374 lines
12 KiB
OCaml
374 lines
12 KiB
OCaml
(***********************************************************************)
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(* *)
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(* Objective Caml *)
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(* *)
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(* Xavier Leroy and Jerome Vouillon, projet Cristal, INRIA Rocquencourt*)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* Automatique. Distributed only by permission. *)
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(* *)
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(***********************************************************************)
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(* $Id$ *)
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(**** Typing of type definitions ****)
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open Misc
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open Parsetree
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open Types
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open Typedtree
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open Typetexp
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type error =
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Repeated_parameter
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| Duplicate_constructor of string
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| Too_many_constructors
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| Duplicate_label of string
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| Recursive_abbrev of string
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| Definition_mismatch of type_expr
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| Unconsistent_constraint
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| Type_clash of (type_expr * type_expr) list
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| Null_arity_external
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exception Error of Location.t * error
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(* Enter all declared types in the environment as abstract types *)
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let rec enter_types env = function
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([], []) ->
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(env, [])
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| ((name, sdecl) :: srem, id :: irem) ->
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let decl =
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{ type_params = List.map (fun _ -> Ctype.newvar ()) sdecl.ptype_params;
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type_arity = List.length sdecl.ptype_params;
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type_kind = Type_abstract;
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type_manifest =
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match sdecl.ptype_manifest with
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None -> None
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| Some _ -> Some (Ctype.newvar ()) }
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in
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let extenv = Env.add_type id decl env in
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let (ext_env, decl_rem) = enter_types extenv (srem, irem) in
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(ext_env, (id, decl) :: decl_rem)
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| _ ->
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fatal_error "Typedecl.enter_types"
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(* Translate one type declaration *)
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module StringSet =
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Set.Make(struct
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type t = string
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let compare = compare
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end)
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(* Check whether an abbreviation expands to itself. *)
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let rec cyclic_abbrev env id ty =
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let ty = Ctype.repr ty in
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match ty.desc with
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Tconstr (Path.Pident id', _, _) when Ident.same id id' ->
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true
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| Tconstr (p, tl, abbrev) ->
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begin try
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cyclic_abbrev env id (Ctype.expand_abbrev env p tl abbrev ty.level)
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with Ctype.Cannot_expand ->
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false
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end
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| _ ->
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false
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(* First pass: parameters, constraints and expansion *)
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let transl_declaration env (name, sdecl) (id, decl) =
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reset_type_variables();
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begin try
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List.iter2
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(fun ty sty -> Ctype.unify env ty (enter_type_variable true sty))
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decl.type_params sdecl.ptype_params
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with Already_bound ->
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raise(Error(sdecl.ptype_loc, Repeated_parameter))
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end;
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let cstr_params =
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List.map (function (v, _, loc) -> type_variable loc v) sdecl.ptype_cstrs
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in
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List.iter2
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(fun (v, sty, loc) ty' ->
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try
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Ctype.unify env (transl_simple_type env false sty) ty'
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with Ctype.Unify _ ->
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raise(Error(loc, Unconsistent_constraint)))
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sdecl.ptype_cstrs cstr_params;
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let decl' =
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{ type_params = decl.type_params;
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type_arity = decl.type_arity;
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type_kind =
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Type_abstract;
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type_manifest =
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begin match (decl.type_manifest, sdecl.ptype_manifest) with
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(None, None) -> None
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| (Some ty, Some sty) ->
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let ty' =
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Ctype.unroll_abbrev id decl.type_params
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(transl_simple_type env true sty)
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in
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if cyclic_abbrev env id ty' then
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raise(Error(sdecl.ptype_loc, Recursive_abbrev name));
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begin try Ctype.unify env ty' ty with Ctype.Unify trace ->
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raise(Error(sdecl.ptype_loc, Type_clash trace))
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end;
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Some ty
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| _ ->
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fatal_error "Typedecl.transl_declaration"
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end } in
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(id, decl')
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(* Second pass: representation *)
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let transl_declaration2 env (name, sdecl) (id, decl) =
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let (params, typ) =
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match decl.type_manifest with
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None -> (Ctype.instance_list decl.type_params, None)
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| Some typ ->
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let (params, typ) =
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Ctype.instance_parameterized_type decl.type_params typ
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in
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(params, Some typ)
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in
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(* Bind type parameters *)
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reset_type_variables();
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List.iter2
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(fun ty sty -> Ctype.unify env ty (enter_type_variable true sty))
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params sdecl.ptype_params;
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let decl' =
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{ type_params = params;
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type_arity = decl.type_arity;
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type_kind =
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begin match sdecl.ptype_kind with
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Ptype_abstract ->
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Type_abstract
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| Ptype_variant cstrs ->
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let all_constrs = ref StringSet.empty in
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List.iter
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(fun (name, args) ->
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if StringSet.mem name !all_constrs then
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raise(Error(sdecl.ptype_loc, Duplicate_constructor name));
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all_constrs := StringSet.add name !all_constrs)
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cstrs;
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if List.length cstrs > Config.max_tag then
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raise(Error(sdecl.ptype_loc, Too_many_constructors));
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Type_variant(List.map
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(fun (name, args) ->
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(name, List.map (transl_simple_type env true) args))
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cstrs)
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| Ptype_record lbls ->
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let all_labels = ref StringSet.empty in
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List.iter
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(fun (name, mut, arg) ->
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if StringSet.mem name !all_labels then
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raise(Error(sdecl.ptype_loc, Duplicate_label name));
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all_labels := StringSet.add name !all_labels)
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lbls;
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Type_record(List.map
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(fun (name, mut, arg) ->
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(name, mut, transl_simple_type env true arg))
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lbls)
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end;
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type_manifest = typ } in
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(id, decl')
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(* Generalize a type declaration *)
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let generalize_decl decl =
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List.iter Ctype.generalize decl.type_params;
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begin match decl.type_kind with
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Type_abstract ->
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()
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| Type_variant v ->
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List.iter (fun (_, tyl) -> List.iter Ctype.generalize tyl) v
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| Type_record r ->
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List.iter (fun (_, _, ty) -> Ctype.generalize ty) r
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end;
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begin match decl.type_manifest with
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None -> ()
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| Some ty -> Ctype.generalize ty
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end
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(*
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If both a variant/record definition and a type equation are given,
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need to check that the equation refers to a type of the same kind
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with the same constructors and labels.
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*)
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let check_abbrev env (_, sdecl) (id, decl) =
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match decl with
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{type_kind = (Type_variant _ | Type_record _); type_manifest = Some ty} ->
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begin match (Ctype.repr ty).desc with
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Tconstr(path, args, _) ->
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begin try
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let decl' = Env.find_type path env in
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if
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List.length args = List.length decl.type_params
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&&
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Ctype.equal env false args decl.type_params
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&&
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Includecore.type_declarations env id
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decl'
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(Subst.type_declaration (Subst.add_type id path Subst.identity)
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decl)
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then ()
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else raise(Error(sdecl.ptype_loc, Definition_mismatch ty))
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with Not_found ->
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raise(Error(sdecl.ptype_loc, Definition_mismatch ty))
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end
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| _ -> raise(Error(sdecl.ptype_loc, Definition_mismatch ty))
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end
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| _ -> ()
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(* Check for ill-defined abbrevs *)
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(* Occur check *)
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let check_recursive_abbrev env (name, sdecl) (id, decl) =
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match decl.type_manifest with
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Some ty ->
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begin try Ctype.correct_abbrev env id decl.type_params ty with
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Ctype.Recursive_abbrev ->
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raise(Error(sdecl.ptype_loc, Recursive_abbrev name))
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end
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| _ ->
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()
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(* Translate a set of mutually recursive type declarations *)
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let transl_type_decl env name_sdecl_list =
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(* Create identifiers. *)
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let id_list =
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List.map (fun (name, _) -> Ident.create name) name_sdecl_list
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in
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(*
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Since we've introduced fresh idents, make sure the definition
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level is at least the binding time of these events. Otherwise,
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passing one of the recursively-defined type constrs as argument
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to an abbreviation may fail.
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*)
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Ctype.init_def(Ident.current_time());
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Ctype.begin_def();
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(* Enter types. *)
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let (temp_env, temp_decl) = enter_types env (name_sdecl_list, id_list) in
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(* Translate each declaration. *)
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let decls =
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List.map2 (transl_declaration temp_env) name_sdecl_list temp_decl in
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(* Generalize intermediate type declarations. *)
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Ctype.end_def();
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List.iter (function (_, decl) -> generalize_decl decl) decls;
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(* Build an env. containing type expansions *)
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let temp_env =
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List.fold_right
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(fun (id, decl) env -> Env.add_type id decl env)
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decls env
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in
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(* Check for recursive abbrevs *)
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List.iter2 (check_recursive_abbrev temp_env) name_sdecl_list decls;
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Ctype.begin_def();
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let decls =
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List.map2 (transl_declaration2 temp_env) name_sdecl_list decls in
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(* Generalize final type declarations. *)
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Ctype.end_def();
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List.iter (function (_, decl) -> generalize_decl decl) decls;
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(* Build the final env. *)
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let newenv =
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List.fold_right
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(fun (id, decl) env -> Env.add_type id decl env)
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decls env
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in
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(* Check re-exportation *)
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List.iter2 (check_abbrev newenv) name_sdecl_list decls;
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(* Done *)
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(decls, newenv)
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(* Translate an exception declaration *)
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let transl_exception env excdecl =
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reset_type_variables();
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Ctype.begin_def();
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let types = List.map (transl_simple_type env true) excdecl in
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Ctype.end_def();
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List.iter Ctype.generalize types;
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types
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(* Translate a value declaration *)
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let transl_value_decl env valdecl =
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let ty = Typetexp.transl_type_scheme env valdecl.pval_type in
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match valdecl.pval_prim with
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[] ->
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{ val_type = ty; val_kind = Val_reg }
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| decl ->
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let arity = Ctype.arity ty in
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if arity = 0 then
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raise(Error(valdecl.pval_type.ptyp_loc, Null_arity_external));
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let prim = Primitive.parse_declaration arity decl in
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{ val_type = ty; val_kind = Val_prim prim }
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(* Translate a "with" constraint -- much simplified version of
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transl_type_decl. *)
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let transl_with_constraint env sdecl =
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reset_type_variables();
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Ctype.begin_def();
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let params =
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try
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List.map (enter_type_variable true) sdecl.ptype_params
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with Already_bound ->
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raise(Error(sdecl.ptype_loc, Repeated_parameter)) in
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List.iter
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(function (v, ty, loc) ->
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try
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Ctype.unify env
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(type_variable loc v) (transl_simple_type env false ty)
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with Ctype.Unify _ ->
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raise(Error(loc, Unconsistent_constraint)))
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sdecl.ptype_cstrs;
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let decl =
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{ type_params = params;
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type_arity = List.length params;
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type_kind = Type_abstract;
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type_manifest =
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begin match sdecl.ptype_manifest with
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None -> None
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| Some sty -> Some(transl_simple_type env true sty)
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end }
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in
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Ctype.end_def();
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generalize_decl decl;
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decl
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(**** Error report ****)
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open Format
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let report_error = function
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Repeated_parameter ->
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print_string "A type parameter occurs several times"
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| Duplicate_constructor s ->
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print_string "Two constructors are named "; print_string s
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| Too_many_constructors ->
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print_string "Too many constructors -- maximum is ";
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print_int Config.max_tag; print_string " constructors"
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| Duplicate_label s ->
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print_string "Two labels are named "; print_string s
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| Recursive_abbrev s ->
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print_string "The type abbreviation "; print_string s;
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print_string " is cyclic" (* " expands to itself" *)
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| Definition_mismatch ty ->
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Printtyp.reset ();
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Printtyp.mark_loops ty;
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print_string
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"The variant or record definition does not match that of type";
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print_space(); Printtyp.type_expr ty
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| Unconsistent_constraint ->
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print_string "The type constraints are not consistent"
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| Type_clash trace ->
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Printtyp.unification_error trace
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(function () ->
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print_string "This type constructor expands to type")
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(function () ->
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print_string "but is here used with type")
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| Null_arity_external ->
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print_string "External identifiers must be functions"
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