bp_setup_nav_menu_item( WP_Post $menu_item )

function bp_setup_nav_menu_item( $menu_item ) {
	if ( is_admin() ) {
		return $menu_item;
	}

	// Prevent a notice error when using the customizer.
	$menu_classes = $menu_item->classes;

	if ( is_array( $menu_classes ) ) {
		$menu_classes = implode( ' ', $menu_item->classes);
	}

	// We use information stored in the CSS class to determine what kind of
	// menu item this is, and how it should be treated.
	preg_match( '/\sbp-(.*)-nav/', $menu_classes, $matches );

	// If this isn't a BP menu item, we can stop here.
	if ( empty( $matches[1] ) ) {
		return $menu_item;
	}

	switch ( $matches[1] ) {
		case 'login' :
			if ( is_user_logged_in() ) {
				$menu_item->_invalid = true;
			} else {
				$menu_item->url = wp_login_url( bp_get_requested_url() );
			}

			break;

		case 'logout' :
			if ( ! is_user_logged_in() ) {
				$menu_item->_invalid = true;
			} else {
				$menu_item->url = wp_logout_url( bp_get_requested_url() );
			}

			break;

		// Don't show the Register link to logged-in users.
		case 'register' :
			if ( is_user_logged_in() ) {
				$menu_item->_invalid = true;
			}

			break;

		// All other BP nav items are specific to the logged-in user,
		// and so are not relevant to logged-out users.
		default:
			if ( is_user_logged_in() ) {
				$menu_item->url = bp_nav_menu_get_item_url( $matches[1] );
			} else {
				$menu_item->_invalid = true;
			}

			break;
	}

	// If component is deactivated, make sure menu item doesn't render.
	if ( empty( $menu_item->url ) ) {
		$menu_item->_invalid = true;

		// Highlight the current page.
	} else {
		$current = bp_get_requested_url();
		if ( strpos( $current, $menu_item->url ) !== false ) {
			if ( is_array( $menu_item->classes ) ) {
				$menu_item->classes[] = 'current_page_item';
				$menu_item->classes[] = 'current-menu-item';
			} else {
				$menu_item->classes = array( 'current_page_item', 'current-menu-item' );
			}
		}
	}

	return $menu_item;
}