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.Hakyll.Regex (substitute)

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

9compressCSS :: String -> String

10compressCSS = compressSeparators

11 . stripComments

12 . compressWhitespace

14-- | Compresses certain forms of separators.

15compressSeparators :: String -> String

16compressSeparators = substitute "; *}" "}"

17 . substitute " *([{};:]) *" "\\1"

18 . substitute ";;*" ";"

20-- | Compresses all whitespace.

21compressWhitespace :: String -> String

22compressWhitespace = substitute "[ \t\n][ \t\n]*" " "

24-- | Function that strips CSS comments away.

25stripComments :: String -> String

26stripComments [] = []

27stripComments str | isPrefixOf "/*" str = stripComments $ eatComments $ drop 2 str

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

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

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

31 | otherwise = eatComments $ tail str'