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   1  <?php
   2  /**
   3   * Nav Menu API: Walker_Nav_Menu class
   4   *
   5   * @package WordPress
   6   * @subpackage Nav_Menus
   7   * @since 4.6.0
   8   */
   9  
  10  /**
  11   * Core class used to implement an HTML list of nav menu items.
  12   *
  13   * @since 3.0.0
  14   *
  15   * @see Walker
  16   */
  17  class Walker_Nav_Menu extends Walker {
  18      /**
  19       * What the class handles.
  20       *
  21       * @since 3.0.0
  22       * @var string
  23       *
  24       * @see Walker::$tree_type
  25       */
  26      public $tree_type = array( 'post_type', 'taxonomy', 'custom' );
  27  
  28      /**
  29       * Database fields to use.
  30       *
  31       * @since 3.0.0
  32       * @todo Decouple this.
  33       * @var string[]
  34       *
  35       * @see Walker::$db_fields
  36       */
  37      public $db_fields = array(
  38          'parent' => 'menu_item_parent',
  39          'id'     => 'db_id',
  40      );
  41  
  42      /**
  43       * Starts the list before the elements are added.
  44       *
  45       * @since 3.0.0
  46       *
  47       * @see Walker::start_lvl()
  48       *
  49       * @param string   $output Used to append additional content (passed by reference).
  50       * @param int      $depth  Depth of menu item. Used for padding.
  51       * @param stdClass $args   An object of wp_nav_menu() arguments.
  52       */
  53  	public function start_lvl( &$output, $depth = 0, $args = null ) {
  54          if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
  55              $t = '';
  56              $n = '';
  57          } else {
  58              $t = "\t";
  59              $n = "\n";
  60          }
  61          $indent = str_repeat( $t, $depth );
  62  
  63          // Default class.
  64          $classes = array( 'sub-menu' );
  65  
  66          /**
  67           * Filters the CSS class(es) applied to a menu list element.
  68           *
  69           * @since 4.8.0
  70           *
  71           * @param string[] $classes Array of the CSS classes that are applied to the menu `<ul>` element.
  72           * @param stdClass $args    An object of `wp_nav_menu()` arguments.
  73           * @param int      $depth   Depth of menu item. Used for padding.
  74           */
  75          $class_names = implode( ' ', apply_filters( 'nav_menu_submenu_css_class', $classes, $args, $depth ) );
  76          $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
  77  
  78          $output .= "{$n}{$indent}<ul$class_names>{$n}";
  79      }
  80  
  81      /**
  82       * Ends the list of after the elements are added.
  83       *
  84       * @since 3.0.0
  85       *
  86       * @see Walker::end_lvl()
  87       *
  88       * @param string   $output Used to append additional content (passed by reference).
  89       * @param int      $depth  Depth of menu item. Used for padding.
  90       * @param stdClass $args   An object of wp_nav_menu() arguments.
  91       */
  92  	public function end_lvl( &$output, $depth = 0, $args = null ) {
  93          if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
  94              $t = '';
  95              $n = '';
  96          } else {
  97              $t = "\t";
  98              $n = "\n";
  99          }
 100          $indent  = str_repeat( $t, $depth );
 101          $output .= "$indent</ul>{$n}";
 102      }
 103  
 104      /**
 105       * Starts the element output.
 106       *
 107       * @since 3.0.0
 108       * @since 4.4.0 The {@see 'nav_menu_item_args'} filter was added.
 109       * @since 5.9.0 Renamed `$item` to `$data_object` and `$id` to `$current_object_id`
 110       *              to match parent class for PHP 8 named parameter support.
 111       *
 112       * @see Walker::start_el()
 113       *
 114       * @param string   $output            Used to append additional content (passed by reference).
 115       * @param WP_Post  $data_object       Menu item data object.
 116       * @param int      $depth             Depth of menu item. Used for padding.
 117       * @param stdClass $args              An object of wp_nav_menu() arguments.
 118       * @param int      $current_object_id Optional. ID of the current menu item. Default 0.
 119       */
 120  	public function start_el( &$output, $data_object, $depth = 0, $args = null, $current_object_id = 0 ) {
 121          // Restores the more descriptive, specific name for use within this method.
 122          $menu_item = $data_object;
 123  
 124          if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
 125              $t = '';
 126              $n = '';
 127          } else {
 128              $t = "\t";
 129              $n = "\n";
 130          }
 131          $indent = ( $depth ) ? str_repeat( $t, $depth ) : '';
 132  
 133          $classes   = empty( $menu_item->classes ) ? array() : (array) $menu_item->classes;
 134          $classes[] = 'menu-item-' . $menu_item->ID;
 135  
 136          /**
 137           * Filters the arguments for a single nav menu item.
 138           *
 139           * @since 4.4.0
 140           *
 141           * @param stdClass $args      An object of wp_nav_menu() arguments.
 142           * @param WP_Post  $menu_item Menu item data object.
 143           * @param int      $depth     Depth of menu item. Used for padding.
 144           */
 145          $args = apply_filters( 'nav_menu_item_args', $args, $menu_item, $depth );
 146  
 147          /**
 148           * Filters the CSS classes applied to a menu item's list item element.
 149           *
 150           * @since 3.0.0
 151           * @since 4.1.0 The `$depth` parameter was added.
 152           *
 153           * @param string[] $classes   Array of the CSS classes that are applied to the menu item's `<li>` element.
 154           * @param WP_Post  $menu_item The current menu item object.
 155           * @param stdClass $args      An object of wp_nav_menu() arguments.
 156           * @param int      $depth     Depth of menu item. Used for padding.
 157           */
 158          $class_names = implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $menu_item, $args, $depth ) );
 159          $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
 160  
 161          /**
 162           * Filters the ID applied to a menu item's list item element.
 163           *
 164           * @since 3.0.1
 165           * @since 4.1.0 The `$depth` parameter was added.
 166           *
 167           * @param string   $menu_id   The ID that is applied to the menu item's `<li>` element.
 168           * @param WP_Post  $menu_item The current menu item.
 169           * @param stdClass $args      An object of wp_nav_menu() arguments.
 170           * @param int      $depth     Depth of menu item. Used for padding.
 171           */
 172          $id = apply_filters( 'nav_menu_item_id', 'menu-item-' . $menu_item->ID, $menu_item, $args, $depth );
 173          $id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
 174  
 175          $output .= $indent . '<li' . $id . $class_names . '>';
 176  
 177          $atts           = array();
 178          $atts['title']  = ! empty( $menu_item->attr_title ) ? $menu_item->attr_title : '';
 179          $atts['target'] = ! empty( $menu_item->target ) ? $menu_item->target : '';
 180          if ( '_blank' === $menu_item->target && empty( $menu_item->xfn ) ) {
 181              $atts['rel'] = 'noopener';
 182          } else {
 183              $atts['rel'] = $menu_item->xfn;
 184          }
 185          $atts['href']         = ! empty( $menu_item->url ) ? $menu_item->url : '';
 186          $atts['aria-current'] = $menu_item->current ? 'page' : '';
 187  
 188          /**
 189           * Filters the HTML attributes applied to a menu item's anchor element.
 190           *
 191           * @since 3.6.0
 192           * @since 4.1.0 The `$depth` parameter was added.
 193           *
 194           * @param array $atts {
 195           *     The HTML attributes applied to the menu item's `<a>` element, empty strings are ignored.
 196           *
 197           *     @type string $title        Title attribute.
 198           *     @type string $target       Target attribute.
 199           *     @type string $rel          The rel attribute.
 200           *     @type string $href         The href attribute.
 201           *     @type string $aria-current The aria-current attribute.
 202           * }
 203           * @param WP_Post  $menu_item The current menu item object.
 204           * @param stdClass $args      An object of wp_nav_menu() arguments.
 205           * @param int      $depth     Depth of menu item. Used for padding.
 206           */
 207          $atts = apply_filters( 'nav_menu_link_attributes', $atts, $menu_item, $args, $depth );
 208  
 209          $attributes = '';
 210          foreach ( $atts as $attr => $value ) {
 211              if ( is_scalar( $value ) && '' !== $value && false !== $value ) {
 212                  $value       = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
 213                  $attributes .= ' ' . $attr . '="' . $value . '"';
 214              }
 215          }
 216  
 217          /** This filter is documented in wp-includes/post-template.php */
 218          $title = apply_filters( 'the_title', $menu_item->title, $menu_item->ID );
 219  
 220          /**
 221           * Filters a menu item's title.
 222           *
 223           * @since 4.4.0
 224           *
 225           * @param string   $title     The menu item's title.
 226           * @param WP_Post  $menu_item The current menu item object.
 227           * @param stdClass $args      An object of wp_nav_menu() arguments.
 228           * @param int      $depth     Depth of menu item. Used for padding.
 229           */
 230          $title = apply_filters( 'nav_menu_item_title', $title, $menu_item, $args, $depth );
 231  
 232          $item_output  = $args->before;
 233          $item_output .= '<a' . $attributes . '>';
 234          $item_output .= $args->link_before . $title . $args->link_after;
 235          $item_output .= '</a>';
 236          $item_output .= $args->after;
 237  
 238          /**
 239           * Filters a menu item's starting output.
 240           *
 241           * The menu item's starting output only includes `$args->before`, the opening `<a>`,
 242           * the menu item's title, the closing `</a>`, and `$args->after`. Currently, there is
 243           * no filter for modifying the opening and closing `<li>` for a menu item.
 244           *
 245           * @since 3.0.0
 246           *
 247           * @param string   $item_output The menu item's starting HTML output.
 248           * @param WP_Post  $menu_item   Menu item data object.
 249           * @param int      $depth       Depth of menu item. Used for padding.
 250           * @param stdClass $args        An object of wp_nav_menu() arguments.
 251           */
 252          $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $menu_item, $depth, $args );
 253      }
 254  
 255      /**
 256       * Ends the element output, if needed.
 257       *
 258       * @since 3.0.0
 259       * @since 5.9.0 Renamed `$item` to `$data_object` to match parent class for PHP 8 named parameter support.
 260       *
 261       * @see Walker::end_el()
 262       *
 263       * @param string   $output      Used to append additional content (passed by reference).
 264       * @param WP_Post  $data_object Menu item data object. Not used.
 265       * @param int      $depth       Depth of page. Not Used.
 266       * @param stdClass $args        An object of wp_nav_menu() arguments.
 267       */
 268  	public function end_el( &$output, $data_object, $depth = 0, $args = null ) {
 269          if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
 270              $t = '';
 271              $n = '';
 272          } else {
 273              $t = "\t";
 274              $n = "\n";
 275          }
 276          $output .= "</li>{$n}";
 277      }
 278  
 279  }