Initial revision

[helm.git] / helm / ocaml / mathql_interpreter / intersect.ml

diff --git a/helm/ocaml/mathql_interpreter/intersect.ml b/helm/ocaml/mathql_interpreter/intersect.ml
index e346101cf9152a19599ba0241b853801ebf67d8b..73bebaa507c2300f5bd90dcc4c5001d887744eae 100644 (file)
--- a/helm/ocaml/mathql_interpreter/intersect.ml
+++ b/helm/ocaml/mathql_interpreter/intersect.ml
@@ -23,118 +23,53 @@
  * http://cs.unibo.it/helm/.
  *)
 
-(*
- * implementazione del comando INTERSECT
- *)
 
-(*
- * eccezione sollevata quando il join dei contesti
- * deve essere vuoto
- *)
-exception Join_must_be_empty;;
+(* Catenates two lists preserving order and getting rid of duplicates *)
+let rec append (l1,l2) =
+  match l1,l2 with
+     [],_ -> l2
+   | _,[] -> l1
+   | s1::tl1, s2::_ when s1 < s2 -> s1::append (tl1,l2)                     
+   | s1::_, s2::tl2 when s2 < s1 -> s2::append (l1,tl2) 
+   | s1::tl1, s2::tl2 -> s1::append (tl1,tl2) 
 
-(*
- * join fra due contesti
- *)
-let xres_join_context h1 l1 h2 l2 =
- match (l1, l2) with
-    ([], _) -> l2
- |  (_, []) -> l1
- |  (_,  _) ->
-     let hh = h2 @ (List.find_all (function t -> not (List.mem t h2)) h1)
-     and m1 = List.combine h1 l1
-     and m2 = List.combine h2 l2
-     in
-       List.map
-        (fun elem ->
-         let value1 = try (List.assoc elem m1) with Not_found -> List.assoc elem m2
-         and value2 = try (List.assoc elem m2) with Not_found -> List.assoc elem m1
-         in
-          if value1 = value2 then value1 else raise Join_must_be_empty
-        )
-        hh
 ;;
 
-(*
- *
- *)
-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
+   | gr1, gr2 when gr1 = 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))
+
 ;;
 
-(*
- * implementazione del comando INTERSECT
- *)
-let intersect_ex l1 l2 =
- let _ = print_string ("INTERSECT ")
- and t = Unix.time () in
-  let result = 
- match (l1, l2) with
-    ((head1::tail1), (head2::tail2)) ->
-     (match (head1, head2) with
-         ([], _) -> assert false (* gli header non devono mai essere vuoti *)
-      |  (_, []) -> assert false (* devono contenere almeno [retVal] *)
-      |  (_,  _) ->
-          (match (tail1, tail2) with
-              ([], _) -> [["retVal"]] (* se una delle due code e' vuota... *)
-           |  (_, []) -> [["retVal"]] (* ... l'intersezione e' vuota *)
-           |  (_,  _) ->
-               [head2 @
-                (List.find_all
-                (function t -> not (List.mem t head2))
-                head1
-               )
-              ] (* header del risultato finale *)
-              @
-              intersect_tails (List.tl head1) tail1 (List.tl head2) tail2
-              (*
-              List.fold_left
-                (fun par1 elem1 -> par1 @
-                 List.map
-                 (fun elem2 ->
-                  [(List.hd elem1)] @
-                  (xres_join_context (List.tl head1) (List.tl elem1)
-                                     (List.tl head2) (List.tl elem2)
-                   )
-                 )
-                  (List.find_all (* *)
-                   (fun elem2 ->    (* trova tutti gli elementi della lista tail2 *)
-                   ((List.hd elem1) = (List.hd elem2)) && (* che stanno in tail1 *)
-                   not ((xres_join_context (List.tl head1) (List.tl elem1)
-                                           (List.tl head2) (List.tl elem2)) = [])
-                   (* e per i quali la xres_join_context non sia vuota *)
-                  )
-                   tail2 (* List.find_all *)
-                 )
-                 )
-               []
-               tail1 (* per ogni elemento di tail1 applica la List.fold_left *)
-              *)
-          ) (* match *)
-     )
- | _ -> []
-  in
-   let _ = print_endline (string_of_float (Unix.time () -. t)); flush stdout in
-    result
+(* Product between an attribute set and a group of attributes *)
+let rec sub_prod (aset, gr) = (*prende un aset e un gr, 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
+    [],_ -> []   
+  | _,[] -> []   
+  | gr1::tl1, _ -> append((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 rec intersect_ex rs1 rs2 =
+  match (rs1, rs2) with
+    [],_
+  | _,[] -> []
+  | (uri1,_)::tl1, (uri2,_)::_ when uri1 < uri2 -> intersect_ex tl1 rs2
+  | (uri1,_)::_, (uri2,_)::tl2 when uri2 < uri1 -> intersect_ex rs1 tl2
+  | (uri1,as1)::tl1, (uri2,as2)::tl2 -> (uri1, prod(as1,as2))::intersect_ex tl1 tl2 
+;;