[tiger.ml.git] / compiler / src / lib / tiger / tiger_semant.ml

module List = ListLabels

module A         = Tiger_absyn
module Env       = Tiger_env
module E         = Tiger_error
module Translate = Tiger_translate
module Type      = Tiger_env_type
module Value     = Tiger_env_value

(* The only reason for having this seemingly-superfluous inner module is to
 * have this nice signature as a summary of what each function does. *)
module Semant : sig
  type expty =
    { exp : Translate.exp
    ; ty  : Type.t
    }

  (* Violating normal naming convention just to make it easier to follow
   * Appel's
   *)
  val transExp : env:Env.t -> A.exp -> expty
  val transVar : env:Env.t -> A.var -> expty
  val transDec : env:Env.t -> A.dec -> Env.t
  val transTy  : env:Env.t -> A.ty  -> Type.t  (* needs only type env *)
end = struct
  type expty =
    { exp : Translate.exp
    ; ty  : Type.t
    }

  let unimplemented () =
    failwith "unimplemented"

  let return ty     = {exp = (); ty}
  let return_unit   = return Type.Unit
  let return_nil    = return Type.Nil
  let return_int    = return Type.Int
  let return_string = return Type.String

  let env_get_typ ~sym ~env ~pos : Type.t =
    match Env.get_typ env sym with
    | Some ty -> ty
    | None    -> E.raise (E.Unknown_type {ty_id=sym; pos})

  let env_get_val ~sym ~env ~pos : Value.t =
    match Env.get_val env sym with
    | Some ty -> ty
    | None    -> E.raise (E.Unknown_id {id=sym; pos})

  let check_same {exp=_; ty=ty_left} {exp=_; ty=ty_right} ~pos : unit =
    if Type.is_equal ty_left ty_right then
      ()
    else
      E.raise (E.Wrong_type {expected=ty_left; given=ty_right; pos})

  let check_int expty ~pos : unit =
    check_same {exp=(); ty=Type.Int} expty ~pos

  (* TODO: actual_ty *)
  (* TODO: mutual recursion *)

  let rec transExp ~env exp =
    let rec trexp exp =
      (match exp with
      | A.NilExp ->
          return_nil
      | A.IntExp _ ->
          return_int
      | A.StringExp {string=_; _} ->
          return_string
      | A.CallExp {func; args; pos} ->
          (match env_get_val ~sym:func ~env ~pos with
          | Value.Fun {formals; result} ->
              List.iter2 formals args ~f:(fun ty_expected exp_given ->
                check_same {exp=(); ty = ty_expected} (trexp exp_given) ~pos;
              );
              return result
          | Value.Var _ ->
              E.raise (E.Id_not_a_function {id=func; pos})
          )
      | A.OpExp {oper; left; right; pos} ->
          trop oper ~left ~right ~pos
      | A.RecordExp {fields=field_exps; typ; pos} ->
          let ty = env_get_typ ~sym:typ ~env ~pos in
          Type.if_record
            ty
            ~f:(fun field_tys ->
              List.iter field_exps ~f:(fun (field, exp, pos) ->
                (match List.assoc_opt field field_tys with
                | Some field_ty ->
                    check_same {exp=(); ty=field_ty} (trexp exp) ~pos
                | None ->
                    E.raise
                      (E.No_such_field_in_record {field; record=ty; pos})
                )
              )
            )
            ~otherwise:(fun () ->
              E.raise (E.Wrong_type_used_as_record {ty_id=typ; ty; pos})
            );
          return ty
      | A.SeqExp exps ->
          (* Ignoring value because we only care if a type-checking exception
           * is raised in one of trexp calls: *)
          List.iter exps ~f:(fun (exp, _) -> ignore (trexp exp));
          (* FIXME: Return type of last expression, not unit. *)
          return_unit
      | A.AssignExp {var; exp; pos} ->
          check_same (trvar var) (trexp exp) ~pos;
          (* TODO: Add var->exp to val env? *)
          return_unit
      | A.IfExp {test; then'; else'; pos} ->
          (* test : must be int, because we have no bool *)
          (* then : must equal else *)
          (* else : must equal then or be None *)
          check_int (trexp test) ~pos;
          (match (trexp then', else') with
          | expty_then, None ->
              expty_then
          | expty_then, Some else' ->
              let expty_else = trexp else' in
              check_same expty_then expty_else ~pos;
              expty_then
          )
      | A.WhileExp {test; body; pos} ->
          (* test : must be int, because we have no bool *)
          check_int (trexp test) ~pos;
          ignore (trexp body);  (* Only care if a type-error is raised *)
          return_unit
      | A.ForExp {var; lo; hi; body; pos; escape=_} ->
          check_int (trexp lo) ~pos;
          check_int (trexp hi) ~pos;
          (* Only care if a type-error is raised *)
          ignore (transExp ~env:(Env.set_typ env var Type.Int) body);
          return_unit
      | A.BreakExp _ ->
          return_unit
      | A.LetExp {decs; body; pos=_} ->
          (* (1) decs augment env *)
          (* (2) body checked against the new env *)
          let env =
            List.fold_left decs ~init:env ~f:(fun env dec -> transDec dec ~env)
          in
          transExp body ~env
      | A.ArrayExp {typ; size; init; pos} ->
          check_int (trexp size) ~pos;
          let ty = env_get_typ ~sym:typ ~env ~pos in
          Type.if_array
            ty
            ~f:(fun ty_elements ->
              check_same {exp=(); ty=ty_elements} (trexp init) ~pos
            )
            ~otherwise:(fun () ->
              E.raise (E.Wrong_type_used_as_array {ty_id=typ; ty; pos})
            );
          return ty
      | A.VarExp var ->
          trvar var
      )
    and trvar =
      (function
      | A.SimpleVar {symbol=sym; pos} ->
          (match env_get_val ~sym ~env ~pos with
          | Value.Fun _    -> E.raise (E.Id_is_a_function {id=sym; pos})
          | Value.Var {ty} -> return ty
          )
      | A.FieldVar {var; symbol; pos} ->
          let {exp=_; ty} = trvar var in
          Type.if_record
            ty
            ~f:(fun fields ->
              (match List.assoc_opt symbol fields with
              | None ->
                  E.raise
                    (E.No_such_field_in_record {field=symbol; record=ty; pos})
              | Some ty ->
                  return ty
              )
            )
            ~otherwise:(fun () -> E.raise (E.Exp_not_a_record {ty; pos}))
      | A.SubscriptVar {var; exp; pos} ->
          let {exp=_; ty} = trvar var in
          check_int (trexp exp) ~pos;
          Type.if_array
            ty
            ~f:(fun ty_elements -> return ty_elements)
            ~otherwise:(fun () -> E.raise (E.Exp_not_an_array {ty; pos}))
      )
    and trop oper ~left ~right ~pos =
      let expty_left  = trexp left in
      let expty_right = trexp right in
      check_same expty_left expty_right ~pos;
      let {exp=_; ty} = expty_left in
      let module T = Type in
      (match oper with
      (* Arithmetic: int *)
      | A.PlusOp
      | A.MinusOp
      | A.TimesOp
      | A.DivideOp ->
          check_int expty_left ~pos;
          return_int
      (* Equality: int, string, array, record *)
      | A.EqOp
      | A.NeqOp ->
          if (T.is_int    ty)
          || (T.is_string ty)
          || (T.is_array  ty)
          || (T.is_record ty)
          then
            return ty
          else
            E.raise (E.Invalid_operand_type
              { oper
              ; valid = ["int"; "string"; "array"; "record"]
              ; given = ty
              ; pos
              })
      (* Order: int, string *)
      | A.LtOp
      | A.LeOp
      | A.GtOp
      | A.GeOp ->
          if (T.is_int    ty)
          || (T.is_string ty)
          then
            return ty
          else
            E.raise (E.Invalid_operand_type
              { oper
              ; valid = ["int"; "string"]
              ; given = ty
              ; pos
              })
      )
    in
    trexp exp
  and transDec ~env dec =
    (match dec with
    | A.VarDec {name; typ=typ_opt; init; pos=pos_outter; escape=_} ->
        let ty =
          (match (typ_opt, transExp ~env init) with
          | None, {ty; exp=()} ->
              ty
          | Some (sym, pos_inner), expty_init ->
              let ty = env_get_typ ~sym ~env ~pos:pos_inner in
              check_same {exp=(); ty} expty_init ~pos:pos_outter;
              ty
          )
        in
        Env.set_val env name (Value.Var {ty})
    | A.TypeDecs typedecs ->
        List.fold_left typedecs ~init:env ~f:(
          fun env (A.TypeDec {name; ty; pos=_}) ->
            let ty = transTy ~env ty in
            Env.set_typ env name ty
        )
    | A.FunDecs fundecs ->
        List.fold_left fundecs ~init:env ~f:(
          fun env (A.FunDec {name; params; result; body; pos=_}) ->
            let (env_for_body, formals_in_reverse_order) =
              List.fold_left params ~init:(env, []) ~f:(
                fun (env, formals) (A.Field {name; escape=_; typ; pos}) ->
                  let ty = env_get_typ ~env ~sym:typ ~pos in
                  let env = Env.set_val env name (Value.Var {ty}) in
                  (env, ty :: formals)
              )
            in
            (* ignore because we only care if an exception is raised *)
            ignore (transExp ~env:env_for_body body);
            let formals = List.rev formals_in_reverse_order in
            let result =
              match result with
              | None ->
                  Type.Unit
              | Some (sym, pos) ->
                  env_get_typ ~sym ~env ~pos
            in
            Env.set_val env name (Value.Fun {formals; result})
        )
    )
  and transTy ~env typ =
    (match typ with
    | A.NameTy {symbol=sym; pos} ->
        env_get_typ ~sym ~env ~pos
    | A.RecordTy fields ->
        let fields =
          List.map fields ~f:(fun (A.Field {name; escape=_; typ; pos}) ->
            let ty = env_get_typ ~sym:typ ~env ~pos in
            (name, ty)
          )
        in
        Type.new_record fields
    | A.ArrayTy {symbol=sym; pos} ->
        let element_ty = env_get_typ ~sym ~env ~pos in
        Type.new_array element_ty
    )

  let transVar ~env:_ var =
    (match var with
    | A.SimpleVar {symbol=_; _} ->
        unimplemented ()
    | A.FieldVar {var=_; symbol=_; _} ->
        unimplemented ()
    | A.SubscriptVar {var=_; exp=_; _} ->
        unimplemented ()
    )
end

open Semant

let transProg absyn =
  let {exp = _; ty = _} = transExp absyn ~env:Env.base in
  ()
Commit	Line	Data
523e2b06 SK	1	module List = ListLabels
523e2b06 SK	2
155ee327 SK	3	module A = Tiger_absyn
	4	module Env = Tiger_env
	5	module E = Tiger_error
155ee327 SK	6	module Translate = Tiger_translate
	7	module Type = Tiger_env_type
	8	module Value = Tiger_env_value
	9
	10	(* The only reason for having this seemingly-superfluous inner module is to
	11	* have this nice signature as a summary of what each function does. *)
	12	module Semant : sig
	13	type expty =
	14	{ exp : Translate.exp
	15	; ty : Type.t
	16	}
	17
	18	(* Violating normal naming convention just to make it easier to follow
	19	* Appel's
	20	*)
	21	val transExp : env:Env.t -> A.exp -> expty
	22	val transVar : env:Env.t -> A.var -> expty
	23	val transDec : env:Env.t -> A.dec -> Env.t
	24	val transTy : env:Env.t -> A.ty -> Type.t (* needs only type env *)
	25	end = struct
	26	type expty =
	27	{ exp : Translate.exp
	28	; ty : Type.t
	29	}
	30
	31	let unimplemented () =
	32	failwith "unimplemented"
	33
523e2b06 SK	34	let return ty = {exp = (); ty}
	35	let return_unit = return Type.Unit
	36	let return_nil = return Type.Nil
	37	let return_int = return Type.Int
	38	let return_string = return Type.String
155ee327	39
523e2b06 SK	40	let env_get_typ ~sym ~env ~pos : Type.t =
	41	match Env.get_typ env sym with
	42	\| Some ty -> ty
	43	\| None -> E.raise (E.Unknown_type {ty_id=sym; pos})
	44
	45	let env_get_val ~sym ~env ~pos : Value.t =
	46	match Env.get_val env sym with
	47	\| Some ty -> ty
	48	\| None -> E.raise (E.Unknown_id {id=sym; pos})
	49
	50	let check_same {exp=_; ty=ty_left} {exp=_; ty=ty_right} ~pos : unit =
	51	if Type.is_equal ty_left ty_right then
	52	()
	53	else
	54	E.raise (E.Wrong_type {expected=ty_left; given=ty_right; pos})
	55
	56	let check_int expty ~pos : unit =
	57	check_same {exp=(); ty=Type.Int} expty ~pos
	58
978cb41c	59	(* TODO: actual_ty *)
def58eef	60	(* TODO: mutual recursion *)
978cb41c	61
523e2b06 SK	62	let rec transExp ~env exp =
	63	let rec trexp exp =
	64	(match exp with
	65	\| A.NilExp ->
	66	return_nil
	67	\| A.IntExp _ ->
	68	return_int
	69	\| A.StringExp {string=_; _} ->
	70	return_string
978cb41c SK	71	\| A.CallExp {func; args; pos} ->
	72	(match env_get_val ~sym:func ~env ~pos with
	73	\| Value.Fun {formals; result} ->
	74	List.iter2 formals args ~f:(fun ty_expected exp_given ->
	75	check_same {exp=(); ty = ty_expected} (trexp exp_given) ~pos;
	76	);
	77	return result
	78	\| Value.Var _ ->
	79	E.raise (E.Id_not_a_function {id=func; pos})
	80	)
523e2b06 SK	81	\| A.OpExp {oper; left; right; pos} ->
523e2b06 SK	82	trop oper ~left ~right ~pos
0ed7a07c SK	83	\| A.RecordExp {fields=field_exps; typ; pos} ->
	84	let ty = env_get_typ ~sym:typ ~env ~pos in
	85	Type.if_record
	86	ty
	87	~f:(fun field_tys ->
	88	List.iter field_exps ~f:(fun (field, exp, pos) ->
	89	(match List.assoc_opt field field_tys with
	90	\| Some field_ty ->
	91	check_same {exp=(); ty=field_ty} (trexp exp) ~pos
	92	\| None ->
	93	E.raise
	94	(E.No_such_field_in_record {field; record=ty; pos})
	95	)
	96	)
	97	)
	98	~otherwise:(fun () ->
	99	E.raise (E.Wrong_type_used_as_record {ty_id=typ; ty; pos})
	100	);
	101	return ty
523e2b06 SK	102	\| A.SeqExp exps ->
	103	(* Ignoring value because we only care if a type-checking exception
	104	* is raised in one of trexp calls: *)
	105	List.iter exps ~f:(fun (exp, _) -> ignore (trexp exp));
76c771a7	106	(* FIXME: Return type of last expression, not unit. *)
523e2b06 SK	107	return_unit
	108	\| A.AssignExp {var; exp; pos} ->
	109	check_same (trvar var) (trexp exp) ~pos;
	110	(* TODO: Add var->exp to val env? *)
	111	return_unit
	112	\| A.IfExp {test; then'; else'; pos} ->
	113	(* test : must be int, because we have no bool *)
	114	(* then : must equal else *)
	115	(* else : must equal then or be None *)
	116	check_int (trexp test) ~pos;
	117	(match (trexp then', else') with
	118	\| expty_then, None ->
	119	expty_then
	120	\| expty_then, Some else' ->
	121	let expty_else = trexp else' in
	122	check_same expty_then expty_else ~pos;
	123	expty_then
	124	)
	125	\| A.WhileExp {test; body; pos} ->
	126	(* test : must be int, because we have no bool *)
	127	check_int (trexp test) ~pos;
	128	ignore (trexp body); (* Only care if a type-error is raised *)
	129	return_unit
	130	\| A.ForExp {var; lo; hi; body; pos; escape=_} ->
	131	check_int (trexp lo) ~pos;
	132	check_int (trexp hi) ~pos;
	133	(* Only care if a type-error is raised *)
	134	ignore (transExp ~env:(Env.set_typ env var Type.Int) body);
	135	return_unit
	136	\| A.BreakExp _ ->
	137	return_unit
8744eb3a SK	138	\| A.LetExp {decs; body; pos=_} ->
	139	(* (1) decs augment env *)
	140	(* (2) body checked against the new env *)
	141	let env =
	142	List.fold_left decs ~init:env ~f:(fun env dec -> transDec dec ~env)
	143	in
	144	transExp body ~env
4c550cd5 SK	145	\| A.ArrayExp {typ; size; init; pos} ->
	146	check_int (trexp size) ~pos;
	147	let ty = env_get_typ ~sym:typ ~env ~pos in
	148	Type.if_array
	149	ty
	150	~f:(fun ty_elements ->
	151	check_same {exp=(); ty=ty_elements} (trexp init) ~pos
	152	)
	153	~otherwise:(fun () ->
	154	E.raise (E.Wrong_type_used_as_array {ty_id=typ; ty; pos})
	155	);
	156	return ty
523e2b06 SK	157	\| A.VarExp var ->
	158	trvar var
	159	)
	160	and trvar =
	161	(function
	162	\| A.SimpleVar {symbol=sym; pos} ->
	163	(match env_get_val ~sym ~env ~pos with
	164	\| Value.Fun _ -> E.raise (E.Id_is_a_function {id=sym; pos})
	165	\| Value.Var {ty} -> return ty
	166	)
	167	\| A.FieldVar {var; symbol; pos} ->
	168	let {exp=_; ty} = trvar var in
	169	Type.if_record
	170	ty
	171	~f:(fun fields ->
	172	(match List.assoc_opt symbol fields with
	173	\| None ->
	174	E.raise
	175	(E.No_such_field_in_record {field=symbol; record=ty; pos})
	176	\| Some ty ->
	177	return ty
	178	)
	179	)
	180	~otherwise:(fun () -> E.raise (E.Exp_not_a_record {ty; pos}))
161a300d SK	181	\| A.SubscriptVar {var; exp; pos} ->
	182	let {exp=_; ty} = trvar var in
	183	check_int (trexp exp) ~pos;
	184	Type.if_array
	185	ty
	186	~f:(fun ty_elements -> return ty_elements)
	187	~otherwise:(fun () -> E.raise (E.Exp_not_an_array {ty; pos}))
523e2b06 SK	188	)
	189	and trop oper ~left ~right ~pos =
	190	let expty_left = trexp left in
	191	let expty_right = trexp right in
	192	check_same expty_left expty_right ~pos;
	193	let {exp=_; ty} = expty_left in
	194	let module T = Type in
	195	(match oper with
	196	(* Arithmetic: int *)
	197	\| A.PlusOp
	198	\| A.MinusOp
	199	\| A.TimesOp
	200	\| A.DivideOp ->
	201	check_int expty_left ~pos;
	202	return_int
	203	(* Equality: int, string, array, record *)
	204	\| A.EqOp
	205	\| A.NeqOp ->
	206	if (T.is_int ty)
	207	\|\| (T.is_string ty)
	208	\|\| (T.is_array ty)
	209	\|\| (T.is_record ty)
	210	then
	211	return ty
	212	else
	213	E.raise (E.Invalid_operand_type
	214	{ oper
	215	; valid = ["int"; "string"; "array"; "record"]
	216	; given = ty
	217	; pos
	218	})
	219	(* Order: int, string *)
	220	\| A.LtOp
	221	\| A.LeOp
	222	\| A.GtOp
	223	\| A.GeOp ->
	224	if (T.is_int ty)
	225	\|\| (T.is_string ty)
	226	then
	227	return ty
	228	else
	229	E.raise (E.Invalid_operand_type
	230	{ oper
	231	; valid = ["int"; "string"]
	232	; given = ty
	233	; pos
	234	})
	235	)
	236	in
	237	trexp exp
8744eb3a SK	238	and transDec ~env dec =
	239	(match dec with
	240	\| A.VarDec {name; typ=typ_opt; init; pos=pos_outter; escape=_} ->
	241	let ty =
	242	(match (typ_opt, transExp ~env init) with
	243	\| None, {ty; exp=()} ->
	244	ty
	245	\| Some (sym, pos_inner), expty_init ->
	246	let ty = env_get_typ ~sym ~env ~pos:pos_inner in
	247	check_same {exp=(); ty} expty_init ~pos:pos_outter;
	248	ty
	249	)
	250	in
	251	Env.set_val env name (Value.Var {ty})
0324a942 SK	252	\| A.TypeDecs typedecs ->
	253	List.fold_left typedecs ~init:env ~f:(
	254	fun env (A.TypeDec {name; ty; pos=_}) ->
	255	let ty = transTy ~env ty in
	256	Env.set_typ env name ty
	257	)
76c771a7 SK	258	\| A.FunDecs fundecs ->
	259	List.fold_left fundecs ~init:env ~f:(
	260	fun env (A.FunDec {name; params; result; body; pos=_}) ->
	261	let (env_for_body, formals_in_reverse_order) =
	262	List.fold_left params ~init:(env, []) ~f:(
	263	fun (env, formals) (A.Field {name; escape=_; typ; pos}) ->
	264	let ty = env_get_typ ~env ~sym:typ ~pos in
	265	let env = Env.set_val env name (Value.Var {ty}) in
	266	(env, ty :: formals)
	267	)
	268	in
	269	(* ignore because we only care if an exception is raised *)
	270	ignore (transExp ~env:env_for_body body);
	271	let formals = List.rev formals_in_reverse_order in
	272	let result =
	273	match result with
	274	\| None ->
	275	Type.Unit
	276	\| Some (sym, pos) ->
	277	env_get_typ ~sym ~env ~pos
	278	in
	279	Env.set_val env name (Value.Fun {formals; result})
	280	)
8744eb3a	281	)
0324a942 SK	282	and transTy ~env typ =
	283	(match typ with
	284	\| A.NameTy {symbol=sym; pos} ->
	285	env_get_typ ~sym ~env ~pos
	286	\| A.RecordTy fields ->
	287	let fields =
	288	List.map fields ~f:(fun (A.Field {name; escape=_; typ; pos}) ->
	289	let ty = env_get_typ ~sym:typ ~env ~pos in
	290	(name, ty)
	291	)
	292	in
	293	Type.new_record fields
	294	\| A.ArrayTy {symbol=sym; pos} ->
	295	let element_ty = env_get_typ ~sym ~env ~pos in
	296	Type.new_array element_ty
	297	)
155ee327 SK	298
	299	let transVar ~env:_ var =
	300	(match var with
	301	\| A.SimpleVar {symbol=_; _} ->
	302	unimplemented ()
	303	\| A.FieldVar {var=_; symbol=_; _} ->
	304	unimplemented ()
	305	\| A.SubscriptVar {var=_; exp=_; _} ->
	306	unimplemented ()
	307	)
155ee327 SK	308	end
155ee327 SK	309
8744eb3a SK	310	open Semant
8744eb3a SK	311
155ee327	312	let transProg absyn =
155ee327 SK	313	let {exp = _; ty = _} = transExp absyn ~env:Env.base in
155ee327 SK	314	()