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module type Spec =
sig
val id_charset : Charset.t
val reserved : string list
end
module Make(S : Spec) =
struct
let reserved : string list ref = ref S.reserved
let mem : string -> bool = fun s ->
List.mem s !reserved
let reserve : string -> unit = fun s ->
if mem s then invalid_arg "already reserved";
reserved := s :: !reserved
let check : string -> unit = fun s ->
if List.mem s !reserved then Earley.give_up ()
let special : string -> unit Earley.grammar = fun s ->
if s = "" then invalid_arg "empty word";
let fn str pos =
let str = ref str in
let pos = ref pos in
for i = 0 to String.length s - 1 do
let (c, str', pos') = Input.read !str !pos in
if c <> s.[i] then Earley.give_up ();
str := str'; pos := pos'
done;
let c = Input.get !str !pos in
if Charset.mem S.id_charset c then Earley.give_up ();
((), !str, !pos)
in
Earley.black_box fn (Charset.singleton s.[0]) false s
let create : string -> unit Earley.grammar = fun s ->
if mem s then invalid_arg "keyword already defined";
reserve s; special s
end