1 files changed, 81 insertions, 0 deletions
diff --git a/plugins/syntax/n_syntax.ml b/plugins/syntax/n_syntax.ml
new file mode 100644
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+++ b/plugins/syntax/n_syntax.ml
@@ -0,0 +1,81 @@
+(************************************************************************)
+(*         *   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)         *)
+(************************************************************************)
+
+open Pp
+open CErrors
+open Names
+open Bigint
+open Positive_syntax_plugin.Positive_syntax
+
+(* Poor's man DECLARE PLUGIN *)
+let __coq_plugin_name = "n_syntax_plugin"
+let () = Mltop.add_known_module __coq_plugin_name
+
+(**********************************************************************)
+(* Parsing N via scopes                                               *)
+(**********************************************************************)
+
+open Globnames
+open Glob_term
+
+let binnums = ["Coq";"Numbers";"BinNums"]
+
+let make_dir l = DirPath.make (List.rev_map Id.of_string l)
+let make_path dir id = Libnames.make_path (make_dir dir) (Id.of_string id)
+
+(* TODO: temporary hack *)
+let make_kn dir id = Globnames.encode_mind dir id
+
+let n_kn = make_kn (make_dir binnums) (Id.of_string "N")
+let glob_n = IndRef (n_kn,0)
+let path_of_N0 = ((n_kn,0),1)
+let path_of_Npos = ((n_kn,0),2)
+let glob_N0 = ConstructRef path_of_N0
+let glob_Npos = ConstructRef path_of_Npos
+
+let n_path = make_path binnums "N"
+
+let n_of_binnat ?loc pos_or_neg n = DAst.make ?loc @@
+  if not (Bigint.equal n zero) then
+    GApp(DAst.make @@ GRef (glob_Npos,None), [pos_of_bignat ?loc n])
+  else
+    GRef(glob_N0, None)
+
+let error_negative ?loc =
+  user_err ?loc ~hdr:"interp_N" (str "No negative numbers in type \"N\".")
+
+let n_of_int ?loc n =
+  if is_pos_or_zero n then n_of_binnat ?loc true n
+  else error_negative ?loc
+
+(**********************************************************************)
+(* Printing N via scopes                                              *)
+(**********************************************************************)
+
+let bignat_of_n n = DAst.with_val (function
+  | GApp (r, [a]) when is_gr r glob_Npos -> bignat_of_pos a
+  | GRef (a,_) when GlobRef.equal a glob_N0 -> Bigint.zero
+  | _ -> raise Non_closed_number
+  ) n
+
+let uninterp_n (AnyGlobConstr p) =
+  try Some (bignat_of_n p)
+  with Non_closed_number -> None
+
+(************************************************************************)
+(* Declaring interpreters and uninterpreters for N *)
+
+let _ = Notation.declare_numeral_interpreter "N_scope"
+  (n_path,binnums)
+  n_of_int
+  ([DAst.make @@ GRef (glob_N0, None);
+    DAst.make @@ GRef (glob_Npos, None)],
+  uninterp_n,
+  true)