(* 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/.
 *)

(*
 *
 *)

open MathQL;;

(*
 * conversione di un pattern
 *)
let rec patterneval p =
 match p with
   [] -> ""
 | head::tail ->
    let h = match head with
               MQBC (s) -> Str.global_replace (Str.regexp "\.") "\\\\\." s
            |  MQBD -> "/"
            |  MQBQ -> "[^/#]?"
            |  MQBS -> "[^/#]*"
            |  MQBSS -> "[^#]*"
    in
     h ^ (patterneval tail)
;;

(*
 * conversione di un fragment identifier
 *)
let fieval fi =
match fi with
    [] -> ""
 |  MQFC i :: tail ->  
     let s = "#xpointer\\\\(1/" ^ string_of_int (i) in
      match tail with
         [] -> s ^ "\\\\)"
      |  MQFC j :: tail2 ->
	  s ^ "/" ^ string_of_int j ^ "\\\\)"
;;

(*
 * valuta l'estensione
 *
 * 20/05/2002: non piu' necessario: l'estensione fa eventualmente
 * parte del pattern precedente
 *)
let exteval ext =
 match ext with
    "" -> ""
 |  _  -> ("\." ^ ext)
;;

(*
 * valuta il preambolo
 *)
let preeval p =
 match p with 
   Some s -> s
;;

(*
 * trasforma un pattern MathQL in un pattern postgresql
 *
 * si utilizzano espressioni regolari POSIX anziche' l'operatore
 * SQL standard LIKE perche' MathQL prevede esperssioni con "*"
 * e con "**".
 *)
let pattern_match (preamble, pattern, fragid) =
 " ~ '" ^ (preeval preamble) ^ ":/" ^ (patterneval pattern) ^ (fieval fragid) ^ "'"
;;