Print Parent Menu Items of Current Page

Question

I would like to create a sidebar in node.tpl.php that prints the parent menu items of the current page with a depth that follows the current page's depth by one level.

So if I have a menu structure like:

A
B
C
--C1
--C2
--C3
D

... and I am on page B, I would see in the sidebar:

A
B
C
D

... or if I am on page C2 I would see in the sidebar:

C1
C2
C3

Answer 1

Answering my own question:

In a custom module (or in your template.php):

1) Create a helper function:

// Helper function used to return the children of a specific menu item
function MODULENAME_menu_subtree_data($item, $tree) {
    foreach ($tree as $cid => $data) {
        if ($item['mlid'] == $data['link']['mlid']) {
            return array($cid => $data);
        }
        if ($data['below']) {
            $return = MODULENAME_menu_subtree_data($item, $data['below']);
            if ($return) {
                return $return;
            }
        }
    }
    return FALSE;
}

2) Create a reusable output function:

// Return all the menu items for the parent of the given page.
// $menuParent = menu_get_active_trail(); Needs to be called on the requesting page 
function MODULENAME_parent_menu($menuParent) {
    // Get active trail to current page
    $menuParent = menu_get_active_trail();
    // Pop off last item of trail as that is the current page
    $menuParentPop = array_pop($menuParent);
    // Store the new last item in the trail as this is the parent menu item
    $menuParent = end($menuParent);
    // Set the depth to which we want to return the parent menu tree
    $max_depth = $menuParent['depth'] +1;
    $mlid = $menuParent['mlid'];                
    $menu_item = menu_link_load($mlid);
    $tree = MODULENAME_menu_subtree_data($menu_item, menu_tree_all_data($menu_item['menu_name'], $link = NULL, $max_depth));
    $tree = array_shift($tree);
    $tree_array = menu_tree_output($tree['below']);
    return drupal_render($tree_array);
}

3) Place this code in your node.tpl.php file wherever you want the menu to be rendered:

<?php
// Print all the menu items for the parent of the current page.
print MODULENAME_parent_menu($menuParent = menu_get_active_trail());
?>

Notes: - Replace MODULENAME with your custom module name or theme name if in template.php - You can adjust the "depth" of what's returned by adjusting the $max_depth variable to suite your needs. 0 = show everything.

Totally welcome any way to improve this!