(***********************************************************************)
(*                                                                     *)
(*                           Objective Caml                            *)
(*                                                                     *)
(*            Xavier Leroy, 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 Q Public License version 1.0.               *)
(*                                                                     *)
(***********************************************************************)

(* $Id$ *)

(* Environment handling *)

open Config
open Misc
open Asttypes
open Longident
open Path
open Types


type error =
    Not_an_interface of string
  | Corrupted_interface of string
  | Illegal_renaming of string * string
  | Inconsistent_import of string * string * string
  | Need_recursive_types of string * string

exception Error of error

type summary =
    Env_empty
  | Env_value of summary * Ident.t * value_description
  | Env_type of summary * Ident.t * type_declaration
  | Env_exception of summary * Ident.t * exception_declaration
  | Env_module of summary * Ident.t * module_type
  | Env_modtype of summary * Ident.t * modtype_declaration
  | Env_class of summary * Ident.t * class_declaration
  | Env_cltype of summary * Ident.t * cltype_declaration
  | Env_open of summary * Path.t

type t = {
  values: (Path.t * value_description) Ident.tbl;
  annotations: (Path.t * Annot.ident) Ident.tbl;
  constrs: constructor_description Ident.tbl;
  labels: label_description Ident.tbl;
  types: (Path.t * type_declaration) Ident.tbl;
  modules: (Path.t * module_type) Ident.tbl;
  modtypes: (Path.t * modtype_declaration) Ident.tbl;
  components: (Path.t * module_components) Ident.tbl;
  classes: (Path.t * class_declaration) Ident.tbl;
  cltypes: (Path.t * cltype_declaration) Ident.tbl;
  summary: summary
}

and module_components = module_components_repr Lazy.t

and module_components_repr =
    Structure_comps of structure_components
  | Functor_comps of functor_components

and structure_components = {
  mutable comp_values: (string, (value_description * int)) Tbl.t;
  mutable comp_annotations: (string, (Annot.ident * int)) Tbl.t;
  mutable comp_constrs: (string, (constructor_description * int)) Tbl.t;
  mutable comp_labels: (string, (label_description * int)) Tbl.t;
  mutable comp_types: (string, (type_declaration * int)) Tbl.t;
  mutable comp_modules: (string, (module_type Lazy.t * int)) Tbl.t;
  mutable comp_modtypes: (string, (modtype_declaration * int)) Tbl.t;
  mutable comp_components: (string, (module_components * int)) Tbl.t;
  mutable comp_classes: (string, (class_declaration * int)) Tbl.t;
  mutable comp_cltypes: (string, (cltype_declaration * int)) Tbl.t
}

and functor_components = {
  fcomp_param: Ident.t;                 (* Formal parameter *)
  fcomp_arg: module_type;               (* Argument signature *)
  fcomp_res: module_type;               (* Result signature *)
  fcomp_env: t;     (* Environment in which the result signature makes sense *)
  fcomp_subst: Subst.t;  (* Prefixing substitution for the result signature *)
  fcomp_cache: (Path.t, module_components) Hashtbl.t  (* For memoization *)
}

let empty = {
  values = Ident.empty; annotations = Ident.empty; constrs = Ident.empty;
  labels = Ident.empty; types = Ident.empty;
  modules = Ident.empty; modtypes = Ident.empty;
  components = Ident.empty; classes = Ident.empty;
  cltypes = Ident.empty;
  summary = Env_empty }

let diff_keys is_local tbl1 tbl2 =
  let keys2 = Ident.keys tbl2 in
  List.filter
    (fun id ->
      is_local (Ident.find_same id tbl2) &&
      try ignore (Ident.find_same id tbl1); false with Not_found -> true)
    keys2

let is_ident = function
    Pident _ -> true
  | Pdot _ | Papply _ -> false

let is_local (p, _) = is_ident p

let is_local_exn = function
    {cstr_tag = Cstr_exception p} -> is_ident p
  | _ -> false

let diff env1 env2 =
  diff_keys is_local env1.values env2.values @
  diff_keys is_local_exn env1.constrs env2.constrs @
  diff_keys is_local env1.modules env2.modules @
  diff_keys is_local env1.classes env2.classes

(* Forward declarations *)

let components_of_module' =
  ref ((fun env sub path mty -> assert false) :
          t -> Subst.t -> Path.t -> module_type -> module_components)
let components_of_functor_appl' =
  ref ((fun f p1 p2 -> assert false) :
          functor_components -> Path.t -> Path.t -> module_components)
let check_modtype_inclusion =
  (* to be filled with Includemod.check_modtype_inclusion *)
  ref ((fun env mty1 path1 mty2 -> assert false) :
          t -> module_type -> Path.t -> module_type -> unit)

(* The name of the compilation unit currently compiled.
   "" if outside a compilation unit. *)

let current_unit = ref ""

(* Persistent structure descriptions *)

type pers_flags = Rectypes

type pers_struct =
  { ps_name: string;
    ps_sig: signature;
    ps_comps: module_components;
    ps_crcs: (string * Digest.t) list;
    ps_filename: string;
    ps_flags: pers_flags list }

let persistent_structures =
  (Hashtbl.create 17 : (string, pers_struct) Hashtbl.t)

(* Consistency between persistent structures *)

let crc_units = Consistbl.create()

let check_consistency filename crcs =
  try
    List.iter
      (fun (name, crc) -> Consistbl.check crc_units name crc filename)
      crcs
  with Consistbl.Inconsistency(name, source, auth) ->
    raise(Error(Inconsistent_import(name, auth, source)))

(* Reading persistent structures from .cmi files *)

let read_pers_struct modname filename =
  let ic = open_in_bin filename in
  try
    let buffer = String.create (String.length cmi_magic_number) in
    really_input ic buffer 0 (String.length cmi_magic_number);
    if buffer <> cmi_magic_number then begin
      close_in ic;
      raise(Error(Not_an_interface filename))
    end;
    let (name, sign) = input_value ic in
    let crcs = input_value ic in
    let flags = input_value ic in
    close_in ic;
    let comps =
      !components_of_module' empty Subst.identity
                             (Pident(Ident.create_persistent name))
                             (Tmty_signature sign) in
    let ps = { ps_name = name;
               ps_sig = sign;
               ps_comps = comps;
               ps_crcs = crcs;
               ps_filename = filename;
               ps_flags = flags } in
    if ps.ps_name <> modname then
      raise(Error(Illegal_renaming(ps.ps_name, filename)));
    check_consistency filename ps.ps_crcs;
    List.iter
      (function Rectypes ->
        if not !Clflags.recursive_types then
          raise(Error(Need_recursive_types(ps.ps_name, !current_unit))))
      ps.ps_flags;
    Hashtbl.add persistent_structures modname ps;
    ps
  with End_of_file | Failure _ ->
    close_in ic;
    raise(Error(Corrupted_interface(filename)))

let find_pers_struct name =
  try
    Hashtbl.find persistent_structures name
  with Not_found ->
    read_pers_struct name (find_in_path_uncap !load_path (name ^ ".cmi"))

let reset_cache () =
  current_unit := "";
  Hashtbl.clear persistent_structures;
  Consistbl.clear crc_units

let set_unit_name name =
  current_unit := name

(* Lookup by identifier *)

let rec find_module_descr path env =
  match path with
    Pident id ->
      begin try
        let (p, desc) = Ident.find_same id env.components
        in desc
      with Not_found ->
        if Ident.persistent id
        then (find_pers_struct (Ident.name id)).ps_comps
        else raise Not_found
      end
  | Pdot(p, s, pos) ->
      begin match Lazy.force(find_module_descr p env) with
        Structure_comps c ->
          let (descr, pos) = Tbl.find s c.comp_components in
          descr
      | Functor_comps f ->
         raise Not_found
      end
  | Papply(p1, p2) ->
      begin match Lazy.force(find_module_descr p1 env) with
        Functor_comps f ->
          !components_of_functor_appl' f p1 p2
      | Structure_comps c ->
          raise Not_found
      end

let find proj1 proj2 path env =
  match path with
    Pident id ->
      let (p, data) = Ident.find_same id (proj1 env)
      in data
  | Pdot(p, s, pos) ->
      begin match Lazy.force(find_module_descr p env) with
        Structure_comps c ->
          let (data, pos) = Tbl.find s (proj2 c) in data
      | Functor_comps f ->
          raise Not_found
      end
  | Papply(p1, p2) ->
      raise Not_found

let find_value =
  find (fun env -> env.values) (fun sc -> sc.comp_values)
and find_type =
  find (fun env -> env.types) (fun sc -> sc.comp_types)
and find_modtype =
  find (fun env -> env.modtypes) (fun sc -> sc.comp_modtypes)
and find_class =
  find (fun env -> env.classes) (fun sc -> sc.comp_classes)
and find_cltype =
  find (fun env -> env.cltypes) (fun sc -> sc.comp_cltypes)

(* Find the manifest type associated to a type when appropriate:
   - the type should be public or should have a private row,
   - the type should have an associated manifest type. *)
let find_type_expansion path env =
  let decl = find_type path env in
  match decl.type_manifest with
  | Some body when decl.type_private = Public
              || decl.type_kind <> Type_abstract
              || Btype.has_constr_row body -> (decl.type_params, body)
  (* The manifest type of Private abstract data types without
     private row are still considered unknown to the type system.
     Hence, this case is caught by the following clause that also handles
     purely abstract data types without manifest type definition. *)
  | _ -> raise Not_found

(* Find the manifest type information associated to a type, i.e.
   the necessary information for the compiler's type-based optimisations.
   In particular, the manifest type associated to a private abstract type
   is revealed for the sake of compiler's type-based optimisations. *)
let find_type_expansion_opt path env =
  let decl = find_type path env in
  match decl.type_manifest with
  (* The manifest type of Private abstract data types can still get
     an approximation using their manifest type. *)
  | Some body -> (decl.type_params, body)
  | _ -> raise Not_found

let find_modtype_expansion path env =
  match find_modtype path env with
    Tmodtype_abstract     -> raise Not_found
  | Tmodtype_manifest mty -> mty

let find_module path env =
  match path with
    Pident id ->
      begin try
        let (p, data) = Ident.find_same id env.modules
        in data
      with Not_found ->
        if Ident.persistent id then
          let ps = find_pers_struct (Ident.name id) in
          Tmty_signature(ps.ps_sig)
        else raise Not_found
      end
  | Pdot(p, s, pos) ->
      begin match Lazy.force (find_module_descr p env) with
        Structure_comps c ->
          let (data, pos) = Tbl.find s c.comp_modules in Lazy.force data
      | Functor_comps f ->
          raise Not_found
      end
  | Papply(p1, p2) ->
      raise Not_found (* not right *)

(* Lookup by name *)

let rec lookup_module_descr lid env =
  match lid with
    Lident s ->
      begin try
        Ident.find_name s env.components
      with Not_found ->
        if s = !current_unit then raise Not_found;
        let ps = find_pers_struct s in
        (Pident(Ident.create_persistent s), ps.ps_comps)
      end
  | Ldot(l, s) ->
      let (p, descr) = lookup_module_descr l env in
      begin match Lazy.force descr with
        Structure_comps c ->
          let (descr, pos) = Tbl.find s c.comp_components in
          (Pdot(p, s, pos), descr)
      | Functor_comps f ->
          raise Not_found
      end
  | Lapply(l1, l2) ->
      let (p1, desc1) = lookup_module_descr l1 env in
      let (p2, mty2) = lookup_module l2 env in
      begin match Lazy.force desc1 with
        Functor_comps f ->
          !check_modtype_inclusion env mty2 p2 f.fcomp_arg;
          (Papply(p1, p2), !components_of_functor_appl' f p1 p2)
      | Structure_comps c ->
          raise Not_found
      end

and lookup_module lid env =
  match lid with
    Lident s ->
      begin try
        Ident.find_name s env.modules
      with Not_found ->
        if s = !current_unit then raise Not_found;
        let ps = find_pers_struct s in
        (Pident(Ident.create_persistent s), Tmty_signature ps.ps_sig)
      end
  | Ldot(l, s) ->
      let (p, descr) = lookup_module_descr l env in
      begin match Lazy.force descr with
        Structure_comps c ->
          let (data, pos) = Tbl.find s c.comp_modules in
          (Pdot(p, s, pos), Lazy.force data)
      | Functor_comps f ->
          raise Not_found
      end
  | Lapply(l1, l2) ->
      let (p1, desc1) = lookup_module_descr l1 env in
      let (p2, mty2) = lookup_module l2 env in
      let p = Papply(p1, p2) in
      begin match Lazy.force desc1 with
        Functor_comps f ->
          !check_modtype_inclusion env mty2 p2 f.fcomp_arg;
          (p, Subst.modtype (Subst.add_module f.fcomp_param p2 f.fcomp_subst)
                            f.fcomp_res)
      | Structure_comps c ->
          raise Not_found
      end

let lookup proj1 proj2 lid env =
  match lid with
    Lident s ->
      Ident.find_name s (proj1 env)
  | Ldot(l, s) ->
      let (p, desc) = lookup_module_descr l env in
      begin match Lazy.force desc with
        Structure_comps c ->
          let (data, pos) = Tbl.find s (proj2 c) in
          (Pdot(p, s, pos), data)
      | Functor_comps f ->
          raise Not_found
      end
  | Lapply(l1, l2) ->
      raise Not_found

let lookup_simple proj1 proj2 lid env =
  match lid with
    Lident s ->
      Ident.find_name s (proj1 env)
  | Ldot(l, s) ->
      let (p, desc) = lookup_module_descr l env in
      begin match Lazy.force desc with
        Structure_comps c ->
          let (data, pos) = Tbl.find s (proj2 c) in
          data
      | Functor_comps f ->
          raise Not_found
      end
  | Lapply(l1, l2) ->
      raise Not_found

let lookup_value =
  lookup (fun env -> env.values) (fun sc -> sc.comp_values)
let lookup_annot id e =
  lookup (fun env -> env.annotations) (fun sc -> sc.comp_annotations) id e
and lookup_constructor =
  lookup_simple (fun env -> env.constrs) (fun sc -> sc.comp_constrs)
and lookup_label =
  lookup_simple (fun env -> env.labels) (fun sc -> sc.comp_labels)
and lookup_type =
  lookup (fun env -> env.types) (fun sc -> sc.comp_types)
and lookup_modtype =
  lookup (fun env -> env.modtypes) (fun sc -> sc.comp_modtypes)
and lookup_class =
  lookup (fun env -> env.classes) (fun sc -> sc.comp_classes)
and lookup_cltype =
  lookup (fun env -> env.cltypes) (fun sc -> sc.comp_cltypes)

(* Expand manifest module type names at the top of the given module type *)

let rec scrape_modtype mty env =
  match mty with
    Tmty_ident path ->
      begin try
        scrape_modtype (find_modtype_expansion path env) env
      with Not_found ->
        mty
      end
  | _ -> mty

(* Compute constructor descriptions *)

let constructors_of_type ty_path decl =
  match decl.type_kind with
    Type_variant cstrs ->
      Datarepr.constructor_descrs
        (Btype.newgenty (Tconstr(ty_path, decl.type_params, ref Mnil)))
        cstrs decl.type_private
  | Type_record _ | Type_abstract -> []

(* Compute label descriptions *)

let labels_of_type ty_path decl =
  match decl.type_kind with
    Type_record(labels, rep) ->
      Datarepr.label_descrs
        (Btype.newgenty (Tconstr(ty_path, decl.type_params, ref Mnil)))
        labels rep decl.type_private
  | Type_variant _ | Type_abstract -> []

(* Given a signature and a root path, prefix all idents in the signature
   by the root path and build the corresponding substitution. *)

let rec prefix_idents root pos sub = function
    [] -> ([], sub)
  | Tsig_value(id, decl) :: rem ->
      let p = Pdot(root, Ident.name id, pos) in
      let nextpos = match decl.val_kind with Val_prim _ -> pos | _ -> pos+1 in
      let (pl, final_sub) = prefix_idents root nextpos sub rem in
      (p::pl, final_sub)
  | Tsig_type(id, decl, _) :: rem ->
      let p = Pdot(root, Ident.name id, nopos) in
      let (pl, final_sub) =
        prefix_idents root pos (Subst.add_type id p sub) rem in
      (p::pl, final_sub)
  | Tsig_exception(id, decl) :: rem ->
      let p = Pdot(root, Ident.name id, pos) in
      let (pl, final_sub) = prefix_idents root (pos+1) sub rem in
      (p::pl, final_sub)
  | Tsig_module(id, mty, _) :: rem ->
      let p = Pdot(root, Ident.name id, pos) in
      let (pl, final_sub) =
        prefix_idents root (pos+1) (Subst.add_module id p sub) rem in
      (p::pl, final_sub)
  | Tsig_modtype(id, decl) :: rem ->
      let p = Pdot(root, Ident.name id, nopos) in
      let (pl, final_sub) =
        prefix_idents root pos
                      (Subst.add_modtype id (Tmty_ident p) sub) rem in
      (p::pl, final_sub)
  | Tsig_class(id, decl, _) :: rem ->
      let p = Pdot(root, Ident.name id, pos) in
      let (pl, final_sub) = prefix_idents root (pos + 1) sub rem in
      (p::pl, final_sub)
  | Tsig_cltype(id, decl, _) :: rem ->
      let p = Pdot(root, Ident.name id, nopos) in
      let (pl, final_sub) = prefix_idents root pos sub rem in
      (p::pl, final_sub)

(* Compute structure descriptions *)

let rec components_of_module env sub path mty =
  lazy(match scrape_modtype mty env with
    Tmty_signature sg ->
      let c =
        { comp_values = Tbl.empty; comp_annotations = Tbl.empty;
          comp_constrs = Tbl.empty;
          comp_labels = Tbl.empty; comp_types = Tbl.empty;
          comp_modules = Tbl.empty; comp_modtypes = Tbl.empty;
          comp_components = Tbl.empty; comp_classes = Tbl.empty;
          comp_cltypes = Tbl.empty } in
      let (pl, sub) = prefix_idents path 0 sub sg in
      let env = ref env in
      let pos = ref 0 in
      List.iter2 (fun item path ->
        match item with
          Tsig_value(id, decl) ->
            let decl' = Subst.value_description sub decl in
            c.comp_values <-
              Tbl.add (Ident.name id) (decl', !pos) c.comp_values;
            if !Clflags.annotations then begin
              c.comp_annotations <-
                Tbl.add (Ident.name id) (Annot.Iref_external, !pos)
                        c.comp_annotations;
            end;
            begin match decl.val_kind with
              Val_prim _ -> () | _ -> incr pos
            end
        | Tsig_type(id, decl, _) ->
            let decl' = Subst.type_declaration sub decl in
            c.comp_types <-
              Tbl.add (Ident.name id) (decl', nopos) c.comp_types;
            List.iter
              (fun (name, descr) ->
                c.comp_constrs <- Tbl.add name (descr, nopos) c.comp_constrs)
              (constructors_of_type path decl');
            List.iter
              (fun (name, descr) ->
                c.comp_labels <- Tbl.add name (descr, nopos) c.comp_labels)
              (labels_of_type path decl');
            env := store_type_infos id path decl !env
        | Tsig_exception(id, decl) ->
            let decl' = Subst.exception_declaration sub decl in
            let cstr = Datarepr.exception_descr path decl' in
            c.comp_constrs <-
              Tbl.add (Ident.name id) (cstr, !pos) c.comp_constrs;
            incr pos
        | Tsig_module(id, mty, _) ->
            let mty' = lazy (Subst.modtype sub mty) in
            c.comp_modules <-
              Tbl.add (Ident.name id) (mty', !pos) c.comp_modules;
            let comps = components_of_module !env sub path mty in
            c.comp_components <-
              Tbl.add (Ident.name id) (comps, !pos) c.comp_components;
            env := store_module id path mty !env;
            incr pos
        | Tsig_modtype(id, decl) ->
            let decl' = Subst.modtype_declaration sub decl in
            c.comp_modtypes <-
              Tbl.add (Ident.name id) (decl', nopos) c.comp_modtypes;
            env := store_modtype id path decl !env
        | Tsig_class(id, decl, _) ->
            let decl' = Subst.class_declaration sub decl in
            c.comp_classes <-
              Tbl.add (Ident.name id) (decl', !pos) c.comp_classes;
            incr pos
        | Tsig_cltype(id, decl, _) ->
            let decl' = Subst.cltype_declaration sub decl in
            c.comp_cltypes <-
              Tbl.add (Ident.name id) (decl', !pos) c.comp_cltypes)
        sg pl;
        Structure_comps c
  | Tmty_functor(param, ty_arg, ty_res) ->
        Functor_comps {
          fcomp_param = param;
          (* fcomp_arg must be prefixed eagerly, because it is interpreted
             in the outer environment, not in env *)
          fcomp_arg = Subst.modtype sub ty_arg;
          (* fcomp_res is prefixed lazily, because it is interpreted in env *)
          fcomp_res = ty_res;
          fcomp_env = env;
          fcomp_subst = sub;
          fcomp_cache = Hashtbl.create 17 }
  | Tmty_ident p ->
        Structure_comps {
          comp_values = Tbl.empty; comp_annotations = Tbl.empty;
          comp_constrs = Tbl.empty;
          comp_labels = Tbl.empty; comp_types = Tbl.empty;
          comp_modules = Tbl.empty; comp_modtypes = Tbl.empty;
          comp_components = Tbl.empty; comp_classes = Tbl.empty;
          comp_cltypes = Tbl.empty })

(* Insertion of bindings by identifier + path *)

and store_value id path decl env =
  { env with
    values = Ident.add id (path, decl) env.values;
    summary = Env_value(env.summary, id, decl) }

and store_annot id path annot env =
  if !Clflags.annotations then
    { env with
      annotations = Ident.add id (path, annot) env.annotations }
  else env

and store_type id path info env =
  { env with
    constrs =
      List.fold_right
        (fun (name, descr) constrs ->
          Ident.add (Ident.create name) descr constrs)
        (constructors_of_type path info)
        env.constrs;
    labels =
      List.fold_right
        (fun (name, descr) labels ->
          Ident.add (Ident.create name) descr labels)
        (labels_of_type path info)
        env.labels;
    types = Ident.add id (path, info) env.types;
    summary = Env_type(env.summary, id, info) }

and store_type_infos id path info env =
  (* Simplified version of store_type that doesn't compute and store
     constructor and label infos, but simply record the arity and
     manifest-ness of the type.  Used in components_of_module to
     keep track of type abbreviations (e.g. type t = float) in the
     computation of label representations. *)
  { env with
    types = Ident.add id (path, info) env.types;
    summary = Env_type(env.summary, id, info) }

and store_exception id path decl env =
  { env with
    constrs = Ident.add id (Datarepr.exception_descr path decl) env.constrs;
    summary = Env_exception(env.summary, id, decl) }

and store_module id path mty env =
  { env with
    modules = Ident.add id (path, mty) env.modules;
    components =
      Ident.add id (path, components_of_module env Subst.identity path mty)
                   env.components;
    summary = Env_module(env.summary, id, mty) }

and store_modtype id path info env =
  { env with
    modtypes = Ident.add id (path, info) env.modtypes;
    summary = Env_modtype(env.summary, id, info) }

and store_class id path desc env =
  { env with
    classes = Ident.add id (path, desc) env.classes;
    summary = Env_class(env.summary, id, desc) }

and store_cltype id path desc env =
  { env with
    cltypes = Ident.add id (path, desc) env.cltypes;
    summary = Env_cltype(env.summary, id, desc) }

(* Compute the components of a functor application in a path. *)

let components_of_functor_appl f p1 p2 =
  try
    Hashtbl.find f.fcomp_cache p2
  with Not_found ->
    let p = Papply(p1, p2) in
    let mty =
      Subst.modtype (Subst.add_module f.fcomp_param p2 Subst.identity)
                    f.fcomp_res in
    let comps = components_of_module f.fcomp_env f.fcomp_subst p mty in
    Hashtbl.add f.fcomp_cache p2 comps;
    comps

(* Define forward functions *)

let _ =
  components_of_module' := components_of_module;
  components_of_functor_appl' := components_of_functor_appl

(* Insertion of bindings by identifier *)

let add_value id desc env =
  store_value id (Pident id) desc env

let add_annot id annot env =
  store_annot id (Pident id) annot env

and add_type id info env =
  store_type id (Pident id) info env

and add_exception id decl env =
  store_exception id (Pident id) decl env

and add_module id mty env =
  store_module id (Pident id) mty env

and add_modtype id info env =
  store_modtype id (Pident id) info env

and add_class id ty env =
  store_class id (Pident id) ty env

and add_cltype id ty env =
  store_cltype id (Pident id) ty env

(* Insertion of bindings by name *)

let enter store_fun name data env =
  let id = Ident.create name in (id, store_fun id (Pident id) data env)

let enter_value = enter store_value
and enter_type = enter store_type
and enter_exception = enter store_exception
and enter_module = enter store_module
and enter_modtype = enter store_modtype
and enter_class = enter store_class
and enter_cltype = enter store_cltype

(* Insertion of all components of a signature *)

let add_item comp env =
  match comp with
    Tsig_value(id, decl)     -> add_value id decl env
  | Tsig_type(id, decl, _)   -> add_type id decl env
  | Tsig_exception(id, decl) -> add_exception id decl env
  | Tsig_module(id, mty, _)  -> add_module id mty env
  | Tsig_modtype(id, decl)   -> add_modtype id decl env
  | Tsig_class(id, decl, _)  -> add_class id decl env
  | Tsig_cltype(id, decl, _) -> add_cltype id decl env

let rec add_signature sg env =
  match sg with
    [] -> env
  | comp :: rem -> add_signature rem (add_item comp env)

(* Open a signature path *)

let open_signature root sg env =
  (* First build the paths and substitution *)
  let (pl, sub) = prefix_idents root 0 Subst.identity sg in
  (* Then enter the components in the environment after substitution *)
  let newenv =
    List.fold_left2
      (fun env item p ->
        match item with
          Tsig_value(id, decl) ->
            let e1 = store_value (Ident.hide id) p
                        (Subst.value_description sub decl) env
            in store_annot (Ident.hide id) p (Annot.Iref_external) e1
        | Tsig_type(id, decl, _) ->
            store_type (Ident.hide id) p
                       (Subst.type_declaration sub decl) env
        | Tsig_exception(id, decl) ->
            store_exception (Ident.hide id) p
                            (Subst.exception_declaration sub decl) env
        | Tsig_module(id, mty, _) ->
            store_module (Ident.hide id) p (Subst.modtype sub mty) env
        | Tsig_modtype(id, decl) ->
            store_modtype (Ident.hide id) p
                          (Subst.modtype_declaration sub decl) env
        | Tsig_class(id, decl, _) ->
            store_class (Ident.hide id) p
                        (Subst.class_declaration sub decl) env
        | Tsig_cltype(id, decl, _) ->
            store_cltype (Ident.hide id) p
                         (Subst.cltype_declaration sub decl) env)
      env sg pl in
  { newenv with summary = Env_open(env.summary, root) }

(* Open a signature from a file *)

let open_pers_signature name env =
  let ps = find_pers_struct name in
  open_signature (Pident(Ident.create_persistent name)) ps.ps_sig env

(* Read a signature from a file *)

let read_signature modname filename =
  let ps = read_pers_struct modname filename in ps.ps_sig

(* Return the CRC of the interface of the given compilation unit *)

let crc_of_unit name =
  let ps = find_pers_struct name in
  try
    List.assoc name ps.ps_crcs
  with Not_found ->
    assert false

(* Return the list of imported interfaces with their CRCs *)

let imported_units() =
  Consistbl.extract crc_units

(* Save a signature to a file *)

let save_signature_with_imports sg modname filename imports =
  Btype.cleanup_abbrev ();
  Subst.reset_for_saving ();
  let sg = Subst.signature (Subst.for_saving Subst.identity) sg in
  let oc = open_out_bin filename in
  try
    output_string oc cmi_magic_number;
    output_value oc (modname, sg);
    flush oc;
    let crc = Digest.file filename in
    let crcs = (modname, crc) :: imports in
    output_value oc crcs;
    let flags = if !Clflags.recursive_types then [Rectypes] else [] in
    output_value oc flags;
    close_out oc;
    (* Enter signature in persistent table so that imported_unit()
       will also return its crc *)
    let comps =
      components_of_module empty Subst.identity
        (Pident(Ident.create_persistent modname)) (Tmty_signature sg) in
    let ps =
      { ps_name = modname;
        ps_sig = sg;
        ps_comps = comps;
        ps_crcs = crcs;
        ps_filename = filename;
        ps_flags = flags } in
    Hashtbl.add persistent_structures modname ps;
    Consistbl.set crc_units modname crc filename
  with exn ->
    close_out oc;
    remove_file filename;
    raise exn

let save_signature sg modname filename =
  save_signature_with_imports sg modname filename (imported_units())

(* Make the initial environment *)

let initial = Predef.build_initial_env add_type add_exception empty

(* Return the environment summary *)

let summary env = env.summary

(* Error report *)

open Format

let report_error ppf = function
  | Not_an_interface filename -> fprintf ppf
      "%s@ is not a compiled interface" filename
  | Corrupted_interface filename -> fprintf ppf
      "Corrupted compiled interface@ %s" filename
  | Illegal_renaming(modname, filename) -> fprintf ppf
      "Wrong file naming: %s@ contains the compiled interface for@ %s"
      filename modname
  | Inconsistent_import(name, source1, source2) -> fprintf ppf
      "@[<hov>The files %s@ and %s@ \
              make inconsistent assumptions@ over interface %s@]"
      source1 source2 name
  | Need_recursive_types(import, export) ->
      fprintf ppf
        "@[<hov>Unit %s imports from %s, which uses recursive types.@ %s@]"
        import export "The compilation flag -rectypes is required"