#
# Check if an internal Rcpp function returns en error
#
.check_cpp_func_error <- function(obj, func_name) {

  if (obj[["errmsg"]] != "") {
    stop(paste0("Internal cpp function (", func_name, "()) failed: ",
                obj[["errmsg"]]), call. = FALSE)
  }
}

#
# Get a specified object
#
.get_obj <- function(obj, obj_name) {
  if (is.null(obj_name) || is.null(obj) || methods::is(obj, obj_name)) {
    obj
  } else {
    .get_obj(attr(obj, "src"), obj_name)
  }
}

#
# Get an argument of the specified source object
#
.get_obj_arg <- function(obj, obj_name, arg_name) {
  if (!is.null(obj_name) && !is.na(obj_name)) {
    obj <- .get_obj(obj, obj_name)
  }
  obj_args <- attr(obj, "args")
  if (is.null(obj_args)) {
    NULL
  } else {
    obj_args[[arg_name]]
  }
}

#
# Use scores and labels to create obj
#
.create_src_obj <- function(obj, obj_name, func, scores, labels,
                                         ...) {
  if (missing(obj)) {
    if (!is.null(scores) && !is.null(labels)) {
      obj <- func(scores = scores, labels = labels, ...)
    } else {
      stop("The first argument must be specified.", call. = FALSE)
    }
  }

  obj
}