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menu.inc

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  • Nathaniel Catchpole's avatar
    Issue #2078583 by dawehner, pwolanin | disasm: Fixed menu callbacks removed...
    catch authored
    Issue #2078583 by dawehner, pwolanin | disasm: Fixed menu callbacks removed from hook_menu() do not display any menus.
    2e6aaf6a
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    menu.inc 123.58 KiB
    <?php
    
    /**
     * @file
     * API for the Drupal menu system.
     */
    
    use Drupal\Component\Utility\NestedArray;
    use Drupal\Core\Cache\CacheBackendInterface;
    use Drupal\Core\Language\Language;
    use Drupal\Core\Template\Attribute;
    use Drupal\menu_link\Entity\MenuLink;
    use Drupal\menu_link\MenuLinkStorageController;
    use Symfony\Cmf\Component\Routing\RouteObjectInterface;
    use Symfony\Component\HttpFoundation\Request;
    use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
    use Symfony\Component\Routing\Route;
    
    /**
     * @defgroup menu Menu system
     * @{
     * Define the navigation menus, and route page requests to code based on URLs.
     *
     * The Drupal menu system drives both the navigation system from a user
     * perspective and the callback system that Drupal uses to respond to URLs
     * passed from the browser. For this reason, a good understanding of the
     * menu system is fundamental to the creation of complex modules. As a note,
     * this is related to, but separate from menu.module, which allows menus
     * (which in this context are hierarchical lists of links) to be customized from
     * the Drupal administrative interface.
     *
     * Drupal's menu system follows a simple hierarchy defined by paths.
     * Implementations of hook_menu() define menu items and assign them to
     * paths (which should be unique). The menu system aggregates these items
     * and determines the menu hierarchy from the paths. For example, if the
     * paths defined were a, a/b, e, a/b/c/d, f/g, and a/b/h, the menu system
     * would form the structure:
     * - a
     *   - a/b
     *     - a/b/c/d
     *     - a/b/h
     * - e
     * - f/g
     * Note that the number of elements in the path does not necessarily
     * determine the depth of the menu item in the tree.
     *
     * When responding to a page request, the menu system looks to see if the
     * path requested by the browser is registered as a menu item with a
     * callback. If not, the system searches up the menu tree for the most
     * complete match with a callback it can find. If the path a/b/i is
     * requested in the tree above, the callback for a/b would be used.
     *
     * The found callback function is called with any arguments specified
     * in the "page arguments" attribute of its menu item. The
     * attribute must be an array. After these arguments, any remaining
     * components of the path are appended as further arguments. In this
     * way, the callback for a/b above could respond to a request for
     * a/b/i differently than a request for a/b/j.
     *
     * For an illustration of this process, see page_example.module.
     *
     * Access to the callback functions is also protected by the menu system.
     * The "access callback" with an optional "access arguments" of each menu
     * item is called before the page callback proceeds. If this returns TRUE,
     * then access is granted; if FALSE, then access is denied. Default local task
     * menu items (see next paragraph) may omit this attribute to use the value
     * provided by the parent item.
     *
     * In the default Drupal interface, you will notice many links rendered as
     * tabs. These are known in the menu system as "local tasks", and they are
     * rendered as tabs by default, though other presentations are possible.
     * Local tasks function just as other menu items in most respects. It is
     * convention that the names of these tasks should be short verbs if
     * possible. In addition, a "default" local task should be provided for
     * each set. When visiting a local task's parent menu item, the default
     * local task will be rendered as if it is selected; this provides for a
     * normal tab user experience. This default task is special in that it
     * links not to its provided path, but to its parent item's path instead.
     * The default task's path is only used to place it appropriately in the
     * menu hierarchy.
     *
     * Everything described so far is stored in the menu_router table. The
     * menu_links table holds the visible menu links. By default these are
     * derived from the same hook_menu definitions, however you are free to
     * add more with menu_link_save().
     */
    
    /**
     * @defgroup menu_flags Menu flags
     * @{
     * Flags for use in the "type" attribute of menu items.
     */
    
    /**
     * Internal menu flag -- menu item is the root of the menu tree.
     */
    const MENU_IS_ROOT = 0x0001;
    
    /**
     * Internal menu flag -- menu item is visible in the menu tree.
     */
    const MENU_VISIBLE_IN_TREE = 0x0002;
    
    /**
     * Internal menu flag -- menu item is visible in the breadcrumb.
     */
    const MENU_VISIBLE_IN_BREADCRUMB = 0x0004;
    
    /**
     * Internal menu flag -- menu item links back to its parent.
     */
    const MENU_LINKS_TO_PARENT = 0x0008;
    
    /**
     * Internal menu flag -- menu item can be modified by administrator.
     */
    const MENU_MODIFIED_BY_ADMIN = 0x0020;
    
    /**
     * Internal menu flag -- menu item was created by administrator.
     */
    const MENU_CREATED_BY_ADMIN = 0x0040;
    
    /**
     * Internal menu flag -- menu item is a local task.
     */
    const MENU_IS_LOCAL_TASK = 0x0080;
    
    /**
     * Internal menu flag -- menu item is a local action.
     */
    const MENU_IS_LOCAL_ACTION = 0x0100;
    
    /**
     * @} End of "defgroup menu_flags".
     */
    
    /**
     * @defgroup menu_item_types Menu item types
     * @{
     * Definitions for various menu item types.
     *
     * Menu item definitions provide one of these constants, which are shortcuts for
     * combinations of @link menu_flags Menu flags @endlink.
     */
    
    /**
     * Menu type -- A "normal" menu item that's shown in menu and breadcrumbs.
     *
     * Normal menu items show up in the menu tree and can be moved/hidden by
     * the administrator. Use this for most menu items. It is the default value if
     * no menu item type is specified.
     */
    define('MENU_NORMAL_ITEM', MENU_VISIBLE_IN_TREE | MENU_VISIBLE_IN_BREADCRUMB);
    
    /**
     * Menu type -- A hidden, internal callback, typically used for API calls.
     *
     * Callbacks simply register a path so that the correct function is fired
     * when the URL is accessed. They do not appear in menus or breadcrumbs.
     */
    const MENU_CALLBACK = 0x0000;
    
    /**
     * Menu type -- A normal menu item, hidden until enabled by an administrator.
     *
     * Modules may "suggest" menu items that the administrator may enable. They act
     * just as callbacks do until enabled, at which time they act like normal items.
     * Note for the value: 0x0010 was a flag which is no longer used, but this way
     * the values of MENU_CALLBACK and MENU_SUGGESTED_ITEM are separate.
     */
    define('MENU_SUGGESTED_ITEM', MENU_VISIBLE_IN_BREADCRUMB | 0x0010);
    
    /**
     * Menu type -- A task specific to the parent item, usually rendered as a tab.
     *
     * Local tasks are menu items that describe actions to be performed on their
     * parent item. An example is the path "node/52/edit", which performs the
     * "edit" task on "node/52".
     */
    define('MENU_LOCAL_TASK', MENU_IS_LOCAL_TASK | MENU_VISIBLE_IN_BREADCRUMB);
    
    /**
     * Menu type -- The "default" local task, which is initially active.
     *
     * Every set of local tasks should provide one "default" task, that links to the
     * same path as its parent when clicked.
     */
    define('MENU_DEFAULT_LOCAL_TASK', MENU_IS_LOCAL_TASK | MENU_LINKS_TO_PARENT | MENU_VISIBLE_IN_BREADCRUMB);
    
    /**
     * Menu type -- An action specific to the parent, usually rendered as a link.
     *
     * Local actions are menu items that describe actions on the parent item such
     * as adding a new user, taxonomy term, etc.
     */
    define('MENU_LOCAL_ACTION', MENU_IS_LOCAL_TASK | MENU_IS_LOCAL_ACTION | MENU_VISIBLE_IN_BREADCRUMB);
    
    /**
     * Menu type -- A task specific to the parent, which is never rendered.
     *
     * Sibling local tasks are not rendered themselves, but affect the breadcrumb
     * trail and need their sibling tasks rendered as tabs.
     */
    define('MENU_SIBLING_LOCAL_TASK', MENU_IS_LOCAL_TASK | MENU_IS_LOCAL_ACTION | MENU_VISIBLE_IN_BREADCRUMB);
    
    /**
     * @} End of "defgroup menu_item_types".
     */
    
    /**
     * @defgroup menu_context_types Menu context types
     * @{
     * Flags for use in the "context" attribute of menu router items.
     */
    
    /**
     * Internal menu flag: Invisible local task.
     *
     * This flag may be used for local tasks like "Delete", so custom modules and
     * themes can alter the default context and expose the task by altering menu.
     */
    const MENU_CONTEXT_NONE = 0x0000;
    
    /**
     * Internal menu flag: Local task should be displayed in page context.
     */
    const MENU_CONTEXT_PAGE = 0x0001;
    
    /**
     * Internal menu flag: Local task should be displayed inline.
     */
    const MENU_CONTEXT_INLINE = 0x0002;
    
    /**
     * @} End of "defgroup menu_context_types".
     */
    
    /**
     * @defgroup menu_status_codes Menu status codes
     * @{
     * Status codes for menu callbacks.
     */
    
    /**
     * Internal menu status code -- Menu item was not found.
     */
    const MENU_NOT_FOUND = 404;
    
    /**
     * Internal menu status code -- Menu item access is denied.
     */
    const MENU_ACCESS_DENIED = 403;
    
    /**
     * Internal menu status code -- Menu item inaccessible because site is offline.
     */
    const MENU_SITE_OFFLINE = 4;
    
    /**
     * Internal menu status code -- Everything is working fine.
     */
    const MENU_SITE_ONLINE = 5;
    
    /**
     * @} End of "defgroup menu_status_codes".
     */
    
    /**
     * @defgroup menu_tree_parameters Menu tree parameters
     * @{
     * Parameters for a menu tree.
     */
    
     /**
     * The maximum number of path elements for a menu callback
     */
    const MENU_MAX_PARTS = 9;
    
    
    /**
     * The maximum depth of a menu links tree - matches the number of p columns.
     *
     * @todo Move this constant to MenuLinkStorageController along with all the tree
     * functionality.
     */
    const MENU_MAX_DEPTH = 9;
    
    
    /**
     * @} End of "defgroup menu_tree_parameters".
     */
    
    /**
     * Reserved key to identify the most specific menu link for a given path.
     *
     * The value of this constant is a hash of the constant name. We use the hash
     * so that the reserved key is over 32 characters in length and will not
     * collide with allowed menu names:
     * @code
     * sha1('MENU_PREFERRED_LINK') = 1cf698d64d1aa4b83907cf6ed55db3a7f8e92c91
     * @endcode
     *
     * @see menu_link_get_preferred()
     */
    const MENU_PREFERRED_LINK = '1cf698d64d1aa4b83907cf6ed55db3a7f8e92c91';
    
    /**
     * Returns the ancestors (and relevant placeholders) for any given path.
     *
     * For example, the ancestors of node/12345/edit are:
     * - node/12345/edit
     * - node/12345/%
     * - node/%/edit
     * - node/%/%
     * - node/12345
     * - node/%
     * - node
     *
     * To generate these, we will use binary numbers. Each bit represents a
     * part of the path. If the bit is 1, then it represents the original
     * value while 0 means wildcard. If the path is node/12/edit/foo
     * then the 1011 bitstring represents node/%/edit/foo where % means that
     * any argument matches that part. We limit ourselves to using binary
     * numbers that correspond the patterns of wildcards of router items that
     * actually exists. This list of 'masks' is built in menu_router_rebuild().
     *
     * @param $parts
     *   An array of path parts, for the above example
     *   array('node', '12345', 'edit').
     *
     * @return
     *   An array which contains the ancestors and placeholders. Placeholders
     *   simply contain as many '%s' as the ancestors.
     */
    function menu_get_ancestors($parts) {
      $number_parts = count($parts);
      $ancestors = array();
      $length =  $number_parts - 1;
      $end = (1 << $number_parts) - 1;
      $masks = Drupal::state()->get('menu.masks');
      // If the optimized menu.masks array is not available use brute force to get
      // the correct $ancestors and $placeholders returned. Do not use this as the
      // default value of the menu.masks variable to avoid building such a big
      // array.
      if (!$masks) {
        $masks = range(511, 1);
      }
      // Only examine patterns that actually exist as router items (the masks).
      foreach ($masks as $i) {
        if ($i > $end) {
          // Only look at masks that are not longer than the path of interest.
          continue;
        }
        elseif ($i < (1 << $length)) {
          // We have exhausted the masks of a given length, so decrease the length.
          --$length;
        }
        $current = '';
        for ($j = $length; $j >= 0; $j--) {
          // Check the bit on the $j offset.
          if ($i & (1 << $j)) {
            // Bit one means the original value.
            $current .= $parts[$length - $j];
          }
          else {
            // Bit zero means means wildcard.
            $current .= '%';
          }
          // Unless we are at offset 0, add a slash.
          if ($j) {
            $current .= '/';
          }
        }
        $ancestors[] = $current;
      }
      return $ancestors;
    }
    
    /**
     * Unserializes menu data, using a map to replace path elements.
     *
     * The menu system stores various path-related information (such as the 'page
     * arguments' and 'access arguments' components of a menu item) in the database
     * using serialized arrays, where integer values in the arrays represent
     * arguments to be replaced by values from the path. This function first
     * unserializes such menu information arrays, and then does the path
     * replacement.
     *
     * The path replacement acts on each integer-valued element of the unserialized
     * menu data array ($data) using a map array ($map, which is typically an array
     * of path arguments) as a list of replacements. For instance, if there is an
     * element of $data whose value is the number 2, then it is replaced in $data
     * with $map[2]; non-integer values in $data are left alone.
     *
     * As an example, an unserialized $data array with elements ('node_load', 1)
     * represents instructions for calling the node_load() function. Specifically,
     * this instruction says to use the path component at index 1 as the input
     * parameter to node_load(). If the path is 'node/123', then $map will be the
     * array ('node', 123), and the returned array from this function will have
     * elements ('node_load', 123), since $map[1] is 123. This return value will
     * indicate specifically that node_load(123) is to be called to load the node
     * whose ID is 123 for this menu item.
     *
     * @param $data
     *   A serialized array of menu data, as read from the database.
     * @param $map
     *   A path argument array, used to replace integer values in $data; an integer
     *   value N in $data will be replaced by value $map[N]. Typically, the $map
     *   array is generated from a call to the arg() function.
     *
     * @return
     *   The unserialized $data array, with path arguments replaced.
     */
    function menu_unserialize($data, $map) {
      if ($data = unserialize($data)) {
        foreach ($data as $k => $v) {
          if (is_int($v)) {
            $data[$k] = isset($map[$v]) ? $map[$v] : '';
          }
        }
        return $data;
      }
      else {
        return array();
      }
    }
    
    
    
    /**
     * Replaces the statically cached item for a given path.
     *
     * @param $path
     *   The path.
     * @param $router_item
     *   The router item. Usually a router entry from menu_get_item() is either
     *   modified or set to a different path. This allows the navigation block,
     *   the page title, the breadcrumb, and the page help to be modified in one
     *   call.
     */
    function menu_set_item($path, $router_item) {
      menu_get_item($path, $router_item);
    }
    
    /**
     * Gets a router item.
     *
     * @param $path
     *   The path; for example, 'node/5'. The function will find the corresponding
     *   node/% item and return that.
     * @param $router_item
     *   Internal use only.
     *
     * @return
     *   The router item or, if an error occurs in _menu_translate(), FALSE. A
     *   router item is an associative array corresponding to one row in the
     *   menu_router table. The value corresponding to the key 'map' holds the
     *   loaded objects. The value corresponding to the key 'access' is TRUE if the
     *   current user can access this page. The values corresponding to the keys
     *   'title', 'page_arguments', 'access_arguments', and 'theme_arguments' will
     *   be filled in based on the database values and the objects loaded.
     */
    function menu_get_item($path = NULL, $router_item = NULL) {
      $router_items = &drupal_static(__FUNCTION__);
      if (!isset($path)) {
        $path = current_path();
      }
      if (isset($router_item)) {
        $router_items[$path] = $router_item;
      }
      if (!isset($router_items[$path])) {
        // Rebuild if we know it's needed, or if the menu masks are missing which
        // occurs rarely, likely due to a race condition of multiple rebuilds.
        if (Drupal::state()->get('menu_rebuild_needed') || !Drupal::state()->get('menu.masks')) {
          menu_router_rebuild();
        }
        $original_map = arg(NULL, $path);
    
        $parts = array_slice($original_map, 0, MENU_MAX_PARTS);
        $ancestors = menu_get_ancestors($parts);
        $router_item = db_query_range('SELECT * FROM {menu_router} WHERE path IN (:ancestors) ORDER BY fit DESC', 0, 1, array(':ancestors' => $ancestors))->fetchAssoc();
    
        if ($router_item) {
          // Allow modules to alter the router item before it is translated and
          // checked for access.
          drupal_alter('menu_get_item', $router_item, $path, $original_map);
    
          $map = _menu_translate($router_item, $original_map);
          $router_item['original_map'] = $original_map;
          if ($map === FALSE) {
            $router_items[$path] = FALSE;
            return FALSE;
          }
          if ($router_item['access']) {
            $router_item['map'] = $map;
            $router_item['page_arguments'] = array_merge(menu_unserialize($router_item['page_arguments'], $map), array_slice($map, $router_item['number_parts']));
            $router_item['theme_arguments'] = array_merge(menu_unserialize($router_item['theme_arguments'], $map), array_slice($map, $router_item['number_parts']));
          }
        }
        $router_items[$path] = $router_item;
      }
      return $router_items[$path];
    }
    
    /**
     * Loads objects into the map as defined in the $item['load_functions'].
     *
     * @param $item
     *   A menu router or menu link item
     * @param $map
     *   An array of path arguments; for example, array('node', '5').
     *
     * @return
     *   Returns TRUE for success, FALSE if an object cannot be loaded.
     *   Names of object loading functions are placed in $item['load_functions'].
     *   Loaded objects are placed in $map[]; keys are the same as keys in the
     *   $item['load_functions'] array.
     *   $item['access'] is set to FALSE if an object cannot be loaded.
     */
    function _menu_load_objects(&$item, &$map) {
      if ($load_functions = $item['load_functions']) {
        // If someone calls this function twice, then unserialize will fail.
        if (!is_array($load_functions)) {
          $load_functions = unserialize($load_functions);
        }
        $path_map = $map;
        foreach ($load_functions as $index => $function) {
          if ($function) {
            $value = isset($path_map[$index]) ? $path_map[$index] : '';
            if (is_array($function)) {
              // Set up arguments for the load function. These were pulled from
              // 'load arguments' in the hook_menu() entry, but they need
              // some processing. In this case the $function is the key to the
              // load_function array, and the value is the list of arguments.
              list($function, $args) = each($function);
              $load_functions[$index] = $function;
    
              // Some arguments are placeholders for dynamic items to process.
              foreach ($args as $i => $arg) {
                if ($arg === '%index') {
                  // Pass on argument index to the load function, so multiple
                  // occurrences of the same placeholder can be identified.
                  $args[$i] = $index;
                }
                if ($arg === '%map') {
                  // Pass on menu map by reference. The accepting function must
                  // also declare this as a reference if it wants to modify
                  // the map.
                  $args[$i] = &$map;
                }
                if (is_int($arg)) {
                  $args[$i] = isset($path_map[$arg]) ? $path_map[$arg] : '';
                }
              }
              array_unshift($args, $value);
              $return = call_user_func_array($function, $args);
            }
            else {
              $return = $function($value);
            }
            // If callback returned an error or there is no callback, trigger 404.
            if (empty($return)) {
              $item['access'] = FALSE;
              $map = FALSE;
              return FALSE;
            }
            $map[$index] = $return;
          }
        }
        $item['load_functions'] = $load_functions;
      }
      return TRUE;
    }
    
    /**
     * Checks access to a menu item using the access callback.
     *
     * @param $item
     *   A menu router or menu link item
     * @param $map
     *   An array of path arguments; for example, array('node', '5').
     *
     * @return
     *   $item['access'] becomes TRUE if the item is accessible, FALSE otherwise.
     */
    function _menu_check_access(&$item, $map) {
      // Determine access callback, which will decide whether or not the current
      // user has access to this path.
      $callback = empty($item['access_callback']) ? 0 : trim($item['access_callback']);
      // Check for a TRUE or FALSE value.
      if (is_numeric($callback)) {
        $item['access'] = (bool) $callback;
      }
      else {
        $arguments = menu_unserialize($item['access_arguments'], $map);
        // As call_user_func_array is quite slow and user_access is a very common
        // callback, it is worth making a special case for it.
        if ($callback == 'user_access') {
          $item['access'] = (count($arguments) == 1) ? user_access($arguments[0]) : user_access($arguments[0], $arguments[1]);
        }
        else {
          $item['access'] = call_user_func_array($callback, $arguments);
        }
      }
    }
    
    /**
     * Localizes the router item title using t() or another callback.
     *
     * Translate the title and description to allow storage of English title
     * strings in the database, yet display of them in the language required
     * by the current user.
     *
     * @param $item
     *   A menu router item or a menu link item.
     * @param $map
     *   The path as an array with objects already replaced. E.g., for path
     *   node/123 $map would be array('node', $node) where $node is the node
     *   object for node 123.
     * @param $link_translate
     *   TRUE if we are translating a menu link item; FALSE if we are
     *   translating a menu router item.
     *
     * @return
     *   No return value.
     *   $item['title'] is localized according to $item['title_callback'].
     *   If an item's callback is check_plain(), $item['options']['html'] becomes
     *   TRUE.
     *   $item['description'] is computed using $item['description_callback'] if
     *   specified; otherwise it is translated using t().
     *   When doing link translation and the $item['options']['attributes']['title']
     *   (link title attribute) matches the description, it is translated as well.
     */
    function _menu_item_localize(&$item, $map, $link_translate = FALSE) {
      $title_callback = $item['title_callback'];
      $item['localized_options'] = $item['options'];
      // All 'class' attributes are assumed to be an array during rendering, but
      // links stored in the database may use an old string value.
      // @todo In order to remove this code we need to implement a database update
      //   including unserializing all existing link options and running this code
      //   on them, as well as adding validation to menu_link_save().
      if (isset($item['options']['attributes']['class']) && is_string($item['options']['attributes']['class'])) {
        $item['localized_options']['attributes']['class'] = explode(' ', $item['options']['attributes']['class']);
      }
      // If we are translating the title of a menu link, and its title is the same
      // as the corresponding router item, then we can use the title information
      // from the router. If it's customized, then we need to use the link title
      // itself; can't localize.
      // If we are translating a router item (tabs, page, breadcrumb), then we
      // can always use the information from the router item.
      if (!$link_translate || ($item['title'] == $item['link_title'])) {
        // t() is a special case. Since it is used very close to all the time,
        // we handle it directly instead of using indirect, slower methods.
        if ($title_callback == 't') {
          if (empty($item['title_arguments'])) {
            $item['title'] = t($item['title']);
          }
          else {
            $item['title'] = t($item['title'], menu_unserialize($item['title_arguments'], $map));
          }
        }
        elseif ($title_callback) {
          if (empty($item['title_arguments'])) {
            $item['title'] = $title_callback($item['title']);
          }
          else {
            $item['title'] = call_user_func_array($title_callback, menu_unserialize($item['title_arguments'], $map));
          }
          // Avoid calling check_plain again on l() function.
          if ($title_callback == 'check_plain') {
            $item['localized_options']['html'] = TRUE;
          }
        }
      }
      elseif ($link_translate) {
        $item['title'] = $item['link_title'];
      }
    
      // Translate description, see the motivation above.
      if (!empty($item['description'])) {
        $original_description = $item['description'];
      }
      if (!empty($item['description_arguments']) || !empty($item['description'])) {
        $description_callback = $item['description_callback'];
        // If the description callback is t(), call it directly.
        if ($description_callback == 't') {
          if (empty($item['description_arguments'])) {
            $item['description'] = t($item['description']);
          }
          else {
            $item['description'] = t($item['description'], menu_unserialize($item['description_arguments'], $map));
          }
        }
        elseif ($description_callback) {
          // If there are no arguments, call the description callback directly.
          if (empty($item['description_arguments'])) {
            $item['description'] = $description_callback($item['description']);
          }
          // Otherwise, use call_user_func_array() to pass the arguments.
          else {
            $item['description'] = call_user_func_array($description_callback, menu_unserialize($item['description_arguments'], $map));
          }
        }
      }
      // If the title and description are the same, use the translated description
      // as a localized title.
      if ($link_translate && isset($original_description) && isset($item['options']['attributes']['title']) && $item['options']['attributes']['title'] == $original_description) {
        $item['localized_options']['attributes']['title'] = $item['description'];
      }
    }
    
    /**
     * Handles dynamic path translation and menu access control.
     *
     * When a user arrives on a page such as node/5, this function determines
     * what "5" corresponds to, by inspecting the page's menu path definition,
     * node/%node. This will call node_load(5) to load the corresponding node
     * object.
     *
     * It also works in reverse, to allow the display of tabs and menu items which
     * contain these dynamic arguments, translating node/%node to node/5.
     *
     * Translation of menu item titles and descriptions are done here to
     * allow for storage of English strings in the database, and translation
     * to the language required to generate the current page.
     *
     * @param $router_item
     *   A menu router item
     * @param $map
     *   An array of path arguments; for example, array('node', '5').
     * @param $to_arg
     *   Execute $item['to_arg_functions'] or not. Use only if you want to render a
     *   path from the menu table, for example tabs.
     *
     * @return
     *   Returns the map with objects loaded as defined in the
     *   $item['load_functions']. $item['access'] becomes TRUE if the item is
     *   accessible, FALSE otherwise. $item['href'] is set according to the map.
     *   If an error occurs during calling the load_functions (like trying to load
     *   a non-existent node) then this function returns FALSE.
     */
    function _menu_translate(&$router_item, $map, $to_arg = FALSE) {
      if ($to_arg && !empty($router_item['to_arg_functions'])) {
        // Fill in missing path elements, such as the current uid.
        _menu_link_map_translate($map, $router_item['to_arg_functions']);
      }
      // The $path_map saves the pieces of the path as strings, while elements in
      // $map may be replaced with loaded objects.
      $path_map = $map;
      if (!empty($router_item['load_functions']) && !_menu_load_objects($router_item, $map)) {
        // An error occurred loading an object.
        $router_item['access'] = FALSE;
        return FALSE;
      }
    
      // Generate the link path for the page request or local tasks.
      $link_map = explode('/', $router_item['path']);
      if (isset($router_item['tab_root'])) {
        $tab_root_map = explode('/', $router_item['tab_root']);
      }
      if (isset($router_item['tab_parent'])) {
        $tab_parent_map = explode('/', $router_item['tab_parent']);
      }
      for ($i = 0; $i < $router_item['number_parts']; $i++) {
        if ($link_map[$i] == '%') {
          $link_map[$i] = $path_map[$i];
        }
        if (isset($tab_root_map[$i]) && $tab_root_map[$i] == '%') {
          $tab_root_map[$i] = $path_map[$i];
        }
        if (isset($tab_parent_map[$i]) && $tab_parent_map[$i] == '%') {
          $tab_parent_map[$i] = $path_map[$i];
        }
      }
      $router_item['href'] = implode('/', $link_map);
      $router_item['tab_root_href'] = implode('/', $tab_root_map);
      $router_item['tab_parent_href'] = implode('/', $tab_parent_map);
      $router_item['options'] = array();
      if (!empty($router_item['route_name'])) {
        // Route-provided menu items do not have menu loaders, so replace the map
        // with the link map.
        $map = $link_map;
    
        $route_provider = Drupal::getContainer()->get('router.route_provider');
        $route = $route_provider->getRouteByName($router_item['route_name']);
        $router_item['access'] = menu_item_route_access($route, $router_item['href'], $map);
      }
      else {
        // @todo: Remove once all routes are converted.
        _menu_check_access($router_item, $map);
      }
    
      // For performance, don't localize an item the user can't access.
      if ($router_item['access']) {
        _menu_item_localize($router_item, $map);
      }
    
      return $map;
    }
    
    /**
     * Translates the path elements in the map using any to_arg helper function.
     *
     * @param $map
     *   An array of path arguments; for example, array('node', '5').
     * @param $to_arg_functions
     *   An array of helper functions; for example, array(2 => 'menu_tail_to_arg').
     *
     * @see hook_menu()
     */
    function _menu_link_map_translate(&$map, $to_arg_functions) {
      $to_arg_functions = unserialize($to_arg_functions);
      foreach ($to_arg_functions as $index => $function) {
        // Translate place-holders into real values.
        $arg = $function(!empty($map[$index]) ? $map[$index] : '', $map, $index);
        if (!empty($map[$index]) || isset($arg)) {
          $map[$index] = $arg;
        }
        else {
          unset($map[$index]);
        }
      }
    }
    
    /**
     * Returns a string containing the path relative to the current index.
     */
    function menu_tail_to_arg($arg, $map, $index) {
      return implode('/', array_slice($map, $index));
    }
    
    /**
     * Loads the path as one string relative to the current index.
     *
     * To use this load function, you must specify the load arguments
     * in the router item as:
     * @code
     * $item['load arguments'] = array('%map', '%index');
     * @endcode
     *
     * @see search_menu().
     */
    function menu_tail_load($arg, &$map, $index) {
      $arg = implode('/', array_slice($map, $index));
      $map = array_slice($map, 0, $index);
      return $arg;
    }
    
    /**
     * Provides menu link access control, translation, and argument handling.
     *
     * This function is similar to _menu_translate(), but it also does
     * link-specific preparation (such as always calling to_arg() functions).
     *
     * @param $item
     *   A menu link.
     * @param $translate
     *   (optional) Whether to try to translate a link containing dynamic path
     *   argument placeholders (%) based on the menu router item of the current
     *   path. Defaults to FALSE. Internally used for breadcrumbs.
     *
     * @return
     *   Returns the map of path arguments with objects loaded as defined in the
     *   $item['load_functions'].
     *   $item['access'] becomes TRUE if the item is accessible, FALSE otherwise.
     *   $item['href'] is generated from link_path, possibly by to_arg functions.
     *   $item['title'] is generated from link_title, and may be localized.
     *   $item['options'] is unserialized; it is also changed within the call here
     *   to $item['localized_options'] by _menu_item_localize().
     */
    function _menu_link_translate(&$item, $translate = FALSE) {
      if (!is_array($item['options'])) {
        $item['options'] = unserialize($item['options']);
      }
      if ($item['external']) {
        $item['access'] = 1;
        $map = array();
        $item['href'] = $item['link_path'];
        $item['title'] = $item['link_title'];
        $item['localized_options'] = $item['options'];
      }
      else {
        // Complete the path of the menu link with elements from the current path,
        // if it contains dynamic placeholders (%).
        $map = explode('/', $item['link_path']);
        if (strpos($item['link_path'], '%') !== FALSE) {
          // Invoke registered to_arg callbacks.
          if (!empty($item['to_arg_functions'])) {
            _menu_link_map_translate($map, $item['to_arg_functions']);
          }
          // Or try to derive the path argument map from the current router item,
          // if this $item's path is within the router item's path. This means
          // that if we are on the current path 'foo/%/bar/%/baz', then
          // menu_get_item() will have translated the menu router item for the
          // current path, and we can take over the argument map for a link like
          // 'foo/%/bar'. This inheritance is only valid for breadcrumb links.
          // @see _menu_tree_check_access()
          // @see menu_get_active_breadcrumb()
          elseif ($translate && ($current_router_item = menu_get_item())) {
            // If $translate is TRUE, then this link is in the active trail.
            // Only translate paths within the current path.
            if (strpos($current_router_item['path'], $item['link_path']) === 0) {
              $count = count($map);
              $map = array_slice($current_router_item['original_map'], 0, $count);
              $item['original_map'] = $map;
              if (isset($current_router_item['map'])) {
                $item['map'] = array_slice($current_router_item['map'], 0, $count);
              }
              // Reset access to check it (for the first time).
              unset($item['access']);
            }
          }
        }
        $item['href'] = implode('/', $map);
    
        // Skip links containing untranslated arguments.
        if (strpos($item['href'], '%') !== FALSE) {
          $item['access'] = FALSE;
          return FALSE;
        }
        // menu_tree_check_access() may set this ahead of time for links to nodes.
        if (!isset($item['access'])) {
          if ($route = $item->getRoute()) {
            $item['access'] = menu_item_route_access($route, $item['href'], $map);
          }
          elseif (!empty($item['load_functions']) && !_menu_load_objects($item, $map)) {
            // An error occurred loading an object.
            $item['access'] = FALSE;
            return FALSE;
          }
          // Apply the access check defined in hook_menu() if there is not route
          // defined.
          else {
            _menu_check_access($item, $map);
          }
        }
        // For performance, don't localize a link the user can't access.
        if ($item['access']) {
          _menu_item_localize($item, $map, TRUE);
        }
      }
    
      // Allow other customizations - e.g. adding a page-specific query string to the
      // options array. For performance reasons we only invoke this hook if the link
      // has the 'alter' flag set in the options array.
      if (!empty($item['options']['alter'])) {
        drupal_alter('translated_menu_link', $item, $map);
      }
    
      return $map;
    }
    
    /**
     * Checks access to a menu item by mocking a request for a path.
     *
     * @param \Symfony\Component\Routing\Route $route
     *   Router for the given menu item.
     * @param string $href
     *   Menu path as returned by $item['href'] of menu_get_item().
     * @param array $map
     *   An array of path arguments; for example, array('node', '5').
     *
     * @return bool
     *   TRUE if the user has access or FALSE if the user should be presented
     *   with access denied.
     *
     * @throws \Symfony\Component\Routing\Exception\ResourceNotFoundException
     *   If the system path in $href does not match the $route.
     */
    function menu_item_route_access(Route $route, $href, &$map) {
      $request = Request::create('/' . $href);
      $request->attributes->set('_system_path', $href);
      // Attempt to match this path to provide a fully built request to the
      // access checker.
      try {
        $request->attributes->add(Drupal::service('router.dynamic')->matchRequest($request));
      }
      catch (NotFoundHttpException $e) {
        return FALSE;
      }
    
      // Populate the map with any matching values from the request.
      $path_bits = explode('/', trim($route->getPath(), '/'));
      foreach ($map as $index => $map_item) {
        $matches = array();
        // Search for placeholders wrapped by curly braces. For example, a path
        // 'foo/{bar}/baz' would return 'bar'.
        if (isset($path_bits[$index]) && preg_match('/{(?<placeholder>.*)}/', $path_bits[$index], $matches)) {
          // If that placeholder is present on the request attributes, replace the
          // placeholder in the map with the value.
          if ($request->attributes->has($matches['placeholder'])) {
            $map[$index] = $request->attributes->get($matches['placeholder']);
          }
        }
      }
    
      return Drupal::service('access_manager')->check($route, $request);
    }
    
    /**
     * Gets a loaded object from a router item.
     *
     * menu_get_object() provides access to objects loaded by the current router
     * item. For example, on the page node/%node, the router loads the %node object,
     * and calling menu_get_object() will return that. Normally, it is necessary to
     * specify the type of object referenced, however node is the default.
     * The following example tests to see whether the node being displayed is of the
     * "story" content type:
     * @code
     * $node = menu_get_object();
     * $story = $node->getType() == 'story';
     * @endcode
     *
     * @param $type
     *   Type of the object. These appear in hook_menu definitions as %type. Core
     *   provides aggregator_feed, aggregator_category, contact, filter_format,
     *   forum_term, menu, menu_link, node, taxonomy_vocabulary, user. See the
     *   relevant {$type}_load function for more on each. Defaults to node.
     * @param $position
     *   The position of the object in the path, where the first path segment is 0.
     *   For node/%node, the position of %node is 1, but for comment/reply/%node,
     *   it's 2. Defaults to 1.
     * @param $path
     *   See menu_get_item() for more on this. Defaults to the current path.
     */
    function menu_get_object($type = 'node', $position = 1, $path = NULL) {
      $router_item = menu_get_item($path);
      if (isset($router_item['load_functions'][$position]) && !empty($router_item['map'][$position]) && $router_item['load_functions'][$position] == $type . '_load') {
        return $router_item['map'][$position];
      }
    }
    
    /**
     * Renders a menu tree based on the current path.
     *
     * The tree is expanded based on the current path and dynamic paths are also
     * changed according to the defined to_arg functions (for example the 'My
     * account' link is changed from user/% to a link with the current user's uid).
     *
     * @param $menu_name
     *   The name of the menu.
     *
     * @return
     *   A structured array representing the specified menu on the current page, to
     *   be rendered by drupal_render().
     */
    function menu_tree($menu_name) {
      $menu_output = &drupal_static(__FUNCTION__, array());
    
      if (!isset($menu_output[$menu_name])) {
        $tree = menu_tree_page_data($menu_name);
        $menu_output[$menu_name] = menu_tree_output($tree);
      }
      return $menu_output[$menu_name];
    }
    
    /**
     * Returns a rendered menu tree.
     *
     * The menu item's LI element is given one of the following classes:
     * - expanded: The menu item is showing its submenu.
     * - collapsed: The menu item has a submenu which is not shown.
     * - leaf: The menu item has no submenu.
     *
     * @param $tree
     *   A data structure representing the tree as returned from menu_tree_data.
     *
     * @return
     *   A structured array to be rendered by drupal_render().
     */
    function menu_tree_output($tree) {
      $build = array();
      $items = array();
    
      // Pull out just the menu links we are going to render so that we
      // get an accurate count for the first/last classes.
      foreach ($tree as $data) {
        if ($data['link']['access'] && !$data['link']['hidden']) {
          $items[] = $data;
        }
      }
    
      $router_item = menu_get_item();
      $num_items = count($items);
      foreach ($items as $i => $data) {
        $class = array();
        if ($i == 0) {
          $class[] = 'first';
        }
        if ($i == $num_items - 1) {
          $class[] = 'last';
        }
        // Set a class for the <li>-tag. Since $data['below'] may contain local
        // tasks, only set 'expanded' class if the link also has children within
        // the current menu.
        if ($data['link']['has_children'] && $data['below']) {
          $class[] = 'expanded';
        }
        elseif ($data['link']['has_children']) {
          $class[] = 'collapsed';
        }
        else {
          $class[] = 'leaf';
        }
        // Set a class if the link is in the active trail.
        if ($data['link']['in_active_trail']) {
          $class[] = 'active-trail';
          $data['link']['localized_options']['attributes']['class'][] = 'active-trail';
        }
        // Normally, l() compares the href of every link with the current path and
        // sets the active class accordingly. But local tasks do not appear in menu
        // trees, so if the current path is a local task, and this link is its
        // tab root, then we have to set the class manually.
        if ($data['link']['href'] == $router_item['tab_root_href'] && $data['link']['href'] != current_path()) {
          $data['link']['localized_options']['attributes']['class'][] = 'active';
        }
    
        // Allow menu-specific theme overrides.
        $element['#theme'] = 'menu_link__' . strtr($data['link']['menu_name'], '-', '_');
        $element['#attributes']['class'] = $class;
        $element['#title'] = $data['link']['title'];
        $element['#href'] = $data['link']['href'];
        $element['#localized_options'] = !empty($data['link']['localized_options']) ? $data['link']['localized_options'] : array();
        $element['#below'] = $data['below'] ? menu_tree_output($data['below']) : $data['below'];
        $element['#original_link'] = $data['link'];
        // Index using the link's unique mlid.
        $build[$data['link']['mlid']] = $element;
      }
      if ($build) {
        // Make sure drupal_render() does not re-order the links.
        $build['#sorted'] = TRUE;
        // Add the theme wrapper for outer markup.
        // Allow menu-specific theme overrides.
        $build['#theme_wrappers'][] = 'menu_tree__' . strtr($data['link']['menu_name'], '-', '_');
      }
    
      return $build;
    }
    
    /**
     * Gets the data structure representing a named menu tree.
     *
     * Since this can be the full tree including hidden items, the data returned
     * may be used for generating an an admin interface or a select.
     *
     * @param $menu_name
     *   The named menu links to return
     * @param $link
     *   A fully loaded menu link, or NULL. If a link is supplied, only the
     *   path to root will be included in the returned tree - as if this link
     *   represented the current page in a visible menu.
     * @param $max_depth
     *   Optional maximum depth of links to retrieve. Typically useful if only one
     *   or two levels of a sub tree are needed in conjunction with a non-NULL
     *   $link, in which case $max_depth should be greater than $link['depth'].
     *
     * @return
     *   An tree of menu links in an array, in the order they should be rendered.
     */
    function menu_tree_all_data($menu_name, $link = NULL, $max_depth = NULL) {
      $tree = &drupal_static(__FUNCTION__, array());
      $language_interface = language(Language::TYPE_INTERFACE);
    
      // Use $mlid as a flag for whether the data being loaded is for the whole tree.
      $mlid = isset($link['mlid']) ? $link['mlid'] : 0;
      // Generate a cache ID (cid) specific for this $menu_name, $link, $language, and depth.
      $cid = 'links:' . $menu_name . ':all:' . $mlid . ':' . $language_interface->id . ':' . (int) $max_depth;
    
      if (!isset($tree[$cid])) {
        // If the static variable doesn't have the data, check {cache_menu}.
        $cache = cache('menu')->get($cid);
        if ($cache && isset($cache->data)) {
          // If the cache entry exists, it contains the parameters for
          // menu_build_tree().
          $tree_parameters = $cache->data;
        }
        // If the tree data was not in the cache, build $tree_parameters.
        if (!isset($tree_parameters)) {
          $tree_parameters = array(
            'min_depth' => 1,
            'max_depth' => $max_depth,
          );
          if ($mlid) {
            // The tree is for a single item, so we need to match the values in its
            // p columns and 0 (the top level) with the plid values of other links.
            $parents = array(0);
            for ($i = 1; $i < MENU_MAX_DEPTH; $i++) {
              if (!empty($link["p$i"])) {
                $parents[] = $link["p$i"];
              }
            }
            $tree_parameters['expanded'] = $parents;
            $tree_parameters['active_trail'] = $parents;
            $tree_parameters['active_trail'][] = $mlid;
          }
    
          // Cache the tree building parameters using the page-specific cid.
          cache('menu')->set($cid, $tree_parameters, CacheBackendInterface::CACHE_PERMANENT, array('menu' => $menu_name));
        }
    
        // Build the tree using the parameters; the resulting tree will be cached
        // by _menu_build_tree()).
        $tree[$cid] = menu_build_tree($menu_name, $tree_parameters);
      }
    
      return $tree[$cid];
    }
    
    /**
     * Sets the path for determining the active trail of the specified menu tree.
     *
     * This path will also affect the breadcrumbs under some circumstances.
     * Breadcrumbs are built using the preferred link returned by
     * menu_link_get_preferred(). If the preferred link is inside one of the menus
     * specified in calls to menu_tree_set_path(), the preferred link will be
     * overridden by the corresponding path returned by menu_tree_get_path().
     *
     * Setting this path does not affect the main content; for that use
     * menu_set_active_item() instead.
     *
     * @param $menu_name
     *   The name of the affected menu tree.
     * @param $path
     *   The path to use when finding the active trail.
     */
    function menu_tree_set_path($menu_name, $path = NULL) {
      $paths = &drupal_static(__FUNCTION__);
      if (isset($path)) {
        $paths[$menu_name] = $path;
      }
      return isset($paths[$menu_name]) ? $paths[$menu_name] : NULL;
    }
    
    /**
     * Gets the path for determining the active trail of the specified menu tree.
     *
     * @param $menu_name
     *   The menu name of the requested tree.
     *
     * @return
     *   A string containing the path. If no path has been specified with
     *   menu_tree_set_path(), NULL is returned.
     */
    function menu_tree_get_path($menu_name) {
      return menu_tree_set_path($menu_name);
    }
    
    /**
     * Gets the data structure for a named menu tree, based on the current page.
     *
     * The tree order is maintained by storing each parent in an individual
     * field, see http://drupal.org/node/141866 for more.
     *
     * @param $menu_name
     *   The named menu links to return.
     * @param $max_depth
     *   (optional) The maximum depth of links to retrieve.
     * @param $only_active_trail
     *   (optional) Whether to only return the links in the active trail (TRUE)
     *   instead of all links on every level of the menu link tree (FALSE). Defaults
     *   to FALSE. Internally used for breadcrumbs only.
     *
     * @return
     *   An array of menu links, in the order they should be rendered. The array
     *   is a list of associative arrays -- these have two keys, link and below.
     *   link is a menu item, ready for theming as a link. Below represents the
     *   submenu below the link if there is one, and it is a subtree that has the
     *   same structure described for the top-level array.
     */
    function menu_tree_page_data($menu_name, $max_depth = NULL, $only_active_trail = FALSE) {
      $tree = &drupal_static(__FUNCTION__, array());
    
      $language_interface = language(Language::TYPE_INTERFACE);
    
      // Check if the active trail has been overridden for this menu tree.
      $active_path = menu_tree_get_path($menu_name);
      // Load the router item corresponding to the current page.
      $request = \Drupal::request();
      $system_path = NULL;
      // @todo Remove once the old router system is removed.
      if ($request->attributes->has('_legacy')) {
        // Page is a 404 if no item is loaded.
        if ($item = menu_get_item($active_path)) {
          $system_path = $item['href'];
          // Variable to indicate that we are not serving an access denied response
          // for this page. Used to limit the number of links rendered.
          $page_not_403 = (int) $item['access'];
        }
      }
      elseif ($route_name = $request->attributes->get(RouteObjectInterface::ROUTE_NAME)) {
        // @todo https://drupal.org/node/2068471 is adding support so we can tell
        // if this is called on a 404/403 page.
        $system_path = $request->attributes->get('_system_path');
        $page_not_403 = 1;
      }
      if (isset($system_path)) {
        if (isset($max_depth)) {
          $max_depth = min($max_depth, MENU_MAX_DEPTH);
        }
        // Generate a cache ID (cid) specific for this page.
        $cid = 'links:' . $menu_name . ':page:' . $system_path . ':' . $language_interface->id . ':' . $page_not_403 . ':' . (int) $max_depth;
        // If we are asked for the active trail only, and $menu_name has not been
        // built and cached for this page yet, then this likely means that it
        // won't be built anymore, as this function is invoked from
        // template_preprocess_page(). So in order to not build a giant menu tree
        // that needs to be checked for access on all levels, we simply check
        // whether we have the menu already in cache, or otherwise, build a minimum
        // tree containing the breadcrumb/active trail only.
        // @see menu_set_active_trail()
        if (!isset($tree[$cid]) && $only_active_trail) {
          $cid .= ':trail';
        }
    
        if (!isset($tree[$cid])) {
          // If the static variable doesn't have the data, check {cache_menu}.
          $cache = cache('menu')->get($cid);
          if ($cache && isset($cache->data)) {
            // If the cache entry exists, it contains the parameters for
            // menu_build_tree().
            $tree_parameters = $cache->data;
          }
          // If the tree data was not in the cache, build $tree_parameters.
          if (!isset($tree_parameters)) {
            $tree_parameters = array(
              'min_depth' => 1,
              'max_depth' => $max_depth,
            );
            // Parent mlids; used both as key and value to ensure uniqueness.
            // We always want all the top-level links with plid == 0.
            $active_trail = array(0 => 0);
    
            // If this page is accessible to the current user, build the tree
            // parameters accordingly.
            if ($page_not_403) {
              // Find a menu link corresponding to the current path. If $active_path
              // is NULL, let menu_link_get_preferred() determine the path.
              if ($active_link = menu_link_get_preferred($active_path, $menu_name)) {
                // The active link may only be taken into account to build the
                // active trail, if it resides in the requested menu. Otherwise,
                // we'd needlessly re-run _menu_build_tree() queries for every menu
                // on every page.
                if ($active_link['menu_name'] == $menu_name) {
                  // Use all the coordinates, except the last one because there
                  // can be no child beyond the last column.
                  for ($i = 1; $i < MENU_MAX_DEPTH; $i++) {
                    if ($active_link['p' . $i]) {
                      $active_trail[$active_link['p' . $i]] = $active_link['p' . $i];
                    }
                  }
                  // If we are asked to build links for the active trail only, skip
                  // the entire 'expanded' handling.
                  if ($only_active_trail) {
                    $tree_parameters['only_active_trail'] = TRUE;
                  }
                }
              }
              $parents = $active_trail;
    
              $expanded = Drupal::state()->get('menu_expanded');
              // Check whether the current menu has any links set to be expanded.
              if (!$only_active_trail && $expanded && in_array($menu_name, $expanded)) {
                // Collect all the links set to be expanded, and then add all of
                // their children to the list as well.
                do {
                  $query = Drupal::entityQuery('menu_link')
                    ->condition('menu_name', $menu_name)
                    ->condition('expanded', 1)
                    ->condition('has_children', 1)
                    ->condition('plid', $parents, 'IN')
                    ->condition('mlid', $parents, 'NOT IN');
                  $result = $query->execute();
                  $parents += $result;
                } while (!empty($result));
              }
              $tree_parameters['expanded'] = $parents;
              $tree_parameters['active_trail'] = $active_trail;
            }
            // If access is denied, we only show top-level links in menus.
            else {
              $tree_parameters['expanded'] = $active_trail;
              $tree_parameters['active_trail'] = $active_trail;
            }
            // Cache the tree building parameters using the page-specific cid.
            cache('menu')->set($cid, $tree_parameters, CacheBackendInterface::CACHE_PERMANENT, array('menu' => $menu_name));
          }
    
          // Build the tree using the parameters; the resulting tree will be cached
          // by _menu_build_tree().
          $tree[$cid] = menu_build_tree($menu_name, $tree_parameters);
        }
        return $tree[$cid];
      }
    
      return array();
    }
    
    /**
     * Builds a menu tree, translates links, and checks access.
     *
     * @param $menu_name
     *   The name of the menu.
     * @param $parameters
     *   (optional) An associative array of build parameters. Possible keys:
     *   - expanded: An array of parent link ids to return only menu links that are
     *     children of one of the plids in this list. If empty, the whole menu tree
     *     is built, unless 'only_active_trail' is TRUE.
     *   - active_trail: An array of mlids, representing the coordinates of the
     *     currently active menu link.
     *   - only_active_trail: Whether to only return links that are in the active
     *     trail. This option is ignored, if 'expanded' is non-empty. Internally
     *     used for breadcrumbs.
     *   - min_depth: The minimum depth of menu links in the resulting tree.
     *     Defaults to 1, which is the default to build a whole tree for a menu
     *     (excluding menu container itself).
     *   - max_depth: The maximum depth of menu links in the resulting tree.
     *   - conditions: An associative array of custom database select query
     *     condition key/value pairs; see _menu_build_tree() for the actual query.
     *
     * @return
     *   A fully built menu tree.
     */
    function menu_build_tree($menu_name, array $parameters = array()) {
      // Build the menu tree.
      $data = _menu_build_tree($menu_name, $parameters);
      // Check access for the current user to each item in the tree.
      menu_tree_check_access($data['tree'], $data['node_links']);
      return $data['tree'];
    }
    
    /**
     * Builds a menu tree.
     *
     * This function may be used build the data for a menu tree only, for example
     * to further massage the data manually before further processing happens.
     * menu_tree_check_access() needs to be invoked afterwards.
     *
     * @see menu_build_tree()
     */
    function _menu_build_tree($menu_name, array $parameters = array()) {
      // Static cache of already built menu trees.
      $trees = &drupal_static(__FUNCTION__, array());
      $language_interface = language(Language::TYPE_INTERFACE);
    
      // Build the cache id; sort parents to prevent duplicate storage and remove
      // default parameter values.
      if (isset($parameters['expanded'])) {
        sort($parameters['expanded']);
      }
      $tree_cid = 'links:' . $menu_name . ':tree-data:' . $language_interface->id . ':' . hash('sha256', serialize($parameters));
    
      // If we do not have this tree in the static cache, check {cache_menu}.
      if (!isset($trees[$tree_cid])) {
        $cache = cache('menu')->get($tree_cid);
        if ($cache && isset($cache->data)) {
          $trees[$tree_cid] = $cache->data;
        }
      }
    
      if (!isset($trees[$tree_cid])) {
        $query = Drupal::entityQuery('menu_link');
        for ($i = 1; $i <= MENU_MAX_DEPTH; $i++) {
          $query->sort('p' . $i, 'ASC');
        }
        $query->condition('menu_name', $menu_name);
        if (!empty($parameters['expanded'])) {
          $query->condition('plid', $parameters['expanded'], 'IN');
        }
        elseif (!empty($parameters['only_active_trail'])) {
          $query->condition('mlid', $parameters['active_trail'], 'IN');
        }
        $min_depth = (isset($parameters['min_depth']) ? $parameters['min_depth'] : 1);
        if ($min_depth != 1) {
          $query->condition('depth', $min_depth, '>=');
        }
        if (isset($parameters['max_depth'])) {
          $query->condition('depth', $parameters['max_depth'], '<=');
        }
        // Add custom query conditions, if any were passed.
        if (isset($parameters['conditions'])) {
          foreach ($parameters['conditions'] as $column => $value) {
            $query->condition($column, $value);
          }
        }
    
        // Build an ordered array of links using the query result object.
        $links = array();
        if ($result = $query->execute()) {
          $links = menu_link_load_multiple($result);
        }
        $active_trail = (isset($parameters['active_trail']) ? $parameters['active_trail'] : array());
        $data['tree'] = menu_tree_data($links, $active_trail, $min_depth);
        $data['node_links'] = array();
        menu_tree_collect_node_links($data['tree'], $data['node_links']);
    
        // Cache the data, if it is not already in the cache.
        cache('menu')->set($tree_cid, $data, CacheBackendInterface::CACHE_PERMANENT, array('menu' => $menu_name));
        $trees[$tree_cid] = $data;
      }
    
      return $trees[$tree_cid];
    }
    
    /**
     * Collects node links from a given menu tree recursively.
     *
     * @param $tree
     *   The menu tree you wish to collect node links from.
     * @param $node_links
     *   An array in which to store the collected node links.
     */
    function menu_tree_collect_node_links(&$tree, &$node_links) {
      foreach ($tree as $key => $v) {
        if ($tree[$key]['link']['router_path'] == 'node/%') {
          $nid = substr($tree[$key]['link']['link_path'], 5);
          if (is_numeric($nid)) {
            $node_links[$nid][$tree[$key]['link']['mlid']] = &$tree[$key]['link'];
            $tree[$key]['link']['access'] = FALSE;
          }
        }
        if ($tree[$key]['below']) {
          menu_tree_collect_node_links($tree[$key]['below'], $node_links);
        }
      }
    }
    
    /**
     * Checks access and performs dynamic operations for each link in the tree.
     *
     * @param $tree
     *   The menu tree you wish to operate on.
     * @param $node_links
     *   A collection of node link references generated from $tree by
     *   menu_tree_collect_node_links().
     */
    function menu_tree_check_access(&$tree, $node_links = array()) {
      if ($node_links) {
        $nids = array_keys($node_links);
        $select = db_select('node_field_data', 'n');
        $select->addField('n', 'nid');
        // @todo This should be actually filtering on the desired node status field
        //   language and just fall back to the default language.
        $select->condition('n.status', 1);
    
        $select->condition('n.nid', $nids, 'IN');
        $select->addTag('node_access');
        $nids = $select->execute()->fetchCol();
        foreach ($nids as $nid) {
          foreach ($node_links[$nid] as $mlid => $link) {
            $node_links[$nid][$mlid]['access'] = TRUE;
          }
        }
      }
      _menu_tree_check_access($tree);
    }
    
    /**
     * Sorts the menu tree and recursively checks access for each item.
     */
    function _menu_tree_check_access(&$tree) {
      $new_tree = array();
      foreach ($tree as $key => $v) {
        $item = &$tree[$key]['link'];
        _menu_link_translate($item);
        if ($item['access'] || ($item['in_active_trail'] && strpos($item['href'], '%') !== FALSE)) {
          if ($tree[$key]['below']) {
            _menu_tree_check_access($tree[$key]['below']);
          }
          // The weights are made a uniform 5 digits by adding 50000 as an offset.
          // After _menu_link_translate(), $item['title'] has the localized link title.
          // Adding the mlid to the end of the index insures that it is unique.
          $new_tree[(50000 + $item['weight']) . ' ' . $item['title'] . ' ' . $item['mlid']] = $tree[$key];
        }
      }
      // Sort siblings in the tree based on the weights and localized titles.
      ksort($new_tree);
      $tree = $new_tree;
    }
    
    /**
     * Sorts and returns the built data representing a menu tree.
     *
     * @param $links
     *   A flat array of menu links that are part of the menu. Each array element
     *   is an associative array of information about the menu link, containing the
     *   fields from the {menu_links} table, and optionally additional information
     *   from the {menu_router} table, if the menu item appears in both tables.
     *   This array must be ordered depth-first. See _menu_build_tree() for a sample
     *   query.
     * @param $parents
     *   An array of the menu link ID values that are in the path from the current
     *   page to the root of the menu tree.
     * @param $depth
     *   The minimum depth to include in the returned menu tree.
     *
     * @return
     *   An array of menu links in the form of a tree. Each item in the tree is an
     *   associative array containing:
     *   - link: The menu link item from $links, with additional element
     *     'in_active_trail' (TRUE if the link ID was in $parents).
     *   - below: An array containing the sub-tree of this item, where each element
     *     is a tree item array with 'link' and 'below' elements. This array will be
     *     empty if the menu item has no items in its sub-tree having a depth
     *     greater than or equal to $depth.
     */
    function menu_tree_data(array $links, array $parents = array(), $depth = 1) {
      // Reverse the array so we can use the more efficient array_pop() function.
      $links = array_reverse($links);
      return _menu_tree_data($links, $parents, $depth);
    }
    
    /**
     * Builds the data representing a menu tree.
     *
     * The function is a bit complex because the rendering of a link depends on
     * the next menu link.
     */
    function _menu_tree_data(&$links, $parents, $depth) {
      $tree = array();
      while ($item = array_pop($links)) {
        // We need to determine if we're on the path to root so we can later build
        // the correct active trail and breadcrumb.
        $item['in_active_trail'] = in_array($item['mlid'], $parents);
        // Add the current link to the tree.
        $tree[$item['mlid']] = array(
          'link' => $item,
          'below' => array(),
        );
        // Look ahead to the next link, but leave it on the array so it's available
        // to other recursive function calls if we return or build a sub-tree.
        $next = end($links);
        // Check whether the next link is the first in a new sub-tree.
        if ($next && $next['depth'] > $depth) {
          // Recursively call _menu_tree_data to build the sub-tree.
          $tree[$item['mlid']]['below'] = _menu_tree_data($links, $parents, $next['depth']);
          // Fetch next link after filling the sub-tree.
          $next = end($links);
        }
        // Determine if we should exit the loop and return.
        if (!$next || $next['depth'] < $depth) {
          break;
        }
      }
      return $tree;
    }
    
    /**
     * Implements template_preprocess_HOOK() for theme_menu_tree().
     */
    function template_preprocess_menu_tree(&$variables) {
      $variables['tree'] = $variables['tree']['#children'];
    }
    
    /**
     * Returns HTML for a wrapper for a menu sub-tree.
     *
     * @param $variables
     *   An associative array containing:
     *   - tree: An HTML string containing the tree's items.
     *
     * @see template_preprocess_menu_tree()
     * @ingroup themeable
     */
    function theme_menu_tree($variables) {
      return '<ul class="menu">' . $variables['tree'] . '</ul>';
    }
    
    /**
     * Returns HTML for a menu link and submenu.
     *
     * @param $variables
     *   An associative array containing:
     *   - element: Structured array data for a menu link.
     *
     * @ingroup themeable
     */
    function theme_menu_link(array $variables) {
      $element = $variables['element'];
      $sub_menu = '';
    
      if ($element['#below']) {
        $sub_menu = drupal_render($element['#below']);
      }
      $output = l($element['#title'], $element['#href'], $element['#localized_options']);
      return '<li' . new Attribute($element['#attributes']) . '>' . $output . $sub_menu . "</li>\n";
    }
    
    /**
     * Returns HTML for a single local task link.
     *
     * @param $variables
     *   An associative array containing:
     *   - element: A render element containing:
     *     - #link: A menu link array with 'title', 'href', and 'localized_options'
     *       keys.
     *     - #active: A boolean indicating whether the local task is active.
     *
     * @ingroup themeable
     */
    function theme_menu_local_task($variables) {
      $link = $variables['element']['#link'];
      $link += array(
        'localized_options' => array(),
      );
      $link_text = $link['title'];
    
      if (!empty($variables['element']['#active'])) {
        // Add text to indicate active tab for non-visual users.
        $active = '<span class="visually-hidden">' . t('(active tab)') . '</span>';
    
        // If the link does not contain HTML already, check_plain() it now.
        // After we set 'html'=TRUE the link will not be sanitized by l().
        if (empty($link['localized_options']['html'])) {
          $link['title'] = check_plain($link['title']);
        }
        $link['localized_options']['html'] = TRUE;
        $link_text = t('!local-task-title!active', array('!local-task-title' => $link['title'], '!active' => $active));
      }
    
      return '<li' . (!empty($variables['element']['#active']) ? ' class="active"' : '') . '>' . l($link_text, $link['href'], $link['localized_options']) . '</li>';
    }
    
    /**
     * Returns HTML for a single local action link.
     *
     * @param $variables
     *   An associative array containing:
     *   - element: A render element containing:
     *     - #link: A menu link array with 'title', 'href', and 'localized_options'
     *       keys.
     *
     * @ingroup themeable
     */
    function theme_menu_local_action($variables) {
      $link = $variables['element']['#link'];
      $link += array(
        'href' => '',
        'localized_options' => array(),
      );
      $link['localized_options']['attributes']['class'][] = 'button';
      $link['localized_options']['attributes']['class'][] = 'button-action';
    
      $output = '<li>';
      $output .= l($link['title'], $link['href'], $link['localized_options']);
      $output .= "</li>";
    
      return $output;
    }
    
    /**
     * Generates elements for the $arg array in the help hook.
     */
    function drupal_help_arg($arg = array()) {
      // Note - the number of empty elements should be > MENU_MAX_PARTS.
      return $arg + array('', '', '', '', '', '', '', '', '', '', '', '');
    }
    
    /**
     * Returns the help associated with the active menu item.
     */
    function menu_get_active_help() {
      $output = '';
      $router_path = menu_tab_root_path();
      // We will always have a path unless we are on a 403 or 404.
      if (!$router_path) {
        return '';
      }
    
      $arg = drupal_help_arg(arg(NULL));
    
      foreach (Drupal::moduleHandler()->getImplementations('help') as $module) {
        $function = $module . '_help';
        // Lookup help for this path.
        if ($help = $function($router_path, $arg)) {
          $output .= $help . "\n";
        }
      }
      return $output;
    }
    
    /**
     * Gets the custom theme for the current page, if there is one.
     *
     * @param $initialize
     *   This parameter should only be used internally; it is set to TRUE in order
     *   to force the custom theme to be initialized for the current page request.
     *
     * @return
     *   The machine-readable name of the custom theme, if there is one.
     *
     * @see menu_set_custom_theme()
     */
    function menu_get_custom_theme($initialize = FALSE) {
      $custom_theme = &drupal_static(__FUNCTION__);
      // Skip this if the site is offline or being installed or updated, since the
      // menu system may not be correctly initialized then.
      if ($initialize && !_menu_site_is_offline(TRUE) && (!defined('MAINTENANCE_MODE') || (MAINTENANCE_MODE != 'update' && MAINTENANCE_MODE != 'install'))) {
        // First allow modules to dynamically set a custom theme for the current
        // page. Since we can only have one, the last module to return a valid
        // theme takes precedence.
        $custom_themes = array_filter(Drupal::moduleHandler()->invokeAll('custom_theme'), 'drupal_theme_access');
        if (!empty($custom_themes)) {
          $custom_theme = array_pop($custom_themes);
        }
        // If there is a theme callback function for the current page, execute it.
        // If this returns a valid theme, it will override any theme that was set
        // by a hook_custom_theme() implementation above.
        $router_item = menu_get_item();
        if (!empty($router_item['access']) && !empty($router_item['theme_callback'])) {
          $theme_name = call_user_func_array($router_item['theme_callback'], $router_item['theme_arguments']);
          if (drupal_theme_access($theme_name)) {
            $custom_theme = $theme_name;
          }
        }
      }
      return $custom_theme;
    }
    
    /**
     * Sets a custom theme for the current page, if there is one.
     */
    function menu_set_custom_theme() {
      menu_get_custom_theme(TRUE);
    }
    
    /**
     * Returns an array containing the names of system-defined (default) menus.
     */
    function menu_list_system_menus() {
      return array(
        'tools' => 'Tools',
        'admin' => 'Administration',
        'account' => 'User account menu',
        'main' => 'Main navigation',
        'footer' => 'Footer menu',
      );
    }
    
    /**
     * Returns an array of links to be rendered as the Main menu.
     */
    function menu_main_menu() {
      $config = Drupal::config('menu.settings');
      $menu_enabled = module_exists('menu');
      // When menu module is not enabled, we need a hardcoded default value.
      $main_links_source = $menu_enabled ? $config->get('main_links') : 'main';
      return menu_navigation_links($main_links_source);
    }
    
    /**
     * Returns an array of links to be rendered as the Secondary links.
     */
    function menu_secondary_menu() {
      $config = Drupal::config('menu.settings');
      $menu_enabled = module_exists('menu');
      // When menu module is not enabled, we need a hardcoded default value.
      $main_links_source = $menu_enabled ? $config->get('main_links') : 'main';
      $secondary_links_source = $menu_enabled ? $config->get('secondary_links') : 'account';
    
      // If the secondary menu source is set as the primary menu, we display the
      // second level of the primary menu.
      if ($secondary_links_source == $main_links_source) {
        return menu_navigation_links($main_links_source, 1);
      }
      else {
        return menu_navigation_links($secondary_links_source, 0);
      }
    }
    
    /**
     * Returns an array of links for a navigation menu.
     *
     * @param $menu_name
     *   The name of the menu.
     * @param $level
     *   Optional, the depth of the menu to be returned.
     *
     * @return
     *   An array of links of the specified menu and level.
     */
    function menu_navigation_links($menu_name, $level = 0) {
      // Don't even bother querying the menu table if no menu is specified.
      if (empty($menu_name)) {
        return array();
      }
    
      // Get the menu hierarchy for the current page.
      $tree = menu_tree_page_data($menu_name, $level + 1);
    
      // Go down the active trail until the right level is reached.
      while ($level-- > 0 && $tree) {
        // Loop through the current level's items until we find one that is in trail.
        while ($item = array_shift($tree)) {
          if ($item['link']['in_active_trail']) {
            // If the item is in the active trail, we continue in the subtree.
            $tree = empty($item['below']) ? array() : $item['below'];
            break;
          }
        }
      }
    
      // Create a single level of links.
      $router_item = menu_get_item();
      $links = array();
      foreach ($tree as $item) {
        if (!$item['link']['hidden']) {
          $class = '';
          $l = $item['link']['localized_options'];
          $l['href'] = $item['link']['href'];
          $l['title'] = $item['link']['title'];
          if ($item['link']['in_active_trail']) {
            $class = ' active-trail';
            $l['attributes']['class'][] = 'active-trail';
          }
          // Normally, l() compares the href of every link with the current path and
          // sets the active class accordingly. But local tasks do not appear in
          // menu trees, so if the current path is a local task, and this link is
          // its tab root, then we have to set the class manually.
          if ($item['link']['href'] == $router_item['tab_root_href'] && $item['link']['href'] != current_path()) {
            $l['attributes']['class'][] = 'active';
          }
          // Keyed with the unique mlid to generate classes in theme_links().
          $links['menu-' . $item['link']['mlid'] . $class] = $l;
        }
      }
      return $links;
    }
    
    /**
     * Collects the local tasks (tabs), action links, and the root path.
     *
     * @param $level
     *   The level of tasks you ask for. Primary tasks are 0, secondary are 1.
     *
     * @return
     *   An array containing
     *   - tabs: Local tasks for the requested level.
     *   - actions: Action links for the requested level.
     *   - root_path: The router path for the current page. If the current page is
     *     a default local task, then this corresponds to the parent tab.
     *
     * @see hook_menu_local_tasks()
     * @see hook_menu_local_tasks_alter()
     */
    function menu_local_tasks($level = 0) {
      $data = &drupal_static(__FUNCTION__);
      $root_path = &drupal_static(__FUNCTION__ . ':root_path', '');
      $empty = array(
        'tabs' => array(),
        'actions' => array(),
        'root_path' => &$root_path,
      );
    
      if (!isset($data)) {
        $data = array();
        // Set defaults in case there are no actions or tabs.
        $actions = $empty['actions'];
        $tabs = array();
    
        $router_item = menu_get_item();
    
        // If this router item points to its parent, start from the parents to
        // compute tabs and actions.
        if ($router_item && ($router_item['type'] & MENU_LINKS_TO_PARENT)) {
          $router_item = menu_get_item($router_item['tab_parent_href']);
        }
    
        // If we failed to fetch a router item or the current user doesn't have
        // access to it, don't bother computing the tabs.
        if (!$router_item || !$router_item['access']) {
          return $empty;
        }
        // @todo remove all code using {menu_router} and anything using MENU_*
        // constants when all local actions and local tasks are converted to
        // plugins. The remaining code should just invoke those managers plus do the
        // invocations of hook_menu_local_tasks() and hook_menu_local_tasks_alter().
    
        // Get all tabs (also known as local tasks) and the root page.
        $result = db_select('menu_router', NULL, array('fetch' => PDO::FETCH_ASSOC))
          ->fields('menu_router')
          ->condition('tab_root', $router_item['tab_root'])
          ->condition('context', MENU_CONTEXT_INLINE, '<>')
          ->orderBy('weight')
          ->orderBy('title')
          ->execute();
        $map = $router_item['original_map'];
        $children = array();
        $tasks = array();
        $root_path = $router_item['path'];
    
        foreach ($result as $item) {
          _menu_translate($item, $map, TRUE);
          if ($item['tab_parent']) {
            // All tabs, but not the root page.
            $children[$item['tab_parent']][$item['path']] = $item;
          }
          // Store the translated item for later use.
          $tasks[$item['path']] = $item;
        }
    
        // Find all tabs below the current path.
        $path = $router_item['path'];
        // Tab parenting may skip levels, so the number of parts in the path may not
        // equal the depth. Thus we use the $depth counter (offset by 1000 for ksort).
        $depth = 1001;
        $actions = array();
        while (isset($children[$path])) {
          $tabs_current = array();
          $actions_current = array();
          $next_path = '';
          $tab_count = 0;
          $action_count = 0;
          foreach ($children[$path] as $item) {
            // Local tasks can be normal items too, so bitmask with
            // MENU_IS_LOCAL_TASK before checking.
            if (!($item['type'] & MENU_IS_LOCAL_TASK)) {
              // This item is not a tab, skip it.
              continue;
            }
            if ($item['access']) {
              $link = $item;
              // The default task is always active. As tabs can be normal items
              // too, so bitmask with MENU_LINKS_TO_PARENT before checking.
              if (($item['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT) {
                // Find the first parent which is not a default local task or action.
                for ($p = $item['tab_parent']; ($tasks[$p]['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT; $p = $tasks[$p]['tab_parent']);
                // Use the path of the parent instead.
                $link['href'] = $tasks[$p]['href'];
                // Mark the link as active, if the current path happens to be the
                // path of the default local task itself (i.e., instead of its
                // tab_parent_href or tab_root_href). Normally, links for default
                // local tasks link to their parent, but the path of default local
                // tasks can still be accessed directly, in which case this link
                // would not be marked as active, since l() only compares the href
                // with current_path().
                if ($link['href'] != current_path()) {
                  $link['localized_options']['attributes']['class'][] = 'active';
                }
                $tabs_current[$link['href']] = array(
                  '#theme' => 'menu_local_task',
                  '#link' => $link,
                  '#active' => TRUE,
                  '#weight' => isset($link['weight']) ? $link['weight'] : NULL,
                );
                $next_path = $item['path'];
                $tab_count++;
              }
              else {
                // Actions can be normal items too, so bitmask with
                // MENU_IS_LOCAL_ACTION before checking.
                if (($item['type'] & MENU_IS_LOCAL_ACTION) == MENU_IS_LOCAL_ACTION) {
                  // The item is an action, display it as such.
                  $actions_current[$link['href']] = array(
                    '#theme' => 'menu_local_action',
                    '#link' => $link,
                    '#weight' => isset($link['weight']) ? $link['weight'] : NULL,
                  );
                  $action_count++;
                }
                else {
                  // Otherwise, it's a normal tab.
                  $tabs_current[$link['href']] = array(
                    '#theme' => 'menu_local_task',
                    '#link' => $link,
                    '#weight' => isset($link['weight']) ? $link['weight'] : NULL,
                  );
                  $tab_count++;
                }
              }
            }
          }
          $path = $next_path;
          $tabs[$depth] = $tabs_current;
          $actions = array_merge($actions, $actions_current);
          $depth++;
        }
        $data['actions'] = $actions;
        // Find all tabs at the same level or above the current one.
        $parent = $router_item['tab_parent'];
        $path = $router_item['path'];
        $current = $router_item;
        $depth = 1000;
        while (isset($children[$parent])) {
          $tabs_current = array();
          $next_path = '';
          $next_parent = '';
          $count = 0;
          foreach ($children[$parent] as $item) {
            // Skip local actions.
            if ($item['type'] & MENU_IS_LOCAL_ACTION) {
              continue;
            }
            if ($item['access']) {
              $count++;
              $link = $item;
              // Local tasks can be normal items too, so bitmask with
              // MENU_LINKS_TO_PARENT before checking.
              if (($item['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT) {
                // Find the first parent which is not a default local task.
                for ($p = $item['tab_parent']; ($tasks[$p]['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT; $p = $tasks[$p]['tab_parent']);
                // Use the path of the parent instead.
                $link['href'] = $tasks[$p]['href'];
                if ($item['path'] == $router_item['path']) {
                  $root_path = $tasks[$p]['path'];
                }
              }
              // We check for the active tab.
              if ($item['path'] == $path) {
                // Mark the link as active, if the current path is a (second-level)
                // local task of a default local task. Since this default local task
                // links to its parent, l() will not mark it as active, as it only
                // compares the link's href to current_path().
                if ($link['href'] != current_path()) {
                  $link['localized_options']['attributes']['class'][] = 'active';
                }
                $tabs_current[$link['href']] = array(
                  '#theme' => 'menu_local_task',
                  '#link' => $link,
                  '#active' => TRUE,
                  '#weight' => isset($link['weight']) ? $link['weight'] : NULL,
                );
                $next_path = $item['tab_parent'];
                if (isset($tasks[$next_path])) {
                  $next_parent = $tasks[$next_path]['tab_parent'];
                }
              }
              else {
                $tabs_current[$link['href']] = array(
                  '#theme' => 'menu_local_task',
                  '#link' => $link,
                  '#weight' => isset($link['weight']) ? $link['weight'] : NULL,
                );
              }
            }
          }
          $path = $next_path;
          $parent = $next_parent;
          $tabs[$depth] = $tabs_current;
          $depth--;
        }
        // Sort by depth.
        ksort($tabs);
        // Remove the depth, we are interested only in their relative placement.
        $tabs = array_values($tabs);
        $data['tabs'] = $tabs;
        // Look for route-based tabs.
        $route_name = Drupal::request()->attributes->get('_route');
        if (!empty($route_name)) {
          $manager = Drupal::service('plugin.manager.menu.local_task');
          $local_tasks = $manager->getTasksBuild($route_name);
          foreach ($local_tasks as $level => $items) {
            $data['tabs'][$level] = empty($data['tabs'][$level]) ? $items : array_merge($data['tabs'][$level], $items);
          }
        }
    
        // Allow modules to dynamically add further tasks.
        $module_handler = Drupal::moduleHandler();
        foreach ($module_handler->getImplementations('menu_local_tasks') as $module) {
          $function = $module . '_menu_local_tasks';
          $function($data, $router_item, $root_path);
        }
        // Allow modules to alter local tasks.
        $module_handler->alter('menu_local_tasks', $data, $router_item, $root_path);
      }
    
      if (isset($data['tabs'][$level])) {
        return array(
          'tabs' => $data['tabs'][$level],
          'actions' => $data['actions'],
          'root_path' => $root_path,
        );
      }
      elseif (!empty($data['actions'])) {
        return array('actions' => $data['actions']) + $empty;
      }
      return $empty;
    }
    
    /**
     * Retrieves contextual links for a path based on registered local tasks.
     *
     * This leverages the menu system to retrieve the first layer of registered
     * local tasks for a given system path. All local tasks of the tab type
     * MENU_CONTEXT_INLINE are taken into account.
     *
     * For example, when considering the following registered local tasks:
     * - node/%node/view (default local task) with no 'context' defined
     * - node/%node/edit with context: MENU_CONTEXT_PAGE | MENU_CONTEXT_INLINE
     * - node/%node/revisions with context: MENU_CONTEXT_PAGE
     * - node/%node/report-as-spam with context: MENU_CONTEXT_INLINE
     *
     * If the path "node/123" is passed to this function, then it will return the
     * links for 'edit' and 'report-as-spam'.
     *
     * @param $module
     *   The name of the implementing module. This is used to prefix the key for
     *   each contextual link, which is transformed into a CSS class during
     *   rendering by theme_links(). For example, if $module is 'block' and the
     *   retrieved local task path argument is 'edit', then the resulting CSS class
     *   will be 'block-edit'.
     * @param $parent_path
     *   The static menu router path of the object to retrieve local tasks for, for
     *   example 'node' or 'admin/structure/block/manage'.
     * @param $args
     *   A list of dynamic path arguments to append to $parent_path to form the
     *   fully-qualified menu router path; for example, array(123) for a certain
     *   node or array('system', 'tools') for a certain block.
     *
     * @return
     *   A list of menu router items that are local tasks for the passed-in path.
     *
     * @see contextual_links_preprocess()
     * @see hook_menu()
     */
    function menu_contextual_links($module, $parent_path, $args) {
      static $path_empty = array();
    
      $links = array();
      // Performance: In case a previous invocation for the same parent path did not
      // return any links, we immediately return here.
      if (isset($path_empty[$parent_path]) && strpos($parent_path, '%') !== FALSE) {
        return $links;
      }
      // Construct the item-specific parent path.
      $path = $parent_path . '/' . implode('/', $args);
    
      // Get the router item for the given parent link path.
      $router_item = menu_get_item($path);
      if (!$router_item || !$router_item['access']) {
        $path_empty[$parent_path] = TRUE;
        return $links;
      }
      $data = &drupal_static(__FUNCTION__, array());
      $root_path = $router_item['path'];
    
      // Performance: For a single, normalized path (such as 'node/%') we only query
      // available tasks once per request.
      if (!isset($data[$root_path])) {
        // Get all contextual links that are direct children of the router item and
        // not of the tab type 'view'.
        $data[$root_path] = db_select('menu_router', 'm')
          ->fields('m')
          ->condition('tab_parent', $router_item['tab_root'])
          ->condition('context', MENU_CONTEXT_NONE, '<>')
          ->condition('context', MENU_CONTEXT_PAGE, '<>')
          ->orderBy('weight')
          ->orderBy('title')
          ->execute()
          ->fetchAllAssoc('path', PDO::FETCH_ASSOC);
      }
      $parent_length = drupal_strlen($root_path) + 1;
      $map = $router_item['original_map'];
      foreach ($data[$root_path] as $item) {
        // Extract the actual "task" string from the path argument.
        $key = drupal_substr($item['path'], $parent_length);
    
        // Denormalize and translate the contextual link.
        _menu_translate($item, $map, TRUE);
        if (!$item['access']) {
          continue;
        }
    
        // If this item is a default local task, rewrite the href to link to its
        // parent item.
        if ($item['type'] == MENU_DEFAULT_LOCAL_TASK) {
          $item['href'] = $item['tab_parent_href'];
        }
    
        // All contextual links are keyed by the actual "task" path argument,
        // prefixed with the name of the implementing module.
        $links[$module . '-' . $key] = $item;
      }
    
      // Allow modules to alter contextual links.
      drupal_alter('menu_contextual_links', $links, $router_item, $root_path);
    
      // Performance: If the current user does not have access to any links for this
      // router path and no other module added further links, we assign FALSE here
      // to skip the entire process the next time the same router path is requested.
      if (empty($links)) {
        $path_empty[$parent_path] = TRUE;
      }
    
      return $links;
    }
    
    /**
     * Returns the rendered local tasks at the top level.
     */
    function menu_primary_local_tasks() {
      $links = menu_local_tasks(0);
      // Do not display single tabs.
      return count(element_get_visible_children($links['tabs'])) > 1 ? $links['tabs'] : '';
    }
    
    /**
     * Returns the rendered local tasks at the second level.
     */
    function menu_secondary_local_tasks() {
      $links = menu_local_tasks(1);
      // Do not display single tabs.
      return count(element_get_visible_children($links['tabs'])) > 1 ? $links['tabs'] : '';
    }
    
    /**
     * Returns the rendered local actions at the current level.
     */
    function menu_get_local_actions() {
      $links = menu_local_tasks();
      $router_item = menu_get_item();
      $manager = Drupal::service('plugin.manager.menu.local_action');
      $local_actions = $manager->getActionsForRoute($router_item['route_name']);
      foreach ($local_actions as $plugin) {
        $route_path = $manager->getPath($plugin);
        $action_router_item = menu_get_item($route_path);
        $links['actions'][$route_path] = array(
          '#theme' => 'menu_local_action',
          '#link' => array(
            'title' => $manager->getTitle($plugin),
            'href' => $route_path,
          ),
          '#access' => $action_router_item['access'],
        );
      }
      return $links['actions'];
    }
    
    /**
     * Returns the router path, or the path for a default local task's parent.
     */
    function menu_tab_root_path() {
      $links = menu_local_tasks();
      return $links['root_path'];
    }
    
    /**
     * Returns a renderable element for the primary and secondary tabs.
     */
    function menu_local_tabs() {
      $build = array(
        '#theme' => 'menu_local_tasks',
        '#primary' => menu_primary_local_tasks(),
        '#secondary' => menu_secondary_local_tasks(),
      );
      return !empty($build['#primary']) || !empty($build['#secondary']) ? $build : array();
    }
    
    /**
     * Returns HTML for primary and secondary local tasks.
     *
     * @param $variables
     *   An associative array containing:
     *     - primary: (optional) An array of local tasks (tabs).
     *     - secondary: (optional) An array of local tasks (tabs).
     *
     * @ingroup themeable
     * @see menu_local_tasks()
     */
    function theme_menu_local_tasks(&$variables) {
      $output = '';
    
      if (!empty($variables['primary'])) {
        $variables['primary']['#prefix'] = '<h2 class="visually-hidden">' . t('Primary tabs') . '</h2>';
        $variables['primary']['#prefix'] .= '<ul class="tabs primary">';
        $variables['primary']['#suffix'] = '</ul>';
        $output .= drupal_render($variables['primary']);
      }
      if (!empty($variables['secondary'])) {
        $variables['secondary']['#prefix'] = '<h2 class="visually-hidden">' . t('Secondary tabs') . '</h2>';
        $variables['secondary']['#prefix'] .= '<ul class="tabs secondary">';
        $variables['secondary']['#suffix'] = '</ul>';
        $output .= drupal_render($variables['secondary']);
      }
    
      return $output;
    }
    
    /**
     * Sets (or gets) the active menu for the current page.
     *
     * The active menu for the page determines the active trail.
     *
     * @return
     *   An array of menu machine names, in order of preference. The
     *   'system.menu.active_menus_default' config item may be used to assert a menu
     *   order different from the order of creation, or to prevent a particular menu
     *   from being used at all in the active trail.
     *   E.g., $conf['system.menu']['active_menus_default'] = array('tools',
     *   'main').
     */
    function menu_set_active_menu_names($menu_names = NULL) {
      $active = &drupal_static(__FUNCTION__);
    
      if (isset($menu_names) && is_array($menu_names)) {
        $active = $menu_names;
      }
      elseif (!isset($active)) {
        $config = Drupal::config('system.menu');
        $active = $config->get('active_menus_default') ?: array_keys(menu_list_system_menus());
      }
      return $active;
    }
    
    /**
     * Gets the active menu for the current page.
     */
    function menu_get_active_menu_names() {
      return menu_set_active_menu_names();
    }
    
    /**
     * Sets the active path, which determines which page is loaded.
     *
     * Note that this may not have the desired effect unless invoked very early
     * in the page load or unless you do a subrequest to generate your page output.
     *
     * @param $path
     *   A Drupal path - not a path alias.
     */
    function menu_set_active_item($path) {
      // Since the active item has changed, the active menu trail may also be out
      // of date.
      drupal_static_reset('menu_set_active_trail');
      // @todo Refactor to use the Symfony Request object.
      _current_path($path);
    }
    
    /**
     * Sets the active trail (path to the menu tree root) of the current page.
     *
     * Any trail set by this function will only be used for functionality that calls
     * menu_get_active_trail(). Drupal core only uses trails set here for
     * breadcrumbs and the page title and not for menu trees or page content.
     * Additionally, breadcrumbs set by drupal_set_breadcrumb() will override any
     * trail set here.
     *
     * To affect the trail used by menu trees, use menu_tree_set_path(). To affect
     * the page content, use menu_set_active_item() instead.
     *
     * @param $new_trail
     *   Menu trail to set; the value is saved in a static variable and can be
     *   retrieved by menu_get_active_trail(). The format of this array should be
     *   the same as the return value of menu_get_active_trail().
     *
     * @return
     *   The active trail. See menu_get_active_trail() for details.
     */
    function menu_set_active_trail($new_trail = NULL) {
      $trail = &drupal_static(__FUNCTION__);
    
      if (isset($new_trail)) {
        $trail = $new_trail;
      }
      elseif (!isset($trail)) {
        $trail = array();
        $trail[] = array(
          'title' => t('Home'),
          'href' => '<front>',
          'link_path' => '',
          'localized_options' => array(),
          'type' => 0,
        );
    
        // Try to retrieve a menu link corresponding to the current path. If more
        // than one exists, the link from the most preferred menu is returned.
        $preferred_link = menu_link_get_preferred();
        $current_item = menu_get_item();
    
        // There is a link for the current path.
        if ($preferred_link) {
          // Pass TRUE for $only_active_trail to make menu_tree_page_data() build
          // a stripped down menu tree containing the active trail only, in case
          // the given menu has not been built in this request yet.
          $tree = menu_tree_page_data($preferred_link['menu_name'], NULL, TRUE);
          list($key, $curr) = each($tree);
        }
        // There is no link for the current path.
        else {
          $preferred_link = $current_item;
          $curr = FALSE;
        }
    
        while ($curr) {
          $link = $curr['link'];
          if ($link['in_active_trail']) {
            // Add the link to the trail, unless it links to its parent.
            if (!($link['type'] & MENU_LINKS_TO_PARENT)) {
              // The menu tree for the active trail may contain additional links
              // that have not been translated yet, since they contain dynamic
              // argument placeholders (%). Such links are not contained in regular
              // menu trees, and have only been loaded for the additional
              // translation that happens here, so as to be able to display them in
              // the breadcumb for the current page.
              // @see _menu_tree_check_access()
              // @see _menu_link_translate()
              if (strpos($link['href'], '%') !== FALSE) {
                _menu_link_translate($link, TRUE);
              }
              if ($link['access']) {
                $trail[] = $link;
              }
            }
            $tree = $curr['below'] ? $curr['below'] : array();
          }
          list($key, $curr) = each($tree);
        }
        // Make sure the current page is in the trail to build the page title, by
        // appending either the preferred link or the menu router item for the
        // current page. Exclude it if we are on the front page.
        $last = end($trail);
        if ($preferred_link && $last['href'] != $preferred_link['href'] && !drupal_is_front_page()) {
          $trail[] = $preferred_link;
        }
      }
      return $trail;
    }
    
    /**
     * Looks up the preferred menu link for a given system path.
     *
     * @param $path
     *   The path; for example, 'node/5'. The function will find the corresponding
     *   menu link ('node/5' if it exists, or fallback to 'node/%').
     * @param $selected_menu
     *   The name of a menu used to restrict the search for a preferred menu link.
     *   If not specified, all the menus returned by menu_get_active_menu_names()
     *   will be used.
     *
     * @return
     *   A fully translated menu link, or FALSE if no matching menu link was
     *   found. The most specific menu link ('node/5' preferred over 'node/%') in
     *   the most preferred menu (as defined by menu_get_active_menu_names()) is
     *   returned.
     */
    function menu_link_get_preferred($path = NULL, $selected_menu = NULL) {
      $preferred_links = &drupal_static(__FUNCTION__);
    
      if (!isset($path)) {
        $path = current_path();
      }
    
      if (empty($selected_menu)) {
        // Use an illegal menu name as the key for the preferred menu link.
        $selected_menu = MENU_PREFERRED_LINK;
      }
    
      if (!isset($preferred_links[$path])) {
        // Look for the correct menu link by building a list of candidate paths,
        // which are ordered by priority (translated hrefs are preferred over
        // untranslated paths). Afterwards, the most relevant path is picked from
        // the menus, ordered by menu preference.
        $item = menu_get_item($path);
        $path_candidates = array();
        // 1. The current item href.
        $path_candidates[$item['href']] = $item['href'];
        // 2. The tab root href of the current item (if any).
        if ($item['tab_parent'] && ($tab_root = menu_get_item($item['tab_root_href']))) {
          $path_candidates[$tab_root['href']] = $tab_root['href'];
        }
        // 3. The current item path (with wildcards).
        $path_candidates[$item['path']] = $item['path'];
        // 4. The tab root path of the current item (if any).
        if (!empty($tab_root)) {
          $path_candidates[$tab_root['path']] = $tab_root['path'];
        }
    
        // Retrieve a list of menu names, ordered by preference.
        $menu_names = menu_get_active_menu_names();
        // Put the selected menu at the front of the list.
        array_unshift($menu_names, $selected_menu);
    
        $menu_links = entity_load_multiple_by_properties('menu_link', array('link_path' => $path_candidates));
    
        // Sort candidates by link path and menu name.
        $candidates = array();
        foreach ($menu_links as $candidate) {
          $candidates[$candidate['link_path']][$candidate['menu_name']] = $candidate;
          // Add any menus not already in the menu name search list.
          if (!in_array($candidate['menu_name'], $menu_names)) {
            $menu_names[] = $candidate['menu_name'];
          }
        }
    
        // Store the most specific link for each menu. Also save the most specific
        // link of the most preferred menu in $preferred_link.
        foreach ($path_candidates as $link_path) {
          if (isset($candidates[$link_path])) {
            foreach ($menu_names as $menu_name) {
              if (empty($preferred_links[$path][$menu_name]) && isset($candidates[$link_path][$menu_name])) {
                $candidate_item = $candidates[$link_path][$menu_name];
                $map = explode('/', $path);
                _menu_translate($candidate_item, $map);
                if ($candidate_item['access']) {
                  $preferred_links[$path][$menu_name] = $candidate_item;
                  if (empty($preferred_links[$path][MENU_PREFERRED_LINK])) {
                    // Store the most specific link.
                    $preferred_links[$path][MENU_PREFERRED_LINK] = $candidate_item;
                  }
                }
              }
            }
          }
        }
      }
    
      return isset($preferred_links[$path][$selected_menu]) ? $preferred_links[$path][$selected_menu] : FALSE;
    }
    
    /**
     * Gets the active trail (path to root menu root) of the current page.
     *
     * If a trail is supplied to menu_set_active_trail(), that value is returned. If
     * a trail is not supplied to menu_set_active_trail(), the path to the current
     * page is calculated and returned. The calculated trail is also saved as a
     * static value for use by subsequent calls to menu_get_active_trail().
     *
     * @return
     *   Path to menu root of the current page, as an array of menu link items,
     *   starting with the site's home page. Each link item is an associative array
     *   with the following components:
     *   - title: Title of the item.
     *   - href: Drupal path of the item.
     *   - localized_options: Options for passing into the l() function.
     *   - type: A menu type constant, such as MENU_DEFAULT_LOCAL_TASK, or 0 to
     *     indicate it's not really in the menu (used for the home page item).
     */
    function menu_get_active_trail() {
      return menu_set_active_trail();
    }
    
    /**
     * Gets the breadcrumb for the current page, as determined by the active trail.
     *
     * @see menu_set_active_trail()
     */
    function menu_get_active_breadcrumb() {
      $breadcrumb = array();
    
      // No breadcrumb for the front page.
      if (drupal_is_front_page()) {
        return $breadcrumb;
      }
    
      $item = menu_get_item();
      if (!empty($item['access'])) {
        $active_trail = menu_get_active_trail();
    
        // Allow modules to alter the breadcrumb, if possible, as that is much
        // faster than rebuilding an entirely new active trail.
        drupal_alter('menu_breadcrumb', $active_trail, $item);
    
        // Don't show a link to the current page in the breadcrumb trail.
        $end = end($active_trail);
        if (Drupal::request()->attributes->get('_system_path') == $end['href']) {
          array_pop($active_trail);
        }
    
        // Remove the tab root (parent) if the current path links to its parent.
        // Normally, the tab root link is included in the breadcrumb, as soon as we
        // are on a local task or any other child link. However, if we are on a
        // default local task (e.g., node/%/view), then we do not want the tab root
        // link (e.g., node/%) to appear, as it would be identical to the current
        // page. Since this behavior also needs to work recursively (i.e., on
        // default local tasks of default local tasks), and since the last non-task
        // link in the trail is used as page title (see menu_get_active_title()),
        // this condition cannot be cleanly integrated into menu_get_active_trail().
        // menu_get_active_trail() already skips all links that link to their parent
        // (commonly MENU_DEFAULT_LOCAL_TASK). In order to also hide the parent link
        // itself, we always remove the last link in the trail, if the current
        // router item links to its parent.
        if (($item['type'] & MENU_LINKS_TO_PARENT) == MENU_LINKS_TO_PARENT) {
          array_pop($active_trail);
        }
    
        foreach ($active_trail as $parent) {
          $breadcrumb[] = l($parent['title'], $parent['href'], $parent['localized_options']);
        }
      }
      return $breadcrumb;
    }
    
    /**
     * Gets the title of the current page, as determined by the active trail.
     */
    function menu_get_active_title() {
      $active_trail = menu_get_active_trail();
    
      foreach (array_reverse($active_trail) as $item) {
        if (!(bool) ($item['type'] & MENU_IS_LOCAL_TASK)) {
          return $item['title'];
        }
      }
    }
    
    /**
     * Clears the cached cached data for a single named menu.
     */
    function menu_cache_clear($menu_name = 'tools') {
      cache('menu')->deleteTags(array('menu' => $menu_name));
      // Also clear the menu system static caches.
      menu_reset_static_cache();
    }
    
    /**
     * Clears all cached menu data.
     *
     * This should be called any time broad changes
     * might have been made to the router items or menu links.
     */
    function menu_cache_clear_all() {
      cache('menu')->deleteAll();
      menu_reset_static_cache();
    }
    
    /**
     * Resets the menu system static cache.
     */
    function menu_reset_static_cache() {
      Drupal::entityManager()
        ->getStorageController('menu_link')->resetCache();
      drupal_static_reset('_menu_build_tree');
      drupal_static_reset('menu_tree');
      drupal_static_reset('menu_tree_all_data');
      drupal_static_reset('menu_tree_page_data');
      drupal_static_reset('menu_link_get_preferred');
    }
    
    /**
     * Populates the database tables used by various menu functions.
     *
     * This function will clear and populate the {menu_router} table, add entries
     * to {menu_links} for new router items, and then remove stale items from
     * {menu_links}.
     *
     * @return
     *   TRUE if the menu was rebuilt, FALSE if another thread was rebuilding
     *   in parallel and the current thread just waited for completion.
     */
    function menu_router_rebuild() {
      if (!lock()->acquire(__FUNCTION__)) {
        // Wait for another request that is already doing this work.
        // We choose to block here since otherwise the router item may not
        // be available during routing resulting in a 404.
        lock()->wait(__FUNCTION__);
        return FALSE;
      }
    
      $transaction = db_transaction();
    
      try {
        list($menu, $masks) = menu_router_build(TRUE);
        _menu_navigation_links_rebuild($menu);
        // Clear the menu, page and block caches.
        menu_cache_clear_all();
        _menu_clear_page_cache();
        // Indicate that the menu has been successfully rebuilt.
        Drupal::state()->delete('menu_rebuild_needed');
      }
      catch (Exception $e) {
        $transaction->rollback();
        watchdog_exception('menu', $e);
      }
    
      lock()->release(__FUNCTION__);
      return TRUE;
    }
    
    /**
     * Collects and alters the menu definitions.
     *
     * @param bool $save
     *   (optional) Save the new router to the database. Defaults to FALSE.
     */
    function menu_router_build($save = FALSE) {
      // We need to manually call each module so that we can know which module
      // a given item came from.
      $callbacks = array();
      foreach (Drupal::moduleHandler()->getImplementations('menu') as $module) {
        $router_items = call_user_func($module . '_menu');
        if (isset($router_items) && is_array($router_items)) {
          foreach (array_keys($router_items) as $path) {
            $router_items[$path]['module'] = $module;
          }
          $callbacks = array_merge($callbacks, $router_items);
        }
      }
      // Alter the menu as defined in modules, keys are like user/%user.
      drupal_alter('menu', $callbacks);
      foreach ($callbacks as $path => $router_item) {
        // If the menu item is a default local task and incorrectly references a
        // route, remove it.
        // @todo This may be removed later depending on the outcome of
        // http://drupal.org/node/1889790
        if (isset($router_item['type']) && $router_item['type'] == MENU_DEFAULT_LOCAL_TASK) {
          unset($callbacks[$path]['route_name']);
        }
        // If the menu item references a route, normalize the route information
        // into the old structure. Note that routes are keyed by name, not path,
        // so the path of the route takes precedence.
        if (isset($router_item['route_name'])) {
          $router_item['page callback'] = 'USES_ROUTE';
          $router_item['access callback'] = TRUE;
          $new_path = _menu_router_translate_route($router_item['route_name']);
    
          unset($callbacks[$path]);
          $callbacks[$new_path] = $router_item;
        }
      }
      list($menu, $masks) = _menu_router_build($callbacks, $save);
      _menu_router_cache($menu);
    
      return array($menu, $masks);
    }
    
    /**
     * Translates a route name to its router item path.
     *
     * @param string $route_name
     *   The route name to translate.
     *
     * @return string
     *   The translated path pattern from the route.
     */
    function _menu_router_translate_route($route_name) {
      $outline = Drupal::service('router.route_provider')
        ->getRouteByName($route_name)
        ->compile()
        ->getPatternOutline();
      return trim($outline, '/');
    }
    
    /**
     * Stores the menu router if we have it in memory.
     */
    function _menu_router_cache($new_menu = NULL) {
      $menu = &drupal_static(__FUNCTION__);
    
      if (isset($new_menu)) {
        $menu = $new_menu;
      }
      return $menu;
    }
    
    /**
     * Gets the menu router.
     */
    function menu_get_router() {
      // Check first if we have it in memory already.
      $menu = _menu_router_cache();
      if (empty($menu)) {
        list($menu, $masks) = menu_router_build();
      }
      return $menu;
    }
    
    /**
     * Builds menu links for the items in the menu router.
     *
     * @todo This function should be removed/refactored.
     */
    function _menu_navigation_links_rebuild($menu) {
      if (!module_exists('menu_link')) {
        // The Menu link module may not be available during install, so rebuild
        // when possible.
        return;
      }
      $menu_link_controller = Drupal::entityManager()
        ->getStorageController('menu_link');
    
      // Add normal and suggested items as links.
      $router_items = array();
      foreach ($menu as $path => $router_item) {
        if ($router_item['_visible']) {
          $router_items[$path] = $router_item;
          $sort[$path] = $router_item['_number_parts'];
        }
      }
      if ($router_items) {
        // Keep an array of processed menu links, to allow
        // Drupal\menu_link\MenuLinkStorageController::save() to check this for
        // parents instead of querying the database.
        $parent_candidates = array();
        // Make sure no child comes before its parent.
        array_multisort($sort, SORT_NUMERIC, $router_items);
    
        foreach ($router_items as $key => $router_item) {
          // For performance reasons, do a straight query now and convert to a menu
          // link entity later.
          // @todo revisit before release.
          $existing_item = db_select('menu_links')
            ->fields('menu_links')
            ->condition('link_path', $router_item['path'])
            ->condition('module', 'system')
            ->execute()->fetchAll();
          if ($existing_item) {
            $existing_item = reset($existing_item);
            $existing_item->options = unserialize($existing_item->options);
    
            $router_item['mlid'] = $existing_item->mlid;
            $router_item['uuid'] = $existing_item->uuid;
            // A change in hook_menu may move the link to a different menu
            if (empty($router_item['menu_name']) || ($router_item['menu_name'] == $existing_item->menu_name)) {
              $router_item['menu_name'] = $existing_item->menu_name;
              $router_item['plid'] = $existing_item->plid;
            }
            else {
              // It moved to a new menu.
              // Let Drupal\menu_link\MenuLinkStorageController::save() try to find
              // a new parent based on the path.
              unset($router_item['plid']);
            }
            $router_item['has_children'] = $existing_item->has_children;
            $router_item['updated'] = $existing_item->updated;
    
            // Convert the existing item to a typed object.
            $existing_item = $menu_link_controller->create(get_object_vars($existing_item));
          }
          else {
            $existing_item = NULL;
          }
    
          if ($existing_item && $existing_item->customized) {
            $parent_candidates[$existing_item->mlid] = $existing_item;
          }
          else {
            $menu_link = MenuLink::buildFromRouterItem($router_item);
            $menu_link->original = $existing_item;
            $menu_link->parentCandidates = $parent_candidates;
            $menu_link_controller->save($menu_link);
            $parent_candidates[$menu_link->id()] = $menu_link;
            unset($router_items[$key]);
          }
        }
      }
    
      $paths = array_keys($menu);
      // Updated and customized items whose router paths are gone need new ones.
      $menu_links = $menu_link_controller->loadUpdatedCustomized($paths);
      foreach ($menu_links as $menu_link) {
        $router_path = _menu_find_router_path($menu_link->link_path);
        if (!empty($router_path) && ($router_path != $menu_link->router_path || $menu_link->updated)) {
          // If the router path and the link path matches, it's surely a working
          // item, so we clear the updated flag.
          $updated = $menu_link->updated && $router_path != $menu_link->link_path;
    
          $menu_link->router_path = $router_path;
          $menu_link->updated = (int) $updated;
          $menu_link_controller->save($menu_link);
        }
      }
    
      // Find any item whose router path does not exist any more.
      $query = Drupal::entityQuery('menu_link')
        ->condition('router_path', $paths, 'NOT IN')
        ->condition('external', 0)
        ->condition('updated', 0)
        ->condition('customized', 0)
        ->sort('depth', 'DESC');
      $result = $query->execute();
    
      // Remove all such items. Starting from those with the greatest depth will
      // minimize the amount of re-parenting done by the menu link controller.
      if (!empty($result)) {
        menu_link_delete_multiple($result, TRUE);
      }
    }
    
    /**
     * Returns an array containing all links for a menu.
     *
     * @param $menu_name
     *   The name of the menu whose links should be returned.
     *
     * @return
     *   An array of menu links.
     */
    function menu_load_links($menu_name) {
      $links = array();
    
      $query = Drupal::entityQuery('menu_link')
        ->condition('menu_name', $menu_name)
        // Order by weight so as to be helpful for menus that are only one level
        // deep.
        ->sort('weight');
      $result = $query->execute();
    
      if (!empty($result)) {
        $links = menu_link_load_multiple($result);
      }
    
      return $links;
    }
    
    /**
     * Deletes all links for a menu.
     *
     * @param $menu_name
     *   The name of the menu whose links will be deleted.
     */
    function menu_delete_links($menu_name) {
      $links = menu_load_links($menu_name);
      menu_link_delete_multiple(array_keys($links), FALSE, TRUE);
    }
    
    /**
     * Clears the page and block caches at most twice per page load.
     */
    function _menu_clear_page_cache() {
      $cache_cleared = &drupal_static(__FUNCTION__, 0);
    
      // Clear the page and block caches, but at most twice, including at
      //  the end of the page load when there are multiple links saved or deleted.
      if ($cache_cleared == 0) {
        cache_invalidate_tags(array('content' => TRUE));
        // Keep track of which menus have expanded items.
        _menu_set_expanded_menus();
        $cache_cleared = 1;
      }
      elseif ($cache_cleared == 1) {
        drupal_register_shutdown_function('cache_invalidate_tags', array('content' => TRUE));
        // Keep track of which menus have expanded items.
        drupal_register_shutdown_function('_menu_set_expanded_menus');
        $cache_cleared = 2;
      }
    }
    
    /**
     * Updates a list of menus with expanded items.
     */
    function _menu_set_expanded_menus() {
      $names = db_query("SELECT menu_name FROM {menu_links} WHERE expanded <> 0 GROUP BY menu_name")->fetchCol();
      Drupal::state()->set('menu_expanded', $names);
    }
    
    /**
     * Finds the router path which will serve this path.
     *
     * @param $link_path
     *  The path for we are looking up its router path.
     *
     * @return
     *  A path from $menu keys or empty if $link_path points to a nonexisting
     *  place.
     */
    function _menu_find_router_path($link_path) {
      // $menu will only have data during a menu rebuild.
      $menu = _menu_router_cache();
    
      $router_path = $link_path;
      $parts = explode('/', $link_path, MENU_MAX_PARTS);
      $ancestors = menu_get_ancestors($parts);
    
      if (empty($menu)) {
        // Not during a menu rebuild, so look up in the database.
        $router_path = (string) db_select('menu_router')
          ->fields('menu_router', array('path'))
          ->condition('path', $ancestors, 'IN')
          ->orderBy('fit', 'DESC')
          ->range(0, 1)
          ->execute()->fetchField();
      }
      elseif (!isset($menu[$router_path])) {
        // Add an empty router path as a fallback.
        $ancestors[] = '';
        foreach ($ancestors as $key => $router_path) {
          if (isset($menu[$router_path])) {
            // Exit the loop leaving $router_path as the first match.
            break;
          }
        }
        // If we did not find the path, $router_path will be the empty string
        // at the end of $ancestors.
      }
      return $router_path;
    }
    
    /**
     * Builds the router table based on the data from hook_menu().
     */
    function _menu_router_build($callbacks, $save = FALSE) {
      // First pass: separate callbacks from paths, making paths ready for
      // matching. Calculate fitness, and fill some default values.
      $menu = array();
      $masks = array();
      $path_roots = array();
      foreach ($callbacks as $path => $item) {
        $load_functions = array();
        $to_arg_functions = array();
        $fit = 0;
        $move = FALSE;
    
        $parts = explode('/', $path, MENU_MAX_PARTS);
        $path_roots[$parts[0]] = $parts[0];
        $number_parts = count($parts);
        // We store the highest index of parts here to save some work in the fit
        // calculation loop.
        $slashes = $number_parts - 1;
        // Extract load and to_arg functions.
        foreach ($parts as $k => $part) {
          $match = FALSE;
          // Look for wildcards in the form allowed to be used in PHP functions,
          // because we are using these to construct the load function names.
          if (preg_match('/^%(|' . DRUPAL_PHP_FUNCTION_PATTERN . ')$/', $part, $matches)) {
            if (empty($matches[1])) {
              $match = TRUE;
              $load_functions[$k] = NULL;
            }
            else {
              if (function_exists($matches[1] . '_to_arg')) {
                $to_arg_functions[$k] = $matches[1] . '_to_arg';
                $load_functions[$k] = NULL;
                $match = TRUE;
              }
              if (function_exists($matches[1] . '_load')) {
                $function = $matches[1] . '_load';
                // Create an array of arguments that will be passed to the _load
                // function when this menu path is checked, if 'load arguments'
                // exists.
                $load_functions[$k] = isset($item['load arguments']) ? array($function => $item['load arguments']) : $function;
                $match = TRUE;
              }
            }
          }
          if ($match) {
            $parts[$k] = '%';
          }
          else {
            $fit |=  1 << ($slashes - $k);
          }
        }
        if ($fit) {
          $move = TRUE;
        }
        else {
          // If there is no %, it fits maximally.
          $fit = (1 << $number_parts) - 1;
        }
        $masks[$fit] = 1;
        $item['_load_functions'] = $load_functions;
        $item['to_arg_functions'] = empty($to_arg_functions) ? '' : serialize($to_arg_functions);
        $item += array(
          'title' => '',
          'type' => MENU_NORMAL_ITEM,
          'module' => '',
          '_number_parts' => $number_parts,
          '_parts' => $parts,
          '_fit' => $fit,
        );
        $item += array(
          // Default MENU_DEFAULT_LOCAL_TASKs to a weight of -10, so they appear as
          // first tab by default.
          'weight' => ($item['type'] & MENU_DEFAULT_LOCAL_TASK) == MENU_DEFAULT_LOCAL_TASK ? -10 : 0,
          '_visible' => (bool) ($item['type'] & MENU_VISIBLE_IN_BREADCRUMB),
          '_tab' => (bool) ($item['type'] & MENU_IS_LOCAL_TASK),
        );
        if ($move) {
          $new_path = implode('/', $item['_parts']);
          $menu[$new_path] = $item;
          $sort[$new_path] = $number_parts;
        }
        else {
          $menu[$path] = $item;
          $sort[$path] = $number_parts;
        }
      }
      array_multisort($sort, SORT_NUMERIC, $menu);
      // Apply inheritance rules.
      foreach ($menu as $path => $v) {
        $item = &$menu[$path];
        if (!$item['_tab']) {
          // Non-tab items.
          $item['tab_parent'] = '';
          $item['tab_root'] = $path;
        }
        // If not specified, assign the default tab type for local tasks.
        elseif (!isset($item['context'])) {
          $item['context'] = MENU_CONTEXT_PAGE;
        }
        for ($i = $item['_number_parts'] - 1; $i; $i--) {
          $parent_path = implode('/', array_slice($item['_parts'], 0, $i));
          if (isset($menu[$parent_path])) {
    
            $parent = &$menu[$parent_path];
    
            // If we have no menu name, try to inherit it from parent items.
            if (!isset($item['menu_name'])) {
              // If the parent item of this item does not define a menu name (and no
              // previous iteration assigned one already), try to find the menu name
              // of the parent item in the currently stored menu links.
              if (!isset($parent['menu_name'])) {
                $menu_name = db_query("SELECT menu_name FROM {menu_links} WHERE router_path = :router_path AND module = 'system'", array(':router_path' => $parent_path))->fetchField();
                if ($menu_name) {
                  $parent['menu_name'] = $menu_name;
                }
              }
              // If the parent item defines a menu name, inherit it.
              if (!empty($parent['menu_name'])) {
                $item['menu_name'] = $parent['menu_name'];
              }
            }
            if (!isset($item['tab_parent'])) {
              // Parent stores the parent of the path.
              $item['tab_parent'] = $parent_path;
            }
            if (!isset($item['tab_root']) && !$parent['_tab']) {
              $item['tab_root'] = $parent_path;
            }
            // If an access callback is not found for a default local task we use
            // the callback from the parent, since we expect them to be identical.
            // In all other cases, the access parameters must be specified.
            if (($item['type'] == MENU_DEFAULT_LOCAL_TASK) && !isset($item['access callback']) && isset($parent['access callback'])) {
              $item['access callback'] = $parent['access callback'];
              if (!isset($item['access arguments']) && isset($parent['access arguments'])) {
                $item['access arguments'] = $parent['access arguments'];
              }
            }
            // Same for page callbacks.
            if (!isset($item['page callback']) && isset($parent['page callback'])) {
              $item['page callback'] = $parent['page callback'];
              if (!isset($item['page arguments']) && isset($parent['page arguments'])) {
                $item['page arguments'] = $parent['page arguments'];
              }
              if (!isset($item['file path']) && isset($parent['file path'])) {
                $item['file path'] = $parent['file path'];
              }
              if (!isset($item['file']) && isset($parent['file'])) {
                $item['file'] = $parent['file'];
                if (empty($item['file path']) && isset($item['module']) && isset($parent['module']) && $item['module'] != $parent['module']) {
                  $item['file path'] = drupal_get_path('module', $parent['module']);
                }
              }
            }
            // Same for theme callbacks.
            if (!isset($item['theme callback']) && isset($parent['theme callback'])) {
              $item['theme callback'] = $parent['theme callback'];
              if (!isset($item['theme arguments']) && isset($parent['theme arguments'])) {
                $item['theme arguments'] = $parent['theme arguments'];
              }
            }
            // Same for load arguments: if a loader doesn't have any explict
            // arguments, try to find arguments in the parent.
            if (!isset($item['load arguments'])) {
              foreach ($item['_load_functions'] as $k => $function) {
                // This loader doesn't have any explict arguments...
                if (!is_array($function)) {
                  // ... check the parent for a loader at the same position
                  // using the same function name and defining arguments...
                  if (isset($parent['_load_functions'][$k]) && is_array($parent['_load_functions'][$k]) && key($parent['_load_functions'][$k]) === $function) {
                    // ... and inherit the arguments on the child.
                    $item['_load_functions'][$k] = $parent['_load_functions'][$k];
                  }
                }
              }
            }
          }
        }
        if (!isset($item['access callback']) && isset($item['access arguments'])) {
          // Default callback.
          $item['access callback'] = 'user_access';
        }
        if (!isset($item['access callback']) || empty($item['page callback'])) {
          $item['access callback'] = 0;
        }
        if (is_bool($item['access callback'])) {
          $item['access callback'] = intval($item['access callback']);
        }
    
        $item['load_functions'] = empty($item['_load_functions']) ? '' : serialize($item['_load_functions']);
        $item += array(
          'access arguments' => array(),
          'access callback' => '',
          'page arguments' => array(),
          'page callback' => '',
          'title arguments' => array(),
          'title callback' => 't',
          'theme arguments' => array(),
          'theme callback' => '',
          'description' => '',
          'description arguments' => array(),
          'description callback' => 't',
          'position' => '',
          'context' => 0,
          'tab_parent' => '',
          'tab_root' => $path,
          'path' => $path,
          'file' => '',
          'file path' => '',
          'include file' => '',
          'route_name' => '',
        );
    
        // Calculate out the file to be included for each callback, if any.
        if ($item['file']) {
          $file_path = $item['file path'] ? $item['file path'] : drupal_get_path('module', $item['module']);
          $item['include file'] = $file_path . '/' . $item['file'];
        }
      }
    
      // Sort the masks so they are in order of descending fit.
      $masks = array_keys($masks);
      rsort($masks);
    
      if ($save) {
        $path_roots = array_values($path_roots);
        // Update the path roots variable and reset the path alias whitelist cache
        // if the list has changed.
        if ($path_roots != Drupal::state()->get('menu_path_roots')) {
          Drupal::state()->set('menu_path_roots', array_values($path_roots));
          drupal_container()->get('path.alias_manager')->cacheClear();
        }
        _menu_router_save($menu, $masks);
      }
    
      return array($menu, $masks);
    }
    
    /**
     * Saves data from menu_router_build() to the router table.
     */
    function _menu_router_save($menu, $masks) {
      // Delete the existing router since we have some data to replace it.
      db_truncate('menu_router')->execute();
    
      // Prepare insert object.
      $insert = db_insert('menu_router')
        ->fields(array(
          'path',
          'load_functions',
          'to_arg_functions',
          'access_callback',
          'access_arguments',
          'page_callback',
          'page_arguments',
          'fit',
          'number_parts',
          'context',
          'tab_parent',
          'tab_root',
          'title',
          'title_callback',
          'title_arguments',
          'theme_callback',
          'theme_arguments',
          'type',
          'description',
          'description_callback',
          'description_arguments',
          'position',
          'weight',
          'include_file',
          'route_name',
        ));
    
      $num_records = 0;
    
      foreach ($menu as $path => $item) {
        // Fill in insert object values.
        $insert->values(array(
          'path' => $item['path'],
          'load_functions' => $item['load_functions'],
          'to_arg_functions' => $item['to_arg_functions'],
          'access_callback' => $item['access callback'],
          'access_arguments' => serialize($item['access arguments']),
          'page_callback' => $item['page callback'],
          'page_arguments' => serialize($item['page arguments']),
          'fit' => $item['_fit'],
          'number_parts' => $item['_number_parts'],
          'context' => $item['context'],
          'tab_parent' => $item['tab_parent'],
          'tab_root' => $item['tab_root'],
          'title' => $item['title'],
          'title_callback' => $item['title callback'],
          'title_arguments' => ($item['title arguments'] ? serialize($item['title arguments']) : ''),
          'theme_callback' => $item['theme callback'],
          'theme_arguments' => serialize($item['theme arguments']),
          'type' => $item['type'],
          'description' => $item['description'],
          'description_callback' => $item['description callback'],
          'description_arguments' => ($item['description arguments'] ? serialize($item['description arguments']) : ''),
          'position' => $item['position'],
          'weight' => $item['weight'],
          'include_file' => $item['include file'],
          'route_name' => $item['route_name'],
        ));
    
        // Execute in batches to avoid the memory overhead of all of those records
        // in the query object.
        if (++$num_records == 20) {
          $insert->execute();
          $num_records = 0;
        }
      }
      // Insert any remaining records.
      $insert->execute();
      // Store the masks.
      Drupal::state()->set('menu.masks', $masks);
    
      return $menu;
    }
    
    /**
     * Checks whether the site is in maintenance mode.
     *
     * This function will log the current user out and redirect to front page
     * if the current user has no 'access site in maintenance mode' permission.
     *
     * @param $check_only
     *   If this is set to TRUE, the function will perform the access checks and
     *   return the site offline status, but not log the user out or display any
     *   messages.
     *
     * @return
     *   FALSE if the site is not in maintenance mode, the user login page is
     *   displayed, or the user has the 'access site in maintenance mode'
     *   permission. TRUE for anonymous users not being on the login page when the
     *   site is in maintenance mode.
     */
    function _menu_site_is_offline($check_only = FALSE) {
      // Check if site is in maintenance mode.
      if (Drupal::config('system.maintenance')->get('enabled')) {
        if (user_access('access site in maintenance mode')) {
          // Ensure that the maintenance mode message is displayed only once
          // (allowing for page redirects) and specifically suppress its display on
          // the maintenance mode settings page.
          if (!$check_only && current_path() != 'admin/config/development/maintenance') {
            if (user_access('administer site configuration')) {
              drupal_set_message(t('Operating in maintenance mode. <a href="@url">Go online.</a>', array('@url' => url('admin/config/development/maintenance'))), 'status', FALSE);
            }
            else {
              drupal_set_message(t('Operating in maintenance mode.'), 'status', FALSE);
            }
          }
        }
        else {
          return TRUE;
        }
      }
      return FALSE;
    }
    
    /**
     * @} End of "defgroup menu".
     */