After Union and Relation

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

diff --git a/helm/ocaml/mathql_interpreter/union.ml b/helm/ocaml/mathql_interpreter/union.ml
index 5573c192ed74d77d3dcaaec436c84f4d23e00090..a02fbd0f5f417a054a9dbf07961f3ab3b828763f 100644 (file)
--- a/helm/ocaml/mathql_interpreter/union.ml
+++ b/helm/ocaml/mathql_interpreter/union.ml
@@ -27,6 +27,7 @@
  * implementazione del comando UNION
  *)
 
+(*
 (*
  * 
  *)
@@ -104,4 +105,36 @@ let union_ex alist1 alist2 =
         ) (* match *)
        )
 ;;
+*)
+(* Merges two attribute group lists preserves order and gets rid of duplicates*)
+let rec merge l1 l2 =
+  match (l1,l2) with
+     [],l
+   | l,[] -> l
+   | g1::tl1,g2::_ when g1 < g2 -> g1::(merge tl1 l2)
+   | g1::_,g2::tl2 when g2 < g1 -> g2::(merge l1 tl2)
+   | g1::tl1,g2::tl2 -> g1::(merge tl1 tl2)
+;;       
 
+(* preserves order and gets rid of duplicates *)
+let rec union_ex rs1 rs2 =
+  match (rs1, rs2) with
+     [],l
+   | l,[] -> l
+   | (uri1,l1)::tl1,(uri2,_)::_ when uri1 < uri2 -> (uri1,l1)::(union_ex tl1 rs2)
+   | (uri1,_)::_,(uri2,l2)::tl2 when uri2 < uri1 -> (uri2,l2)::(union_ex rs1 tl2)
+   | (uri1,l1)::tl1,(uri2,l2)::tl2 -> if l1 = l2 then (uri1,l1)::(union_ex tl1 tl2)
+                                     else (uri1,merge l1 l2)::(union_ex tl1 tl2)       
+;;
+
+let union_ex l1 l2 =
+ let before = Unix.time () in
+ let res = union_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
+  print_endline ("UNION(" ^ ll1 ^ "," ^ ll2 ^ "): " ^ diff ^ "s") ;
+  flush stdout ;
+  res
+;;