minor stuff

[proglang.git] / Interpret.hs

diff --git a/Interpret.hs b/Interpret.hs
index 5a792b9b2bbbe27be026d99096d17df1ef5cffa2..0728d5181c967cf6d109f3327f2d8905e6738b1e 100644 (file)
--- a/Interpret.hs
+++ b/Interpret.hs
@@ -1,4 +1,4 @@
-module Interpret (eval, execute, Value(VInt, VBool)) where
+module Interpret (interpret, eval, execute, Value(VInt, VBool)) where
 
 import Abssyntax
 import Control.Monad.State
@@ -9,24 +9,24 @@ data Value = VInt Integer | VBool Bool deriving Eq
 
 instance Show Value where
        show (VInt n) = show n
-       show (VBool b) = show b
+       show (VBool True) = "1"
+       show (VBool False) = "0"
 
 type Variables = [Map Ident Value]
 
-inList :: Eq a => a -> [a] -> Bool
-inList _ [] = False
-inList a (x:xs) = if a == x then True else inList a xs
+interpret :: [Stm] -> IO ()
+interpret s = runStateT (mapM execute s) [empty] >> return ()
 
 --eval :: (MonadState Variables m) => Exp -> m Value
 eval :: Exp -> StateT Variables IO Value
 eval (EBool b) = return (VBool b)
 eval (EInt n) = return (VInt n)
 eval (EVar i) = getVariableValue i
-eval (EAss i e) = setVariableValue i e 
+eval (EAss i e) = setVariableValue i e
 eval (BiOpExp e o e') = do
        v <- eval e
        v'<- eval e'
-       if inList o [Eq,NEq] then return $ opE o v v'
+       if elem o [Eq,NEq] then return $ opE o v v'
                else let (VInt n1) = v in let (VInt n2) = v' in return $ op o n1 n2
 eval (EPost i o) = do
        (VInt n) <- getVariableValue i
@@ -43,24 +43,24 @@ eval EReadI = do
        return $ VInt $ read s
 eval EReadB = do
        s <- lift $ getWord
-       return $ VBool $ read s
+       return $ VBool $ if (read s == 0) then False else True
 
 getWord :: IO String
 getWord =  do
        c <- getChar
-       if inList c ['\n','\r',' ', '\t']
+       if elem c [' ', '\n', '\t', '\r']
                then return ""
                else do
                        l <- getWord
-                       return (c:l) 
+                       return (c:l)
 
 -- op :: Op -> (a -> a -> Value)
 opE Eq = \e e' -> VBool $ e == e'
 opE NEq = \e e' -> VBool $ not (e == e')
 op Plus = \e e' -> VInt $ e + e'
-op Minus = \e e' -> VInt $ e - e' 
-op Times = \e e' -> VInt $ e * e' 
-op Div = \e e' -> VInt $ e `div` e' 
+op Minus = \e e' -> VInt $ e - e'
+op Times = \e e' -> VInt $ e * e'
+op Div = \e e' -> VInt $ e `div` e'
 op Lt = \e e' -> VBool $ e < e'
 op ELt = \e e' -> VBool $ e <= e'
 op Gt = \e e' -> VBool $ e > e'
@@ -89,6 +89,11 @@ updateVariable :: Ident -> Value -> Variables -> Variables
 updateVariable _ _ [] = []
 updateVariable i v (m:ms) = if member i m then insert i v m:ms else m:updateVariable i v ms
 
+pushAndPop :: (MonadState Variables m) => m a -> m ()
+pushAndPop s = do
+       modify (empty:)
+       s
+       modify tail
 
 -- execute :: (MonadState Variables m) => Stm -> m ()
 execute :: Stm -> StateT Variables IO ()
@@ -96,18 +101,18 @@ execute (SNoop) = return ()
 execute (SExp e) = eval e >> return ()
 execute (SIf b s s') = do
        (VBool b') <- eval b
-       if b' then execute s else execute s'
+       pushAndPop $ if b' then execute s else execute s'
 execute (SPrint e) = do
        e' <- eval e
        lift $ print e'
-execute (SBlock ss) = do
-       modify (empty:)
-       mapM execute ss
-       modify tail
+execute (SBlock ss) = pushAndPop $ mapM execute ss
 execute (SWhile e s) = do
        (VBool b) <- eval e
-       if b then execute s >> execute (SWhile e s) else return ()
+       if b then pushAndPop (execute s) >> execute (SWhile e s) else return ()
+execute (SDeclD t i) = execute $ SDecl t i $ case t of
+       TInt -> EInt 0
+       TBool -> EBool False
 execute (SDecl t i e) =do
-       e' <- eval e
+       v <- eval e
        (m:ms) <- get
-       put $ (insert i e' m):ms
+       put $ (insert i v m):ms