module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar) where
+
import Abssyntax
import Control.Monad.State
import Data.Map as Map
import Prelude hiding (lookup)
-type Types = Map Ident Type
+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
+assert :: Monad m => Bool -> String -> m ()
+assert True _ = return ()
+assert False s = fail s
+
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
+ assert (t1 == t2) "The parameters for the binary operator aren't equal"
+ if inList o [Eq,NEq] then return TBool
+ else do
+ assert (t1 == TInt) "The parameters need to be of type int"
+ 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!"
+ t <- typeCheckVar i
+ t2 <- typeCheckExp e
+ assert (t == t2) $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
+ return t
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
+typeCheckExp (ENot e) = do
+ TBool <- typeCheckExp e
+ return TBool
typeCheckVar :: (MonadState Types m) => Ident -> m Type
typeCheckVar i = do
- e <- get
- lookup i e
+ ms <- get
+ findVariable i ms
+
+findVariable :: (MonadState Types m) => Ident -> Types -> m Type
+findVariable i [] = fail $ "Variable "++show i++" not found in any scope."
+findVariable i (m:ms) = if member i m then lookup i m else findVariable i ms
-typeCheckStm :: (MonadState Types m) => Stm -> m Type
-typeCheckStm SNoop = return NoType
+typeCheckStm :: (MonadState Types m) => Stm -> m ()
+typeCheckStm SNoop = return ()
typeCheckStm (SExp e) = do
typeCheckExp e
- return NoType
+ return ()
typeCheckStm (SBlock ss) = do
+ modify (empty:)
mapM typeCheckStm ss
- return NoType
+ modify tail
typeCheckStm (SIf e s s') = do
TBool <- typeCheckExp e
- NoType <- typeCheckStm s
- NoType <- typeCheckStm s
- return NoType
+ modify (empty:)
+ typeCheckStm s
+ modify (\s -> empty:tail s)
+ typeCheckStm s'
+ modify tail
typeCheckStm (SWhile e s) = do
TBool <- typeCheckExp e
- NoType <- typeCheckStm s
- return NoType
+ modify (empty:)
+ typeCheckStm s
+ modify tail
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
+ assert (t == t2) $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t
+ (m:ms) <- get
+ case insertLookupWithKey (\k a1 a2 -> a1) i t m of
+ (Nothing,m') -> put (m':ms)
+ _ -> fail $ "Duplicate variable declaration: "++show i
typeCheckStm (SPrint e) = do
typeCheckExp e
- return NoType
+ return ()