bundles/menhirLib/menhir-20120123/src/lookahead.mli

   1 (**************************************************************************)
   2 (*                                                                        *)
   3 (*  Menhir                                                                *)
   4 (*                                                                        *)
   5 (*  François Pottier, INRIA Rocquencourt                                  *)
   6 (*  Yann Régis-Gianas, PPS, Université Paris Diderot                      *)
   7 (*                                                                        *)
   8 (*  Copyright 2005-2008 Institut National de Recherche en Informatique    *)
   9 (*  et en Automatique. All rights reserved. This file is distributed      *)
  10 (*  under the terms of the Q Public License version 1.0, with the change  *)
  11 (*  described in file LICENSE.                                            *)
  12 (*                                                                        *)
  13 (**************************************************************************)
  14
  15 (* These are the operations required of lookahead sets during
  16    a closure computation. This signature is exploited by the
  17    functor [Item.Closure]. *)
  18
  19 module type S = sig
  20
  21   (* The type of lookahead sets. *)
  22   type t
  23
  24   (* The empty lookahead set. Redundant with the following, but
  25      convenient. *)
  26   val empty: t
  27
  28   (* A concrete, constant set of terminal symbols. *)
  29   val constant: Grammar.TerminalSet.t -> t
  30
  31   (* [union s1 s2] returns the union of [s1] and [s2].  *)
  32   val union: t -> t -> t
  33
  34 end
  35