(* 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://www.cs.unibo.it/helm/.
 *)

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

(* output data structures ***************************************************)

type path            = string list            (* the name of an attribute *)

type value           = string list            (* the value of an attribute *)

type attribute       = path * value           (* an attribute *)

type attribute_group = attribute list         (* a group of attributes *)

type attribute_set   = attribute_group list   (* the attributes of an URI *)

type resource        = string * attribute_set (* an attributed URI *)

type resource_set    = resource list          (* the query result *)

type result = resource_set


(* input data structures ****************************************************)

type svar = string (* the name of a variable for a resource set *)

type avar = string (* the name of a variable for a resource *)

type inverse = bool 

type refine = RefineExact
            | RefineSub
	    | RefineSuper

type main = path

type pattern = bool

type exp = path * (path option) 

type exp_list = exp list

type allbut = bool

type xml = bool

type source = bool

type gen = GenFJoin (* full union - with attr handling *)
         | GenFMeet (* full intersection - with attr handling *)

type query = Const of result
	   | SVar of svar
	   | AVar of avar
	   | Dot of avar * path
	   | Ex of avar list * query
	   | Select of avar * query * query
	   | Let of svar option * query * query
	   | Fun of path * path list * query list
	   | Gen of path * query list
	   | Add of bool * groups * query
	   | For of gen * avar * query * query
	   | While of gen * query * query
	   | Property of inverse * refine * path * 
	                 main * istrue * isfalse list * exp_list *
	                 pattern * query

and groups = Attr of (path * query) list list
           | From of avar

and con = pattern * path * query

and istrue = con list

and isfalse = con list