(*
    ||M||  This file is part of HELM, an Hypertextual, Electronic        
    ||A||  Library of Mathematics, developed at the Computer Science     
    ||T||  Department, University of Bologna, Italy.                     
    ||I||                                                                
    ||T||  HELM is free software; you can redistribute it and/or         
    ||A||  modify it under the terms of the GNU General Public License   
    \   /  version 2 or (at your option) any later version.              
     \ /   This software is distributed as is, NO WARRANTY.              
      V_______________________________________________________________ *)

module U = NUri
module L = Log
module H = U.UriHash
module Y = Entity
module B = Bag

exception ObjectNotFound of B.message

let hsize = 7000 
let env = H.create hsize

(* Internal functions *******************************************************)

let get_age = 
   let age = ref 0 in
   fun () -> incr age; !age

let error uri = raise (ObjectNotFound (L.items1 (U.string_of_uri uri)))

(* Interface functions ******************************************************)

let set_entity f (a, uri, b) =
   let age = get_age () in
   let entry = (Y.Apix age :: a), uri, b in
   H.add env uri entry; f entry

let get_entity f uri =
   try f (H.find env uri) with Not_found -> error uri