X-Git-Url: https://ruin.nu/git/?p=proglang.git;a=blobdiff_plain;f=Typecheck.hs;h=a78f8f02c6a51d5d6d643d01ee8a4232f4223dab;hp=cc416e28d8f166dbfc62cf7adc551ccfffad61a3;hb=565fbd61dca527c23888e08783d0d91cee458524;hpb=a05f5aee2ceddec9721ce04ae596734524b80940

diff --git a/Typecheck.hs b/Typecheck.hs
index cc416e2..a78f8f0 100644
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,29 +1,89 @@
-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 
+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 ()
+typeCheckStm SNoop = return ()
+typeCheckStm (SExp e) = do 
+	typeCheckExp e
+	return ()
+typeCheckStm (SBlock ss) = do 
+	modify (empty:)
 	mapM typeCheckStm ss
-	return NoType
-SIf e s s' = do
+	modify tail
+typeCheckStm (SIf e s s') = do
 	TBool <- typeCheckExp e
-	NoType <- typeCheckStm s
-	NoType <- typeCheckStm s
-	return NoType
-SWhile e s = do
+	modify (empty:)
+	typeCheckStm s
+	modify (\s -> empty:tail s)
+	typeCheckStm s'
+	modify tail
+typeCheckStm (SWhile e s) = do
 	TBool <- typeCheckExp e
-	NoType <- typeCheckStm s
-
+	modify (empty:)
+	typeCheckStm s
+	modify tail
+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 ()