-module Typecheck where
+module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar) where
import Abssyntax
+import Control.Monad.State
+import Data.Map as Map
+import Prelude hiding (lookup)
-typeCheckExp :: Exp -> Maybe Type
-BExp e o e' = do
- TInt <- typeCheck e
- TInt <- typeCheck e'
- return TBool
-OpExp e o e' = do
- TInt <- typeCheck e
- TInt <- typeCheck e'
+
+type Types = Map Ident Type
+
+inList :: Eq a => a -> [a] -> Bool
+inList _ [] = False
+inList a (x:xs) = if a == x then True else inList a xs
+
+typeCheckExp :: (MonadState Types m) => Exp -> m Type
+typeCheckExp (BiOpExp e o e') = do
+ t1 <- typeCheckExp e
+ t2 <- typeCheckExp e'
+ if not(t1 == t2) then fail "The parameters for the binary operator aren't equal"
+ else if inList o [Eq,NEq] then return TBool
+ else if not(t1 == TInt) then fail "The parameters need to be of type int"
+ else if inList o [Plus,Minus,Times,Div]
+ then return TInt
+ else return TBool
+typeCheckExp (EVar i) = typeCheckVar i
+typeCheckExp (EAss i e) = do
+ a <- typeCheckVar i
+ b <- typeCheckExp e
+ if a == b then return a else fail "FEL!"
+typeCheckExp (EInt i) = return TInt
+typeCheckExp (EBool b) = return TBool
+typeCheckExp EReadI = return TInt
+typeCheckExp EReadB = return TBool
+typeCheckExp (ExpT t e) = do
+ t2 <- typeCheckExp e
+ if t == t2 then return t else fail "FEL!"
+typeCheckExp EDefault = return NoType
+typeCheckExp (EPost i op) = do
+ TInt <- typeCheckVar i
return TInt
+typeCheckExp (ENeg e) = do
+ TInt <- typeCheckExp e
+ return TInt
+
-typeCheckStm :: Stm -> Maybe Type
-SNoop = return NoType
-SExp e = typeCheckExp e
-SBlock ss = do
+typeCheckVar :: (MonadState Types m) => Ident -> m Type
+typeCheckVar i = do
+ e <- get
+ lookup i e
+
+typeCheckStm :: (MonadState Types m) => Stm -> m Type
+typeCheckStm SNoop = return NoType
+typeCheckStm (SExp e) = do
+ typeCheckExp e
+ return NoType
+typeCheckStm (SBlock ss) = do
mapM typeCheckStm ss
return NoType
-SIf e s s' = do
+typeCheckStm (SIf e s s') = do
TBool <- typeCheckExp e
NoType <- typeCheckStm s
NoType <- typeCheckStm s
return NoType
-SWhile e s = do
+typeCheckStm (SWhile e s) = do
TBool <- typeCheckExp e
NoType <- typeCheckStm s
+ return NoType
+typeCheckStm (SDecl t i e) = do
+ t2 <- typeCheckExp e
+ if t == t2 || t2 == NoType then do
+ m <- get
+ case insertLookupWithKey (\k a1 a2 -> a1) i t m of
+ (Nothing,m') -> put m'
+ _ -> fail $ "Duplicate variable declaration: "++show i
+ return NoType
+ else fail $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
+typeCheckStm (SPrint e) = do
+ typeCheckExp e
+ return NoType