introduced pushAndPop in the typechecker too

[proglang.git] / Typecheck.hs

diff --git a/Typecheck.hs b/Typecheck.hs
index 35ed382d11e00e572eb4094153101ba54a34453e..cdba298976ad2aefcecaf7e71a52b74ebb6415f0 100644 (file)
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,70 +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)
 
+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
 
-type Types = Map Ident Type
+assert :: Monad m => Bool -> String -> m ()
+assert True _ = return ()
+assert False s = fail s
 
 typeCheckExp :: (MonadState Types m) => Exp -> m Type
-typeCheckExp (BExp e o e') = do
-       TInt <- typeCheckExp e
-       TInt <- typeCheckExp e'
-       return TBool
-typeCheckExp (OpExp e o e') = do
-       TInt <- typeCheckExp e
-       TInt <- typeCheckExp e'
-       return TInt
+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
-       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
+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 NoType
-typeCheckStm (SBlock ss) = do 
-       mapM typeCheckStm ss
-       return NoType
+       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
+       pushAndPop $ typeCheckStm s
+       pushAndPop $ typeCheckStm s'
 typeCheckStm (SWhile e s) = do
        TBool <- typeCheckExp e
-       NoType <- typeCheckStm s
-       return NoType
+       pushAndPop $ typeCheckStm s
 typeCheckStm (SDecl t i e) = do
        t2 <- typeCheckExp e
-       if t == t2 then do
-               m <- get
-               put (insert i t m)
-               return NoType
-               else fail $ "Illegal to assign an expression of type "++show t2++" to variable "++show i++" of type "++show t2
+       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 ()