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

git.iko.soy/typeable/pandoc

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1{-# LANGUAGE NoImplicitPrelude #-}

2module Text.Pandoc.CSS ( foldOrElse

3 , pickStyleAttrProps

4 , pickStylesToKVs

5 )

6where

8import Prelude

9import Text.Pandoc.Shared (trim)

10import Text.Parsec

11import Text.Parsec.String

13ruleParser :: Parser (String, String)

14ruleParser = do

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

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

17 return (trim p, trim v)

19styleAttrParser :: Parser [(String, String)]

20styleAttrParser = many1 ruleParser

22orElse :: Eq a => a -> a -> a -> a

23orElse v x y = if v == x then y else x

25foldOrElse :: Eq a => a -> [a] -> a

26foldOrElse v xs = foldr (orElse v) v xs

28eitherToMaybe :: Either a b -> Maybe b

29eitherToMaybe (Right x) = Just x

30eitherToMaybe _ = Nothing

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

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

34pickStylesToKVs :: [String] -> String -> [(String, String)]

35pickStylesToKVs props styleAttr =

36 case parse styleAttrParser "" styleAttr of

37 Left _ -> []

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

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

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

42pickStyleAttrProps :: [String] -> String -> Maybe String

43pickStyleAttrProps lookupProps styleAttr = do

44 styles <- eitherToMaybe $ parse styleAttrParser "" styleAttr

45 foldOrElse Nothing $ map (`lookup` styles) lookupProps