1 files changed, 46 insertions, 0 deletions
diff --git a/library/keys.ml b/library/keys.ml
new file mode 100644
index 000000000..5c295a385
--- /dev/null
+++ b/library/keys.ml
@@ -0,0 +1,46 @@
+open Globnames
+open Term
+open Libobject
+
+(* Union-find structure for references to be considered equivalent *)
+
+module RefUF = Unionfind.Make(Refset)(Refmap)
+
+let keys = (* Summary.ref ( *)RefUF.create ()(* ) ~name:"Keys_decl" *)
+
+let add_key k v = RefUF.union k v keys
+
+let equiv_keys k k' = RefUF.find k keys == RefUF.find k' keys
+
+(** Registration of keys as an object *)
+
+let load_key _ (_,(ref,ref')) =
+  add_key ref ref'
+
+let cache_key o =
+  load_key 1 o
+
+let subst_key (subst,(ref,ref')) =
+  (subst_global_reference subst ref,
+   subst_global_reference subst ref')
+
+let discharge_key (_,refs) =
+  match refs with 
+  | VarRef _, _ | _, VarRef _ -> None
+  | ref, ref' -> Some (pop_global_reference ref, pop_global_reference ref')
+
+let rebuild_key (ref,ref') = (ref, ref')
+
+type key_obj = global_reference * global_reference
+
+let inKeys : key_obj -> obj =
+  declare_object {(default_object "KEYS") with
+    cache_function = cache_key;
+    load_function = load_key;
+    subst_function = subst_key;
+    classify_function = (fun x -> Substitute x);
+    discharge_function = discharge_key;
+    rebuild_function = rebuild_key }
+
+let declare_keys ref ref' =
+  Lib.add_anonymous_leaf (inKeys (ref,ref'))