src/Text/Pandoc/CSS.hs · typeable/pandoc

git.iko.soy/typeable/pandoc

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1module Text.Pandoc.CSS ( foldOrElse

2 , pickStyleAttrProps

3 , pickStylesToKVs

4 )

5where

7import Text.Pandoc.Shared (trim)

8import Text.Parsec

9import Text.Parsec.String

11ruleParser :: Parser (String, String)

12ruleParser = do

13 p <- many1 (noneOf ":") <* char ':'

14 v <- many1 (noneOf ":;") <* (optional $ char ';') <* spaces

15 return (trim p, trim v)

17styleAttrParser :: Parser [(String, String)]

18styleAttrParser = many1 ruleParser

20orElse :: Eq a => a -> a -> a -> a

21orElse v x y = if v == x then y else x

23foldOrElse :: Eq a => a -> [a] -> a

24foldOrElse v xs = foldr (orElse v) v xs

26eitherToMaybe :: Either a b -> Maybe b

27eitherToMaybe (Right x) = Just x

28eitherToMaybe _ = Nothing

30-- | takes a list of keys/properties and a CSS string and

31-- returns the corresponding key-value-pairs.

32pickStylesToKVs :: [String] -> String -> [(String, String)]

33pickStylesToKVs props styleAttr =

34 case parse styleAttrParser "" styleAttr of

35 Left _ -> []

36 Right styles -> filter (\s -> fst s `elem` props) styles

38-- | takes a list of key/property synonyms and a CSS string and maybe

39-- returns the value of the first match (in order of the supplied list)

40pickStyleAttrProps :: [String] -> String -> Maybe String

41pickStyleAttrProps lookupProps styleAttr = do

42 styles <- eitherToMaybe $ parse styleAttrParser "" styleAttr

43 foldOrElse Nothing $ map (flip lookup styles) lookupProps