-lex :: [Char] -> (Int -> (Either String Token, [Char], Int))
-lex [] = ret EndOfFileToken []
-lex ['/':'/':xs] = lex (dropWhile ((<>) '\n') xs)
-lex ['/':'*':xs] = \i.let (c, r) = span ((<>) ('*','/')) $ zip2 [' ':xs] xs in
- lex (tl $ map snd $ tl $ r) (i + length [x\\(x, _)<-c | x == '\n'])
-lex ['v':'a':'r':xs] = ret VarToken xs
-lex ['V':'o':'i':'d':xs] = ret VoidToken xs
-lex ['r':'e':'t':'u':'r':'n':xs] = ret ReturnToken xs
-lex ['i':'f':xs] = ret IfToken xs
-lex ['e':'l':'s':'e':xs] = ret ElseToken xs
-lex ['w':'h':'i':'l':'e':xs] = ret WhileToken xs
-lex ['T':'r':'u':'e':xs] = ret TrueToken xs
-lex ['F':'a':'l':'s':'e':xs] = ret FalseToken xs
-lex ['I':'n':'t':xs] = ret IntTypeToken xs
-lex ['C':'h':'a':'r':xs] = ret CharTypeToken xs
-lex ['B':'o':'o':'l':xs] = ret BoolTypeToken xs
-lex [':':':':xs] = ret DoubleColonToken xs
-lex ['!':'=':xs] = ret NotEqualToken xs
-lex ['<':'=':xs] = ret LesserEqToken xs
-lex ['>':'=':xs] = ret GreaterEqToken xs
-lex ['=':'=':xs] = ret EqualsToken xs
-lex ['&':'&':xs] = ret AmpersandsToken xs
-lex ['|':'|':xs] = ret PipesToken xs
-lex ['-':'>':xs] = ret ArrowToken xs
-lex ['\'':x:'\'':xs] = ret (CharToken x) xs
-lex ['\'':'\\':x:'\'':xs] = case get x EscapeMap of
- Just t = ret (CharToken t) xs
- _ = err ("Unknown escape: \\" +++ toString x)
-lex ['-':t=:[x:xs]]
-| isDigit x = let (n, r) = span isDigit t in ret (NumberToken ['-':n]) r
-| otherwise = ret DashToken xs
-lex t=:[x:xs] = case get x SingleCharTokens of
- (Just tok) = ret tok xs
- Nothing
- | x == '\n' = \i.lex xs (i+1)
- | isSpace x = lex xs
- | isDigit x = let (v, r) = span isDigit t in ret (NumberToken v) r
- | isAlpha x = let (v, r) = span isIdent t in ret (IdentToken v) r
- with isIdent c = isAlphanum c || c == '_'
- | otherwise = err ("Unexpected character: " +++ toString x)
+ lexEscape :: Parser Char LexItem
+ lexEscape = item '\'' *> item '\\' *> top <* item '\''
+ >>= \char->pure case char of
+ 'a' = LexToken 4 (CharToken $ toChar 7)
+ 'b' = LexToken 4 (CharToken '\b')
+ 'b' = LexToken 4 (CharToken '\b')
+ 'f' = LexToken 4 (CharToken '\f')
+ 'n' = LexToken 4 (CharToken '\n')
+ 'r' = LexToken 4 (CharToken '\t')
+ 'v' = LexToken 4 (CharToken '\v')
+ '\'' =LexToken 4 (CharToken '\'')
+ c = (LexItemError $ "Unknown escape: " +++ toString c)