-module Typecheck where
+module Typecheck (typeCheckExp, typeCheckStm, typeCheckVar, typeCheckFunction, addFunction, emptyState, State(..)) where
+
import Abssyntax
+import Control.Monad.State hiding (State)
+import Data.Map as Map hiding (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]
+type Function = (Type, [Type])
+
+data State = State {variables::Types,functions::(Map Ident Function),function::Ident}
+
+emptyState = State{variables=[empty], functions=(empty), function=(Ident "")}
+
+assert :: Monad m => Bool -> String -> m ()
+assert True _ = return ()
+assert False s = fail s
+
+typeCheckExp :: (MonadState State 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 elem o [Eq,NEq] then return TBool
+ else do
+ assert (t1 == TInt) "The parameters need to be of type int"
+ if elem 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
+typeCheckExp (EFunc i as) = do
+ state <- get
+ (t,ts) <- lookup i $ functions state
+ checkParams as ts
+ return t
+
+checkParams :: (MonadState State m) => [Exp] -> [Type] -> m ()
+checkParams [] [] = return ()
+checkParams [] _ = fail "Too for arguments when calling function"
+checkParams _ [] = fail "Too many arguments when calling function"
+checkParams (e:es) (t:ts) = do
+ t2 <- typeCheckExp e
+ assert (t == t2) "Arugments does not match"
+ checkParams es ts
+
+typeCheckVar :: (MonadState State m) => Ident -> m Type
+typeCheckVar i = do
+ s <- get
+ findVariable i $ variables s
+
+findVariable :: (MonadState State 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 :: Stm -> Maybe Type
-SNoop = return NoType
-SExp e = typeCheckExp e
-SBlock ss = do
- mapM typeCheckStm ss
- return NoType
-SIf e s s' = do
+pushAndPop :: (MonadState State m) => m a -> m ()
+pushAndPop s = do
+ modify (\s -> s { variables = empty:variables s})
+ s
+ modify (\s -> s { variables = tail $ variables s})
+
+typeCheckStm :: (MonadState State 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 (SDeclD t i) = addVariable i t
+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
+ addVariable i t
+typeCheckStm (SPrint e) = do
+ typeCheckExp e
+ return ()
+typeCheckStm (SReturn e) = do
+ t <- typeCheckExp e
+ state <- get
+ (t2,_) <- lookup (function state) $ functions state
+ assert (t == t2) $ "Illegal to return "++show t++" in function "++show (function state)++" which returns "++show t2
+
+
+addVariable :: (MonadState State m) => Ident -> Type -> m ()
+addVariable i t = do
+ s <- get
+ let (m:ms) = variables s in case insertLookupWithKey (\k a1 a2 -> a1) i t m of
+ (Nothing,m') -> modify (\s -> s{ variables = m':ms})
+ _ -> fail $ "Duplicate variable declaration: "++show i
+
+typeCheckFunction :: (MonadState State m) => Func -> m ()
+typeCheckFunction (Func t i d s) = do
+ state <- get
+ modify (\s -> s{variables=[empty], function=i})
+ mapM (\(Decl t i) -> addVariable i t) d
+ mapM typeCheckStm s
+ put state
+addFunction :: (MonadState State m) => Func -> m ()
+addFunction (Func t i d _) = do
+ s <- get
+ let m = functions s in case insertLookupWithKey (\k a1 a2 -> a1) i (t, map (\(Decl t i) -> t) d) m of
+ (Nothing,m') -> modify (\s -> s{ functions = m'})
+ _ -> fail $ "Duplicate variable declaration: "++show i