1 files changed, 64 insertions, 0 deletions
diff --git a/kernel/context.ml b/kernel/context.ml
new file mode 100644
index 000000000..4bc268da1
--- /dev/null
+++ b/kernel/context.ml
@@ -0,0 +1,64 @@
+(************************************************************************)
+(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
+(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2012     *)
+(*   \VV/  **************************************************************)
+(*    //   *      This file is distributed under the terms of the       *)
+(*         *       GNU Lesser General Public License Version 2.1        *)
+(************************************************************************)
+
+open Names
+
+(***************************************************************************)
+(*     Type of assumptions                                                 *)
+(***************************************************************************)
+
+type named_declaration = Id.t * Constr.t option * Constr.t
+type rel_declaration = Name.t * Constr.t option * Constr.t
+
+let map_named_declaration f (id, (v : Constr.t option), ty) =
+  (id, Option.map f v, f ty)
+
+let map_rel_declaration = map_named_declaration
+
+let fold_named_declaration f (_, v, ty) a = f ty (Option.fold_right f v a)
+let fold_rel_declaration = fold_named_declaration
+
+let exists_named_declaration f (_, v, ty) = Option.cata f false v || f ty
+let exists_rel_declaration f (_, v, ty) = Option.cata f false v || f ty
+
+let for_all_named_declaration f (_, v, ty) = Option.cata f true v && f ty
+let for_all_rel_declaration f (_, v, ty) = Option.cata f true v && f ty
+
+let eq_named_declaration (i1, c1, t1) (i2, c2, t2) =
+  Id.equal i1 i2 && Option.equal Constr.equal c1 c2 && Constr.equal t1 t2
+
+let eq_rel_declaration (n1, c1, t1) (n2, c2, t2) =
+  Name.equal n1 n2 && Option.equal Constr.equal c1 c2 && Constr.equal t1 t2
+
+(***************************************************************************)
+(*     Type of local contexts (telescopes)                                 *)
+(***************************************************************************)
+
+(*s Signatures of ordered optionally named variables, intended to be
+   accessed by de Bruijn indices (to represent bound variables) *)
+
+type rel_context = rel_declaration list
+
+let empty_rel_context = []
+
+let add_rel_decl d ctxt = d::ctxt
+
+let rec lookup_rel n sign =
+  match n, sign with
+  | 1, decl :: _ -> decl
+  | n, _ :: sign -> lookup_rel (n-1) sign
+  | _, []        -> raise Not_found
+
+let rel_context_length = List.length
+
+let rel_context_nhyps hyps =
+  let rec nhyps acc = function
+    | [] -> acc
+    | (_,None,_)::hyps -> nhyps (1+acc) hyps
+    | (_,Some _,_)::hyps -> nhyps acc hyps in
+  nhyps 0 hyps