menu.inc

<?php
// $Id$

/**
 * @file
 * API for the Drupal menu system.
 */

/**
 * @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.
 *
 * 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. Menu items may
 * omit this attribute to use the value provided by an ancestor 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().
 */

/**
 * @name Menu flags
 * @{
 * Flags for use in the "type" attribute of menu items.
 */

/**
 * Internal menu flag -- menu item is the root of the menu tree.
 */
define('MENU_IS_ROOT', 0x0001);

/**
 * Internal menu flag -- menu item is visible in the menu tree.
 */
define('MENU_VISIBLE_IN_TREE', 0x0002);

/**
 * Internal menu flag -- menu item is visible in the breadcrumb.
 */
define('MENU_VISIBLE_IN_BREADCRUMB', 0x0004);

/**
 * Internal menu flag -- menu item links back to its parnet.
 */
define('MENU_LINKS_TO_PARENT', 0x0008);

/**
 * Internal menu flag -- menu item can be modified by administrator.
 */
define('MENU_MODIFIED_BY_ADMIN', 0x0020);

/**
 * Internal menu flag -- menu item was created by administrator.
 */
define('MENU_CREATED_BY_ADMIN', 0x0040);

/**
 * Internal menu flag -- menu item is a local task.
 */
define('MENU_IS_LOCAL_TASK', 0x0080);

/**
 * @} End of "Menu flags".
 */

/**
 * @name Menu item types
 * @{
 * Menu item definitions provide one of these constants, which are shortcuts for
 * combinations of the above flags.
 */

/**
 * 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 are not shown in the menu.
 */
define('MENU_CALLBACK', MENU_VISIBLE_IN_BREADCRUMB);

/**
 * 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 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);

/**
 * @} End of "Menu item types".
 */

/**
 * @name Menu status codes
 * @{
 * Status codes for menu callbacks.
 */

/**
 * Internal menu status code -- Menu item was found.
 */
define('MENU_FOUND', 1);

/**
 * Internal menu status code -- Menu item was not found.
 */
define('MENU_NOT_FOUND', 2);

/**
 * Internal menu status code -- Menu item access is denied.
 */
define('MENU_ACCESS_DENIED', 3);

/**
 * Internal menu status code -- Menu item inaccessible because site is offline.
 */
define('MENU_SITE_OFFLINE', 4);

/**
 * @} End of "Menu status codes".
 */

/**
 * @Name Menu tree parameters
 * @{
 * Menu tree
 */

 /**
 * The maximum number of path elements for a menu callback
 */
define('MENU_MAX_PARTS', 7);


/**
 * The maximum depth of a menu links tree - matches the number of p columns.
 */
define('MENU_MAX_DEPTH', 9);


/**
 * @} End of "Menu tree parameters".
 */

/**
 * 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_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);
  $placeholders = array();
  $ancestors = array();
  $length =  $number_parts - 1;
  $end = (1 << $number_parts) - 1;
  $masks = variable_get('menu_masks', array());
  // Only examine patterns that actually exist as router items (the masks).
  foreach ($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; $j--) {
      if ($i & (1 << $j)) {
        $current .= $parts[$length - $j];
      }
      else {
        $current .= '%';
      }
      if ($j) {
        $current .= '/';
      }
    }
    $placeholders[] = "'%s'";
    $ancestors[] = $current;
  }
  return array($ancestors, $placeholders);
}

/**
 * The menu system uses serialized arrays stored in the database for
 * arguments. However, often these need to change according to the
 * current path. This function unserializes such an array and does the
 * necessary change.
 *
 * Integer values are mapped according to the $map parameter. For
 * example, if unserialize($data) is array('view', 1) and $map is
 * array('node', '12345') then 'view' will not be changed because
 * it is not an integer, but 1 will as it is an integer. As $map[1]
 * is '12345', 1 will be replaced with '12345'. So the result will
 * be array('node_load', '12345').
 *
 * @param @data
 *   A serialized array.
 * @param @map
 *   An array of potential replacements.
 * @return
 *   The $data array unserialized and mapped.
 */
function menu_unserialize($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 $router_item
 *   The router item. Usually you take a router entry from menu_get_item and
 *   set it back either modified or to a different path. This lets you modify the
 *   navigation block, the page title, the breadcrumb and the page help in one
 *   call.
 */
function menu_set_item($path, $router_item) {
  menu_get_item($path, $router_item);
}

/**
 * Get a router item.
 *
 * @param $path
 *   The path, for example node/5. The function will find the corresponding
 *   node/% item and return that.
 * @param $router_item
 *   Internal use only.
 * @return
 *   The router item, an associate array corresponding to one row in the
 *   menu_router table. The value of key map holds the loaded objects. The
 *   value of key access is TRUE if the current user can access this page.
 *   The values for key title, page_arguments, access_arguments will be
 *   filled in based on the database values and the objects loaded.
 */
function menu_get_item($path = NULL, $router_item = NULL) {
  static $router_items;
  if (!isset($path)) {
    $path = $_GET['q'];
  }
  if (isset($router_item)) {
    $router_items[$path] = $router_item;
  }
  if (!isset($router_items[$path])) {
    $original_map = arg(NULL, $path);
    $parts = array_slice($original_map, 0, MENU_MAX_PARTS);
    list($ancestors, $placeholders) = menu_get_ancestors($parts);

    if ($router_item = db_fetch_array(db_query_range('SELECT * FROM {menu_router} WHERE path IN (' . implode (',', $placeholders) . ') ORDER BY fit DESC', $ancestors, 0, 1))) {
      $map = _menu_translate($router_item, $original_map);
      if ($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']));
      }
    }
    $router_items[$path] = $router_item;
  }
  return $router_items[$path];
}

/**
 * Execute the page callback associated with the current path
 */
function menu_execute_active_handler($path = NULL) {
  if (_menu_site_is_offline()) {
    return MENU_SITE_OFFLINE;
  }
  if (variable_get('menu_rebuild_needed', FALSE)) {
    menu_rebuild();
  }
  if ($router_item = menu_get_item($path)) {
    registry_load_path_files();
    if ($router_item['access']) {
      if (drupal_function_exists($router_item['page_callback'])) {
        return call_user_func_array($router_item['page_callback'], $router_item['page_arguments']);
      }
    }
    else {
      return MENU_ACCESS_DENIED;
    }
  }
  return MENU_NOT_FOUND;
}

/**
 * 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 (ex: 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 = $item['load_functions']) {
    // If someone calls this function twice, then unserialize will fail.
    if ($load_functions_unserialized = unserialize($load_functions)) {
      $load_functions = $load_functions_unserialized;
    }
    $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
              // occurances 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 ($return === FALSE) {
          $item['access'] = FALSE;
          $map = FALSE;
          return FALSE;
        }
        $map[$index] = $return;
      }
    }
    $item['load_functions'] = $load_functions;
  }
  return TRUE;
}

/**
 * Check 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 (ex: 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);
    }
  }
}

/**
 * Localize 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 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) {
  $callback = $item['title_callback'];
  $item['localized_options'] = $item['options'];
  // If we are not doing link translation or if the title matches the
  // link title of its router item, localize it.
  if (!$link_translate || (!empty($item['title']) && ($item['title'] == $item['link_title']))) {
    // t() is a special case. Since it is used very close to all the time,
    // we handle it directly instead of using indirect, slower methods.
    if ($callback == 't') {
      if (empty($item['title_arguments'])) {
        $item['title'] = t($item['title']);
      }
      else {
        $item['title'] = t($item['title'], menu_unserialize($item['title_arguments'], $map));
      }
    }
    elseif ($callback) {
      if (empty($item['title_arguments'])) {
        $item['title'] = $callback($item['title']);
      }
      else {
        $item['title'] = call_user_func_array($callback, menu_unserialize($item['title_arguments'], $map));
      }
      // Avoid calling check_plain again on l() function.
      if ($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'];
    $item['description'] = t($item['description']);
    if ($link_translate && isset($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 (ex: 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. $item['href'] is set according to the map.
 *   If an error occurs during calling the load_functions (like trying to load
 *   a non existing node) then this function return FALSE.
 */
function _menu_translate(&$router_item, $map, $to_arg = FALSE) {
  $path_map = $map;
  if (!_menu_load_objects($router_item, $map)) {
    // An error occurred loading an object.
    $router_item['access'] = FALSE;
    return FALSE;
  }
  if ($to_arg) {
    _menu_link_map_translate($path_map, $router_item['to_arg_functions']);
  }

  // Generate the link path for the page request or local tasks.
  $link_map = explode('/', $router_item['path']);
  for ($i = 0; $i < $router_item['number_parts']; $i++) {
    if ($link_map[$i] == '%') {
      $link_map[$i] = $path_map[$i];
    }
  }
  $router_item['href'] = implode('/', $link_map);
  $router_item['options'] = array();
  _menu_check_access($router_item, $map);

  _menu_item_localize($router_item, $map);

  return $map;
}

/**
 * This function translates the path elements in the map using any to_arg
 * helper function. These functions take an argument and return an object.
 * See http://drupal.org/node/109153 for more information.
 *
 * @param map
 *   An array of path arguments (ex: array('node', '5'))
 * @param $to_arg_functions
 *   An array of helper function (ex: array(2 => 'menu_tail_to_arg'))
 */
function _menu_link_map_translate(&$map, $to_arg_functions) {
  if ($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]);
      }
    }
  }
}

function menu_tail_to_arg($arg, $map, $index) {
  return implode('/', array_slice($map, $index));
}

/**
 * This function is similar to _menu_translate() but does link-specific
 * preparation such as always calling to_arg functions
 *
 * @param $item
 *   A menu link
 * @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) {
  $item['options'] = unserialize($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 {
    $map = explode('/', $item['link_path']);
    _menu_link_map_translate($map, $item['to_arg_functions']);
    $item['href'] = implode('/', $map);

    // Note - skip callbacks without real values for their 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 (!_menu_load_objects($item, $map)) {
        // An error occurred loading an object.
        $item['access'] = FALSE;
        return FALSE;
      }
      _menu_check_access($item, $map);
    }

    _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;
}

/**
 * Get a loaded object from a router item.
 *
 * menu_get_object() will provide you the current node on paths like node/5,
 * node/5/revisions/48 etc. menu_get_object('user') will give you the user
 * account on user/5 etc. Note - this function should never be called within a
 * _to_arg function (like user_current_to_arg()) since this may result in an
 * infinite recursion.
 *
 * @param $type
 *   Type of the object. These appear in hook_menu definitons as %type. Core
 *   provides aggregator_feed, aggregator_category, contact, filter_format,
 *   forum_term, menu, menu_link, node, taxonomy_vocabulary, user. See the
 *   relevant {$type}_load function for more on each. Defaults to node.
 * @param $position
 *   The expected position for $type object. For node/%node this is 1, for
 *   comment/reply/%node this is 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];
  }
}

/**
 * Render 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 $menu_name
 *   The name of the menu.
 * @return
 *   The rendered HTML of that menu on the current page.
 */
function menu_tree($menu_name = 'navigation') {
  static $menu_output = 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.
 *
 * @param $tree
 *   A data structure representing the tree as returned from menu_tree_data.
 * @return
 *   The rendered HTML of that data structure.
 */
function menu_tree_output($tree) {
  $output = '';
  $items = array();

  // Pull out just the menu items we are going to render so that we
  // get an accurate count for the first/last classes.
  foreach ($tree as $data) {
    if (!$data['link']['hidden']) {
      $items[] = $data;
    }
  }

  $num_items = count($items);
  foreach ($items as $i => $data) {
    $extra_class = NULL;
    if ($i == 0) {
      $extra_class = 'first';
    }
    if ($i == $num_items - 1) {
      $extra_class = 'last';
    }
    $link = theme('menu_item_link', $data['link']);
    if ($data['below']) {
      $output .= theme('menu_item', $link, $data['link']['has_children'], menu_tree_output($data['below']), $data['link']['in_active_trail'], $extra_class);
    }
    else {
      $output .= theme('menu_item', $link, $data['link']['has_children'], '', $data['link']['in_active_trail'], $extra_class);
    }
  }
  return $output ? theme('menu_tree', $output) : '';
}

/**
 * Get 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 $item
 *   A fully loaded menu link, or NULL.  If a link is supplied, only the
 *   path to root will be included in the returned tree- as if this link
 *   represented the current page in a visible menu.
 * @return
 *   An tree of menu links in an array, in the order they should be rendered.
 */
function menu_tree_all_data($menu_name = 'navigation', $item = NULL) {
  static $tree = array();

  // Use $mlid as a flag for whether the data being loaded is for the whole tree.
  $mlid = isset($item['mlid']) ? $item['mlid'] : 0;
  // Generate a cache ID (cid) specific for this $menu_name and $item.
  $cid = 'links:' . $menu_name . ':all-cid:' . $mlid;

  if (!isset($tree[$cid])) {
    // If the static variable doesn't have the data, check {cache_menu}.
    $cache = cache_get($cid, 'cache_menu');
    if ($cache && isset($cache->data)) {
      // If the cache entry exists, it will just be the cid for the actual data.
      // This avoids duplication of large amounts of data.
      $cache = cache_get($cache->data, 'cache_menu');
      if ($cache && isset($cache->data)) {
        $data = $cache->data;
      }
    }
    // If the tree data was not in the cache, $data will be NULL.
    if (!isset($data)) {
      // Build and run the query, and build the tree.
      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.
        $args = array(0);
        for ($i = 1; $i < MENU_MAX_DEPTH; $i++) {
          $args[] = $item["p$i"];
        }
        $args = array_unique($args);
        $placeholders = implode(', ', array_fill(0, count($args), '%d'));
        $where = ' AND ml.plid IN (' . $placeholders . ')';
        $parents = $args;
        $parents[] = $item['mlid'];
      }
      else {
        // Get all links in this menu.
        $where = '';
        $args = array();
        $parents = array();
      }
      array_unshift($args, $menu_name);
      // Select the links from the table, and recursively build the tree.  We
      // LEFT JOIN since there is no match in {menu_router} for an external
      // link.
      $data['tree'] = menu_tree_data(db_query("
        SELECT m.load_functions, m.to_arg_functions, m.access_callback, m.access_arguments, m.page_callback, m.page_arguments, m.title, m.title_callback, m.title_arguments, m.type, m.description, ml.*
        FROM {menu_links} ml LEFT JOIN {menu_router} m ON m.path = ml.router_path
        WHERE ml.menu_name = '%s'" . $where . "
        ORDER BY p1 ASC, p2 ASC, p3 ASC, p4 ASC, p5 ASC, p6 ASC, p7 ASC, p8 ASC, p9 ASC", $args), $parents);
      $data['node_links'] = array();
      menu_tree_collect_node_links($data['tree'], $data['node_links']);
      // Cache the data, if it is not already in the cache.
      $tree_cid = _menu_tree_cid($menu_name, $data);
      if (!cache_get($tree_cid, 'cache_menu')) {
        cache_set($tree_cid, $data, 'cache_menu');
      }
      // Cache the cid of the (shared) data using the menu and item-specific cid.
      cache_set($cid, $tree_cid, 'cache_menu');
    }
    // Check access for the current user to each item in the tree.
    menu_tree_check_access($data['tree'], $data['node_links']);
    $tree[$cid] = $data['tree'];
  }

  return $tree[$cid];
}

/**
 * Get the data structure representing 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 $menu_name
 *   The named menu links to return
 * @return
 *   An array of menu links, in the order they should be rendered. The array
 *   is a list of associative arrays -- these have two keys, link and below.
 *   link is a menu item, ready for theming as a link. Below represents the
 *   submenu below the link if there is one, and it is a subtree that has the
 *   same structure described for the top-level array.
 */
function menu_tree_page_data($menu_name = 'navigation') {
  static $tree = array();

  // Load the menu item corresponding to the current page.
  if ($item = menu_get_item()) {
    // Generate a cache ID (cid) specific for this page.
    $cid = 'links:' . $menu_name . ':page-cid:' . $item['href'] . ':' . (int)$item['access'];

    if (!isset($tree[$cid])) {
      // If the static variable doesn't have the data, check {cache_menu}.
      $cache = cache_get($cid, 'cache_menu');
      if ($cache && isset($cache->data)) {
        // If the cache entry exists, it will just be the cid for the actual data.
        // This avoids duplication of large amounts of data.
        $cache = cache_get($cache->data, 'cache_menu');
        if ($cache && isset($cache->data)) {
          $data = $cache->data;
        }
      }
      // If the tree data was not in the cache, $data will be NULL.
      if (!isset($data)) {
        // Build and run the query, and build the tree.
        if ($item['access']) {
          // Check whether a menu link exists that corresponds to the current path.
          $args = array($menu_name, $item['href']);
          $placeholders = "'%s'";
          if (drupal_is_front_page()) {
            $args[] = '<front>';
            $placeholders .= ", '%s'";
          }
          $parents = db_fetch_array(db_query("SELECT p1, p2, p3, p4, p5, p6, p7, p8 FROM {menu_links} WHERE menu_name = '%s' AND link_path IN (" . $placeholders . ")", $args));

          if (empty($parents)) {
            // If no link exists, we may be on a local task that's not in the links.
            // TODO: Handle the case like a local task on a specific node in the menu.
            $parents = db_fetch_array(db_query("SELECT p1, p2, p3, p4, p5, p6, p7, p8 FROM {menu_links} WHERE menu_name = '%s' AND link_path = '%s'", $menu_name, $item['tab_root']));
          }
          // We always want all the top-level links with plid == 0.
          $parents[] = '0';

          // Use array_values() so that the indices are numeric for array_merge().
          $args = $parents = array_unique(array_values($parents));
          $placeholders = implode(', ', array_fill(0, count($args), '%d'));
          $expanded = variable_get('menu_expanded', array());
          // Check whether the current menu has any links set to be expanded.
          if (in_array($menu_name, $expanded)) {
            // Collect all the links set to be expanded, and then add all of
            // their children to the list as well.
            do {
              $result = db_query("SELECT mlid FROM {menu_links} WHERE menu_name = '%s' AND expanded = 1 AND has_children = 1 AND plid IN (" . $placeholders . ') AND mlid NOT IN (' . $placeholders . ')', array_merge(array($menu_name), $args, $args));
              $num_rows = FALSE;
              while ($item = db_fetch_array($result)) {
                $args[] = $item['mlid'];
                $num_rows = TRUE;
              }
              $placeholders = implode(', ', array_fill(0, count($args), '%d'));
            } while ($num_rows);
          }
          array_unshift($args, $menu_name);
        }
        else {
          // Show only the top-level menu items when access is denied.
          $args = array($menu_name, '0');
          $placeholders = '%d';
          $parents = array();
        }
        // Select the links from the table, and recursively build the tree. We
        // LEFT JOIN since there is no match in {menu_router} for an external
        // link.
        $data['tree'] = menu_tree_data(db_query("
          SELECT m.load_functions, m.to_arg_functions, m.access_callback, m.access_arguments, m.page_callback, m.page_arguments, m.title, m.title_callback, m.title_arguments, m.type, m.description, ml.*
          FROM {menu_links} ml LEFT JOIN {menu_router} m ON m.path = ml.router_path
          WHERE ml.menu_name = '%s' AND ml.plid IN (" . $placeholders . ")
          ORDER BY p1 ASC, p2 ASC, p3 ASC, p4 ASC, p5 ASC, p6 ASC, p7 ASC, p8 ASC, p9 ASC", $args), $parents);
        $data['node_links'] = array();
        menu_tree_collect_node_links($data['tree'], $data['node_links']);
        // Cache the data, if it is not already in the cache.
        $tree_cid = _menu_tree_cid($menu_name, $data);
        if (!cache_get($tree_cid, 'cache_menu')) {
          cache_set($tree_cid, $data, 'cache_menu');
        }
        // Cache the cid of the (shared) data using the page-specific cid.
        cache_set($cid, $tree_cid, 'cache_menu');
      }
      // Check access for the current user to each item in the tree.
      menu_tree_check_access($data['tree'], $data['node_links']);
      $tree[$cid] = $data['tree'];
    }
    return $tree[$cid];
  }

  return array();
}

/**
 * Helper function - compute the real cache ID for menu tree data.