src/Text/Hakyll/CompressCSS.hs · hakyll

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hakyll/src/Text/Hakyll/CompressCSS.hs

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1module Text.Hakyll.CompressCSS

2 ( compressCSS

3 ) where

5import Data.List (isPrefixOf)

6import Text.Regex (subRegex, mkRegex)

8-- | subRegex with arguments flipped for easy function composition.

9subRegex' :: String -> String -> String -> String

10subRegex' pattern replacement str = subRegex (mkRegex pattern) str replacement

12-- | Compress CSS to speed up your site.

13compressCSS :: String -> String

14compressCSS = compressSeparators

15 . compressWhitespace

16 . stripComments

18-- | Compresses certain forms of separators.

19compressSeparators :: String -> String

20compressSeparators = subRegex' ";\\s*}" "}"

21 . subRegex' "\\s*([{};:])\\s*" "\\1"

22 . subRegex' ";;*" ";"

24-- | Compresses all whitespace.

25compressWhitespace :: String -> String

26compressWhitespace = subRegex' "\\s\\s*" " "

28-- | Function that strips CSS comments away.

29stripComments :: String -> String

30stripComments [] = []

31stripComments str | isPrefixOf "/*" str = stripComments $ eatComments $ drop 2 str

32 | otherwise = (head str) : (stripComments $ tail str)

33 where eatComments str' | null str' = []

34 | isPrefixOf "*/" str' = drop 2 str'

35 | otherwise = eatComments $ tail str'