X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Focaml%2Fmathql_interpreter%2Funion.ml;h=e2d9fcb01a7e75be68bc141783eca03ccb1423bf;hb=515c1195a3b3ff86bf002091b4535bc812aa40ea;hp=2a759535a1b7c08bf54ad4e6d29c2ef76cc4f822;hpb=8abd42ec1af0d5daef1d026ec550b49b07de8340;p=helm.git

diff --git a/helm/ocaml/mathql_interpreter/union.ml b/helm/ocaml/mathql_interpreter/union.ml
index 2a759535a..e2d9fcb01 100644
--- a/helm/ocaml/mathql_interpreter/union.ml
+++ b/helm/ocaml/mathql_interpreter/union.ml
@@ -27,75 +27,26 @@
  * implementazione del comando UNION
  *)
 
-(*
- * 
- *)
-let xres_fill_context hr h1 l1 =
- match l1 with
-    [] -> []
- |   _ ->
-     let hh = List.combine h1 l1
-     in
-      List.map
-       (fun x ->
-        if (List.mem_assoc x hh) then
-	 List.assoc x hh
-	else
-	 ""
-       )
-       hr
-;;
 
-(*
- * implementazione del comando UNION
- *)
-let union_ex alist1 alist2 =
- let head1 = List.hd alist1
- and tail1 = List.tl alist1
- and head2 = List.hd alist2
- and tail2 = List.tl alist2 (* e fin qui ... *)
- in
-  match (head1, head2) with
-     ([], _) -> assert false (* gli header non devono mai essere vuoti *)
-  |  (_, []) -> assert false (* devono contenere almeno [retVal] *)
-  |  (_,  _) -> let headr = (head2 @
-                            (List.find_all
-			     (function t -> not (List.mem t head2))
-			     head1)
-			    ) in (* header del risultato finale *)
-      List.append (* il risultato finale e' la concatenazione ...*)
-       [headr] (* ... dell'header costruito prima ...*)
-       (match (tail1, tail2) with (* e di una coda "unione" *)
-           ([], _) -> tail2 (* va bene perche' l'altra lista e' vuota *)
-        |  (_, []) -> tail1 (* va bene perche' l'altra lista e' vuota *)
-        |  (_,  _) ->
-	    let first = (* parte dell'unione che riguarda solo il primo set *)
-	     List.map (fun l -> [List.hd l] @
-	               xres_fill_context
-	                (List.tl headr) (List.tl head1) (List.tl l)
-		      ) tail1
-            in
-	     List.fold_left
-	      (fun par x ->
-	       let y = (* elemento candidato ad entrare *)
-	        [List.hd x]
-		@
-	        xres_fill_context
-	         (List.tl headr) (List.tl head2) (List.tl x)
-	       in
-	        par @ if (List.find_all (fun t -> t = y) par) = [] then
-		       [y]
-		      else
-		       []
-	      )
-	      first
-	      tail2
-(*	     first @
-	     List.map (fun l -> [List.hd l] @
-	               xres_fill_context
-	                (List.tl headr) (List.tl head2) (List.tl l)
-		      ) tail2
-*)
-       ) (* 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)	
 ;;
 
+