Nmm_ocaml : Tags.expander_of

let expander_of_file (path : string) : Doc_types.ts_tag -> (string * string) option = (* TODO *)
	let file_string = IO.string_of_file path in
	let lines = String.split_on_char '\n' file_string in
	let rec collect_tags_singular (line_list : string list) (acc : (string*string*string) list) =
		match line_list with
		|[] -> acc
		|hd::tl -> 
			match String.split_on_char '\t' hd with
			|""::_ -> collect_tags_singular tl acc
			|singular::(_::(exp_ref::(exp_lbl::_))) -> collect_tags_singular tl ((singular, exp_lbl, exp_ref)::acc)
			|_ -> collect_tags_singular tl acc
	in
	let tag_list_singular : (string * string * string) list = collect_tags_singular lines [] in
	let rec collect_tags_plural (line_list : string list) (acc : (string*string*string) list) =
		match line_list with
		|[] -> acc
		|hd::tl -> 
			match String.split_on_char '\t' hd with
			|_::(""::_) -> collect_tags_plural tl acc
			|_::(plural::(_::(_::(exp_ref::(exp_lbl::_))))) -> collect_tags_plural tl ((plural, exp_lbl, exp_ref)::acc)
			|_ -> collect_tags_plural tl acc
	in
	let tag_list : (string * string * string) list = collect_tags_plural lines tag_list_singular in
	let rec match_tag_rec (tag_string : string) (lst : (string * string * string) list) : (string * string) option =
		match lst with
		|[] -> let _ : unit = IO.print_warning ("WARNING: undefined tag: " ^ tag_string) in None
		|(tag,exp_lbl,exp_ref)::tl ->
			if tag=tag_string then Some (exp_lbl, exp_ref) else match_tag_rec tag_string tl
	in
	let expand_tag (tag : Doc_types.ts_tag) : (string * string) option =
		if List.mem tag standard_tags then None else
		match tag with
		|Cs_tag tag_string -> match_tag_rec tag_string tag_list
	in expand_tag