-module Interpret (eval, execute, Value(VInt, VBool)) where
+module Interpret (eval, execute,addFunction, emptyState, Value(..), State(..)) where
import Abssyntax
-import Control.Monad.State
+import Control.Monad.State hiding (State)
+import Control.Monad.Error
+import Control.Concurrent.MVar
import Data.Map as Map
import Prelude hiding (lookup)
+emptyState = State{variables=[empty], functions=(empty)}
+
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]
+type Function = ([Decl],[Stm])
-inList :: Eq a => a -> [a] -> Bool
-inList _ [] = False
-inList a (x:xs) = if a == x then True else inList a xs
+data State = State {variables::Variables,functions::(Map Ident Function),ret::(MVar Value)}
--eval :: (MonadState Variables m) => Exp -> m Value
-eval :: Exp -> StateT Variables IO Value
+eval :: Exp -> StateT State 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
return $ VInt $ read s
eval EReadB = do
s <- lift $ getWord
- return $ VBool $ read s
+ return $ VBool $ if (read s == 0) then False else True
+eval (EFunc i as) = do
+ vs <- mapM eval as
+ state <- get
+ (ds,ss) <- lookup i $ functions state
+ modify (\s -> s{variables=[empty]})
+ addParams vs ds
+ mapM_ execute ss `catchError` (\_ -> return ())
+ put state
+ v <- lift $ takeMVar $ ret state
+ return v
+
+addParams :: [Value] -> [Decl] -> StateT State IO ()
+addParams [] [] = return ()
+addParams (v:vs) ((Decl t i):ds) = do
+ state <- get
+ let (m:ms) = variables state in modify (\s -> s{variables=insert i v m:ms })
+ addParams vs ds
+
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'
op EGt = \e e' -> VBool $ e >= e'
-getVariableValue :: (MonadState Variables m) => Ident -> m Value
+getVariableValue :: (MonadState State m) => Ident -> m Value
getVariableValue i = do
- ms <- get
- findVariable i ms
+ s <- get
+ findVariable i $ variables s
-findVariable :: (MonadState Variables m) => Ident -> Variables -> m Value
+findVariable :: (MonadState State m) => Ident -> Variables -> m Value
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
--setVariableValue :: (MonadState Variables m) => Ident -> Exp -> m Value
--setVariableValue :: (MonadState Variables m) => Ident -> Exp -> m Value
-setVariableValue :: Ident -> Exp -> StateT Variables IO Value
+setVariableValue :: Ident -> Exp -> StateT State IO Value
setVariableValue i e = do
v <- eval e
- ms <- get
- put $ updateVariable i v ms
+ state <- get
+ modify (\s -> s{variables= updateVariable i v $ variables state} )
return v
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 State m) => m a -> m ()
+pushAndPop s = do
+ modify (\s -> s { variables = empty:variables s})
+ s
+ modify (\s -> s { variables = tail $ variables s})
-- execute :: (MonadState Variables m) => Stm -> m ()
-execute :: Stm -> StateT Variables IO ()
+execute :: Stm -> StateT State IO ()
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
- (m:ms) <- get
- put $ (insert i e' m):ms
+ v <- eval e
+ state <- get
+ let (m:ms) = variables state in modify (\s -> s{variables=insert i v m:ms })
+execute (SReturn e) = do
+ v <- eval e
+ s <- get
+ lift $ putMVar (ret s) v
+ throwError $ userError "Returning.."
+
+addFunction :: (MonadState State m) => Func -> m ()
+addFunction (Func _ i d ss) = modify (\s -> s{functions=insert i (d,ss) (functions s) })