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|
module Text.Pandoc.CSS ( foldOrElse
, pickStyleAttrProps
, pickStylesToKVs
)
where
import Text.Pandoc.Shared (trim)
import Text.Parsec
import Text.Parsec.String
ruleParser :: Parser (String, String)
ruleParser = do
p <- many1 (noneOf ":") <* char ':'
v <- many1 (noneOf ":;") <* optional (char ';') <* spaces
return (trim p, trim v)
styleAttrParser :: Parser [(String, String)]
styleAttrParser = many1 ruleParser
orElse :: Eq a => a -> a -> a -> a
orElse v x y = if v == x then y else x
foldOrElse :: Eq a => a -> [a] -> a
foldOrElse v xs = foldr (orElse v) v xs
eitherToMaybe :: Either a b -> Maybe b
eitherToMaybe (Right x) = Just x
eitherToMaybe _ = Nothing
-- | takes a list of keys/properties and a CSS string and
-- returns the corresponding key-value-pairs.
pickStylesToKVs :: [String] -> String -> [(String, String)]
pickStylesToKVs props styleAttr =
case parse styleAttrParser "" styleAttr of
Left _ -> []
Right styles -> filter (\s -> fst s `elem` props) styles
-- | takes a list of key/property synonyms and a CSS string and maybe
-- returns the value of the first match (in order of the supplied list)
pickStyleAttrProps :: [String] -> String -> Maybe String
pickStyleAttrProps lookupProps styleAttr = do
styles <- eitherToMaybe $ parse styleAttrParser "" styleAttr
foldOrElse Nothing $ map (flip lookup styles) lookupProps
|
