013-2023 Nicola Bonelli <nicola@larthia.com>
  --
  -- This program is free software; you can redistribute it and/or modify
  -- it under the terms of the GNU General Public License as published by
  -- the Free Software Foundation; either version 2 of the License, or
  -- (at your option) any later version.
  --
  -- This program is distributed in the hope that it will be useful,
  -- but WITHOUT ANY WARRANTY; without even the implied warranty of
  -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  -- GNU General Public License for more details.
  --
  -- You should have received a copy of the GNU General Public License
  -- along with this program; if not, write to the Free Software
  -- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  --
  
  module Util where
  
  import Data.Char (toLower)
  import Data.Maybe (listToMaybe)
  
  import qualified Data.ByteString.Char8 as C
  import Data.Sequence (Seq (Empty, (:<|), (:|>)), (|>))
  import qualified Data.Sequence as S
  import Text.Read (readMaybe)
  
  partitionM :: (Monad m) => (a -> m Bool) -> [a] -> m ([a], [a])
  partitionM _ [] = return ([], [])
  partitionM f (x : xs) = do
      res <- f x
      (as, bs) <- partitionM f xs
      return ([x | res] <> as, [x | not res] <> bs)
  {-# INLINE partitionM #-}
  
  xor :: Bool -> Bool -> Bool
  a `xor` b = a && not b || not a && b
  {-# INLINE xor #-}
  
  prettyRead :: (Read a) => String -> String -> a
  prettyRead xs err =
      case readMaybe xs of
          Just v -> v
          _ -> errorWithoutStackTrace $ err <> ": parse error near '" <> take 40 xs <> "'"
  
  spanGroup :: Int -> [a] -> [[a]]
  spanGroup _ [] = []
  spanGroup 1 xs = map (: []) xs
  spanGroup n xs = take n xs : spanGroup n (tail xs)
  {-# INLINE spanGroup #-}
  
  spanGroupSeq :: Int -> S.Seq a -> [S.Seq a]
  spanGroupSeq _ S.Empty = []
  spanGroupSeq 1 xs = [xs]
  spanGroupSeq n xs = S.take n xs : spanGroupSeq n (S.drop 1 xs)
  {-# INLINE spanGroupSeq #-}
  
  rmQuote :: String -> String
  rmQuote [] = []
  rmQuote [x] = [x]
  rmQuote y@(x : xs)
      | x == '"' || x == '\'' =
          if x == last xs
              then init xs
              else y
      | otherwise = y
  {-# INLINE rmQuote #-}
  
  rmQuote8 :: C.ByteString -> C.ByteString
  rmQuote8 b
      | C.length b < 2 = b
      | otherwise =
          case C.uncons b of
              Just (x, xs) -> if (x == '"' || x == '\'') && (x == C.last b) then C.init xs else b
              _ -> b
  {-# INLINE rmQuote8 #-}
  
  mapMaybe' :: (Foldable f) => (a -> Maybe b) -> f a -> [b]
  mapMaybe' f = foldr g []
    where
      g x rest
          | Just y <- f x = y : rest
          | otherwise = rest
  
  findWithIndex :: forall a. (a -> Bool) -> [a] -> (# Int, Maybe a #)
  findWithIndex predicate = go predicate 0
    where
      go :: forall a. (a -> Bool) -> Int -> [a] -> (# Int, Maybe a #)
      go p _ [] = (# 0, Nothing #)
      go p !index (x : xs)
          | p x = (# index, Just x #)
          | otherwise = go p (index + 1) xs