introduced pushAndPop in the typechecker too

[proglang.git] / Typecheck.hs

diff --git a/Typecheck.hs b/Typecheck.hs
index cc416e28d8f166dbfc62cf7adc551ccfffad61a3..cdba298976ad2aefcecaf7e71a52b74ebb6415f0 100644 (file)
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,29 +1,87 @@
-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
+
+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'
+       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
+       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 (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
+       ms <- get
+       findVariable i ms
 
-typeCheckStm :: Stm -> Maybe Type
-SNoop = return NoType
-SExp e = typeCheckExp e
-SBlock ss = do 
-       mapM typeCheckStm ss
-       return NoType
-SIf e s s' = do
+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
+
+pushAndPop :: (MonadState Types m) => m a -> m ()
+pushAndPop s = do
+       modify (empty:)
+       s
+       modify tail
+
+typeCheckStm :: (MonadState Types m) => Stm -> m ()
+typeCheckStm SNoop = return ()
+typeCheckStm (SExp e) = do 
+       typeCheckExp e
+       return ()
+typeCheckStm (SBlock ss) = pushAndPop $ mapM typeCheckStm ss
+typeCheckStm (SIf e s s') = do
        TBool <- typeCheckExp e
-       NoType <- typeCheckStm s
-       NoType <- typeCheckStm s
-       return NoType
-SWhile e s = do
+       pushAndPop $ typeCheckStm s
+       pushAndPop $ typeCheckStm s'
+typeCheckStm (SWhile e s) = do
        TBool <- typeCheckExp e
-       NoType <- typeCheckStm s
-
+       pushAndPop $ typeCheckStm s
+typeCheckStm (SDecl t i e) = do
+       t2 <- typeCheckExp e
+       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 ()