let debug = false
let debug_print = if debug then prerr_endline else ignore

let loc = (0, 0)

let expand_unicode_macro macro =
  debug_print (Printf.sprintf "Expanding macro '%s' ..." macro);
  let expansion = Macro.expand macro in
  <:expr< $str:expansion$ >>

let _ =
  Quotation.add "unicode"
    (Quotation.ExAst (expand_unicode_macro, (fun _ -> assert false)))

open Pa_extend

EXTEND
  symbol: FIRST
    [
      [ x = UIDENT; q = QUOTATION ->
        let (quotation, arg) =
          let pos = String.index q ':' in
          (String.sub q 0 pos,
           String.sub q (pos + 1) (String.length q - pos - 1))
        in
        debug_print (Printf.sprintf "QUOTATION = %s; ARG = %s" quotation arg);
        if quotation = "unicode" then
          let text = TXtok (loc, x, expand_unicode_macro arg) in
          {used = []; text = text; styp = STlid (loc, "string")}
        else
          assert false
      ]
    ];
END