Full template

menu.html.twig

{#
/**
 * @file
 * Theme override to display a menu.
 */
#}
{% import _self as menus %}

{#
  We call a macro which calls itself to render the full tree.
  @see http://twig.sensiolabs.org/doc/tags/macro.html

  1. We use menu_name (see above) to create a CSS class name from it.
  See https://www.drupal.org/node/2649076
#}
{{ menus.menu_links(items, attributes, 0, menu_name) }} {# 1. #}

{% macro menu_links(items, attributes, menu_level, menu_name) %} {# 1. #}
  {% import _self as menus %}
  {# 1. #}
  {%
    set menu_classes = [
      'o-menu',
      'c-menu-' ~ menu_name|clean_class,
    ]
  %}
  {# 1. #}
  {%
    set submenu_classes = [
      'o-menu',
      'c-menu-' ~ menu_name|clean_class ~ '__submenu',
    ]
  %}
  {% if items %}
    {% if menu_level == 0 %}
      <ul{{ attributes.addClass(menu_classes) }}> {# 1. #}
    {% else %}
      <ul{{ attributes.removeClass(menu_classes).addClass(submenu_classes) }}> {# 1. #}
    {% endif %}
    {% for item in items %}
      {# 1. #}
      {%
        set item_classes = [
          'c-menu-' ~ menu_name|clean_class ~ '__item',
          item.is_expanded ? 'c-menu-' ~ menu_name|clean_class ~ '__item--expanded',
          item.is_collapsed ? 'c-menu-' ~ menu_name|clean_class ~ '__item--collapsed',
          item.in_active_trail ? 'c-menu-' ~ menu_name|clean_class ~ '__item--active-trail',
        ]
      %}
      {# 1. #}
      {%
        set link_classes = [
          'c-menu-' ~ menu_name|clean_class ~ '__link',
        ]
      %}
      <li{{ item.attributes.addClass(item_classes) }}>{# 1. #}
        {# 1. #}
        {{
          link(
            item.title,
            item.url,
            item.attributes.removeClass(item_classes).addClass(link_classes)
          )
        }}
        {% if item.below %}
          {{ menus.menu_links(item.below, attributes, menu_level + 1, menu_name) }} {# 1. #}
        {% endif %}
      </li>
    {% endfor %}
    </ul>
  {% endif %}
{% endmacro %}