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|
(************************************************************************)
(* * The Coq Proof Assistant / The Coq Development Team *)
(* v * INRIA, CNRS and contributors - Copyright 1999-2018 *)
(* <O___,, * (see CREDITS file for the list of authors) *)
(* \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) *)
(************************************************************************)
(* Poor's man DECLARE PLUGIN *)
let __coq_plugin_name = "nat_syntax_plugin"
let () = Mltop.add_known_module __coq_plugin_name
(* This file defines the printer for natural numbers in [nat] *)
(*i*)
open Glob_term
open Bigint
open Coqlib
open Pp
open CErrors
(*i*)
(**********************************************************************)
(* Parsing via scopes *)
(* For example, (nat_of_string "3") is <<(S (S (S O)))>> *)
let threshold = of_int 5000
let warn_large_nat =
CWarnings.create ~name:"large-nat" ~category:"numbers"
(fun () -> strbrk "Stack overflow or segmentation fault happens when " ++
strbrk "working with large numbers in nat (observed threshold " ++
strbrk "may vary from 5000 to 70000 depending on your system " ++
strbrk "limits and on the command executed).")
let nat_of_int ?loc n =
if is_pos_or_zero n then begin
if less_than threshold n then warn_large_nat ();
let ref_O = DAst.make ?loc @@ GRef (glob_O, None) in
let ref_S = DAst.make ?loc @@ GRef (glob_S, None) in
let rec mk_nat acc n =
if n <> zero then
mk_nat (DAst.make ?loc @@ GApp (ref_S, [acc])) (sub_1 n)
else
acc
in
mk_nat ref_O n
end
else
user_err ?loc ~hdr:"nat_of_int"
(str "Cannot interpret a negative number as a number of type nat")
(************************************************************************)
(* Printing via scopes *)
exception Non_closed_number
let rec int_of_nat x = DAst.with_val (function
| GApp (r, [a]) ->
begin match DAst.get r with
| GRef (s,_) when Globnames.eq_gr s glob_S -> add_1 (int_of_nat a)
| _ -> raise Non_closed_number
end
| GRef (z,_) when Globnames.eq_gr z glob_O -> zero
| _ -> raise Non_closed_number
) x
let uninterp_nat (AnyGlobConstr p) =
try
Some (int_of_nat p)
with
Non_closed_number -> None
(************************************************************************)
(* Declare the primitive parsers and printers *)
let _ =
Notation.declare_numeral_interpreter "nat_scope"
(nat_path,datatypes_module_name)
nat_of_int
([DAst.make @@ GRef (glob_S,None); DAst.make @@ GRef (glob_O,None)], uninterp_nat, true)
|
