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(**************************************************************************)
(* *)
(* OCaml *)
(* *)
(* Xavier Leroy and Jerome Vouillon, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* en Automatique. *)
(* *)
(* All rights reserved. This file is distributed under the terms of *)
(* the GNU Lesser General Public License version 2.1, with the *)
(* special exception on linking described in the file LICENSE. *)
(* *)
(**************************************************************************)
(* Basic operations on core types *)
open Misc
open Asttypes
open Types
(**** Sets, maps and hashtables of types ****)
module TypeSet = Set.Make(TypeOps)
module TypeMap = Map.Make (TypeOps)
module TypeHash = Hashtbl.Make(TypeOps)
(**** Forward declarations ****)
let print_raw =
ref (fun _ -> assert false : Format.formatter -> type_expr -> unit)
(**** Type level management ****)
let generic_level = 100000000
(* Used to mark a type during a traversal. *)
let lowest_level = 0
let pivot_level = 2 * lowest_level - 1
(* pivot_level - lowest_level < lowest_level *)
(**** Some type creators ****)
let new_id = ref (-1)
let newty2 level desc =
incr new_id; { desc; level; id = !new_id }
let newgenty desc = newty2 generic_level desc
let newgenvar ?name () = newgenty (Tvar name)
(*
let newmarkedvar level =
incr new_id; { desc = Tvar; level = pivot_level - level; id = !new_id }
let newmarkedgenvar () =
incr new_id;
{ desc = Tvar; level = pivot_level - generic_level; id = !new_id }
*)
(**** Check some types ****)
let is_Tvar = function {desc=Tvar _} -> true | _ -> false
let is_Tunivar = function {desc=Tunivar _} -> true | _ -> false
let is_Tconstr = function {desc=Tconstr _} -> true | _ -> false
let dummy_method = "*dummy method*"
let default_mty = function
Some mty -> mty
| None -> Mty_signature []
(**** Definitions for backtracking ****)
type change =
Ctype of type_expr * type_desc
| Ccompress of type_expr * type_desc * type_desc
| Clevel of type_expr * int
| Cname of
(Path.t * type_expr list) option ref * (Path.t * type_expr list) option
| Crow of row_field option ref * row_field option
| Ckind of field_kind option ref * field_kind option
| Ccommu of commutable ref * commutable
| Cuniv of type_expr option ref * type_expr option
| Ctypeset of TypeSet.t ref * TypeSet.t
type changes =
Change of change * changes ref
| Unchanged
| Invalid
let trail = Weak.create 1
let log_change ch =
match Weak.get trail 0 with None -> ()
| Some r ->
let r' = ref Unchanged in
r := Change (ch, r');
Weak.set trail 0 (Some r')
(**** Representative of a type ****)
let rec field_kind_repr =
function
Fvar {contents = Some kind} -> field_kind_repr kind
| kind -> kind
let rec repr_link compress t d =
function
{desc = Tlink t' as d'} ->
repr_link true t d' t'
| {desc = Tfield (_, k, _, t') as d'} when field_kind_repr k = Fabsent ->
repr_link true t d' t'
| t' ->
if compress then begin
log_change (Ccompress (t, t.desc, d)); t.desc <- d
end;
t'
let repr t =
match t.desc with
Tlink t' as d ->
repr_link false t d t'
| Tfield (_, k, _, t') as d when field_kind_repr k = Fabsent ->
repr_link false t d t'
| _ -> t
let rec commu_repr = function
Clink r when !r <> Cunknown -> commu_repr !r
| c -> c
let rec row_field_repr_aux tl = function
Reither(_, tl', _, {contents = Some fi}) ->
row_field_repr_aux (tl@tl') fi
| Reither(c, tl', m, r) ->
Reither(c, tl@tl', m, r)
| Rpresent (Some _) when tl <> [] ->
Rpresent (Some (List.hd tl))
| fi -> fi
let row_field_repr fi = row_field_repr_aux [] fi
let rec rev_concat l ll =
match ll with
[] -> l
| l'::ll -> rev_concat (l'@l) ll
let rec row_repr_aux ll row =
match (repr row.row_more).desc with
| Tvariant row' ->
let f = row.row_fields in
row_repr_aux (if f = [] then ll else f::ll) row'
| _ ->
if ll = [] then row else
{row with row_fields = rev_concat row.row_fields ll}
let row_repr row = row_repr_aux [] row
let rec row_field tag row =
let rec find = function
| (tag',f) :: fields ->
if tag = tag' then row_field_repr f else find fields
| [] ->
match repr row.row_more with
| {desc=Tvariant row'} -> row_field tag row'
| _ -> Rabsent
in find row.row_fields
let rec row_more row =
match repr row.row_more with
| {desc=Tvariant row'} -> row_more row'
| ty -> ty
let row_fixed row =
let row = row_repr row in
row.row_fixed ||
match (repr row.row_more).desc with
Tvar _ | Tnil -> false
| Tunivar _ | Tconstr _ -> true
| _ -> assert false
let static_row row =
let row = row_repr row in
row.row_closed &&
List.for_all
(fun (_,f) -> match row_field_repr f with Reither _ -> false | _ -> true)
row.row_fields
let hash_variant s =
let accu = ref 0 in
for i = 0 to String.length s - 1 do
accu := 223 * !accu + Char.code s.[i]
done;
(* reduce to 31 bits *)
accu := !accu land (1 lsl 31 - 1);
(* make it signed for 64 bits architectures *)
if !accu > 0x3FFFFFFF then !accu - (1 lsl 31) else !accu
let proxy ty =
let ty0 = repr ty in
match ty0.desc with
| Tvariant row when not (static_row row) ->
row_more row
| Tobject (ty, _) ->
let rec proxy_obj ty =
match ty.desc with
Tfield (_, _, _, ty) | Tlink ty -> proxy_obj ty
| Tvar _ | Tunivar _ | Tconstr _ -> ty
| Tnil -> ty0
| _ -> assert false
in proxy_obj ty
| _ -> ty0
(**** Utilities for fixed row private types ****)
let row_of_type t =
match (repr t).desc with
Tobject(t,_) ->
let rec get_row t =
let t = repr t in
match t.desc with
Tfield(_,_,_,t) -> get_row t
| _ -> t
in get_row t
| Tvariant row ->
row_more row
| _ ->
t
let has_constr_row t =
not (is_Tconstr t) && is_Tconstr (row_of_type t)
let is_row_name s =
let l = String.length s in
if l < 4 then false else String.sub s (l-4) 4 = "#row"
let is_constr_row ~allow_ident t =
match t.desc with
Tconstr (Path.Pident id, _, _) when allow_ident ->
is_row_name (Ident.name id)
| Tconstr (Path.Pdot (_, s, _), _, _) -> is_row_name s
| _ -> false
(**********************************)
(* Utilities for type traversal *)
(**********************************)
let rec iter_row f row =
List.iter
(fun (_, fi) ->
match row_field_repr fi with
| Rpresent(Some ty) -> f ty
| Reither(_, tl, _, _) -> List.iter f tl
| _ -> ())
row.row_fields;
match (repr row.row_more).desc with
Tvariant row -> iter_row f row
| Tvar _ | Tunivar _ | Tsubst _ | Tconstr _ | Tnil ->
Misc.may (fun (_,l) -> List.iter f l) row.row_name
| _ -> assert false
let iter_type_expr f ty =
match ty.desc with
Tvar _ -> ()
| Tarrow (_, ty1, ty2, _) -> f ty1; f ty2
| Ttuple l -> List.iter f l
| Tconstr (_, l, _) -> List.iter f l
| Tobject(ty, {contents = Some (_, p)})
-> f ty; List.iter f p
| Tobject (ty, _) -> f ty
| Tvariant row -> iter_row f row; f (row_more row)
| Tfield (_, _, ty1, ty2) -> f ty1; f ty2
| Tnil -> ()
| Tlink ty -> f ty
| Tsubst ty -> f ty
| Tunivar _ -> ()
| Tpoly (ty, tyl) -> f ty; List.iter f tyl
| Tpackage (_, _, l) -> List.iter f l
let rec iter_abbrev f = function
Mnil -> ()
| Mcons(_, _, ty, ty', rem) -> f ty; f ty'; iter_abbrev f rem
| Mlink rem -> iter_abbrev f !rem
type type_iterators =
{ it_signature: type_iterators -> signature -> unit;
it_signature_item: type_iterators -> signature_item -> unit;
it_value_description: type_iterators -> value_description -> unit;
it_type_declaration: type_iterators -> type_declaration -> unit;
it_extension_constructor: type_iterators -> extension_constructor -> unit;
it_module_declaration: type_iterators -> module_declaration -> unit;
it_modtype_declaration: type_iterators -> modtype_declaration -> unit;
it_class_declaration: type_iterators -> class_declaration -> unit;
it_class_type_declaration: type_iterators -> class_type_declaration -> unit;
it_module_type: type_iterators -> module_type -> unit;
it_class_type: type_iterators -> class_type -> unit;
it_type_kind: type_iterators -> type_kind -> unit;
it_do_type_expr: type_iterators -> type_expr -> unit;
it_type_expr: type_iterators -> type_expr -> unit;
it_path: Path.t -> unit; }
let iter_type_expr_cstr_args f = function
| Cstr_tuple tl -> List.iter f tl
| Cstr_record lbls -> List.iter (fun d -> f d.ld_type) lbls
let map_type_expr_cstr_args f = function
| Cstr_tuple tl -> Cstr_tuple (List.map f tl)
| Cstr_record lbls ->
Cstr_record (List.map (fun d -> {d with ld_type=f d.ld_type}) lbls)
let iter_type_expr_kind f = function
| Type_abstract -> ()
| Type_variant cstrs ->
List.iter
(fun cd ->
iter_type_expr_cstr_args f cd.cd_args;
Misc.may f cd.cd_res
)
cstrs
| Type_record(lbls, _) ->
List.iter (fun d -> f d.ld_type) lbls
| Type_open ->
()
let type_iterators =
let it_signature it =
List.iter (it.it_signature_item it)
and it_signature_item it = function
Sig_value (_, vd) -> it.it_value_description it vd
| Sig_type (_, td, _) -> it.it_type_declaration it td
| Sig_typext (_, td, _) -> it.it_extension_constructor it td
| Sig_module (_, md, _) -> it.it_module_declaration it md
| Sig_modtype (_, mtd) -> it.it_modtype_declaration it mtd
| Sig_class (_, cd, _) -> it.it_class_declaration it cd
| Sig_class_type (_, ctd, _) -> it.it_class_type_declaration it ctd
and it_value_description it vd =
it.it_type_expr it vd.val_type
and it_type_declaration it td =
List.iter (it.it_type_expr it) td.type_params;
may (it.it_type_expr it) td.type_manifest;
it.it_type_kind it td.type_kind
and it_extension_constructor it td =
it.it_path td.ext_type_path;
List.iter (it.it_type_expr it) td.ext_type_params;
iter_type_expr_cstr_args (it.it_type_expr it) td.ext_args;
may (it.it_type_expr it) td.ext_ret_type
and it_module_declaration it md =
it.it_module_type it md.md_type
and it_modtype_declaration it mtd =
may (it.it_module_type it) mtd.mtd_type
and it_class_declaration it cd =
List.iter (it.it_type_expr it) cd.cty_params;
it.it_class_type it cd.cty_type;
may (it.it_type_expr it) cd.cty_new;
it.it_path cd.cty_path
and it_class_type_declaration it ctd =
List.iter (it.it_type_expr it) ctd.clty_params;
it.it_class_type it ctd.clty_type;
it.it_path ctd.clty_path
and it_module_type it = function
Mty_ident p
| Mty_alias(_, p) -> it.it_path p
| Mty_signature sg -> it.it_signature it sg
| Mty_functor (_, mto, mt) ->
may (it.it_module_type it) mto;
it.it_module_type it mt
and it_class_type it = function
Cty_constr (p, tyl, cty) ->
it.it_path p;
List.iter (it.it_type_expr it) tyl;
it.it_class_type it cty
| Cty_signature cs ->
it.it_type_expr it cs.csig_self;
Vars.iter (fun _ (_,_,ty) -> it.it_type_expr it ty) cs.csig_vars;
List.iter
(fun (p, tl) -> it.it_path p; List.iter (it.it_type_expr it) tl)
cs.csig_inher
| Cty_arrow (_, ty, cty) ->
it.it_type_expr it ty;
it.it_class_type it cty
and it_type_kind it kind =
iter_type_expr_kind (it.it_type_expr it) kind
and it_do_type_expr it ty =
iter_type_expr (it.it_type_expr it) ty;
match ty.desc with
Tconstr (p, _, _)
| Tobject (_, {contents=Some (p, _)})
| Tpackage (p, _, _) ->
it.it_path p
| Tvariant row ->
may (fun (p,_) -> it.it_path p) (row_repr row).row_name
| _ -> ()
and it_path _p = ()
in
{ it_path; it_type_expr = it_do_type_expr; it_do_type_expr;
it_type_kind; it_class_type; it_module_type;
it_signature; it_class_type_declaration; it_class_declaration;
it_modtype_declaration; it_module_declaration; it_extension_constructor;
it_type_declaration; it_value_description; it_signature_item; }
let copy_row f fixed row keep more =
let fields = List.map
(fun (l, fi) -> l,
match row_field_repr fi with
| Rpresent(Some ty) -> Rpresent(Some(f ty))
| Reither(c, tl, m, e) ->
let e = if keep then e else ref None in
let m = if row.row_fixed then fixed else m in
let tl = List.map f tl in
Reither(c, tl, m, e)
| _ -> fi)
row.row_fields in
let name =
match row.row_name with None -> None
| Some (path, tl) -> Some (path, List.map f tl) in
{ row_fields = fields; row_more = more;
row_bound = (); row_fixed = row.row_fixed && fixed;
row_closed = row.row_closed; row_name = name; }
let rec copy_kind = function
Fvar{contents = Some k} -> copy_kind k
| Fvar _ -> Fvar (ref None)
| Fpresent -> Fpresent
| Fabsent -> assert false
let copy_commu c =
if commu_repr c = Cok then Cok else Clink (ref Cunknown)
(* Since univars may be used as row variables, we need to do some
encoding during substitution *)
let rec norm_univar ty =
match ty.desc with
Tunivar _ | Tsubst _ -> ty
| Tlink ty -> norm_univar ty
| Ttuple (ty :: _) -> norm_univar ty
| _ -> assert false
let rec copy_type_desc ?(keep_names=false) f = function
Tvar _ as ty -> if keep_names then ty else Tvar None
| Tarrow (p, ty1, ty2, c)-> Tarrow (p, f ty1, f ty2, copy_commu c)
| Ttuple l -> Ttuple (List.map f l)
| Tconstr (p, l, _) -> Tconstr (p, List.map f l, ref Mnil)
| Tobject(ty, {contents = Some (p, tl)})
-> Tobject (f ty, ref (Some(p, List.map f tl)))
| Tobject (ty, _) -> Tobject (f ty, ref None)
| Tvariant _ -> assert false (* too ambiguous *)
| Tfield (p, k, ty1, ty2) -> (* the kind is kept shared *)
Tfield (p, field_kind_repr k, f ty1, f ty2)
| Tnil -> Tnil
| Tlink ty -> copy_type_desc f ty.desc
| Tsubst _ -> assert false
| Tunivar _ as ty -> ty (* always keep the name *)
| Tpoly (ty, tyl) ->
let tyl = List.map (fun x -> norm_univar (f x)) tyl in
Tpoly (f ty, tyl)
| Tpackage (p, n, l) -> Tpackage (p, n, List.map f l)
(* Utilities for copying *)
let saved_desc = ref []
(* Saved association of generic nodes with their description. *)
let save_desc ty desc =
saved_desc := (ty, desc)::!saved_desc
let saved_kinds = ref [] (* duplicated kind variables *)
let new_kinds = ref [] (* new kind variables *)
let dup_kind r =
(match !r with None -> () | Some _ -> assert false);
if not (List.memq r !new_kinds) then begin
saved_kinds := r :: !saved_kinds;
let r' = ref None in
new_kinds := r' :: !new_kinds;
r := Some (Fvar r')
end
(* Restored type descriptions. *)
let cleanup_types () =
List.iter (fun (ty, desc) -> ty.desc <- desc) !saved_desc;
List.iter (fun r -> r := None) !saved_kinds;
saved_desc := []; saved_kinds := []; new_kinds := []
(* Mark a type. *)
let rec mark_type ty =
let ty = repr ty in
if ty.level >= lowest_level then begin
ty.level <- pivot_level - ty.level;
iter_type_expr mark_type ty
end
let mark_type_node ty =
let ty = repr ty in
if ty.level >= lowest_level then begin
ty.level <- pivot_level - ty.level;
end
let mark_type_params ty =
iter_type_expr mark_type ty
let type_iterators =
let it_type_expr it ty =
let ty = repr ty in
if ty.level >= lowest_level then begin
mark_type_node ty;
it.it_do_type_expr it ty;
end
in
{type_iterators with it_type_expr}
(* Remove marks from a type. *)
let rec unmark_type ty =
let ty = repr ty in
if ty.level < lowest_level then begin
ty.level <- pivot_level - ty.level;
iter_type_expr unmark_type ty
end
let unmark_iterators =
let it_type_expr _it ty = unmark_type ty in
{type_iterators with it_type_expr}
let unmark_type_decl decl =
unmark_iterators.it_type_declaration unmark_iterators decl
let unmark_extension_constructor ext =
List.iter unmark_type ext.ext_type_params;
iter_type_expr_cstr_args unmark_type ext.ext_args;
Misc.may unmark_type ext.ext_ret_type
let unmark_class_signature sign =
unmark_type sign.csig_self;
Vars.iter (fun _l (_m, _v, t) -> unmark_type t) sign.csig_vars
let unmark_class_type cty =
unmark_iterators.it_class_type unmark_iterators cty
(*******************************************)
(* Memorization of abbreviation expansion *)
(*******************************************)
(* Search whether the expansion has been memorized. *)
let lte_public p1 p2 = (* Private <= Public *)
match p1, p2 with
| Private, _ | _, Public -> true
| Public, Private -> false
let rec find_expans priv p1 = function
Mnil -> None
| Mcons (priv', p2, _ty0, ty, _)
when lte_public priv priv' && Path.same p1 p2 -> Some ty
| Mcons (_, _, _, _, rem) -> find_expans priv p1 rem
| Mlink {contents = rem} -> find_expans priv p1 rem
(* debug: check for cycles in abbreviation. only works with -principal
let rec check_expans visited ty =
let ty = repr ty in
assert (not (List.memq ty visited));
match ty.desc with
Tconstr (path, args, abbrev) ->
begin match find_expans path !abbrev with
Some ty' -> check_expans (ty :: visited) ty'
| None -> ()
end
| _ -> ()
*)
let memo = ref []
(* Contains the list of saved abbreviation expansions. *)
let cleanup_abbrev () =
(* Remove all memorized abbreviation expansions. *)
List.iter (fun abbr -> abbr := Mnil) !memo;
memo := []
let memorize_abbrev mem priv path v v' =
(* Memorize the expansion of an abbreviation. *)
mem := Mcons (priv, path, v, v', !mem);
(* check_expans [] v; *)
memo := mem :: !memo
let rec forget_abbrev_rec mem path =
match mem with
Mnil ->
assert false
| Mcons (_, path', _, _, rem) when Path.same path path' ->
rem
| Mcons (priv, path', v, v', rem) ->
Mcons (priv, path', v, v', forget_abbrev_rec rem path)
| Mlink mem' ->
mem' := forget_abbrev_rec !mem' path;
raise Exit
let forget_abbrev mem path =
try mem := forget_abbrev_rec !mem path with Exit -> ()
(* debug: check for invalid abbreviations
let rec check_abbrev_rec = function
Mnil -> true
| Mcons (_, ty1, ty2, rem) ->
repr ty1 != repr ty2
| Mlink mem' ->
check_abbrev_rec !mem'
let check_memorized_abbrevs () =
List.for_all (fun mem -> check_abbrev_rec !mem) !memo
*)
(**********************************)
(* Utilities for labels *)
(**********************************)
let is_optional = function Optional _ -> true | _ -> false
let label_name = function
Nolabel -> ""
| Labelled s
| Optional s -> s
let prefixed_label_name = function
Nolabel -> ""
| Labelled s -> "~" ^ s
| Optional s -> "?" ^ s
let rec extract_label_aux hd l = function
[] -> raise Not_found
| (l',t as p) :: ls ->
if label_name l' = l then (l', t, List.rev hd, ls)
else extract_label_aux (p::hd) l ls
let extract_label l ls = extract_label_aux [] l ls
(**********************************)
(* Utilities for backtracking *)
(**********************************)
let undo_change = function
Ctype (ty, desc) -> ty.desc <- desc
| Ccompress (ty, desc, _) -> ty.desc <- desc
| Clevel (ty, level) -> ty.level <- level
| Cname (r, v) -> r := v
| Crow (r, v) -> r := v
| Ckind (r, v) -> r := v
| Ccommu (r, v) -> r := v
| Cuniv (r, v) -> r := v
| Ctypeset (r, v) -> r := v
type snapshot = changes ref * int
let last_snapshot = ref 0
let log_type ty =
if ty.id <= !last_snapshot then log_change (Ctype (ty, ty.desc))
let link_type ty ty' =
log_type ty;
let desc = ty.desc in
ty.desc <- Tlink ty';
(* Name is a user-supplied name for this unification variable (obtained
* through a type annotation for instance). *)
match desc, ty'.desc with
Tvar name, Tvar name' ->
begin match name, name' with
| Some _, None -> log_type ty'; ty'.desc <- Tvar name
| None, Some _ -> ()
| Some _, Some _ ->
if ty.level < ty'.level then (log_type ty'; ty'.desc <- Tvar name)
| None, None -> ()
end
| _ -> ()
(* ; assert (check_memorized_abbrevs ()) *)
(* ; check_expans [] ty' *)
let set_level ty level =
if ty.id <= !last_snapshot then log_change (Clevel (ty, ty.level));
ty.level <- level
let set_univar rty ty =
log_change (Cuniv (rty, !rty)); rty := Some ty
let set_name nm v =
log_change (Cname (nm, !nm)); nm := v
let set_row_field e v =
log_change (Crow (e, !e)); e := Some v
let set_kind rk k =
log_change (Ckind (rk, !rk)); rk := Some k
let set_commu rc c =
log_change (Ccommu (rc, !rc)); rc := c
let set_typeset rs s =
log_change (Ctypeset (rs, !rs)); rs := s
let snapshot () =
let old = !last_snapshot in
last_snapshot := !new_id;
match Weak.get trail 0 with Some r -> (r, old)
| None ->
let r = ref Unchanged in
Weak.set trail 0 (Some r);
(r, old)
let rec rev_log accu = function
Unchanged -> accu
| Invalid -> assert false
| Change (ch, next) ->
let d = !next in
next := Invalid;
rev_log (ch::accu) d
let backtrack (changes, old) =
match !changes with
Unchanged -> last_snapshot := old
| Invalid -> failwith "Btype.backtrack"
| Change _ as change ->
cleanup_abbrev ();
let backlog = rev_log [] change in
List.iter undo_change backlog;
changes := Unchanged;
last_snapshot := old;
Weak.set trail 0 (Some changes)
let rec rev_compress_log log r =
match !r with
Unchanged | Invalid ->
log
| Change (Ccompress _, next) ->
rev_compress_log (r::log) next
| Change (_, next) ->
rev_compress_log log next
let undo_compress (changes, _old) =
match !changes with
Unchanged
| Invalid -> ()
| Change _ ->
let log = rev_compress_log [] changes in
List.iter
(fun r -> match !r with
Change (Ccompress (ty, desc, d), next) when ty.desc == d ->
ty.desc <- desc; r := !next
| _ -> ())
log
|