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 6bd620a108596575477b8c44cdf12cb426ed10d0..73bebaa507c2300f5bd90dcc4c5001d887744eae 100644 (file)
--- a/helm/ocaml/mathql_interpreter/intersect.ml
+++ b/helm/ocaml/mathql_interpreter/intersect.ml
@@ -23,54 +23,53 @@
  * http://cs.unibo.it/helm/.
  *)
 
-exception NotCompatible;;
 
-(* intersect_attributes is successful iff there is no attribute with *)
-(* two different values in the two lists. The returned list is the   *)
-(* union of the two lists.                                           *)
-let rec intersect_attributes (attr1, attr2) =
- match attr1, attr2 with
-    [],_ -> attr2
-  | _,[] -> attr1
-  | (key1,value1)::tl1, (key2,_)::_ when key1 < key2 ->
-      (key1,value1)::(intersect_attributes (tl1,attr2))
-  | (key1,_)::_, (key2,value2)::tl2 when key2 < key1 ->
-      (key2,value2)::(intersect_attributes (attr1,tl2))
-  | entry1::tl1, entry2::tl2 when entry1 = entry2 ->
-     entry1::(intersect_attributes (tl1,tl2))
-  | _, _ -> raise NotCompatible  (* same keys, different values *)
+(* 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) 
+
+;;
+
+
+(* 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))
+
+;;
+
+(* 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)) 
 ;;
 
-(* preserves order and gets rid of duplicates *)
-let rec intersect_ex l1 l2 =
- let module S = Mathql_semantics in
-  match (l1, l2) with
-     [],_
-   | _,[] -> []
-   | {S.uri = uri1}::tl1,
-     {S.uri = uri2}::_ when uri1 < uri2 -> intersect_ex tl1 l2
-   | {S.uri = uri1}::_,
-     {S.uri = uri2}::tl2 when uri2 < uri1 -> intersect_ex l1 tl2
-   | {S.uri = uri1 ; S.attributes = attributes1}::tl1,
-     {S.uri = uri2 ; S.attributes = attributes2}::tl2 ->
-       try
-        let attributes' = intersect_attributes (attributes1,attributes2) in
-         {S.uri = uri1 ; S.attributes = attributes'}::(intersect_ex tl1 tl2)
-       with
-        NotCompatible ->
-         intersect_ex tl1 tl2
+
+(* 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 *)
 ;;
 
-let intersect_ex l1 l2 =
- let before = Unix.time () in
- let res = intersect_ex l1 l2 in
- let after = Unix.time () in
-  let ll1 = string_of_int (List.length l1) in
-  let ll2 = string_of_int (List.length l2) in
-  let diff = string_of_float (after -. before) in
-  prerr_endline
-   ("INTERSECT(" ^ ll1 ^ "," ^ ll2 ^ ") = " ^ string_of_int (List.length res) ^
-    ": " ^ diff ^ "s") ;
-  flush stderr ;
-  res
+(* 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 
 ;;