minor change

[proglang.git] / Typecheck.hs

diff --git a/Typecheck.hs b/Typecheck.hs
index cc416e28d8f166dbfc62cf7adc551ccfffad61a3..a8c10e55f5dc570e99e79fd9b30b9ad085664d11 100644 (file)
--- a/Typecheck.hs
+++ b/Typecheck.hs
@@ -1,29 +1,136 @@
-module Typecheck where 
+module Typecheck (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
+
+typeCheck :: [Func] -> [Stm] -> IO ()
+typeCheck fun st = do
+       runStateT (do mapM addFunction fun; mapM typeCheckFunction fun; mapM typeCheckStm st) emptyState
+       return ()
+
+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
+       case last s of
+               (SReturn _) -> return ()
+               _ -> fail $ "Function "++show i++" doesn't end with return statement"
+       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