module RegChars ( regChars,
) where
(&&&) :: (a -> Bool) -> (a -> Bool) -> (a -> Bool)
(&&&) a b c = a c && b c
(|||) :: (a -> Bool) -> (a -> Bool) -> (a -> Bool)
(|||) a b c = a c || b c
regChars :: String -> (Char -> Bool)
regChars ('^':cs) = not . normalRegChars (unescapeChars cs)
regChars ('\\':'^':cs) = normalRegChars $ unescapeChars $ '^':cs
regChars cs = normalRegChars $ unescapeChars cs
unescapeChars :: String -> String
unescapeChars ('\\':'n':cs) = '\n' : unescapeChars cs
unescapeChars ('\\':'t':cs) = '\t' : unescapeChars cs
unescapeChars ('\\':'^':cs) = '^' : unescapeChars cs
unescapeChars (c:cs) = c : unescapeChars cs
unescapeChars [] = []
normalRegChars :: String -> (Char -> Bool)
normalRegChars ('\\':'.':cs) = (=='.') ||| normalRegChars cs
normalRegChars ('\\':'-':cs) = (=='-') ||| normalRegChars cs
normalRegChars ('\\':'\\':cs) = (=='\\') ||| normalRegChars cs
normalRegChars ('\\':c:_) = error $ "'\\"++[c]++"' not supported."
normalRegChars (c1:'-':c2:cs) = ((>= c1) &&& (<= c2)) ||| normalRegChars cs
normalRegChars (c:cs) = (== c) ||| normalRegChars cs
normalRegChars [] = \_ -> False