1<?php
  2/**
  3 * Post API: Walker_PageDropdown class
  4 *
  5 * @package WordPress
  6 * @subpackage Post
  7 * @since 4.4.0
  8 */
  9
 10/**
 11 * Core class used to create an HTML drop-down list of pages.
 12 *
 13 * @since 2.1.0
 14 *
 15 * @see Walker
 16 */
 17class Walker_PageDropdown extends Walker {
 18
 19	/**
 20	 * What the class handles.
 21	 *
 22	 * @since 2.1.0
 23	 * @var string
 24	 *
 25	 * @see Walker::$tree_type
 26	 */
 27	public $tree_type = 'page';
 28
 29	/**
 30	 * Database fields to use.
 31	 *
 32	 * @since 2.1.0
 33	 * @var string[]
 34	 *
 35	 * @see Walker::$db_fields
 36	 * @todo Decouple this
 37	 */
 38	public $db_fields = array(
 39		'parent' => 'post_parent',
 40		'id'     => 'ID',
 41	);
 42
 43	/**
 44	 * Starts the element output.
 45	 *
 46	 * @since 2.1.0
 47	 * @since 5.9.0 Renamed `$page` to `$data_object` and `$id` to `$current_object_id`
 48	 *              to match parent class for PHP 8 named parameter support.
 49	 *
 50	 * @see Walker::start_el()
 51	 *
 52	 * @param string  $output            Used to append additional content. Passed by reference.
 53	 * @param WP_Post $data_object       Page data object.
 54	 * @param int     $depth             Optional. Depth of page in reference to parent pages.
 55	 *                                   Used for padding. Default 0.
 56	 * @param array   $args              Optional. Uses 'selected' argument for selected page to
 57	 *                                   set selected HTML attribute for option element. Uses
 58	 *                                   'value_field' argument to fill "value" attribute.
 59	 *                                   See wp_dropdown_pages(). Default empty array.
 60	 * @param int     $current_object_id Optional. ID of the current page. Default 0.
 61	 */
 62	public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {
 63		// Restores the more descriptive, specific name for use within this method.
 64		$page = $data_object;
 65
 66		$pad = str_repeat( '&nbsp;', $depth * 3 );
 67
 68		if ( ! isset( $args['value_field'] ) || ! isset( $page->{$args['value_field']} ) ) {
 69			$args['value_field'] = 'ID';
 70		}
 71
 72		$output .= "\t<option class=\"level-$depth\" value=\"" . esc_attr( $page->{$args['value_field']} ) . '"';
 73		if ( $page->ID === (int) $args['selected'] ) {
 74			$output .= ' selected="selected"';
 75		}
 76		$output .= '>';
 77
 78		$title = $page->post_title;
 79		if ( '' === $title ) {
 80			/* translators: %d: ID of a post. */
 81			$title = sprintf( __( '#%d (no title)' ), $page->ID );
 82		}
 83
 84		/**
 85		 * Filters the page title when creating an HTML drop-down list of pages.
 86		 *
 87		 * @since 3.1.0
 88		 *
 89		 * @param string  $title Page title.
 90		 * @param WP_Post $page  Page data object.
 91		 */
 92		$title = apply_filters( 'list_pages', $title, $page );
 93
 94		$output .= $pad . esc_html( $title );
 95		$output .= "</option>\n";
 96	}
 97}
 98