(* Copyright (C) 2000, HELM Team.
 * 
 * This file is part of HELM, an Hypertextual, Electronic
 * Library of Mathematics, developed at the Computer Science
 * Department, University of Bologna, Italy.
 * 
 * HELM is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * HELM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HELM; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA  02111-1307, USA.
 * 
 * For details, see the HELM World-Wide-Web page,
 * http://cs.unibo.it/helm/.
 *)

(*
 * implementazione dei comandi USE/USED BY
 *)

open Utility;;
open Dbconn;;

(*
 * implementazione dei comandi USE/USED BY
 *
 * parametri:
 * alist: string list list; lista su cui eseguire il comando USE/USED BY
 * asvar: string; nome della variabile del comando use
 * usek: string; nome della tabella in cui ricercare le occorrenze;
 *               la distinzione fra l'esecuzione del comando USE e USED BY
 *               sta nell'utilizzo della tabella 'backPointer' per USE
 *               e 'refObj' per USED BY
 *
 * output: string list list; lista su cui e' stato eseguito il 
 *                           comando USE/USED BY
 *)
let use_ex alist asvar usek =
 let _ = print_string ("USE ")
 and t = Unix.time () in
 let result =
 let c = pgc ()
 in
  [ (List.hd alist) @ [asvar] ]
  @
  Sort.list
   (fun l m -> List.hd l < List.hd m)
   (List.fold_left
    (fun parziale xres ->
     (*let r1 = helm_property_id usek
     and r2 = helm_property_id "position"
     and r3 = helm_property_id "occurrence"
     in
      let qq = "select distinct t" ^ r3 ^ ".att1, t" ^ r2 ^ ".att1 " ^
       "from t" ^ r3 ^ ", t" ^ r2 ^ ", t" ^ r1 ^ " " ^
       "where " ^ "t" ^ r1 ^ ".att0 = '" ^ (List.hd xres) ^ "' and t" ^ r1 ^
       ".att1 = t" ^ r2 ^ ".att0 and t" ^ r1 ^ ".att1 = t" ^ r3 ^
       ".att0 order by t" ^ r3 ^ ".att1 asc"*)
      let tv = pgresult_to_string (c#exec ("select id from registry where uri='" ^ (List.hd xres) ^ "'")) in
      let qq = "select uri, context from t" ^ tv ^ " where back_for='" ^ usek ^ "'"
      in
      let res = c#exec qq in
       (List.map
        (fun l -> [List.hd l] @ List.tl xres @ List.tl l)
        res#get_list
       )
       @
       parziale
    )
    []
    (List.tl alist)
   )
 in
  let _ = print_endline (string_of_float (Unix.time () -. t)); flush stdout in
   result
;;