+*****************************************************************************)
+
+let init () = () (* FG: implementare l'apertura del database *)
+
+let close () = () (* FG: implementare la chiusura del database *)
+
+
+
+exception BooleExpTrue
+
+(* valuta una MathQL.set_exp e ritorna un MathQL.resource_set *)
+
+let rec exec_set_exp c = function
+ |MathQL.SVar svar -> List.assoc svar c.svars
+ |MathQL.RVar rvar -> [List.assoc rvar c.rvars]
+ | MathQL.Ref vexp -> List.map (fun s -> (s,[])) (exec_val_exp c vexp)
+ | MathQL.Intersect (sexp1, sexp2) -> intersect_ex (exec_set_exp c sexp1) (exec_set_exp c sexp2)
+ | MathQL.Union (sexp1, sexp2) -> union_ex (exec_set_exp c sexp1) (exec_set_exp c sexp2)
+ | MathQL.LetSVar (svar, sexp1, sexp2) -> let _ = (svar, (exec_set_exp c sexp1)):: (List.remove_assoc svar c.svars)
+ in (exec_set_exp c sexp2)
+ | MathQL.LetVVar (vvar, vexp, sexp) -> let _ = (vvar, (exec_val_exp c vexp)):: (List.remove_assoc vvar c.vvars)
+ in (exec_set_exp c sexp)
+ | MathQL.Relation (rop, path, sexp, attl) -> relation_ex rop path (exec_set_exp c sexp) attl
+ | MathQL.Select (rvar, sexp, bexp) -> let rset = (exec_set_exp c sexp) in
+ let rec select_ex rset =
+ match rset with
+ [] -> []
+ | r::tl -> upd_rvars c ((rvar,r)::c.rvars);
+ if (exec_boole_exp c bexp) then r::(select_ex tl)
+ else select_ex tl
+ in select_ex rset
+
+
+
+ | MathQL.Diff (sexp1, sexp2) -> diff_ex (exec_set_exp c sexp1) (exec_set_exp c sexp2)
+ | _ -> assert false
+
+(* valuta una MathQL.boole_exp e ritorna un boole *)
+
+and exec_boole_exp c = function
+ | MathQL.False -> false
+ | MathQL.True -> true
+ | MathQL.Not x -> not (exec_boole_exp c x)
+ | MathQL.And (x, y) -> (exec_boole_exp c x) && (exec_boole_exp c y)
+ | MathQL.Or (x, y) -> (exec_boole_exp c x) || (exec_boole_exp c y)
+ | MathQL.Sub (vexp1, vexp2) -> sub_ex (exec_val_exp c vexp1) (exec_val_exp c vexp2)
+ | MathQL.Meet (vexp1, vexp2) -> meet_ex (exec_val_exp c vexp1) (exec_val_exp c vexp2)
+ | MathQL.Eq (vexp1, vexp2) -> (exec_val_exp c vexp1) = (exec_val_exp c vexp2)
+ | MathQL.Ex l bexp ->
+ if l = [] then (exec_boole_exp c bexp)
+ else
+ let latt = List.map (fun uri ->
+ let (r,attl) = List.assoc uri c.rvars
+ in (uri,attl)) l (*latt = l + attributi*)
+ in
+ try
+ let rec prod c = function
+ [] -> if (exec_boole_exp c bexp) then raise BooleExpTrue
+ | (uri,attl)::tail1 -> let rec sub_prod attl =
+ match attl with
+(*per ogni el. di attl *) [] -> ()
+(*devo andare in ric. su tail1*) | att::tail2 -> upd_groups c ((uri,att)::c.groups);
+ prod c tail1; sub_prod tail2
+ in
+ sub_prod attl
+ in
+ prod c latt; false
+ with BooleExpTrue -> true
+ | _ -> assert false
+
+(* valuta una MathQL.val_exp e ritorna un MathQL.value *)
+
+and exec_val_exp c = function
+ | MathQL.Const x -> List.sort compare x
+ | MathQL.Record (rvar, vvar) -> List.assoc vvar (List.assoc rvar c.groups)
+
+ | MathQL.VVar s -> List.assoc s c.vvars
+ | MathQL.RefOf sexp -> List.map (fun (s,_) -> s) (exec_set_exp c sexp)
+
+ | _ -> assert false
+
+
+(* valuta una MathQL.set_exp nel contesto vuoto e ritorna un MathQL.resource_set *)
+
+and execute x =
+ exec_set_exp {svars = []; rvars = []; groups = []; vvars = []} x
+