(* 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>
 *)

module U = MQueryUtil

type pg_map = (MathQL.path * (bool * string * string option)) list

type pg_tables = (bool * string) list

type pg_alias = (string * string) list

let empty_map () = [], []

let read_map () =
   let map = Helm_registry.get "mathql_interpreter.db_map" in
   let ich = open_in map in 
   let rec aux r s =
      let d = input_line ich in 
      match Str.split (Str.regexp "[ \t]+") d with
	 | []                  -> aux r s
	 | "#" :: _            -> aux r s
	 | t ::      "<-" :: p -> aux ((p, (false, t, None)) :: r) s 
	 | t :: c :: "<-" :: p -> aux ((p, (false, t, Some c)) :: r) s
	 | t ::      "<+" :: p -> aux ((p, (true, t, None)) :: r) s 
	 | t :: c :: "<+" :: p -> aux ((p, (true, t, Some c)) :: r) s
	 | [a; "->"; t]        -> aux r ((a, t) :: s) 
	 | ["->"]              -> r, s
	 | _                   -> raise (Failure "MQIMap.read_map")
   in
   let pgm, pga = aux [] [] in
   close_in ich;
   pgm, pga

let comp c1 c2 = match c1, c2 with
   | (_, t1), (_, t2) when t1 < t2 -> U.Lt
   | (_, t1), (_, t2) when t1 > t2 -> U.Gt
   | (b1, t), (b2, _)              -> U.Eq (b1 || b2, t)

let get_tables pgm p =
   let aux l = function
      | q, (b, t, _) when q = p -> U.list_join comp l [(b, t)]
      | _, _                    -> l
    in
    List.fold_left aux [] pgm  

let rec refine_tables l1 l2 = 
   U.list_meet comp l1 l2
      
let default_table = function
   | [(_, a)] -> a
   | l        -> 
      try List.assoc true l 
      with Not_found -> raise (Failure "MQIMap.default_table")

let get_field pgm p t =
   let aux = function
      | q, (_, u, _) when q = p && u = t -> true
      | _                                -> false
   in 
   match List.filter aux pgm with
      | [_, (_, _, None)]   -> "" 
      | [_, (_, _, Some c)] -> c
      | _                   -> raise (Failure "MQIMap.get_field")

let resolve pga a =
   try List.assoc a pga with Not_found -> a