(* Copyright (C) 2004, 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://helm.cs.unibo.it/
 *)

open Printf

open DisambiguateTypes

exception Invalid_choice
exception Choice_not_found of string

let symbol_choices = Hashtbl.create 1023
let num_choices = ref []

let add_symbol_choice symbol codomain_item =
  let current_choices =
    try
      Hashtbl.find symbol_choices symbol
    with Not_found -> []
  in
  Hashtbl.replace symbol_choices symbol (codomain_item :: current_choices)

let add_binary_op symbol dsc appl_head =
  add_symbol_choice symbol
    (dsc,
      (fun env _ args ->
        let t1, t2 =
          match args with
          | [t1; t2] -> t1, t2
          | _ -> raise Invalid_choice
        in
        Cic.Appl [ appl_head; t1; t2 ]))

let add_unary_op symbol dsc appl_head =
  add_symbol_choice symbol
    (dsc,
      (fun env _ args ->
        let t = match args with [t] -> t | _ -> raise Invalid_choice in
        Cic.Appl [ appl_head; t ]))

let add_num_choice choice = num_choices := choice :: !num_choices

let lookup_symbol_choices symbol =
  try
    Hashtbl.find symbol_choices symbol
  with Not_found -> []

let lookup_num_choices () = !num_choices

let has_description dsc = (fun x -> fst x = dsc)

let lookup_symbol_by_dsc symb dsc =
  try
    List.find (has_description dsc) (Hashtbl.find symbol_choices symb)
  with Not_found ->
    raise (Choice_not_found (sprintf "Symbol %s, dsc %s" symb dsc))

let lookup_num_by_dsc dsc =
  try
    List.find (has_description dsc) !num_choices
  with Not_found -> raise (Choice_not_found ("Num with dsc " ^  dsc))

  (** initial table contents *)

let _ =
  add_binary_op "exists" "exists"
    (Cic.MutInd (HelmLibraryObjects.Logic.ex_URI, 0, []));
  add_symbol_choice "cast"
    ("type cast",
      (fun env _ args ->
        let t1, t2 =
          match args with 
          | [t1; t2] -> t1, t2
          | _ -> raise Invalid_choice
        in
        Cic.Cast (t1, t2)));