+lexToken :: Parser Char (Maybe TokenValue)
+lexToken =
+ //Comments
+ (list (fromString "//") >>| lexUntilNL >>| pure Nothing) <|>
+ (list (fromString "/*") >>| lexUntilCommentClose >>| pure Nothing) <|>
+ //Keyword tokens
+ lexKw "var" VarToken <|>
+ lexKw "Void" VoidToken <|>
+ lexKw "return" ReturnToken <|>
+ lexKw "if" IfToken <|>
+ lexKw "else" ElseToken <|>
+ lexKw "while" WhileToken <|>
+ lexKw "True" TrueToken <|>
+ lexKw "False" FalseToken <|>
+ lexKw "Int" IntTypeToken <|>
+ lexKw "Bool" BoolTypeToken <|>
+ lexKw "Char" CharTypeToken <|>
+ //Escape chars tokens
+ liftM (Just o CharToken)
+ (list (fromString "'\\") *> lexEscape <* item '\'') <|>
+ //Normal chars tokens
+ liftM (Just o CharToken)
+ (item '\'' *> satisfy ((<>) '\'') <* item '\'') <|>
+ //Two char ops tokens
+ lexOp "::" DoubleColonToken <|> lexOp "!=" NotEqualToken <|>
+ lexOp "<=" LesserEqToken <|> lexOp ">=" GreaterEqToken <|>
+ lexOp "==" EqualsToken <|> lexOp "&&" AmpersandsToken <|>
+ lexOp "||" PipesToken <|> lexOp "[]" EmptyListToken <|>
+ lexOp "->" ArrowToken <|>
+ //One char ops tokens
+ lexOp "(" BraceOpenToken <|>
+ lexOp ")" BraceCloseToken <|> lexOp "{" CBraceOpenToken <|>
+ lexOp "}" CBraceCloseToken <|> lexOp "[" SquareOpenToken <|>
+ lexOp "]" SquareCloseToken <|> lexOp "," CommaToken <|>
+ lexOp ":" ColonToken <|> lexOp ";" SColonToken <|>
+ lexOp "." DotToken <|> lexOp "+" PlusToken <|>
+ lexOp "*" StarToken <|> lexOp "/" SlashToken <|>
+ lexOp "%" PercentToken <|> lexOp "=" AssignmentToken <|>
+ lexOp "<" LesserToken <|> lexOp ">" BiggerToken <|>
+ lexOp "!" ExclamationToken <|> lexOp "-" DashToken <|>
+ //Number tokens
+ liftM (Just o NumberToken o toInt o toString) (some $ satisfy isDigit) <|>
+ //Ident tokens
+ liftM (Just o IdentToken o toString) (some $ satisfy isIdentChar) <|>
+ (satisfy isSpace >>| pure Nothing)
+ where
+ lexUntilNL = top until (eof <|> (item '\n' >>| pure Void))
+ lexUntilCommentClose = top until (list (fromString "*/"))
+ isIdentChar c = isAlphanum c || c == '_'
+ lexOp s tv = list (fromString s) >>| pure (Just tv)
+ lexKw kw tv = lexOp kw tv <* check (not o isIdentChar)
+ lexEscape = fromJust <$> ((
+ lexOp "a" (toChar 7) <|> lexOp "b" '\b' <|> lexOp "f" '\f' <|>
+ lexOp "n" '\n' <|> lexOp "r" '\t' <|> lexOp "v" '\v' <|>
+ lexOp "'" '\'') <?> ("Unknown escape", 0))