(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *         Copyright INRIA, CNRS and contributors             *)
(* <O___,, * (see version control and CREDITS file for authors & dates) *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
(************************************************************************)

(** This file defines a lot of different notions of names used pervasively in
    the kernel as well as in other places. The essential datatypes exported by
    this API are:

    - Id.t is the type of identifiers, that is morally a subset of strings which
      only contains Unicode characters of the Letter kind (and a few more).
    - Name.t is an ad-hoc variant of Id.t option allowing to handle optionally
      named objects.
    - DirPath.t represents generic paths as sequences of identifiers.
    - Label.t is an equivalent of Id.t made distinct for semantical purposes.
    - ModPath.t are module paths.
    - KerName.t are absolute names of objects in Coq.
*)

open Util

(** {6 Identifiers } *)

(** Representation and operations on identifiers. *)
module Id :
sig
  type t
  (** Values of this type represent (Coq) identifiers. *)

  val equal : t -> t -> bool
  (** Equality over identifiers. *)

  val compare : t -> t -> int
  (** Comparison over identifiers. *)

  val hash : t -> int
  (** Hash over identifiers. *)

  val is_valid : string -> bool
  (** Check that a string may be converted to an identifier. *)

  val is_valid_ident_part : string -> bool
  (** Check that a string is a valid part of an identifier *)

  val of_bytes : bytes -> t
  val of_string : string -> t
  (** Converts a string into an identifier.
      @raise UserError if the string is invalid as an identifier. *)

  val of_string_soft : string -> t
  (** Same as {!of_string} except that any string made of supported UTF-8 characters is accepted.
      @raise UserError if the string is invalid as an UTF-8 string. *)

  val to_string : t -> string
  (** Converts a identifier into an string. *)

  val print : t -> Pp.t
  (** Pretty-printer. *)

  module Set : Set.S with type elt = t
  (** Finite sets of identifiers. *)

  module Map : Map.ExtS with type key = t and module Set := Set
  (** Finite maps of identifiers. *)

  module Pred : Predicate.S with type elt = t
  (** Predicates over identifiers. *)

  module List : List.MonoS with type elt = t
  (** Operations over lists of identifiers. *)

  val hcons : t -> t
  (** Hashconsing of identifiers. *)

end

(** Representation and operations on identifiers that are allowed to be anonymous
    (i.e. "_" in concrete syntax). *)
module Name :
sig
  type t = Anonymous     (** anonymous identifier *)
         | Name of Id.t  (** non-anonymous identifier *)

  val mk_name : Id.t -> t
  (** constructor *)

  val is_anonymous : t -> bool
  (** Return [true] iff a given name is [Anonymous]. *)

  val is_name : t -> bool
  (** Return [true] iff a given name is [Name _]. *)

  val compare : t -> t -> int
  (** Comparison over names. *)

  val equal : t -> t -> bool
  (** Equality over names. *)

  val hash : t -> int
  (** Hash over names. *)

  val hcons : t -> t
  (** Hashconsing over names. *)

  val print : t -> Pp.t
  (** Pretty-printer (print "_" for [Anonymous]. *)

end

(** {6 Type aliases} *)

type name = Name.t = Anonymous | Name of Id.t
[@@ocaml.deprecated "Use Name.t"]

type variable = Id.t
type module_ident = Id.t

module ModIdset : Set.S with type elt = module_ident
module ModIdmap : Map.ExtS with type key = module_ident and module Set := ModIdset

(** {6 Directory paths = section names paths } *)

module DirPath :
sig
  type t
  (** Type of directory paths. Essentially a list of module identifiers. The
      order is reversed to improve sharing. E.g. A.B.C is ["C";"B";"A"] *)

  val equal : t -> t -> bool
  (** Equality over directory paths. *)

  val compare : t -> t -> int
  (** Comparison over directory paths. *)

  val hash : t -> int
  (** Hash over directory paths. *)

  val make : module_ident list -> t
  (** Create a directory path. (The list must be reversed). *)

  val repr : t -> module_ident list
  (** Represent a directory path. (The result list is reversed). *)

  val empty : t
  (** The empty directory path. *)

  val is_empty : t -> bool
  (** Test whether a directory path is empty. *)

  val dummy : t
  (** Used in [Safe_typing.empty_environment] and similar *)

  val hcons : t -> t
  (** Hashconsing of directory paths. *)

  val to_string : t -> string
  (** Print non-empty directory paths as ["coq_root.module.submodule"] *)

  val print : t -> Pp.t
end

module DPset : Set.S with type elt = DirPath.t
module DPmap : Map.ExtS with type key = DirPath.t and module Set := DPset

(** {6 Names of structure elements } *)

module Label :
sig
  type t
  (** Type of labels *)

  val equal : t -> t -> bool
  (** Equality over labels *)

  val compare : t -> t -> int
  (** Comparison over labels. *)

  val hash : t -> int
  (** Hash over labels. *)

  val make : string -> t
  (** Create a label out of a string. *)

  val of_id : Id.t -> t
  (** Conversion from an identifier. *)

  val to_id : t -> Id.t
  (** Conversion to an identifier. *)

  val to_string : t -> string
  (** Conversion to string. *)

  val print : t -> Pp.t
  (** Pretty-printer. *)

  module Set : Set.S with type elt = t
  module Map : Map.ExtS with type key = t and module Set := Set

  val hcons : t -> t

end

(** {6 Unique names for bound modules} *)

module MBId :
sig
  type t
  (** Unique names for bound modules. Each call to [make] constructs a fresh
      unique identifier. *)

  val equal : t -> t -> bool
  (** Equality over unique bound names. *)

  val compare : t -> t -> int
  (** Comparison over unique bound names. *)

  val hash : t -> int
  (** Hash over unique bound names. *)

  val make : DirPath.t -> Id.t -> t
  (** The first argument is a file name, to prevent conflict between different
      files. *)

  val repr : t -> int * Id.t * DirPath.t
  (** Reverse of [make]. *)

  val to_id : t -> Id.t
  (** Return the identifier contained in the argument. *)

  val to_string : t -> string
  (** Encode as a string (not to be used for user-facing messages). *)

  val debug_to_string : t -> string
  (** Same as [to_string], but outputs extra information related to debug. *)

end

module MBIset : Set.S with type elt = MBId.t
module MBImap : Map.ExtS with type key = MBId.t and module Set := MBIset

(** {6 The module part of the kernel name } *)

module ModPath :
sig
  type t =
    | MPfile of DirPath.t
    | MPbound of MBId.t
    | MPdot of t * Label.t

  val compare : t -> t -> int
  val equal : t -> t -> bool
  val hash : t -> int

  val is_bound : t -> bool

  val dummy : t
  (** ([= MPfile DirPath.dummy]) *)

  val dp : t -> DirPath.t

  val to_string : t -> string
  (** Converts a identifier into an string. *)

  val print : t -> Pp.t
  (** Pretty-printer. *)

  val debug_to_string : t -> string
  (** Same as [to_string], but outputs extra information related to debug. *)

end

module MPset : Set.S with type elt = ModPath.t
module MPmap : Map.ExtS with type key = ModPath.t and module Set := MPset

(** {6 The absolute names of objects seen by kernel } *)

module KerName :
sig
  type t

  (** Constructor and destructor *)
  val make : ModPath.t -> Label.t -> t
  val repr : t -> ModPath.t * Label.t

  (** Projections *)
  val modpath : t -> ModPath.t
  val label : t -> Label.t

  val to_string : t -> string
  (** Encode as a string (not to be used for user-facing messages). *)

  val print : t -> Pp.t
  (** Print internal representation (not to be used for user-facing messages). *)

  val debug_to_string : t -> string
  (** Same as [to_string], but outputs extra information related to debug. *)

  val debug_print : t -> Pp.t
  (** Same as [print], but outputs extra information related to debug. *)

  (** Comparisons *)
  val compare : t -> t -> int
  val equal : t -> t -> bool
  val hash : t -> int
end

module KNset  : CSig.SetS with type elt = KerName.t
module KNpred : Predicate.S with type elt = KerName.t
module KNmap  : Map.ExtS with type key = KerName.t and module Set := KNset

(** {6 Signature for quotiented names} *)

module type EqType =
sig
  type t
  val compare : t -> t -> int
  val equal : t -> t -> bool
  val hash : t -> int
end

module type QNameS =
sig
  type t
  (** A type of reference that implements an implicit quotient by containing
      two different names. The first one is the user name, i.e. what the user
      sees when printing. The second one is the canonical name, which is the
      actual absolute name of the reference.

      This mechanism is fundamentally tied to the module system of Coq. Functor
      application and module inclusion are the typical ways to introduce names
      where the canonical and user components differ. In particular, the two
      components should be undistinguishable from the point of view of typing,
      i.e. from a "kernel" ground. This aliasing only makes sense inside an
      environment, but at this point this notion is not even defined so, this
      dual name trick is fragile. One has to ensure many invariants when
      creating such names, but the kernel is quite lenient when it comes to
      checking that these invariants hold. (Read: there are soundness bugs
      lurking in the module system.)

      One could enforce the invariants by splitting the names and storing that
      information in the environment instead, but unfortunately, this wreaks
      havoc in the upper layers. The latter are infamously not stable by
      syntactic equality, in particular they might observe the difference
      between canonical and user names if not packed together.

      For this reason, it is discouraged to use the canonical-accessing API
      in the upper layers, notably the [CanOrd] module below. Instead, one
      should use their quotiented versions defined in the [Environ] module.
      Eventually all uses to [CanOrd] outside of the kernel should be removed.

      CAVEAT: name sets and maps are still exposing a canonical-accessing API
      surreptitiously. *)

  module CanOrd : EqType with type t = t
  (** Equality functions over the canonical name. Their use should be
      restricted to the kernel. *)

  module UserOrd : EqType with type t = t
  (** Equality functions over the user name. *)

  module SyntacticOrd : EqType with type t = t
  (** Equality functions using both names, for low-level uses. *)
end

(** {6 Constant Names } *)

module Constant:
sig
  type t

  (** Constructors *)

  val make : KerName.t -> KerName.t -> t
  (** Builds a constant name from a user and a canonical kernel name. *)

  val make1 : KerName.t -> t
  (** Special case of [make] where the user name is canonical.  *)

  val make2 : ModPath.t -> Label.t -> t
  (** Shortcut for [(make1 (KerName.make2 ...))] *)

  (** Projections *)

  val user : t -> KerName.t
  val canonical : t -> KerName.t

  val modpath : t -> ModPath.t
  (** Shortcut for [KerName.modpath (user ...)] *)

  val label : t -> Label.t
  (** Shortcut for [KerName.label (user ...)] *)

  (** Comparisons *)

  include QNameS with type t := t

  val equal : t -> t -> bool [@@ocaml.deprecated "Use QConstant.equal"]
  (** Default comparison, alias for [CanOrd.equal] *)

  val hash : t -> int [@@ocaml.deprecated "Use QConstant.hash"]
  (** Hashing function *)

  val change_label : t -> Label.t -> t
  (** Builds a new constant name with a different label *)

  (** Displaying *)

  val to_string : t -> string
  (** Encode as a string (not to be used for user-facing messages). *)

  val print : t -> Pp.t
  (** Print internal representation (not to be used for user-facing messages). *)

  val debug_to_string : t -> string
  (** Same as [to_string], but outputs extra information related to debug. *)

  val debug_print : t -> Pp.t
  (** Same as [print], but outputs extra information related to debug. *)

end

(** The [*_env] modules consider an order on user part of names
   the others consider an order on canonical part of names*)
module Cpred : Predicate.S with type elt = Constant.t
module Cset : CSig.SetS with type elt = Constant.t
module Cset_env  : CSig.SetS with type elt = Constant.t

module Cmap : Map.ExtS with type key = Constant.t and module Set := Cset
(** A map whose keys are constants (values of the {!Constant.t} type).
    Keys are ordered wrt. "canonical form" of the constant. *)

module Cmap_env : Map.ExtS with type key = Constant.t and module Set := Cset_env
(** A map whose keys are constants (values of the {!Constant.t} type).
    Keys are ordered wrt. "user form" of the constant. *)

(** {6 Inductive names} *)

module MutInd :
sig
  type t

  (** Constructors *)

  val make : KerName.t -> KerName.t -> t
  (** Builds a mutual inductive name from a user and a canonical kernel name. *)

  val make1 : KerName.t -> t
  (** Special case of [make] where the user name is canonical.  *)

  val make2 : ModPath.t -> Label.t -> t
  (** Shortcut for [(make1 (KerName.make2 ...))] *)

  (** Projections *)

  val user : t -> KerName.t
  val canonical : t -> KerName.t

  val modpath : t -> ModPath.t
  (** Shortcut for [KerName.modpath (user ...)] *)

  val label : t -> Label.t
  (** Shortcut for [KerName.label (user ...)] *)

  (** Comparisons *)

  include QNameS with type t := t

  val equal : t -> t -> bool [@@ocaml.deprecated "Use QMutInd.equal"]
 (** Default comparison, alias for [CanOrd.equal] *)

  val hash : t -> int [@@ocaml.deprecated "Use QMutInd.hash"]

  (** Displaying *)

  val to_string : t -> string
  (** Encode as a string (not to be used for user-facing messages). *)

  val print : t -> Pp.t
  (** Print internal representation (not to be used for user-facing messages). *)

  val debug_to_string : t -> string
  (** Same as [to_string], but outputs extra information related to debug. *)

  val debug_print : t -> Pp.t
  (** Same as [print], but outputs extra information related to debug. *)

end

module Mindset : CSig.SetS with type elt = MutInd.t
module Mindmap : Map.ExtS with type key = MutInd.t and module Set := Mindset
module Mindmap_env : CMap.ExtS with type key = MutInd.t

module Ind :
sig
  (** Designation of a (particular) inductive type. *)
  type t = MutInd.t      (* the name of the inductive type *)
         * int           (* the position of this inductive type
                                    within the block of mutually-recursive inductive types.
                                    BEWARE: indexing starts from 0. *)
  val modpath : t -> ModPath.t

  include QNameS with type t := t

end

type inductive = Ind.t

module Construct :
sig
  (** Designation of a (particular) constructor of a (particular) inductive type. *)
  type t = Ind.t   (* designates the inductive type *)
         * int     (* the index of the constructor
                                    BEWARE: indexing starts from 1. *)

  val modpath : t -> ModPath.t

  include QNameS with type t := t

end

type constructor = Construct.t

module Indset : CSet.S with type elt = inductive
module Constrset : CSet.S with type elt = constructor
module Indset_env : CSet.S with type elt = inductive
module Constrset_env : CSet.S with type elt = constructor
module Indmap : CMap.ExtS with type key = inductive and module Set := Indset
module Constrmap : CMap.ExtS with type key = constructor and module Set := Constrset
module Indmap_env : CMap.ExtS with type key = inductive and module Set := Indset_env
module Constrmap_env : CMap.ExtS with type key = constructor and module Set := Constrset_env

val ith_mutual_inductive : inductive -> int -> inductive
val ith_constructor_of_inductive : inductive -> int -> constructor
val inductive_of_constructor : constructor -> inductive
val index_of_constructor : constructor -> int

(** {6 Hash-consing } *)

val hcons_con : Constant.t -> Constant.t
val hcons_mind : MutInd.t -> MutInd.t
val hcons_ind : inductive -> inductive
val hcons_construct : constructor -> constructor

(******)

type 'a tableKey =
  | ConstKey of 'a
  | VarKey of Id.t
  | RelKey of Int.t

type inv_rel_key = int (** index in the [rel_context] part of environment
                          starting by the end, {e inverse}
                          of de Bruijn indice *)

val eq_table_key : ('a -> 'a -> bool) -> 'a tableKey -> 'a tableKey -> bool
val hash_table_key : ('a -> int) -> 'a tableKey -> int
val eq_constant_key : Constant.t -> Constant.t -> bool

(** equalities on constant and inductive names (for the checker) *)

val eq_ind_chk : inductive -> inductive -> bool

(** {5 Module paths} *)

type module_path = ModPath.t =
  | MPfile of DirPath.t
  | MPbound of MBId.t
  | MPdot of ModPath.t * Label.t
[@@ocaml.deprecated "Alias type"]

module Projection : sig
  module Repr : sig
    type t

    val make : inductive -> proj_npars:int -> proj_arg:int -> Label.t -> t

    include QNameS with type t := t

    val constant : t -> Constant.t
    (** Don't use this if you don't have to. *)

    val inductive : t -> inductive
    val mind : t -> MutInd.t
    val npars : t -> int
    val arg : t -> int
    val label : t -> Label.t

    val equal : t -> t -> bool [@@ocaml.deprecated "Use QProjection.equal"]
    val hash : t -> int [@@ocaml.deprecated "Use QProjection.hash"]
    val compare : t -> t -> int [@@ocaml.deprecated "Use QProjection.compare"]

    val map : (MutInd.t -> MutInd.t) -> t -> t
    val map_npars : (int -> int) -> t -> t

    val to_string : t -> string
    (** Encode as a string (not to be used for user-facing messages). *)

    val print : t -> Pp.t
    (** Print internal representation (not to be used for user-facing messages). *)

  end
  type t (* = Repr.t * bool *)

  val make : Repr.t -> bool -> t
  val repr : t -> Repr.t

  include QNameS with type t := t

  val constant : t -> Constant.t
  val mind : t -> MutInd.t
  val inductive : t -> inductive
  val npars : t -> int
  val arg : t -> int
  val label : t -> Label.t
  val unfolded : t -> bool
  val unfold : t -> t

  val equal : t -> t -> bool
  [@@ocaml.deprecated "Use QProjection.equal"]
  val hash : t -> int
  [@@ocaml.deprecated "Use QProjection.hash"]
  val hcons : t -> t
  (** Hashconsing of projections. *)

  val repr_equal : t -> t -> bool
  [@@ocaml.deprecated "Use an explicit projection of Repr"]
  (** Ignoring the unfolding boolean. *)

  val compare : t -> t -> int
  [@@ocaml.deprecated "Use QProjection.compare"]

  val map : (MutInd.t -> MutInd.t) -> t -> t
  val map_npars : (int -> int) -> t -> t

  val to_string : t -> string
  (** Encode as a string (not to be used for user-facing messages). *)

  val print : t -> Pp.t
  (** Print internal representation (not to be used for user-facing messages). *)

end

(** {6 Global reference is a kernel side type for all references together } *)

module GlobRef : sig

  type t =
    | VarRef of variable           (** A reference to the section-context. *)
    | ConstRef of Constant.t       (** A reference to the environment. *)
    | IndRef of inductive          (** A reference to an inductive type. *)
    | ConstructRef of constructor  (** A reference to a constructor of an inductive type. *)

  val equal : t -> t -> bool
  [@@ocaml.deprecated "Use QGlobRef.equal"]

  val is_bound : t -> bool

  include QNameS with type t := t

  module Set_env : CSig.SetS with type elt = t
  module Map_env : Map.ExtS
    with type key = t and module Set := Set_env

  module Set : CSig.SetS with type elt = t
  module Map : Map.ExtS
    with type key = t and module Set := Set

  val print : t -> Pp.t
  (** Print internal representation (not to be used for user-facing messages). *)

end

(** Located identifiers and objects with syntax. *)

type lident = Id.t CAst.t
type lname = Name.t CAst.t
type lstring = string CAst.t

val lident_eq : lident -> lident -> bool
