(* 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/.
 *)

(*  AUTOR: Ferruccio Guidi <fguidi@cs.unibo.it>
 *)

type connection = Mysql.dbd

let init connection_string =
   try
    Some
     (Mysql.quick_connect
       ~host:"mowgli.cs.unibo.it" ~database:"mowgli" ~user:"helm" ())
   with _ -> raise (Failure ("MQIPostgres.init: " ^ connection_string))

let close = function
   |  None   -> ()
   |  Some c -> Mysql.disconnect c

let exec c q = match c with
   | None   -> []
   | Some c ->
      Mysql.map
       ~f:(function a ->
         List.map
          (function
              None -> raise (Failure ("NULL found in a table"))
            | Some v -> v
          ) (Array.to_list a)
       ) (Mysql.exec c q)
   
let quote s =
   let rec quote_aux s =
      try
         let l = String.length s in
         let i = String.index s '\'' in
         String.sub s 0 i ^ "\\'" ^ quote_aux (String.sub s (succ i) (l - (succ i)))
      with Not_found -> s
   in
   "'" ^ quote_aux s ^ "'"