_sub_menu.twig

{% macro display_menu_item(item, loop) %}
    {% from _self import display_menu_item %}
    <li class="index-{{ loop.index }}{% if loop.first %} first{% endif %}{% if loop.last %} last{% endif %}{% if item.submenu is defined %} has-dropdown{% endif %}{% if item|current %} active{% endif %}">
        <a href="{{ item.link }}" {% if item.title is defined %}title='{{ item.title|escape }}'{% endif %}
            class='{% if item.class is defined %}{{item.class}}{% endif %}'>
            {% if item.label is defined %}{{item.label}}{% else %} - {% endif %}
        </a>
        {% if item.submenu is defined %}
            <ul class="dropdown">
            {% for submenu in item.submenu %}
                {{ display_menu_item(submenu, loop) }}
            {% endfor %}
            </ul>
        {% endif %}
    </li>
{% endmacro %}

{% from _self import display_menu_item %}

{% for item in menu %}
    {% if item.label is defined %}
        {{ display_menu_item(item, loop) }}
    {% endif %}
{% endfor %}