path: root/parsing/pcoq.ml4

(************************************************************************)
(*  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        *)
(************************************************************************)

(*i $Id$ i*)

open Pp
open Util
open Names
open Libnames
open Rawterm
open Topconstr
open Ast
open Genarg
open Tacexpr
open Ppextend
open Extend

(* The lexer of Coq *)

(* Note: removing a token.
   We do nothing because [remove_token] is called only when removing a grammar
   rule with [Grammar.delete_rule]. The latter command is called only when
   unfreezing the state of the grammar entries (see GRAMMAR summary, file
   env/metasyntax.ml). Therefore, instead of removing tokens one by one,
   we unfreeze the state of the lexer. This restores the behaviour of the
   lexer. B.B. *)

let lexer = {
  Token.func = Lexer.func;
  Token.using = Lexer.add_token;
  Token.removing = (fun _ -> ());
  Token.tparse = Lexer.tparse;
  Token.text = Lexer.token_text }

module L =
  struct
    let lexer = lexer
  end

(* The parser of Coq *)

module G = Grammar.Make(L)

let grammar_delete e rls =
  List.iter
    (fun (_,_,lev) ->
       List.iter (fun (pil,_) -> G.delete_rule e pil) (List.rev lev))
    (List.rev rls)

(* grammar_object is the superclass of all grammar entry *)
module type Gramobj =
sig
  type grammar_object
  val weaken_entry : 'a G.Entry.e -> grammar_object G.Entry.e
end

module Gramobj : Gramobj =
struct
  type grammar_object = Obj.t
  let weaken_entry e = Obj.magic e
end

type grammar_object = Gramobj.grammar_object
type typed_entry = entry_type * grammar_object G.Entry.e
let in_typed_entry t e = (t,Gramobj.weaken_entry e)
let type_of_typed_entry (t,e) = t
let object_of_typed_entry (t,e) = e
let weaken_entry x = Gramobj.weaken_entry x

module type Gramtypes =
sig
  open Decl_kinds
  val inGramObj : 'a raw_abstract_argument_type -> 'a G.Entry.e -> typed_entry
  val outGramObj : 'a raw_abstract_argument_type -> typed_entry -> 'a G.Entry.e
end

module Gramtypes : Gramtypes =
struct
  let inGramObj rawwit = in_typed_entry (unquote rawwit)
  let outGramObj (a:'a raw_abstract_argument_type) o =
    if type_of_typed_entry o <> unquote a
      then anomaly "outGramObj: wrong type";
    (* downcast from grammar_object *)
    Obj.magic (object_of_typed_entry o)
end

open Gramtypes

type ext_kind =
  | ByGrammar of
      grammar_object G.Entry.e * Gramext.position option *
      (string option * Gramext.g_assoc option *
       (Token.t Gramext.g_symbol list * Gramext.g_action) list) list
  | ByGEXTEND of (unit -> unit) * (unit -> unit)

let camlp4_state = ref []

(* The apparent parser of Coq; encapsulate G to keep track of the
   extensions. *)
module Gram =
  struct
    include G
    let extend e pos rls =
      camlp4_state :=
      (ByGEXTEND ((fun () -> grammar_delete e rls),
                  (fun () -> G.extend e pos rls)))
      :: !camlp4_state;
      G.extend e pos rls
    let delete_rule e pil =
      errorlabstrm "Pcoq.delete_rule" (str "GDELETE_RULE forbidden.")
  end


let camlp4_verbosity silent f x =
  let a = !Gramext.warning_verbose in
  Gramext.warning_verbose := silent;
  f x;
  Gramext.warning_verbose := a

(* This extension command is used by the Grammar constr *)

let grammar_extend te pos rls =
  camlp4_state := ByGrammar (Gramobj.weaken_entry te,pos,rls) :: !camlp4_state;
  camlp4_verbosity (Options.is_verbose ()) (G.extend te pos) rls

(* n is the number of extended entries (not the number of Grammar commands!)
   to remove. *)
let rec remove_grammars n =
  if n>0 then
    (match !camlp4_state with
       | [] -> anomaly "Pcoq.remove_grammars: too many rules to remove"
       | ByGrammar(g,_,rls)::t ->
           grammar_delete g rls;
           camlp4_state := t;
           remove_grammars (n-1)
       | ByGEXTEND (undo,redo)::t ->
           undo();
           camlp4_state := t;
           remove_grammars n;
           redo();
           camlp4_state := ByGEXTEND (undo,redo) :: !camlp4_state)

(* An entry that checks we reached the end of the input. *)
let eoi_entry en =
  let e = Gram.Entry.create ((Gram.Entry.name en) ^ "_eoi") in
  GEXTEND Gram
    e: [ [ x = en; EOI -> x ] ]
    ;
  END;
  e

let map_entry f en =
  let e = Gram.Entry.create ((Gram.Entry.name en) ^ "_map") in
  GEXTEND Gram
    e: [ [ x = en -> f x ] ]
    ;
  END;
  e

(* Parse a string, does NOT check if the entire string was read
   (use eoi_entry) *)

let parse_string f x =
  let strm = Stream.of_string x in Gram.Entry.parse f (Gram.parsable strm)

type gram_universe = (string, typed_entry) Hashtbl.t

let trace = ref false

(* The univ_tab is not part of the state. It contains all the grammar that
   exist or have existed before in the session. *)

let univ_tab = (Hashtbl.create 7 : (string, string * gram_universe) Hashtbl.t)

let create_univ s =
  let u = s, Hashtbl.create 29 in Hashtbl.add univ_tab s u; u

let uprim   = create_univ "prim"
let uconstr = create_univ "constr"
let umodule = create_univ "module"
let utactic = create_univ "tactic"
let uvernac = create_univ "vernac"

let create_univ_if_new s =
  (* compatibilite *)
  let s = if s = "command" then (warning "'command' grammar universe is obsolete; use name 'constr' instead"; "constr") else s in
  try
    Hashtbl.find univ_tab s
  with Not_found -> 
    if !trace then begin 
      Printf.eprintf "[Creating univ %s]\n" s; flush stderr; () 
    end;
    let u = s, Hashtbl.create 29 in Hashtbl.add univ_tab s u; u

let get_univ = create_univ_if_new

let get_entry (u, utab) s =
  try
    Hashtbl.find utab s 
  with Not_found -> 
    errorlabstrm "Pcoq.get_entry"
      (str "unknown grammar entry " ++ str u ++ str ":" ++ str s)

let new_entry etyp (u, utab) s =
  let ename = u ^ ":" ^ s in
  let e = in_typed_entry etyp (Gram.Entry.create ename) in
  Hashtbl.add utab s e; e

let entry_type (u, utab) s =
  try
    let e = Hashtbl.find utab s in
    Some (type_of_typed_entry e)
  with Not_found -> None

let get_entry_type (u,n) =  type_of_typed_entry (get_entry (get_univ u) n)

let create_entry_if_new (u, utab) s etyp =
  try
    if type_of_typed_entry (Hashtbl.find utab s) <> etyp then
      failwith ("Entry " ^ u ^ ":" ^ s ^ " already exists with another type")
  with Not_found ->
    if !trace then begin
      Printf.eprintf "[Creating entry %s:%s]\n" u s; flush stderr; ()
    end;
    let _ = new_entry etyp (u, utab) s in ()

let create_entry (u, utab) s etyp =
  try
    let e = Hashtbl.find utab s in
    if type_of_typed_entry e <> etyp then
      failwith ("Entry " ^ u ^ ":" ^ s ^ " already exists with another type");
    e
  with Not_found ->
    if !trace then begin
      Printf.eprintf "[Creating entry %s:%s]\n" u s; flush stderr; ()
    end;
    new_entry etyp (u, utab) s

let create_constr_entry u s =
  outGramObj rawwit_constr (create_entry u s ConstrArgType)

let create_generic_entry s wit = 
  let (u,utab) = utactic in
  let etyp = unquote wit in
  try
    let e = Hashtbl.find utab s in
    if type_of_typed_entry e <> etyp then
      failwith ("Entry " ^ u ^ ":" ^ s ^ " already exists with another type");
    outGramObj wit e
  with Not_found ->
    if !trace then begin
      Printf.eprintf "[Creating entry %s:%s]\n" u s; flush stderr; ()
    end;
  let e = Gram.Entry.create s in
  Hashtbl.add utab s (inGramObj wit e); e

let get_generic_entry s =
  let (u,utab) = utactic in
  try
    object_of_typed_entry (Hashtbl.find utab s)
  with Not_found -> 
    error ("unknown grammar entry "^u^":"^s)

let get_generic_entry_type (u,utab) s =
  try type_of_typed_entry (Hashtbl.find utab s)
  with Not_found -> 
    error ("unknown grammar entry "^u^":"^s)

let force_entry_type (u, utab) s etyp =
  try
    let entry = Hashtbl.find utab s in
    let extyp = type_of_typed_entry entry in
    if etyp = extyp then 
      entry
    else begin
      prerr_endline
        ("Grammar entry " ^ u ^ ":" ^ s ^
         " redefined with another type;\n older entry hidden.");
      Hashtbl.remove utab s;
      new_entry etyp (u, utab) s
    end
  with Not_found -> 
    new_entry etyp (u, utab) s

(* [make_gen_entry] builds entries extensible by giving its name (a string) *)
(* For entries extensible only via the ML name, Gram.Entry.create is enough *)

let make_gen_entry (u,univ) rawwit s =
  let e = Gram.Entry.create (u ^ ":" ^ s) in
  Hashtbl.add univ s (inGramObj rawwit e); e

(* Grammar entries *)

module Prim =
  struct
    let gec_gen x = make_gen_entry uprim x
    
    (* Entries that can be refered via the string -> Gram.Entry.e table *)
    (* Typically for tactic or vernac extensions *)
    let preident = gec_gen rawwit_pre_ident "preident"
    let ident = gec_gen rawwit_ident "ident"
    let natural = gec_gen rawwit_int "natural"
    let integer = gec_gen rawwit_int "integer"
    let bigint = Gram.Entry.create "Prim.bigint"
    let string = gec_gen rawwit_string "string"
    let reference = make_gen_entry uprim rawwit_ref "reference"

    (* parsed like ident but interpreted as a term *)
    let hyp = gec_gen rawwit_ident "hyp"

    (* synonym of hyp/ident (before semantics split) for v7 compatibility *)
    let var = gec_gen rawwit_ident "var"

    let name = Gram.Entry.create "Prim.name"
    let identref = Gram.Entry.create "Prim.identref"

    (* A synonym of ident - maybe ident will be located one day *)
    let base_ident = Gram.Entry.create "Prim.base_ident"

    let qualid = Gram.Entry.create "Prim.qualid"
    let dirpath = Gram.Entry.create "Prim.dirpath"

    let ne_string = Gram.Entry.create "Prim.ne_string"

    (* For old ast printer *)
    let astpat = Gram.Entry.create "Prim.astpat"
    let ast = Gram.Entry.create "Prim.ast"
    let astlist = Gram.Entry.create "Prim.astlist"
    let ast_eoi = eoi_entry ast
    let astact = Gram.Entry.create "Prim.astact"
  end


module Constr =
  struct
    let gec_constr = make_gen_entry uconstr rawwit_constr
    let gec_constr_list = make_gen_entry uconstr (wit_list0 rawwit_constr)

    (* Entries that can be refered via the string -> Gram.Entry.e table *)
    let constr = gec_constr "constr"
    let operconstr = gec_constr "operconstr"
    let constr_eoi = eoi_entry constr
    let lconstr = gec_constr "lconstr"
    let binder_constr = create_constr_entry uconstr "binder_constr"
    let ident = make_gen_entry uconstr rawwit_ident "ident"
    let global = make_gen_entry uconstr rawwit_ref "global"
    let sort = make_gen_entry uconstr rawwit_sort "sort"
    let pattern = Gram.Entry.create "constr:pattern"
    let annot = Gram.Entry.create "constr:annot"
    let constr_pattern = gec_constr "constr_pattern"
    let lconstr_pattern = gec_constr "lconstr_pattern"
    let binder = Gram.Entry.create "constr:binder"
    let binder_let = Gram.Entry.create "constr:binder_let"
  end

module Module =
  struct
    let module_expr = Gram.Entry.create "module_expr"
    let module_type = Gram.Entry.create "module_type"
  end

module Tactic =
  struct
    (* Main entry for extensions *)
    let simple_tactic = Gram.Entry.create "tactic:simple_tactic"

    (* Entries that can be refered via the string -> Gram.Entry.e table *)
    (* Typically for tactic user extensions *)
    let castedopenconstr = 
      make_gen_entry utactic rawwit_casted_open_constr "castedopenconstr"
    let constr_with_bindings =
      make_gen_entry utactic rawwit_constr_with_bindings "constr_with_bindings"
    let bindings =
      make_gen_entry utactic rawwit_bindings "bindings"
    let constrarg = make_gen_entry utactic rawwit_constr_may_eval "constrarg"
    let quantified_hypothesis =
      make_gen_entry utactic rawwit_quant_hyp "quantified_hypothesis"
    let int_or_var = make_gen_entry utactic rawwit_int_or_var "int_or_var"
    let red_expr = make_gen_entry utactic rawwit_red_expr "red_expr"
    let simple_intropattern = 
      make_gen_entry utactic rawwit_intro_pattern "simple_intropattern"

    (* Main entries for ltac *)
    let tactic_arg = Gram.Entry.create "tactic:tactic_arg"
    let tactic = make_gen_entry utactic rawwit_tactic "tactic"

    (* Main entry for quotations *)
    let tactic_eoi = eoi_entry tactic
  end


module Vernac_ =
  struct
    let gec_vernac s = Gram.Entry.create ("vernac:" ^ s)

    (* The different kinds of vernacular commands *)
    let gallina = gec_vernac "gallina"
    let gallina_ext = gec_vernac "gallina_ext"
    let command = gec_vernac "command"
    let syntax = gec_vernac "syntax_command"
    let vernac = gec_vernac "Vernac_.vernac"

    let vernac_eoi = eoi_entry vernac
  end


(* Prim is not re-initialized *)
let reset_all_grammars () =
  let f = Gram.Unsafe.clear_entry in
  List.iter f
    [Constr.constr;Constr.operconstr;Constr.lconstr;Constr.annot;
     Constr.constr_pattern;Constr.lconstr_pattern];
  f Constr.ident; f Constr.global; f Constr.sort; f Constr.pattern;
  f Module.module_expr; f Module.module_type;
  f Tactic.simple_tactic;
  f Tactic.castedopenconstr;
  f Tactic.constr_with_bindings;
  f Tactic.bindings;
  f Tactic.constrarg;
  f Tactic.quantified_hypothesis;
  f Tactic.int_or_var;
  f Tactic.red_expr;
  f Tactic.tactic_arg;
  f Tactic.tactic;
  f Vernac_.gallina;
  f Vernac_.gallina_ext;
  f Vernac_.command;
  f Vernac_.syntax;
  f Vernac_.vernac;
  Lexer.init()

let main_entry = Gram.Entry.create "vernac"

GEXTEND Gram
  main_entry:
    [ [ a = Vernac_.vernac -> Some (loc,a) | EOI -> None ] ]
  ;
END

(* Quotations *)

open Prim
open Constr
open Tactic
open Vernac_

(* current file and toplevel/vernac.ml *)
let globalizer = ref (fun x -> failwith "No globalizer")
let set_globalizer f = globalizer := f

let define_ast_quotation default s (e:Coqast.t G.Entry.e) =
  (if default then
    GEXTEND Gram
      ast: [ [ "<<"; c = e; ">>" -> c ] ];
     (* Uncomment this to keep compatibility with old grammar syntax
     constr: [ [ "<<"; c = e; ">>" -> c ] ];
     vernac: [ [ "<<"; c = e; ">>" -> c ] ];
     tactic: [ [ "<<"; c = e; ">>" -> c ] ];
     *)
   END);
  (GEXTEND Gram
     GLOBAL: ast constr command tactic;
     ast:
       [ [ "<:"; IDENT $s$; ":<"; c = e; ">>" -> c ] ];
     (* Uncomment this to keep compatibility with old grammar syntax
     constr:
       [ [ "<:"; IDENT $s$; ":<"; c = e; ">>" -> c ] ];
     command:
       [ [ "<:"; IDENT $s$; ":<"; c = e; ">>" -> c ] ];
     tactic:
       [ [ "<:"; IDENT $s$; ":<"; c = e; ">>" -> c ] ];
     *)
   END)

(*
let _ = define_ast_quotation false "ast" ast in ()
*)

let dynconstr = Gram.Entry.create "Constr.dynconstr"
let dyncasespattern = Gram.Entry.create "Constr.dyncasespattern"

GEXTEND Gram
  dynconstr:
  [ [ a = Constr.constr -> ConstrNode a 
    (* For compatibility *)
    | "<<"; a = Constr.lconstr; ">>" -> ConstrNode a ] ]
  ;
  dyncasespattern: [ [ a = Constr.pattern -> CasesPatternNode a ] ];
END

(**********************************************************************)
(* The following is to dynamically set the parser in Grammar actions  *)
(* and Syntax pattern, according to the universe of the rule defined  *)

type parser_type =
  | ConstrParser
  | CasesPatternParser

let default_action_parser_ref = ref dynconstr

let get_default_action_parser () = !default_action_parser_ref

let entry_type_of_parser =  function
  | ConstrParser -> Some ConstrArgType
  | CasesPatternParser -> failwith "entry_type_of_parser: cases_pattern, TODO"

let parser_type_from_name =  function
  | "constr" -> ConstrParser
  | "cases_pattern" -> CasesPatternParser
  | "tactic" -> assert false
  | "vernac" -> error "No longer supported"
  | s -> ConstrParser

let set_default_action_parser = function
  | ConstrParser  -> default_action_parser_ref := dynconstr
  | CasesPatternParser  -> default_action_parser_ref := dyncasespattern

let default_action_parser =
  Gram.Entry.of_parser "default_action_parser" 
    (fun strm -> Gram.Entry.parse_token (get_default_action_parser ()) strm)

(**********************************************************************)
(* This determines (depending on the associativity of the current
   level and on the expected associativity) if a reference to constr_n is
   a reference to the current level (to be translated into "SELF" on the
   left border and into "constr LEVEL n" elsewhere), to the level below
   (to be translated into "NEXT") or to an below wrt associativity (to be
   translated in camlp4 into "constr" without level) or to another level
   (to be translated into "constr LEVEL n") *)

let assoc_level = function
  | Some Gramext.LeftA when !Options.v7 -> "L"
  | _ -> ""

let constr_level = function
  | n,assoc -> (string_of_int n)^(assoc_level assoc)

let constr_level2 = function
  | n,assoc -> (string_of_int n)^(assoc_level (Some assoc))

let default_levels_v7 =
  [10,Gramext.RightA;
   9,Gramext.RightA;
   8,Gramext.RightA;
   1,Gramext.RightA;
   0,Gramext.RightA]

let default_levels_v8 =
  [200,Gramext.RightA;
   100,Gramext.RightA;
   99,Gramext.RightA;
   90,Gramext.RightA;
   10,Gramext.RightA;
   9,Gramext.RightA;
   1,Gramext.LeftA;
   0,Gramext.RightA]

let default_pattern_levels_v8 =
  [10,Gramext.LeftA;
   0,Gramext.RightA]

let level_stack = 
  ref 
    [if !Options.v7 then (default_levels_v7, default_levels_v7)
     else (default_levels_v8, default_pattern_levels_v8)]

(* At a same level, LeftA takes precedence over RightA and NoneA *)
(* In case, several associativity exists for a level, we make two levels, *)
(* first LeftA, then RightA and NoneA together *)
exception Found of Gramext.g_assoc

open Ppextend

let admissible_assoc = function
  | Gramext.LeftA, Some (Gramext.RightA | Gramext.NonA) -> false
  | Gramext.RightA, Some Gramext.LeftA -> false
  | _ -> true

let create_assoc = function
  | None -> Gramext.RightA
  | Some a -> a

let error_level_assoc p current expected =
  let pr_assoc = function
    | Gramext.LeftA -> str "left"
    | Gramext.RightA -> str "right" 
    | Gramext.NonA -> str "non" in
  errorlabstrm ""
    (str "Level " ++ int p ++ str " is already declared " ++
     pr_assoc current ++ str " associative while it is now expected to be " ++
     pr_assoc expected ++ str " associative")

let find_position forpat other assoc lev =
  let default = if !Options.v7 then Some (10,Gramext.RightA) else None in
  let ccurrent,pcurrent as current = List.hd !level_stack in 
  match lev with
  | None ->
      level_stack := current :: !level_stack;
      None, (if other then assoc else None), None
  | Some n ->
      if !Options.v7 & n = 8 & assoc = Some Gramext.LeftA then 
	error "Left associativity not allowed at level 8";
      let after = ref default in
      let rec add_level q = function
        | (p,_ as pa)::l when p > n -> pa :: add_level (Some pa) l
        | (p,a as pa)::l as l' when p = n ->
	    if admissible_assoc (a,assoc) then raise (Found a);
	    (* No duplication of levels in v8 *)
	    if not !Options.v7 then error_level_assoc p a (out_some assoc);
	    (* Maybe this was (p,Left) and p occurs a second time *)
	    if a = Gramext.LeftA then
	      match l with
		| (p,a)::_ as l' when p = n -> raise (Found a)
		| _ -> after := Some pa; pa::(n,create_assoc assoc)::l
	    else
	      (* This was not (p,LeftA) hence assoc is RightA *)
	      (after := q; (n,create_assoc assoc)::l')
	| l ->
	    after := q; (n,create_assoc assoc)::l
      in
      try
	(* Create the entry *)
	let updated =
	  if forpat then (ccurrent, add_level default pcurrent)
	  else (add_level default ccurrent, pcurrent) in
        level_stack := updated:: !level_stack;
	let assoc = create_assoc assoc in
	(if !after = None then Some Gramext.First
	else Some (Gramext.After (constr_level2 (out_some !after)))),
	Some assoc, Some (constr_level2 (n,assoc))
      with
          Found a ->
            level_stack := current :: !level_stack;
	    (* Just inherit the existing associativity and name (None) *)
	    Some (Gramext.Level (constr_level2 (n,a))), None, None

let remove_levels n =
  level_stack := list_skipn n !level_stack

(* Camlp4 levels do not treat NonA: use RightA with a NEXT on the left *)
let camlp4_assoc = function
  | Some Gramext.NonA | Some Gramext.RightA -> Gramext.RightA 
  | None | Some Gramext.LeftA -> Gramext.LeftA

(* [adjust_level assoc from prod] where [assoc] and [from] are the name
   and associativity of the level where to add the rule; the meaning of
   the result is

     None = SELF
     Some None = NEXT
     Some (Some (n,cur)) = constr LEVEL n
         s.t. if [cur] is set then [n] is the same as the [from] level *)
let adjust_level assoc from = function
(* Associativity is None means force the level *)
  | (NumLevel n,BorderProd (_,None)) -> Some (Some (n,true))
(* Compute production name on the right side *)
  (* If NonA or LeftA on the right-hand side, set to NEXT *)
  | (NumLevel n,BorderProd (false,Some (Gramext.NonA|Gramext.LeftA))) ->
      Some None
  (* If RightA on the right-hand side, set to the explicit (current) level *)
  | (NumLevel n,BorderProd (false,Some Gramext.RightA)) ->
      Some (Some (n,true))
(* Compute production name on the left side *)
  (* If NonA on the left-hand side, adopt the current assoc ?? *)
  | (NumLevel n,BorderProd (true,Some Gramext.NonA)) -> None
  (* If the expected assoc is the current one, set to SELF *)
  | (NumLevel n,BorderProd (true,Some a)) when a = camlp4_assoc assoc ->
      None
  (* Otherwise, force the level, n or n-1, according to expected assoc *)
  | (NumLevel n,BorderProd (true,Some a)) ->
      if a = Gramext.LeftA then Some (Some (n,true)) else Some None
  (* None means NEXT *)
  | (NextLevel,_) -> Some None
(* Compute production name elsewhere *)
  | (NumLevel n,InternalProd) ->
      match from with
	| ETConstr (p,()) when p = n+1 -> Some None
	| ETConstr (p,()) -> Some (Some (n,n=p))
	| _ -> Some (Some (n,false))

(*
  (* If NonA on the right-hand side, set to NEXT *)
  | (n,BorderProd (false,Some Gramext.NonA)) -> Some None
  (* If NonA on the left-hand side, adopt the current assoc ?? *)
  | (n,BorderProd (true,Some Gramext.NonA)) -> None
  (* Associativity is None means force the level *)
  | (n,BorderProd (_,None)) -> Some (Some (n,true))
  (* If left assoc at a left level, set NEXT on the right *)
  | (n,BorderProd (false,Some (Gramext.LeftA as a)))
      when Gramext.LeftA = camlp4_assoc assoc -> Some None
  (* If right or none assoc expected is the current assoc, set explicit 
     level on the right side *)
  | (n,BorderProd (false,Some a)) when a = camlp4_assoc assoc ->
      Some (Some (n,true))
  (* If the expected assoc is the current one, SELF on the left sides *)
  | (n,BorderProd (true,Some a)) when a = camlp4_assoc assoc -> None
  (* Otherwise, force the level, n or n-1, according to expected assoc *)
  | (n,BorderProd (left,Some a)) ->
      if (left & a = Gramext.LeftA) or ((not left) & a = Gramext.RightA)
      then Some (Some (n,true)) else Some (Some (n-1,false))
(*  | (8,InternalProd) -> None (* Or (Some 8) for factorization ? *)*)
  | (n,InternalProd) ->
      match from with
	| ETConstr (p,()) when p = n+1 -> Some None
	| ETConstr (p,()) -> Some (Some (n,n=p))
	| _ -> Some (Some (n,false))
*)

let compute_entry allow_create adjust forpat = function
  | ETConstr (n,q) ->
      (if forpat then weaken_entry Constr.pattern
       else weaken_entry Constr.operconstr),
      (if forpat & !Options.v7 then None else adjust (n,q)), false
  | ETIdent -> weaken_entry Constr.ident, None, false
  | ETBigint -> weaken_entry Prim.bigint, None, false
  | ETReference -> weaken_entry Constr.global, None, false
  | ETPattern -> weaken_entry Constr.pattern, None, false
  | ETOther ("constr","annot") -> 
      weaken_entry Constr.annot, None, false
  | ETConstrList _ -> error "List of entries cannot be registered"
  | ETOther (u,n) ->
      let u = get_univ u in
      let e =
        try get_entry u n
        with e when allow_create -> create_entry u n ConstrArgType in
      object_of_typed_entry e, None, true

(* This computes the name of the level where to add a new rule *)
let get_constr_entry forpat en =
  match en with
      ETConstr(200,()) when not !Options.v7 & not forpat ->
	snd (get_entry (get_univ "constr") "binder_constr"),
        None,
        false
    | _ -> compute_entry true (fun (n,()) -> Some n) forpat en

(* This computes the name to give to a production knowing the name and
   associativity of the level where it must be added *)
let get_constr_production_entry ass from forpat en =
  (* first 2 cases to help factorisation *)
  match en with
    | ETConstr (NumLevel 10,q) when !Options.v7 & not forpat ->
        weaken_entry Constr.lconstr, None, false
(*
    | ETConstr (8,q) when !Options.v7 ->
        weaken_entry Constr.constr, None, false
*)
    | _ -> compute_entry false (adjust_level ass from) forpat en

let constr_prod_level assoc cur lev =
  if !Options.v7 then
    if cur then constr_level (lev,assoc) else
      match lev with
	| 4 when !Options.v7 -> "4L"
	| n -> string_of_int n
  else
    (* No duplication L/R of levels in v8 *)
    constr_level (lev,assoc)

let is_self from e =
  match from, e with
      ETConstr(n,()), ETConstr(NumLevel n',
        BorderProd(false, _ (* Some(Gramext.NonA|Gramext.LeftA) *))) -> false
    | ETConstr(n,()), ETConstr(NumLevel n',BorderProd(true,_)) -> n=n'
    | (ETIdent,ETIdent | ETReference, ETReference | ETBigint,ETBigint
      | ETPattern, ETPattern) -> true
    | ETOther(s1,s2), ETOther(s1',s2') -> s1=s1' & s2=s2'
    | _ -> false

let is_binder_level from e =
  match from, e with
      ETConstr(200,()),
      ETConstr(NumLevel 200,(BorderProd(false,_)|InternalProd)) ->
        not !Options.v7
    | _ -> false

let rec symbol_of_production assoc from forpat typ =
  if is_binder_level from typ then
    let eobj = snd (get_entry (get_univ "constr") "operconstr") in
    Gramext.Snterml (Gram.Entry.obj eobj,"200")
  else if is_self from typ then Gramext.Sself
  else
    match typ with
    | ETConstrList (typ',[]) ->
        Gramext.Slist1 (symbol_of_production assoc from forpat (ETConstr typ'))
    | ETConstrList (typ',tkl) ->
        Gramext.Slist1sep
          (symbol_of_production assoc from forpat (ETConstr typ'),
           Gramext.srules
             [List.map (fun x -> Gramext.Stoken x) tkl,
              List.fold_right (fun _ v -> Gramext.action (fun _ -> v)) tkl
                (Gramext.action (fun loc -> ()))])
    | _ ->
    match get_constr_production_entry assoc from forpat typ with
      | (eobj,None,_) -> Gramext.Snterm (Gram.Entry.obj eobj)
      | (eobj,Some None,_) -> Gramext.Snext
      | (eobj,Some (Some (lev,cur)),_) -> 
          Gramext.Snterml (Gram.Entry.obj eobj,constr_prod_level assoc cur lev)