module Haddock.Backends.Hyperlinker.Parser ( parse , Token(..), TokenType(..) , Position(..), Span(..) ) where import Data.Char import Data.List data Token = Token { tkType :: TokenType , tkValue :: String , tkSpan :: Span } data Position = Position { posRow :: !Int , posCol :: !Int } data Span = Span { spStart :: Position , spEnd :: Position } data TokenType = TkIdentifier | TkKeyword | TkString | TkChar | TkNumber | TkOperator | TkGlyph | TkSpecial | TkSpace | TkComment | TkCpp | TkPragma | TkUnknown parse :: String -> [Token] parse = tokenize . tag . chunk chunk :: String -> [String] chunk [] = [] chunk str@(c:_) | isSpace c = chunk' $ span isSpace str chunk str | "--" `isPrefixOf` str = chunk' $ span (not . (== '\n')) str | "{-" `isPrefixOf` str = chunk' $ chunkComment 0 str | otherwise = chunk' $ head $ lex str chunk' :: (String, String) -> [String] chunk' (c, rest) = c:(chunk rest) chunkComment :: Int -> String -> (String, String) chunkComment _ [] = ("", "") chunkComment depth ('{':'-':str) = let (c, rest) = chunkComment (depth + 1) str in ("{-" ++ c, rest) chunkComment depth ('-':'}':str) | depth == 1 = ("-}", str) | otherwise = let (c, rest) = chunkComment (depth - 1) str in ("-}" ++ c, rest) chunkComment depth (e:str) = let (c, rest) = chunkComment depth str in (e:c, rest) tag :: [String] -> [(Span, String)] tag = reverse . snd . foldl aux (Position 1 1, []) where aux (pos, cs) c = let pos' = move pos c in (pos', ((Span pos pos', c):cs)) move pos str@(c:_) | isSpace c = foldl move' pos str move pos str = pos { posCol = posCol pos + length str } move' pos '\n' = pos { posRow = posRow pos + 1, posCol = 1 } move' pos _ = pos { posCol = posCol pos + 1 } tokenize :: [(Span, String)] -> [Token] tokenize = map aux where aux (sp, str) = Token { tkType = classify str , tkValue = str , tkSpan = sp } classify :: String -> TokenType classify str | "--" `isPrefixOf` str = TkComment | "{-#" `isPrefixOf` str = TkPragma | "{-" `isPrefixOf` str = TkComment classify (c:_) | isSpace c = TkSpace | isDigit c = TkNumber | c `elem` special = TkSpecial | c == '#' = TkCpp | c == '"' = TkString | c == '\'' = TkChar classify str | str `elem` keywords = TkKeyword | str `elem` glyphs = TkGlyph | all (`elem` symbols) str = TkOperator | isIdentifier str = TkIdentifier | otherwise = TkUnknown keywords :: [String] keywords = [ "as" , "case" , "class" , "data" , "default" , "deriving" , "do" , "else" , "hiding" , "if" , "import" , "in" , "infix" , "infixl" , "infixr" , "instance" , "let" , "module" , "newtype" , "of" , "qualified" , "then" , "type" , "where" , "forall" , "mdo" ] glyphs :: [String] glyphs = [ ".." , ":" , "::" , "=" , "\\" , "|" , "<-" , "->" , "@" , "~" , "~#" , "=>" , "-" , "!" ] special :: [Char] special = "()[]{},;`" -- TODO: Add support for any Unicode symbol or punctuation. -- source: http://stackoverflow.com/questions/10548170/what-characters-are-permitted-for-haskell-operators symbols :: [Char] symbols = "!#$%&*+./<=>?@\\^|-~:" isIdentifier :: String -> Bool isIdentifier (s:str) | (isLower' s || isUpper s) && all isAlphaNum' str = True where isLower' c = isLower c || c == '_' isAlphaNum' c = isAlphaNum c || c == '_' || c == '\'' isIdentifier _ = False