(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

(* $Id: recordops.ml 11309 2008-08-06 10:30:35Z herbelin $ *)

open Util
open Pp
open Names
open Libnames
open Nametab
open Term
open Termops
open Typeops
open Libobject
open Library
open Classops
open Mod_subst
open Reductionops

(*s A structure S is a non recursive inductive type with a single
   constructor (the name of which defaults to Build_S) *)

(* Table des structures: le nom de la structure (un [inductive]) donne
   le nom du constructeur, le nombre de paramètres et pour chaque
   argument réel du constructeur, le nom de la projection
   correspondante, si valide, et un booléen disant si c'est une vraie
   projection ou bien une fonction constante (associée à un LetIn) *)

type struc_typ = {
  s_CONST : identifier; 
  s_EXPECTEDPARAM : int;
  s_PROJKIND : bool list;
  s_PROJ : constant option list }

let structure_table = ref (Indmap.empty : struc_typ Indmap.t)
let projection_table = ref Cmap.empty

let load_structure i (_,(ind,id,kl,projs)) =
  let n = (fst (Global.lookup_inductive ind)).Declarations.mind_nparams in
  let struc =
    { s_CONST = id; s_EXPECTEDPARAM = n; s_PROJ = projs; s_PROJKIND = kl } in
  structure_table := Indmap.add ind struc !structure_table;
  projection_table := 
    List.fold_right (Option.fold_right (fun proj -> Cmap.add proj struc))
      projs !projection_table

let cache_structure o =
  load_structure 1 o

let subst_structure (_,subst,((kn,i),id,kl,projs as obj)) = 
  let kn' = subst_kn subst kn in
  let projs' =
   (* invariant: struc.s_PROJ is an evaluable reference. Thus we can take *)
   (* the first component of subst_con.                                   *)
   list_smartmap 
     (Option.smartmap (fun kn -> fst (subst_con subst kn)))
    projs
  in
    if projs' == projs && kn' == kn then obj else
      ((kn',i),id,kl,projs')

let discharge_structure (_,(ind,id,kl,projs)) =
  Some (Lib.discharge_inductive ind, id, kl,
        List.map (Option.map Lib.discharge_con) projs)

let (inStruc,outStruc) =
  declare_object {(default_object "STRUCTURE") with 
    cache_function = cache_structure;
    load_function = load_structure;
    subst_function = subst_structure;
    classify_function = (fun (_,x) -> Substitute x);
    discharge_function = discharge_structure;
    export_function = (function x -> Some x) }

let declare_structure (s,c,kl,pl) = 
  Lib.add_anonymous_leaf (inStruc (s,c,kl,pl))

let lookup_structure indsp = Indmap.find indsp !structure_table

let lookup_projections indsp = (lookup_structure indsp).s_PROJ

let find_projection_nparams = function
  | ConstRef cst -> (Cmap.find cst !projection_table).s_EXPECTEDPARAM
  | _ -> raise Not_found


(************************************************************************)
(*s A canonical structure declares "canonical" conversion hints between *)
(*  the effective components of a structure and the projections of the  *)
(*  structure *)

(* Table des definitions "object" : pour chaque object c,

  c := [x1:B1]...[xk:Bk](Build_R a1...am t1...t_n)

  If ti has the form (ci ui1...uir) where ci is a global reference and
if the corresponding projection Li of the structure R is defined, one
declare a "conversion" between ci and Li

    x1:B1..xk:Bk |- (Li a1..am (c x1..xk)) =_conv (ci ui1...uir)

that maps the pair (Li,ci) to the following data

    o_DEF = c
    o_TABS = B1...Bk
    o_PARAMS = a1...am
    o_NARAMS = m
    o_TCOMP = ui1...uir

*)

type obj_typ = {
  o_DEF : constr;
  o_INJ : int;      (* position of trivial argument (negative= none) *)
  o_TABS : constr list;    (* ordered *)
  o_TPARAMS : constr list; (* ordered *)
  o_NPARAMS : int;
  o_TCOMPS : constr list } (* ordered *)

type cs_pattern =
    Const_cs of global_reference
  | Prod_cs
  | Sort_cs of sorts_family
  | Default_cs

let object_table = ref (Refmap.empty : (cs_pattern * obj_typ) list Refmap.t)

let canonical_projections () = 
  Refmap.fold (fun x -> List.fold_right (fun (y,c) acc -> ((x,y),c)::acc))
    !object_table []

let keep_true_projections projs kinds =
  map_succeed (function (p,true) -> p | _ -> failwith "")
    (List.combine projs kinds)

let cs_pattern_of_constr t =
  match kind_of_term t with
      App (f,vargs) -> 
	begin 
	  try  Const_cs (global_of_constr f) , -1, Array.to_list vargs with
	      _ -> raise Not_found 
	end 
    | Rel n -> Default_cs, pred n, []
    | Prod (_,a,b) when not (dependent (mkRel 1) b) -> Prod_cs, -1, [a;pop b]
    | Sort s -> Sort_cs (family_of_sort s), -1, []
    | _ -> 
	begin 
	  try  Const_cs (global_of_constr t) , -1, [] with
	      _ -> raise Not_found 
	end 

(* Intended to always succeed *)
let compute_canonical_projections (con,ind) =
  let v = mkConst con in
  let c = Environ.constant_value (Global.env()) con in
  let lt,t = Reductionops.splay_lambda (Global.env()) Evd.empty c in
  let lt = List.rev (List.map snd lt) in
  let args = snd (decompose_app t) in
  let { s_EXPECTEDPARAM = p; s_PROJ = lpj; s_PROJKIND = kl } = 
    lookup_structure ind in
  let params, projs = list_chop p args in
  let lpj = keep_true_projections lpj kl in
  let lps = List.combine lpj projs in
  let comp =
    List.fold_left
      (fun l (spopt,t) -> (* comp=components *)
	 match spopt with
           | Some proji_sp ->
	       begin
		 try 
		   let patt, n , args = cs_pattern_of_constr t in
		     ((ConstRef proji_sp, patt, n, args) :: l)
		 with Not_found -> l 
	       end
	   | _ -> l)
      [] lps in
  List.map (fun (refi,c,inj,argj) ->
    (refi,c),
    {o_DEF=v; o_INJ=inj; o_TABS=lt; 
     o_TPARAMS=params; o_NPARAMS=List.length params; o_TCOMPS=argj})
    comp

let open_canonical_structure i (_,o) =
  if i=1 then
    let lo = compute_canonical_projections o in
    List.iter (fun ((proj,cs_pat),s) ->
      let l = try Refmap.find proj !object_table with Not_found -> [] in
      if not (List.mem_assoc cs_pat l) then
        object_table := Refmap.add proj ((cs_pat,s)::l) !object_table) lo

let cache_canonical_structure o =
  open_canonical_structure 1 o

let subst_canonical_structure (_,subst,(cst,ind as obj)) =
  (* invariant: cst is an evaluable reference. Thus we can take *)
  (* the first component of subst_con.                                   *)
  let cst' = fst (subst_con subst cst) in
  let ind' = Inductiveops.subst_inductive subst ind in
  if cst' == cst & ind' == ind then obj else (cst',ind')

let discharge_canonical_structure (_,(cst,ind)) =
  Some (Lib.discharge_con cst,Lib.discharge_inductive ind)

let (inCanonStruc,outCanonStruct) =
  declare_object {(default_object "CANONICAL-STRUCTURE") with 
    open_function = open_canonical_structure;
    cache_function = cache_canonical_structure;
    subst_function = subst_canonical_structure;
    classify_function = (fun (_,x) -> Substitute x);
    discharge_function = discharge_canonical_structure;
    export_function = (function x -> Some x) }

let add_canonical_structure x = Lib.add_anonymous_leaf (inCanonStruc x)

(*s High-level declaration of a canonical structure *)

let error_not_structure ref =
  errorlabstrm "object_declare"
    (Nameops.pr_id (id_of_global ref) ++ str" is not a structure object.")

let check_and_decompose_canonical_structure ref =
  let sp = match ref with ConstRef sp -> sp | _ -> error_not_structure ref in
  let env = Global.env () in
  let vc = match Environ.constant_opt_value env sp with
    | Some vc -> vc
    | None -> error_not_structure ref in
  let body = snd (splay_lambda (Global.env()) Evd.empty vc) in
  let f,args = match kind_of_term body with
    | App (f,args) -> f,args
    | _ -> error_not_structure ref in
  let indsp = match kind_of_term f with
    | Construct (indsp,1) -> indsp
    | _ -> error_not_structure ref in
  let s = try lookup_structure indsp with Not_found -> error_not_structure ref in
  let ntrue_projs = List.length (List.filter (fun x -> x) s.s_PROJKIND) in
  if s.s_EXPECTEDPARAM + ntrue_projs > Array.length args then
    error_not_structure ref;
  (sp,indsp)

let declare_canonical_structure ref =
  add_canonical_structure (check_and_decompose_canonical_structure ref)

let outCanonicalStructure x = fst (outCanonStruct x)

let lookup_canonical_conversion (proj,pat) =
  List.assoc pat (Refmap.find proj !object_table)

let is_open_canonical_projection sigma (c,args) =
  try 
    let l = Refmap.find (global_of_constr c) !object_table in
    let n = (snd (List.hd l)).o_NPARAMS in
    try isEvar (whd_evar sigma (List.nth args n)) with Failure _ -> false
  with Not_found -> false

let freeze () =
  !structure_table, !projection_table, !object_table

let unfreeze (s,p,o) = 
  structure_table := s; projection_table := p; object_table := o

let init () =
  structure_table := Indmap.empty; projection_table := Cmap.empty;
  object_table := Refmap.empty

let _ = init()

let _ = 
  Summary.declare_summary "objdefs"
    { Summary.freeze_function = freeze;
      Summary.unfreeze_function = unfreeze;
      Summary.init_function = init;
      Summary.survive_module = false;
      Summary.survive_section = false }