data Stm =
SExp Exp
| SBlock [Stm]
+ | SDecl Type Ident Exp
+ | SDeclD Type Ident
| SWhile Exp Stm
| SIf Exp Stm Stm
| SPrint Exp
| SNoop
- | SDecl Type Ident Exp
deriving (Eq,Ord,Show)
data Exp =
compileStm (SPrint e) = "printf(\"%d\\n\","++compileExp e++");\n"
compileStm (SBlock ss) = "{\n"++concat (map (("\t"++).compileStm) ss)++"\n}\n"
compileStm (SWhile e s) = "while("++compileExp e++")"++compileStm s
+compileStm (SDeclD t i) = compileStm (SDecl t i $ case t of
+ TInt -> EInt 0
+ TBool -> EBool False
+ )
compileStm (SDecl t (Ident i) e) = "int "++i++"="++compileExp e++";\n"
\begin{tabular}{lll}
{\nonterminal{Stm}} & {\arrow} &{\nonterminal{Exp}} {\terminal{;}} \\
& {\delimit} &{\terminal{\{}} {\nonterminal{ListStm}} {\terminal{\}}} \\
- & {\delimit} &{\terminal{int}} {\nonterminal{Ident}} {\terminal{{$=$}}} {\nonterminal{Exp}} {\terminal{;}} \\
- & {\delimit} &{\terminal{bool}} {\nonterminal{Ident}} {\terminal{{$=$}}} {\nonterminal{Exp}} {\terminal{;}} \\
- & {\delimit} &{\terminal{int}} {\nonterminal{Ident}} {\terminal{;}} \\
- & {\delimit} &{\terminal{bool}} {\nonterminal{Ident}} {\terminal{;}} \\
+ & {\delimit} &{\nonterminal{Type}} {\nonterminal{Ident}} {\terminal{{$=$}}} {\nonterminal{Exp}} {\terminal{;}} \\
+ & {\delimit} &{\nonterminal{Type}} {\nonterminal{Ident}} {\terminal{;}} \\
& {\delimit} &{\terminal{while}} {\terminal{(}} {\nonterminal{Exp}} {\terminal{)}} {\nonterminal{Stm}} \\
& {\delimit} &{\terminal{if}} {\terminal{(}} {\nonterminal{Exp}} {\terminal{)}} {\nonterminal{Stm}} {\terminal{else}} {\nonterminal{Stm}} \\
& {\delimit} &{\terminal{if}} {\terminal{(}} {\nonterminal{Exp}} {\terminal{)}} {\nonterminal{Stm}} \\
execute (SWhile e s) = do
(VBool b) <- eval e
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
Stm :: { Stm }
Stm : Exp ';' { SExp $1 }
| '{' ListStm '}' { SBlock (reverse $2) }
- | 'int' Ident '=' Exp ';' { declIntE_ $2 $4 }
- | 'bool' Ident '=' Exp ';' { declBoolE_ $2 $4 }
- | 'int' Ident ';' { declInt_ $2 }
- | 'bool' Ident ';' { declBool_ $2 }
+ | Type Ident '=' Exp ';' { SDecl $1 $2 $4 }
+ | Type Ident ';' { SDeclD $1 $2 }
| 'while' '(' Exp ')' Stm { SWhile $3 $5 }
| 'if' '(' Exp ')' Stm 'else' Stm { SIf $3 $5 $7 }
| 'if' '(' Exp ')' Stm { if_ $3 $5 }
Bad $ "syntax error at " ++ tokenPos ts ++ if null ts then [] else (" before " ++ unwords (map prToken (take 4 ts)))
myLexer = tokens
-declIntE_ x_ e_ = SDecl TInt x_ e_
-declBoolE_ x_ e_ = SDecl TBool x_ e_
-declInt_ x_ = SDecl TInt x_ (EInt 0)
-declBool_ x_ = SDecl TBool x_ (EBool False)
if_ e_ s_ = SIf e_ s_ SNoop
compExp_ e1_ o_ e2_ = BiOpExp e1_ o_ e2_
op1_ e1_ o_ e2_ = BiOpExp e1_ o_ e2_
prt i e = case e of
SExp exp -> prPrec i 0 (concatD [prt 0 exp , doc (showString ";")])
SBlock stms -> prPrec i 0 (concatD [doc (showString "{") , prt 0 stms , doc (showString "}")])
+ SDecl type' id exp -> prPrec i 0 (concatD [prt 0 type' , prt 0 id , doc (showString "=") , prt 0 exp , doc (showString ";")])
+ SDeclD type' id -> prPrec i 0 (concatD [prt 0 type' , prt 0 id , doc (showString ";")])
SWhile exp stm -> prPrec i 0 (concatD [doc (showString "while") , doc (showString "(") , prt 0 exp , doc (showString ")") , prt 0 stm])
SIf exp stm0 stm -> prPrec i 0 (concatD [doc (showString "if") , doc (showString "(") , prt 0 exp , doc (showString ")") , prt 0 stm0 , doc (showString "else") , prt 0 stm])
SPrint exp -> prPrec i 0 (concatD [doc (showString "print") , prt 0 exp , doc (showString ";")])
SNoop -> prPrec i 0 (concatD [])
- SDecl type' id exp -> prPrec i 0 (concatD [prt 0 type' , prt 0 id , doc (showString "=") , prt 0 exp , doc (showString ";")])
prtList es = case es of
[] -> (concatD [])
transStm x = case x of
SExp exp -> failure x
SBlock stms -> failure x
+ SDecl type' id exp -> failure x
+ SDeclD type' id -> failure x
SWhile exp stm -> failure x
SIf exp stm0 stm -> failure x
SPrint exp -> failure x
SNoop -> failure x
- SDecl type' id exp -> failure x
transExp :: Exp -> Result
typeCheckStm (SWhile e s) = do
TBool <- typeCheckExp e
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 ()
+
+addVariable :: (MonadState Types m) => Ident -> Type -> m ()
+addVariable i t = do
(m:ms) <- get
case insertLookupWithKey (\k a1 a2 -> a1) i t m of
(Nothing,m') -> put (m':ms)
_ -> fail $ "Duplicate variable declaration: "++show i
-typeCheckStm (SPrint e) = do
- typeCheckExp e
- return ()
SExp. Stm ::= Exp ";" ;
SBlock. Stm ::= "{" [Stm] "}" ;
-declIntE. Stm ::= "int" Ident "=" Exp ";" ;
-declBoolE. Stm ::= "bool" Ident "=" Exp ";" ;
-define declIntE x e = SDecl TInt x e;
-define declBoolE x e = SDecl TBool x e;
-declInt. Stm ::= "int" Ident ";" ;
-declBool. Stm ::= "bool" Ident ";" ;
-define declInt x = SDecl TInt x (EInt 0);
-define declBool x = SDecl TBool x (EBool False);
+SDecl. Stm ::= Type Ident "=" Exp ";" ;
+SDeclD. Stm ::= Type Ident ";" ;
SWhile. Stm ::= "while" "(" Exp ")" Stm ;
internal EPost. Exp ::= Ident Op1 ;
internal SNoop. Stm ::= ;
-internal SDecl. Stm ::= Type Ident "=" Exp ";" ;
comment "/*" "*/" ;
comment "//" ;