+ fun returns nil = false
+ | returns (A.Assign _ :: stms) = returns stms
+ | returns (A.Return _ :: stms) = true
+ | returns (A.Nop :: stms) = returns stms
+ | returns (A.Break :: stms) = true (* blah *)
+ | returns (A.Continue :: stms) = true (* blah *)
+ | returns (A.If (_, s1, NONE) :: stms) = returns stms
+ | returns (A.If (_, s1, SOME s2) :: stms) = (returns s1 andalso returns s2) orelse returns stms
+ | returns (A.For _ :: stms) = returns stms
+ | returns (A.While _ :: stms) = returns stms
+ | returns (A.MarkedStm m :: stms) = returns (Mark.kane m :: stms)
+
+ fun breakcheck nil mark = ()
+ | breakcheck (A.Break :: stms) mark = ( ErrorMsg.error mark ("Illegal break outside loop") ;
+ raise ErrorMsg.Error )
+ | breakcheck (A.Continue :: stms) mark = ( ErrorMsg.error mark ("Illegal continue outside loop") ;
+ raise ErrorMsg.Error )
+ | breakcheck (A.If (_, s1, NONE) :: stms) mark =
+ ( breakcheck s1 mark;
+ breakcheck stms mark)
+ | breakcheck (A.If (_, s1, SOME s2) :: stms) mark =
+ ( breakcheck s1 mark;
+ breakcheck s2 mark;
+ breakcheck stms mark)
+ | breakcheck (A.MarkedStm m :: stms) mark = (breakcheck [(Mark.kane m)] (Mark.ext m); breakcheck stms mark)
+ | breakcheck (_ :: stms) mark = breakcheck stms mark
+
+ fun varcheck_exp env fenv (A.Var v) mark : Ast.vtype =
+ ( case Symbol.look env v
+ of NONE => ( ErrorMsg.error mark ("undefined variable `" ^ Symbol.name v ^ "'") ;
+ raise ErrorMsg.Error )
+ | SOME (t, UNASSIGNED) => ( ErrorMsg.error mark ("usage of unassigned variable `" ^ Symbol.name v ^ "'") ;
+ raise ErrorMsg.Error )
+ | SOME (t, ASSIGNED) => t)
+ | varcheck_exp env fenv (A.ConstExp _) mark = (A.Int)
+ | varcheck_exp env fenv (A.OpExp (_, l)) mark = (List.app (fn znt => (varcheck_exp env fenv znt mark; ())) l; A.Int)
+ | varcheck_exp env fenv (A.FuncCall (f, l)) mark =
+ let
+ val types = map (fn znt => varcheck_exp env fenv znt mark) l
+ val func = case Symbol.look fenv f
+ of NONE => ( ErrorMsg.error mark ("undefined function `" ^ Symbol.name f ^ "'") ;
+ raise ErrorMsg.Error )
+ | SOME a => a
+ val (rtype, params) = case func
+ of A.Extern (rtype, _, params) => (rtype, params)
+ | A.Function (rtype, _, params, _, _) => (rtype, params)
+ val paramtypes = map (fn (i, t) => t) params
+ val () = if not (types = paramtypes)
+ then ( ErrorMsg.error mark ("incorrect parameters for function `" ^ Symbol.name f ^ "'") ;
+ raise ErrorMsg.Error )
+ else ()
+ in
+ rtype
+ end
+ | varcheck_exp env fenv (A.Marked m) mark = varcheck_exp env fenv (Mark.kane m) (Mark.ext m)
+
+ fun computeassigns env nil = env
+ | computeassigns env (A.Assign (id,e) :: stms) =
+ computeassigns (Symbol.bind env (id, (A.Int, ASSIGNED))) stms
+ | computeassigns env (A.Return _ :: stms) = env
+ | computeassigns env (A.Nop :: stms) = computeassigns env stms
+ | computeassigns env (A.Break :: stms) = env
+ | computeassigns env (A.Continue :: stms) = env
+ | computeassigns env (A.If (e, s1, NONE) :: stms) = computeassigns env stms
+ | computeassigns env (A.If (e, s1, SOME s2) :: stms) =
+ let
+ val env1 = computeassigns env s1
+ val env2 = computeassigns env s2
+ val env' =
+ Symbol.intersect
+ (fn ((t, ASSIGNED), (t', ASSIGNED)) => (t, ASSIGNED) (* XXX check types for equality *)
+ | ((t, _), (t', _)) => (t, UNASSIGNED))
+ (env1, env2)
+ val env' =
+ if (returns s1) then env2
+ else if (returns s2) then env1
+ else env'
+ in
+ computeassigns env' stms
+ end
+ | computeassigns env (A.While (e, s1) :: stms) = computeassigns env stms
+ | computeassigns env (A.For (sbegin, e, sloop, inner) :: stms) =
+ let
+ val env' = case sbegin
+ of SOME(s) => computeassigns env [s]
+ | NONE => env
+ in
+ computeassigns env' stms
+ end
+ | computeassigns env (A.MarkedStm m :: stms) = computeassigns env ((Mark.kane m) :: stms)
+
+ fun varcheck env fenv nil mark = nil
+ | varcheck env fenv (A.Assign (id, e) :: stms) mark =
+ let
+ val sym = Symbol.look env id
+ val _ = if not (isSome sym)
+ then (ErrorMsg.error mark ("assignment to undeclared variable " ^ (Symbol.name id)); raise ErrorMsg.Error)
+ else ()
+ val (t, a) = valOf sym
+ val t' = varcheck_exp env fenv e mark
+ in
+ A.Assign (id, e) :: (varcheck (Symbol.bind env (id, (t, ASSIGNED))) fenv stms mark)
+ end
+ | varcheck env fenv (A.Return (e) :: stms) mark =
+ ( varcheck_exp env fenv e mark;
+ A.Return (e) :: nil )
+ | varcheck env fenv (A.Nop :: stms) mark =
+ ( A.Nop :: (varcheck env fenv stms mark))
+ | varcheck env fenv (A.Break :: stms) mark =
+ ( A.Break :: nil )
+ | varcheck env fenv (A.Continue :: stms) mark =
+ ( A.Continue :: nil )
+ | varcheck env fenv (A.If (e, s1, NONE) :: stms) mark =
+ ( varcheck_exp env fenv e mark ;
+ varcheck env fenv s1 mark ;
+ A.If (e, s1, NONE) :: (varcheck env fenv stms mark) )
+ | varcheck env fenv ((i as A.If (e, s1, SOME s2)) :: stms) mark =
+ ( varcheck_exp env fenv e mark ;
+ varcheck env fenv s1 mark ;
+ varcheck env fenv s2 mark ;
+ A.If (e, s1, SOME s2) ::
+ (if (returns [i])
+ then nil
+ else varcheck (computeassigns env [i]) fenv stms mark) )
+ | varcheck env fenv (A.While (e, s1) :: stms) mark =
+ ( varcheck_exp env fenv e mark ;
+ varcheck env fenv s1 mark ;
+ A.While (e, s1) :: (varcheck env fenv stms mark) )
+ | varcheck env fenv (A.For (sbegin, e, sloop, inner) :: stms) mark =
+ let
+ val sbegin = case sbegin
+ of SOME(s) => SOME (hd (varcheck env fenv [s] mark))
+ | NONE => NONE
+ val env' = case sbegin
+ of SOME(s) => computeassigns env [s]
+ | NONE => env
+ val _ = varcheck_exp env' fenv e
+ val inner = varcheck env' fenv inner mark
+ val env'' = computeassigns env' inner
+ val sloop = case sloop
+ of SOME(s) => SOME (hd (varcheck env'' fenv [s] mark))
+ | NONE => NONE
+ in
+ A.For (sbegin, e, sloop, inner) :: (varcheck env' fenv stms mark)
+ end
+ | varcheck env fenv (A.MarkedStm m :: stms) mark = varcheck env fenv ((Mark.kane m) :: stms) (Mark.ext m)