(******************************************************************************)
(*  SXSI : XPath evaluator                                                    *)
(*  Kim Nguyen (Kim.Nguyen@nicta.com.au)                                      *)
(*  Copyright NICTA 2008                                                      *)
(*  Distributed under the terms of the LGPL (see LICENCE)                     *)
(******************************************************************************)
(*  maybe utf8 string... *)


type t = int
type pool

external null_pool : unit -> pool = "caml_xml_tree_nullt"
external null_tag : unit -> t = "caml_xml_tree_nullt"
external register_tag : pool -> string -> t = "caml_xml_tree_register_tag"
external tag_name : pool -> t -> string = "caml_xml_tree_tag_name"

let nullt = null_tag ()   
let pcdata = max_int
let attribute = max_int - 1

let pool = ref (null_pool ())

let init p = pool := p

let tag s = match s with
  | "<$>" -> pcdata
  | "<@>" -> attribute
  | _ -> register_tag !pool s

let compare = (-)
let equal = (==)
let to_string t = 
  if t = pcdata then "<$>"
  else if t = attribute then "<@>"
  else tag_name !pool t


let print ppf t = Format.fprintf ppf "%s" (to_string t)