open Markup

type element = {
    namespace : string;
    local_name : string;
    attributes : (string * string) list;
    children : (element, string) Either.t list;
  }

let tree s : element option =
  let element (namespace, name) attributes children =
    Either.Left {
        namespace;
        local_name=name;
        attributes=List.filter_map
                     (fun ((ns, name), content) ->
                       (* remove xmlns -- we don't need it. *)
                       match ns with
                       | "http://www.w3.org/2000/xmlns/" -> None
                       | _ -> Some (name, content))
                     attributes;
        children;
      }
  and text ss = Either.Right (String.concat "" ss) in
  let opt_el = tree ~text ~element s in
  Option.bind opt_el (Either.fold ~left:Option.some ~right:(fun _ -> None))