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(************************************************************************)
(* v * The Coq Proof Assistant / The Coq Development Team *)
(* <O___,, * CNRS-Ecole Polytechnique-INRIA Futurs-Universite Paris Sud *)
(* \VV/ **************************************************************)
(* // * The HELM Project / The EU MoWGLI Project *)
(* * University of Bologna *)
(************************************************************************)
(* This file is distributed under the terms of the *)
(* GNU Lesser General Public License Version 2.1 *)
(* *)
(* Copyright (C) 2000-2004, HELM Team. *)
(* http://helm.cs.unibo.it *)
(************************************************************************)
exception CanNotUnshare;;
(* [unshare t] gives back a copy of t where all sharing has been removed *)
(* Physical equality becomes meaningful on unshared terms. Hashtables that *)
(* use physical equality can now be used to associate information to evey *)
(* node of the term. *)
let unshare ?(already_unshared = function _ -> false) t =
let obj = Obj.repr t in
let rec aux obj =
if already_unshared (Obj.obj obj) then
obj
else
(if Obj.is_int obj then
obj
else if Obj.is_block obj then
begin
let tag = Obj.tag obj in
if tag < Obj.no_scan_tag then
begin
let size = Obj.size obj in
let new_obj = Obj.new_block 0 size in
Obj.set_tag new_obj tag ;
for i = 0 to size - 1 do
Obj.set_field new_obj i (aux (Obj.field obj i))
done ;
new_obj
end
else if tag = Obj.string_tag then
obj
else
raise CanNotUnshare
end
else
raise CanNotUnshare
)
in
Obj.obj (aux obj)
;;
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