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|
(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2016 *)
(* \VV/ **************************************************************)
(* // * This file is distributed under the terms of the *)
(* * GNU Lesser General Public License Version 2.1 *)
(************************************************************************)
(* This file defines the printer for natural numbers in [nat] *)
(*i*)
open Glob_term
open Bigint
open Coqlib
open Pp
open Errors
(*i*)
(**********************************************************************)
(* Parsing via scopes *)
(* For example, (nat_of_string "3") is <<(S (S (S O)))>> *)
let threshold = of_int 5000
let nat_of_int dloc n =
if is_pos_or_zero n then begin
if less_than threshold n then
msg_warning
(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 ref_O = GRef (dloc, glob_O, None) in
let ref_S = GRef (dloc, glob_S, None) in
let rec mk_nat acc n =
if n <> zero then
mk_nat (GApp (dloc,ref_S, [acc])) (sub_1 n)
else
acc
in
mk_nat ref_O n
end
else
user_err_loc (dloc, "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 = function
| GApp (_,GRef (_,s,_),[a]) when Globnames.eq_gr s glob_S -> add_1 (int_of_nat a)
| GRef (_,z,_) when Globnames.eq_gr z glob_O -> zero
| _ -> raise Non_closed_number
let uninterp_nat 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
([GRef (Loc.ghost,glob_S,None); GRef (Loc.ghost,glob_O,None)], uninterp_nat, true)
|
