src/Parse/ParserLib.hs · elk

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elk/src/Parse/ParserLib.hs

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1module ParserLib where

3import Ast

4import Combinators

5import Data.Char (isUpper,isLower)

6import Control.Monad (liftM,guard)

7import Tokens

9varNoSpace = do { t <- item; case t of { ID v -> return v; _ -> zero } }

10var = whitespace >> varNoSpace

11capVar = do whitespace; t <- item

12 case t of { ID (v:vs) -> guard (isUpper v) >> return (v:vs) ; _ -> zero }

13lowVar = do whitespace; t <- item

14 case t of { ID (v:vs) -> guard (isLower v) >> return (v:vs) ; _ -> zero }

16chr = do { whitespace; t <- item; case t of { CHAR c -> return c; _ -> zero } }

18tNoSpace token = sat (==token)

19tWithSpace token = forcedWS >> sat (==token)

20t token = whitespace >> sat (==token)

22forcedWS = do { sat (==SPACES); star nl_space } +|+ plus nl_space

23 where nl_space = plus (sat (==NEWLINE)) >> sat (==SPACES)

24whitespace = optional forcedWS

26accessible exp = do

27 e <- exp

28 access <- optional $ opParserNospace (==".")

29 case access of

30 Just "." -> accessible (Access e `liftM` var)

31 Nothing -> return e

33opParserNospace pred =

34 do { t <- item

35 ; case t of { OP op -> if pred op then return op else zero; _ -> zero } }

36opParser pred = whitespace >> opParserNospace pred

37anyOp = opParser (const True)

38assign = opParser (=="=")