has_render_content() function

common.inc

/**
 * Checks that a render array has content that can be rendered.
 *
 * @param $element
 *   The element to check.
 *
 * @param $offset
 *   The key of the child to check.
 *
 * @return bool
 *   TRUE if the element has access granted and content that can be rendered.
 */
function has_render_content($element, $offset) {
  // Require element and offset.
  if (!$element || !$offset || empty($element[$offset])) {
    return FALSE;
  }
  // Stop if access is denied.
  if (isset($element[$offset]['#access']) && !$element[$offset]['#access']) {
    return FALSE;
  }
  // Check for first renderable child.
  $children = element_get_visible_children($element[$offset]);
  if (!empty($children)) {
    $child_checks = array();
    foreach ($children as $key) {
      if (has_render_content($element[$offset], $key)) {
        $child_checks[$key] = TRUE;
        continue;
      }
    }
    return !empty($child_checks);
  }
  else {
    // We are checking an element with no renderable children.
    // i.e. stark.tools in #region sidebar_first
    // How do we know this element should be shown?
    //
    return !empty($element[$offset]['#children']);
  }
}