(* 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/.
 *)

(******************************************************************************)
(*                                                                            *)
(*                               PROJECT HELM                                 *)
(*                                                                            *)
(*                     Ferruccio Guidi <fguidi@cs.unibo.it>                   *)
(*                     Domenico Lordi  <lordi@cs.unibo.it>                    *)
(*                                 30/04/2002                                 *)
(*                                                                            *)
(*                                                                            *)
(******************************************************************************)

exception MQInvalidURI of string
exception MQConnectionFailed of string
exception MQInvalidConnection of string

(* Input types **************************************************************)
(* main type is mquery                                                      *)

type mqrvar = string                       (* name *)

type mqsvar = string                       (* name *)

type mqpt = string option                  (* PROTOCOL TOKENS *)
                                           (* Some = constant string *)
                                           (* None = single star: '*' *)

type mqbt =                                (* BODY TOKENS *)
   | MQBC of string                        (* a constant string *)
   | MQBD                                  (* a slash: '/' *)
   | MQBQ                                  (* a question mark: '?' *)
   | MQBS                                  (* a single star: '*' *)
   | MQBSS                                 (* a double star: '**' *)

type mqft =                                (* FRAGMENT TOKENS *)
   | MQFC of int                           (* a constant integer *)
   | MQFS                                  (* a single star: '*' *)
   | MQFSS                                 (* a double star: '**' *)

type mqtref = mqpt * (mqbt list) * (mqft list) (* tokenized reference *)

type mqpattern = mqtref                     (* constant pattern *)

type mqfunc =
   | MQName                                 (* NAME *)
   | MQTheory
   | MQTitle
   | MQContributor
   | MQCreator
   | MQPublisher
   | MQSubject
   | MQDescription
   | MQDate
   | MQType
   | MQFormat
   | MQIdentifier
   | MQLanguage
   | MQRelation
   | MQSource
   | MQCoverage
   | MQRights
   | MQInstitution
   | MQContact
   | MQFirstVersion
   | MQModified

type mqstring =
   | MQCons of string                       (* constant *)
   | MQFunc of mqfunc * mqrvar              (* function, rvar *)
   | MQRVar of mqrvar                       (* rvar *)
   | MQSVar of mqsvar                       (* svar *)
   | MQMConclusion                          (* main conclusion *)
   | MQConclusion                           (* inner conclusion *)

type mqorder =
   | MQAsc
   | MQDesc

type mqbool =
   | MQTrue
   | MQFalse
   | MQAnd of mqbool * mqbool
   | MQOr of mqbool * mqbool
   | MQNot of mqbool
   | MQIs of mqstring * mqstring            (* operands                   *)
   | MQSetEqual of mqlist * mqlist          (* the two lists denote the   *)
                                            (* same set                   *)
   | MQSubset of mqlist * mqlist            (* the two lists denote two   *)
                                            (* sets, the first one        *)
                                            (* subsect of the second one. *)

and mqlist =
   | MQSelect of mqrvar * mqlist * mqbool   (* rvar, list, boolean        *) 
   | MQUse of mqlist * mqsvar               (* list, Position attribute   *)
   | MQUsedBy of mqlist * mqsvar            (* list, Position attribute   *)
   | MQPattern of mqpattern                 (* pattern                    *)
   | MQUnion of mqlist * mqlist             (* operands                   *)
   | MQIntersect of mqlist * mqlist         (* operands                   *)
   | MQSortedBy of mqlist * mqorder * mqfunc (*  *)
   | MQRVarOccur of mqrvar
   | MQDiff of mqlist * mqlist               (*  *)

type mquery =
   | MQList of mqlist
   
(* Output types *************************************************************)
(* main type is mqresult                                                    *)

(* TODO: usare le uri in questo formato *)
type mquref = UriManager.uri * (int list)   (* uri, fragment identifier *)

type mqrefs = string list                   (* list of references (helper) *)

type mqresult =
   | MQRefs of mqrefs