type uri = Item.uri
type id = Item.id
+type attr = Name of bool * id (* real?, name *)
+ | Apix of int (* additional position index *)
+
+type attrs = attr list
+
type bind = Void (* exclusion *)
| Abst of term (* abstraction *)
| Abbr of term (* abbreviation *)
| Appl of attrs * term * term (* attrs, argument, function *)
| Bind of attrs * bind * term (* attrs, binder, scope *)
-and attr = Name of bool * id (* real?, name *)
- | Entry of int * bind (* age, binder *)
-
-and attrs = attr list
-
type obj = bind Item.obj (* age, uri, binder *)
type item = bind Item.item
-type context = (attrs * bind) list (* attrs, binder *)
+type context = Null
+(* Cons: tail, relative context, attrs, binder *)
+ | Cons of context * context option * attrs * bind
type message = (context, term) Log.item list
(* context handling functions ***********************************************)
-let empty_context = []
+let empty_context = Null
-let push f es a b =
- let c = (a, b) :: es in f c
+let push f es ?c a b =
+ let es = Cons (es, c, a, b) in f es
-let append f es1 es2 =
- f (List.append es2 es1)
-
-let map f map es =
- Cps.list_map f map es
-
-let contents f es = f es
-
-let get f es i =
- let rec aux e i = function
- | [] -> f e None
- | hd :: tl ->
- if i = 0 then f e (Some hd) else
- let e = match hd with _, Abst _ -> succ e | _ -> e in
- aux e (pred i) tl
+let get err f es i =
+ let rec aux j = function
+ | Null -> err i
+ | Cons (tl, None, a, b) when j = 0 -> f tl a b
+ | Cons (_, Some c, a, b) when j = 0 -> f c a b
+ | Cons (tl, _, _, _) -> aux (pred j) tl
in
- aux 0 i es
-
-let rec name f = function
- | [] -> f None
- | Name (r, n) :: _ -> f (Some (r, n))
- | _ :: tl -> name f tl
+ aux i es
+
+let rec rev_iter f map = function
+ | Null -> f ()
+ | Cons (tl, None, a, b) ->
+ let f () = map f tl a b in rev_iter f map tl
+ | Cons (tl, Some c, a, b) ->
+ let f () = map f c a b in rev_iter f map tl
+
+let rec fold_left f map x = function
+ | Null -> f x
+ | Cons (tl, _, a, b) ->
+ let f x = fold_left f map x tl in
+ map f x a b
+
+let rec name err f = function
+ | [] -> err ()
+ | Name (r, n) :: _ -> f n r
+ | _ :: tl -> name err f tl
+
+let rec apix err f = function
+ | [] -> err ()
+ | Apix i :: _ -> f i
+ | _ :: tl -> apix err f tl