wai-app-static/Util.hs · typeable/wai

git.iko.soy/typeable/wai

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1{-# LANGUAGE OverloadedStrings, ViewPatterns #-}

2module Util

3 ( relativeDirFromPieces

4 , defaultMkRedirect

5 , replace

6 , remove

7 , dropLastIfNull

8 ) where

10import WaiAppStatic.Types

11import qualified Data.Text as T

12import Data.ByteString (ByteString)

13import qualified Data.ByteString.Char8 as S8

14import qualified Data.Text.Encoding as TE

16-- alist helper functions

17replace :: Eq a => a -> b -> [(a, b)] -> [(a, b)]

18replace k v [] = [(k,v)]

19replace k v (x:xs) | fst x == k = (k,v):xs

20 | otherwise = x:replace k v xs

22remove :: Eq a => a -> [(a, b)] -> [(a, b)]

23remove _ [] = []

24remove k (x:xs) | fst x == k = xs

25 | otherwise = x:remove k xs

27-- | Turn a list of pieces into a relative path to the root folder.

28relativeDirFromPieces :: Pieces -> T.Text

29relativeDirFromPieces pieces = T.concat $ map (const "../") (drop 1 pieces) -- last piece is not a dir

31-- | Construct redirects with relative paths.

32defaultMkRedirect :: Pieces -> ByteString -> S8.ByteString

33defaultMkRedirect pieces newPath

34 | S8.null newPath || S8.null relDir ||

35 S8.last relDir /= '/' || S8.head newPath /= '/' =

36 relDir `S8.append` newPath

37 | otherwise = relDir `S8.append` S8.tail newPath

38 where

39 relDir = TE.encodeUtf8 (relativeDirFromPieces pieces)

41dropLastIfNull :: [Piece] -> [Piece]

42dropLastIfNull pieces = case pieces of

43 [fromPiece -> ""] -> []

44 (a : r) -> a : dropLastIfNull r

45 [] -> []