-module Interpret (eval, execute, Value(VInt, VBool)) where
+module Interpret (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), ret=(VInt 0)}
+
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])
+
+data State = State {variables::Variables,functions::(Map Ident Function),ret::Value}
-inList :: Eq a => a -> [a] -> Bool
-inList _ [] = False
-inList a (x:xs) = if a == x then True else inList a xs
+type EvalM m = ErrorT String m
---eval :: (MonadState Variables m) => Exp -> m Value
-eval :: Exp -> StateT Variables IO Value
+interpret :: [Func] -> [Stm] -> IO ()
+interpret fun st = do
+ runStateT (runErrorT (do mapM addFunction fun; mapM_ execute st)) emptyState
+ return ()
+
+eval :: (MonadState State m, MonadIO m) => Exp -> EvalM m 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 EDefault = return (VInt 0) --FIXME!!!
+eval (EAss i e) = do
+ v <- eval e
+ setVariableValue i v
eval (BiOpExp e o e') = do
v <- eval e
v'<- eval e'
- if inList 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
-typeCheckExp (EPost i op) = do
+ 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
- setVariableValue i $ EInt $ n+1
+ setVariableValue i $ op o n 1
return $ VInt n
+eval (ENeg e) = do
+ (VInt n) <- eval e
+ return $ VInt $ -n
+eval (ENot e) = do
+ (VBool b) <- eval e
+ return $ VBool $ not b
+eval EReadI = do
+ s <- liftIO $ getNumber
+ return $ VInt $ read s
+eval EReadB = do
+ s <- liftIO $ getNumber
+ 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
+ let m = foldr (\((Decl t i),v) m -> insert i v m) empty $ zip ds vs
+ in modify (\s -> s{variables=[m]})
+ (mapM_ execute ss >> (fail $ "Function "++show i++" didn't return anything."))
+ `catchError` (\_ ->return ()) --Only errors thrown in ErrorT can be caught here, runtime errors pass through, so no need to check the error
+ v <- liftM ret get
+ put state
+ return v
+
+--Stricter evaluation of the input
+getNumber :: IO String
+getNumber = do
+ c <- getChar
+ if elem c $ '-':['0'..'9']
+ then do
+ l <- getNumber2
+ return (c:l)
+ else fail "Non integer input."
+
+getNumber2 :: IO String
+getNumber2 = do
+ c <- getChar
+ if elem c ['0'..'9']
+ then do
+ l <- getNumber2
+ return (c:l)
+ else return ""
-- 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'
-
-getVariableValue :: (MonadState Variables m) => Ident -> m Value
-getVariableValue i = do
- ms <- get
- findVariable i ms
+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 _ 0 = error "Division by zero"
+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'
---setVariableValue :: (MonadState Variables m) => Ident -> Exp -> m Value
-setVariableValue :: Ident -> Exp -> StateT Variables IO Value
-setVariableValue i e = do
- e' <- eval e
- (m:ms) <- get
- put $ (insert i e' m):ms
- return e'
+getVariableValue :: (MonadState State m) => Ident -> m Value
+getVariableValue i = do
+ s <- get
+ findVariable i $ variables s
-findVariable :: (MonadState Variables m) => Ident -> Variables -> m Value
+findVariable :: (Monad 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
--- execute :: (MonadState Variables m) => Stm -> m ()
-execute :: Stm -> StateT Variables IO ()
+setVariableValue :: (MonadState State m) => Ident -> Value -> EvalM m Value
+setVariableValue i v = do
+ modify (\s -> s{variables= updateVariable i v $ variables s} )
+ 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 State m, MonadIO m) => Stm -> EvalM m ()
+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 (SNoop) = return ()
-execute (SBlock ss) = do
- modify (empty:)
- mapM execute ss
- modify tail
+ liftIO $ print e'
+execute (SBlock ss) = pushAndPop $ mapM execute ss
execute (SWhile e s) = do
(VBool b) <- eval e
- if b then execute (SWhile e s) else return ()
-execute (SDecl t i EDefault) = do
- case t of
- TInt -> setVariableValue i (EInt 0)
- TBool -> setVariableValue i (EBool False)
- return ()
-execute (SDecl t i e) = setVariableValue i e >> 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
+ v <- eval e
+ (m:ms) <- liftM variables get
+ modify (\s -> s{variables=insert i v m:ms })
+execute (SReturn e) = do
+ v <- eval e
+ modify (\s -> s{ret=v})
+ throwError "Returning.."
+
+addFunction :: (MonadState State m) => Func -> m ()
+addFunction (Func _ i d ss) = modify (\s -> s{functions=insert i (d,ss) (functions s) })
projects / proglang.git / blobdiff