-(*
- *
- *)
-let intersect_tails h1 t1 h2 t2 =
- let rec aux t1 t2 =
- match (t1, t2) with
- ([], _)
- | (_, []) -> []
- | ((l1::tl1)::tll1, (l2::tl2)::tll2) ->
- if l1 = l2 then
- try
- (*match xres_join_context h1 tl1 h2 tl2 with
- [] -> aux tll1 tll2
- | t -> (l1::(xres_join_context h1 tl1 h2 tl2))::(aux tll1 tll2)*)
- (l1::(tl1 @ tl2))::(aux tll1 tll2)
- with
- Join_must_be_empty -> aux tll1 tll2
- else
- if l1 < l2 then
- aux tll1 t2
- else
- aux t1 tll2
- | _ -> assert false
- in
- aux t1 t2
+
+(* Sums two attribute groups preserving order *)
+let rec sum_groups(gr1, gr2) =
+ match gr1, gr2 with
+ [],_ -> gr2
+ | _,[] -> gr1
+ | (key1,l1)::tl1, (key2,l2)::_ when key1 < key2 -> (key1,l1)::(sum_groups (tl1,gr2))
+ | (key1,l1)::_, (key2,l2)::tl2 when key2 < key1 -> (key2,l2)::(sum_groups (gr1,tl2))
+ | (key1,l1)::tl1, (key2,l2)::tl2 -> (key1,(append (l1,l2)))::(sum_groups (tl1,tl2))
+
+;;
+
+(* Product between an attribute set and a group of attributes *)
+let rec sub_prod (aset, gr) = (*prende un aset e un gr e fa la somma tra tutti i gruppi di aset e gr *)
+ match aset with
+ [] -> []
+ | gr1::tl1 -> sum_groups (gr1, gr)::(sub_prod(tl1, gr))
+;;
+
+
+(* Cartesian product between two attribute sets*)
+let rec prod (as1, as2) =
+ match as1, as2 with
+ [],_ -> as2
+ | _,[] -> as1
+ | gr1::tl1, _ -> (sub_prod (as2, gr1))@(prod (tl1, as2)) (* chiamo la sub_prod con un el. as1 e as2 *)
+;;
+
+(* Intersection between two resource sets, preserves order and gets rid of duplicates *)
+let intersect_ex rs1 rs2 =
+ let rec intersect_aux rs1 rs2 =
+ match (rs1, rs2) with
+ [],_
+ | _,[] -> []
+ | (uri1,_)::tl1,
+ (uri2,_)::_ when uri1 < uri2 -> intersect_aux tl1 rs2
+ | (uri1,_)::_,
+ (uri2,_)::tl2 when uri2 < uri1 -> intersect_aux rs1 tl2
+ | (uri1,as1)::tl1,
+ (uri2,as2)::tl2 -> (uri1, prod(as1,as2))::intersect_aux tl1 tl2
+ in
+ let before = Sys.time () in
+ let res = intersect_aux rs1 rs2 in
+ let after = Sys.time () in
+ let ll1 = string_of_int (List.length rs1) in
+ let ll2 = string_of_int (List.length rs2) in
+ let diff = string_of_float (after -. before) in
+ print_endline
+ ("INTERSECT(" ^ ll1 ^ "," ^ ll2 ^ ") = " ^ string_of_int (List.length res) ^
+ ": " ^ diff ^ "s") ;
+ flush stdout ;
+ res