Add Sexp.Of_sexp.capture

Signed-off-by: Jeremie Dimino <jeremie@dimino.org>

src/stdune/sexp.ml

@@ -199,6 +199,12 @@ module Of_sexp = struct
     let ctx = Values (Ast.loc sexp, None, context) in
     result ctx (t ctx [sexp])
 
+  let capture ctx state =
+    let f t =
+      result ctx (t ctx state)
+    in
+    (f, [])
+
   let end_of_list (Values (loc, cstr, _)) =
     match cstr with
     | None ->

src/stdune/sexp.mli

@@ -122,6 +122,9 @@ module Of_sexp : sig
       until the end of sequence is reached. *)
   val repeat : 'a t -> 'a list t
 
+  (** Capture the rest of the input for later parsing *)
+  val capture : ('a t -> 'a) t
+
   (** [enter t] expect the next element of the input to be a list and
       parse its contents with [t]. *)
   val enter : 'a t -> 'a t