(* 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/.
 *)

(*  
 *) 

(* 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 vvar = string (* the name of a variable for an attribute value *)

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 bin = BinFJoin (* full union - with attr handling *)
         | BinFMeet (* full intersection - with attr handling *)
         | BinFDiff (* full difference - with attr handling *)

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

type test = Xor
          | Or
	  | And
          | Sub
	  | Meet
	  | Eq
	  | Le
	  | Lt

type query = Empty
           | SVar of svar
	   | AVar of avar
           | Subj of msval
	   | Property of inverse * refine * path * 
	                 main * istrue * isfalse list * exp_list *
	                 pattern * msval
           | Select of avar * query * msval
	   | Bin of bin * query * query
	   | LetSVar of svar * query * query
	   | LetVVar of vvar * msval * query
	   | For of gen * avar * query * query 
	   | Add of bool * groups * query
	   | If of msval * query * query
	   | Log of xml * source * query
	   | StatQuery of query
   	   | Keep of allbut * path list * query
	   
and msval = False
          | True
          | Not of msval
	  | Ex of avar list * msval
	  | Test of test * msval * msval
	  | Const of string
	  | Set of msval list
          | Proj of path option * query 
	  | Dot of avar * path
	  | VVar of vvar
	  | StatVal of msval
	  | Count of msval
	  | Align of string * msval

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

and con = pattern * path * msval

and istrue = con list

and isfalse = con list