X-Git-Url: https://ruin.nu/git/?p=proglang.git;a=blobdiff_plain;f=Typecheck.hs;h=cdba298976ad2aefcecaf7e71a52b74ebb6415f0;hp=38ee8fe070973d51b4602dc6a39e90c928c9fcce;hb=fe6d5e0ac088e6b648a5029b101402c017fd04de;hpb=de34a0eeb75a54ce9ae058797327cd5ddc853ecc

diff --git a/Typecheck.hs b/Typecheck.hs
index 38ee8fe..cdba298 100644
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,77 +1,87 @@
 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
+
+pushAndPop :: (MonadState Types m) => m a -> m ()
+pushAndPop s = do
+	modify (empty:)
+	s
+	modify tail
 
-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
-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 || 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 ()