How to set limit only on top levels of wp_nav_menu?

How can I set a limit to the top level menu items in wp_nav_menu?

Example:

I have this menu in my admin dashboard:

I would like to count ONLY the top level items and display a limited number of them, let’s say 5.

So no matter if you’re in the admin dashboard and you have 100’s of top levels, it should only display 5.

The sub-pages should be displayed as well, normally, without any limit.

I searched for an answer here and on the web and I saw this answer but big problem is that this solution counts top and sub-pages altogether and I need to count only top pages.

I would like to see some solution with a custom walker class if possible or PHP in general and not with CSS and jQuery tricks and hacks.

According to the codex, you just need to use depthparameter to display only top-level pages :

<?php wp_nav_menu( array( 'location' => 'your_location', 'depth' => 1 ) ); ?>

For more reference see this.

You could also fix both of your problem by using [wp_get_nav_menu_items][2] and then using a custom loop to parse only first and top-level pages.

EDIT***
I did spent some time starting something to help, unfortunately I cannot finish it right now, and maybe could make it more elegant, but that could be a start :

<?php 
    $menu_name="principal";
        if ( ( $locations = get_nav_menu_locations() ) && isset( $locations[ $menu_name ] ) ) {
        $menu_test = wp_get_nav_menu_object( $locations[ $menu_name ] );
                    // WE GET THE ITEMS IN menu_order
        $menu_test_items = wp_get_nav_menu_items( $menu_test->term_id );
        $top_items = array();
                    // LOOP THEM AND CREATE NESTED ARRAY LIKE THE MENU 
        foreach( $menu_test_items as $menu_test_item ) {
            if ( $menu_test_item->menu_item_parent == 0 ) {
                $top_items[$menu_test_item->ID][$menu_test_item->ID] = $menu_test_item;     
            } else {
                $top_items[$menu_test_item->menu_item_parent][$menu_test_item->ID] = $menu_test_item;
            }

        }
                    // THEN WE COULD JUST LOOP IT x TIMES AND BREAK
        foreach ( $top_items as $top_item ) {  
            // Npw you need to loop x times
            // and display $top_item with another foreach
        }
    }
?>