class-nav-walker.php

<?php

namespace Chamber\Theme;

/**
 * Cleaner walker for wp_nav_menu()
 * 
 * @package    Soil
 * @author     roots.io
 * @copyright  Copyright (c) Roots
 * @link       https://github.com/roots/soil
 *
 * Walker_Nav_Menu (WordPress default) example output:
 *   <li id="menu-item-8" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-8"><a href="/">Home</a></li>
 *   <li id="menu-item-9" class="menu-item menu-item-type-post_type menu-item-object-page menu-item-9"><a href="/sample-page/">Sample Page</a></l
 *
 * NavWalker example output:
 *   <li class="menu-home"><a href="/">Home</a></li>
 *   <li class="menu-sample-page"><a href="/sample-page/">Sample Page</a></li>
 *
 * You can enable/disable this feature in functions.php (or lib/setup.php if you're using Sage):
 * add_theme_support('chamber-nav-walker');
 */
class NavWalker extends \Walker_Nav_Menu {
    private $cpt; // Boolean, is current post a custom post type
    private $archive; // Stores the archive page for current URL

    /**
     * Boot the nav-walker.
     * 
     * @return void
     */
    public function boot() {
        add_filter('nav_menu_css_class', [ $this, 'cssClasses' ], 10, 2);
        add_filter('nav_menu_item_id', '__return_null');
        $cpt           = get_post_type();
        $this->cpt     = in_array( $cpt, get_post_types( ['_builtin' => false ] ) );
        $this->archive = get_post_type_archive_link($cpt);
    }

    public function checkCurrent($classes) {
        return preg_match('/(current[-_])|active/', $classes);
    }

    /**
     * Compare URL against relative URL
     */
    function url_compare($url, $rel) {
      $url = trailingslashit($url);
      $rel = trailingslashit($rel);
      return ((strcasecmp($url, $rel) === 0) || root_relative_url($url) == $rel);
    }

    // @codingStandardsIgnoreStart
    public function display_element($element, &$children_elements, $max_depth, $depth = 0, $args, &$output) {
        $element->is_subitem = ((!empty($children_elements[$element->ID]) && (($depth + 1) < $max_depth || ($max_depth === 0))));

        if ($element->is_subitem) {
            foreach ($children_elements[$element->ID] as $child) {
                if ($child->current_item_parent || $this->url_compare($this->archive, $child->url)) {
                    $element->classes[] = 'active';
                }
            }
        }

        $element->is_active = (!empty($element->url) && strpos($this->archive, $element->url));

        if ($element->is_active) {
            $element->classes[] = 'active';
        }

        parent::display_element($element, $children_elements, $max_depth, $depth, $args, $output);
    }
    // @codingStandardsIgnoreEnd

    public function cssClasses($classes, $item) {
        $slug = sanitize_title($item->title);

        // Fix core `active` behavior for custom post types
        if ($this->cpt) {
            $classes = str_replace('current_page_parent', '', $classes);

            if ($this->url_compare($this->archive, $item->url)) {
                $classes[] = 'active';
            }
        }

        // Remove most core classes
        $classes = preg_replace('/(current(-menu-|[-_]page[-_])(item|parent|ancestor))/', 'active', $classes);
        $classes = preg_replace('/^((menu|page)[-_\w+]+)+/', '', $classes);

        // Re-add core `menu-item` class
        $classes[] = 'menu-item';

        // Re-add core `menu-item-has-children` class on parent elements
        if ($item->is_subitem) {
            $classes[] = 'menu-item-has-children';
        }

        // Add `menu-<slug>` class
        $classes[] = 'menu-' . $slug;

        $classes = array_unique($classes);
        $classes = array_map('trim', $classes);

        return array_filter($classes);
    }
}

// (new NavWalker)->boot();

/**
 * Clean up wp_nav_menu_args
 *
 * Remove the container
 * Remove the id="" on nav menu items
 */
function nav_menu_args($args = '') {
    $nav_menu_args = [];
    $nav_menu_args['container'] = false;

    if (!$args['items_wrap']) {
        $nav_menu_args['items_wrap'] = '<ul class="%2$s">%3$s</ul>';
    }

    if (!$args['walker']) {
        $nav_menu_args['walker'] = new NavWalker();
    }

    return array_merge($args, $nav_menu_args);
}
add_filter('wp_nav_menu_args', __NAMESPACE__ . '\\nav_menu_args');
add_filter('nav_menu_item_id', '__return_null');