(* 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/.
 *)

(*
 * implementazione del comando SELECT
 *)

open MathQL;;
open Func;;
open Utility;;

exception ExecuteFunctionNotInitialized;;
let execute =
 ref
  (function _ -> raise ExecuteFunctionNotInitialized)
;;

(*
 * valutazione di una stringa
 *)
let stringeval env =
 let module S = Mathql_semantics in
  function
     MQCons s ->
      s
  |  MQFunc (f, rvar) ->
      let {S.uri = uri} = List.assoc rvar env in
       apply_func f uri
  |  MQRVar rvar ->
      let {S.uri = uri} = List.assoc rvar env in
       uri
  |  MQSVar svar ->
      let (_,{S.attributes = attributes}) = List.hd env in
       List.assoc svar attributes
  |  MQMConclusion ->
      "MainConclusion"
  |  MQConclusion ->
      "InConclusion"
;;

(*
 *
 *)
let rec is_good env =
 let module S = Mathql_semantics in
  function
     MQAnd (b1, b2) ->
      (is_good env b1) && (is_good env b2)
  |  MQOr (b1, b2) ->
      (is_good env b1) || (is_good env b2)
  |  MQNot b1 ->
      not (is_good env b1)
  |  MQTrue ->
      true
  |  MQFalse ->
      false
  |  MQIs (s1, s2) ->
      (stringeval env s1) = (stringeval env s2)
(*CSC: magari le prossime funzioni dovrebbero  andare in un file a parte, *)
(*CSC: insieme alla [execute] che utilizzano                              *)
  |  MQSetEqual (q1,q2) ->
      (* set_of_result returns an ordered list of uris without duplicates *)
      let rec set_of_result =
       function
          _,[] -> []
        | (Some olduri as v),{S.uri = uri}::tl when uri = olduri ->
            set_of_result (v,tl)
        | _,{S.uri = uri}::tl ->
            uri::(set_of_result (Some uri, tl))
      in
       let ul1 = set_of_result (None,!execute env q1) in
       let ul2 = set_of_result (None,!execute env q2) in
prerr_endline ("MQSETEQUAL(" ^ string_of_int (List.length (!execute env q1)) ^ ">" ^ string_of_int (List.length ul1) ^ "," ^ string_of_int (List.length (!execute env q2)) ^ ">" ^ string_of_int (List.length ul2) ^ ")") ; flush stderr ;
        (try
          List.fold_left2 (fun b uri1 uri2 -> b && uri1=uri2) true ul1 ul2
         with
          _ -> false)
  |  MQSubset (q1,q2) ->
(*CSC: codice cut&paste da sopra: ridurlo facendo un'unica funzione h.o. *)
      (* set_of_result returns an ordered list of uris without duplicates *)
      let rec set_of_result =
       function
          _,[] -> []
        | (Some olduri as v),{S.uri = uri}::tl when uri = olduri ->
            set_of_result (v,tl)
        | _,{S.uri = uri}::tl ->
            uri::(set_of_result (Some uri, tl))
      in
       let ul1 = set_of_result (None,!execute env q1) in
       let ul2 = set_of_result (None,!execute env q2) in
prerr_endline ("MQSUBSET(" ^ string_of_int (List.length (!execute env q1)) ^ ">" ^ string_of_int (List.length ul1) ^ "," ^ string_of_int (List.length (!execute env q2)) ^ ">" ^ string_of_int (List.length ul2) ^ ")") ; flush stderr ;
        let rec is_subset s1 s2 =
         match s1,s2 with
            [],_ -> true
          | _,[] -> false
          | uri1::tl1,uri2::tl2 when uri1 = uri2 ->
             is_subset tl1 tl2
          | uri1::_,uri2::tl2 when uri1 > uri2 ->
             is_subset s1 tl2
          | _,_ -> false
        in
         is_subset ul1 ul2
;;

(*
 * implementazione del comando SELECT
 *)
let select_ex env avar alist abool =
 let _ = print_string ("SELECT = ")
 and t = Unix.time () in
  let result = 
   List.filter (function entry -> is_good ((avar,entry)::env) abool) alist
  in
   print_string (string_of_int (List.length result) ^ ": ") ;
   print_endline (string_of_float (Unix.time () -. t) ^ "s") ;
   flush stdout ;
   result
;;