-(* L1 Compiler
+(* L3 Compiler
* TypeChecker
* Author: Alex Vaynberg <alv@andrew.cmu.edu>
* Modified: Frank Pfenning <fp@cs.cmu.edu>
- *
- * Simple typechecker that is based on a unit Symbol.table
- * This is all that is needed since there is only an integer type present
+ * Modified: Joshua Wise <jwise>
+ * Modified: Chris Lu <czl>
*)
signature TYPE_CHECK =
sig
(* prints error message and raises ErrorMsg.error if error found *)
- val typecheck : Ast.program -> unit
+ val typecheck : Ast.program -> Ast.program
end;
structure TypeChecker :> TYPE_CHECK =
struct
structure A = Ast
+
+ datatype asn = ASSIGNED | UNASSIGNED
- (* tc_exp : unit Symbol.table -> Ast.exp -> Mark.ext option -> unit *)
- fun tc_exp env (A.Var(id)) ext =
- (case Symbol.look env id
- of NONE => ( ErrorMsg.error ext ("undefined variable `" ^ Symbol.name id ^ "'") ;
- raise ErrorMsg.Error )
- | SOME _ => ())
- | tc_exp env (A.ConstExp(c)) ext = ()
- | tc_exp env (A.OpExp(oper,es)) ext =
- (* Note: it is syntactically impossible in this language to
- * apply an operator to an incorrect number of arguments
- * so we only check each of the arguments
- *)
- List.app (fn e => tc_exp env e ext) es
- | tc_exp env (A.Marked(marked_exp)) ext =
- tc_exp env (Mark.data marked_exp) (Mark.ext marked_exp)
+ 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)
- (* tc_stms : unit Symbol.table -> Ast.program -> unit *)
- fun tc_stms env nil = ()
- | tc_stms env (A.Assign(id,e)::stms) =
- ( tc_exp env e NONE ;
- tc_stms (Symbol.bind env (id, ())) stms )
- | tc_stms env (A.Return(e)::nil) =
- tc_exp env e NONE
- | tc_stms env (A.Return _ :: _) =
- ( ErrorMsg.error NONE ("`return' not last statement") ;
- raise ErrorMsg.Error )
+ fun bindvars sym stat l = foldr (fn ((i,t), s) => Symbol.bind s (i,(t, stat))) sym l
+ fun bindfuns sym l =
+ foldr
+ (fn (a as (A.Function (_, id, _, _, _)), s) => Symbol.bind s (id, a)
+ | (a as (A.Extern (_, id, _)), s) => Symbol.bind s (id, a))
+ sym l
- fun typecheck prog = tc_stms Symbol.empty prog
+ fun dupchk l =
+ List.app
+ (fn (n, _) =>
+ let
+ val name = Symbol.name n
+ val all = List.filter (fn (n', _) => name = (Symbol.name n')) l
+ val count = length all
+ in
+ if count = 1
+ then ()
+ else ( ErrorMsg.error NONE ("multiple definition of variable " ^ (Symbol.name n));
+ raise ErrorMsg.Error )
+ end) l
+ fun typecheck_fn p (e as (A.Extern (t, id, al))) = (dupchk al; e)
+ | typecheck_fn p (A.Function (t, id, al, vl, sl)) =
+ let
+ val () = breakcheck sl NONE
+ val () = if not (returns sl)
+ then ( ErrorMsg.error NONE ("function `"^ Symbol.name id ^ "' does not return in all cases");
+ raise ErrorMsg.Error )
+ else ()
+ val env = Symbol.empty
+ val env = bindvars env ASSIGNED al
+ val env = bindvars env UNASSIGNED vl
+ val fenv = bindfuns Symbol.empty p
+ val () = dupchk (al @ vl)
+ in
+ A.Function (t, id, al, vl, varcheck env fenv sl NONE)
+ end
+
+ fun typecheck p =
+ let
+ fun getFun n =
+ List.find (fn A.Extern (_, id, _) => ((Symbol.name id) = n)
+ | A.Function (_, id, _, _, _) => ((Symbol.name id) = n))
+ p
+ val main = case (getFun "main")
+ of NONE => ( ErrorMsg.error NONE ("no function named main");
+ raise ErrorMsg.Error )
+ | SOME m => m
+ val () = case main
+ of A.Extern _ => ( ErrorMsg.error NONE ("you anus, main can't be an extern");
+ raise ErrorMsg.Error )
+ | A.Function (A.Int, _, nil, _, _) => ()
+ | A.Function (A.Int, _, _, _, _) => ( ErrorMsg.error NONE ("main should take no parameters");
+ raise ErrorMsg.Error )
+ val () = List.app
+ (fn a =>
+ let
+ val id = case a
+ of A.Extern (_, id, _) => id
+ | A.Function (_, id, _, _, _) => id
+ val name = Symbol.name id
+ val all = List.filter
+ (fn A.Extern (_, id, _) => (Symbol.name id) = name
+ | A.Function (_, id, _, _, _) => (Symbol.name id) = name)
+ p
+ val num = length all
+ in
+ if num = 1
+ then ()
+ else ( ErrorMsg.error NONE ("multiple definition of " ^ name);
+ raise ErrorMsg.Error )
+ end) p
+ in
+ List.map (typecheck_fn p) p
+ end
end
git.joshuawise.com / snipe.git / blobdiff