Walker_Page::start_el( string $output, WP_Post $data_object, int $depth = 0, array $args = array(), int $current_object_id = 0 )

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$outputstring

Used to append additional content. Passed by reference.

$data_objectWP_Post

Page data object.

$depthintoptional

Depth of page. Used for padding. Default 0.Default: 0

$argsarrayoptional

Array of arguments. Default empty array.Default: array()

$current_object_idintoptional

ID of the current page. Default 0.Default: 0

Performance profile

How much work a call to Walker_Page::start_el() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reaches the database via get_post().

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

107–157

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 215.

Plugin surface

3 hooks

Third-party callbacks on 'page_css_class', 'page_menu_link_attributes', 'the_title' run inside this call, and their cost is not bounded by anything here.

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

• querycontent queryget_post()called directly
• optionoption read or writeget_option()called directly
• hookthird-party callbacksapply_filters()called directly
• cacheobject cachewp_cache_get()one call below Walker_Page::start_el()
• serializeserialisationmaybe_unserialize()one call below Walker_Page::start_el()

Further down the call graph this can also reach transient. That is the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 16 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost Walker_Page::start_el() can have, taken from its control-flow graph on PHP 8.5.

This body has more branch combinations than are worth enumerating, so the table covers the outcomes found first rather than every one that exists.

Hooks and filters fired · 3

3 hooks fire while Walker_Page::start_el() runs, in this order:

1. 1
   apply_filters( page_css_class )filterline 159 (+54 into the body)

   Filters the list of CSS classes to include with each page item in the list.

2. 2
   apply_filters( page_menu_link_attributes )filterline 190 (+85 into the body)

   Filters the HTML attributes applied to a page menu item's anchor element.

3. 3
   apply_filters( the_title )filterline 206 (+101 into the body)

   Filters the post title.

Uses · 8

• get_post()Retrieves post data given a post ID or post object.
• get_option()Retrieves an option value based on an option name.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• esc_attr()Escaping for HTML attributes.
• __()Retrieves the translation of $text.
• get_permalink()Retrieves the full permalink for the current post or post ID.
• esc_url()Checks and cleans a URL.
• mysql2date()Converts given MySQL date string into a different format.

Source code

View on Trac ↗View on GitHub ↗

105	public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {106		// Restores the more descriptive, specific name for use within this method.107		$page = $data_object;108 109		$current_page_id = $current_object_id;110 111		if ( isset( $args['item_spacing'] ) && 'preserve' === $args['item_spacing'] ) {112			$t = "\t";113			$n = "\n";114		} else {115			$t = '';116			$n = '';117		}118		if ( $depth ) {119			$indent = str_repeat( $t, $depth );120		} else {121			$indent = '';122		}123 124		$css_class = array( 'page_item', 'page-item-' . $page->ID );125 126		if ( isset( $args['pages_with_children'][ $page->ID ] ) ) {127			$css_class[] = 'page_item_has_children';128		}129 130		if ( ! empty( $current_page_id ) ) {131			$_current_page = get_post( $current_page_id );132 133			if ( $_current_page && in_array( $page->ID, $_current_page->ancestors, true ) ) {134				$css_class[] = 'current_page_ancestor';135			}136 137			if ( $page->ID === (int) $current_page_id ) {138				$css_class[] = 'current_page_item';139			} elseif ( $_current_page && $page->ID === $_current_page->post_parent ) {140				$css_class[] = 'current_page_parent';141			}142		} elseif ( (int) get_option( 'page_for_posts' ) === $page->ID ) {143			$css_class[] = 'current_page_parent';144		}145 146		/**147		 * Filters the list of CSS classes to include with each page item in the list.148		 *149		 * @since 2.8.0150		 *151		 * @see wp_list_pages()152		 *153		 * @param string[] $css_class       An array of CSS classes to be applied to each list item.154		 * @param WP_Post  $page            Page data object.155		 * @param int      $depth           Depth of page, used for padding.156		 * @param array    $args            An array of arguments.157		 * @param int      $current_page_id ID of the current page.158		 */159		$css_classes = implode( ' ', apply_filters( 'page_css_class', $css_class, $page, $depth, $args, $current_page_id ) );160		$css_classes = $css_classes ? ' class="' . esc_attr( $css_classes ) . '"' : '';161 162		if ( '' === $page->post_title ) {163			/* translators: %d: ID of a post. */164			$page->post_title = sprintf( __( '#%d (no title)' ), $page->ID );165		}166 167		$args['link_before'] = empty( $args['link_before'] ) ? '' : $args['link_before'];168		$args['link_after']  = empty( $args['link_after'] ) ? '' : $args['link_after'];169 170		$atts                 = array();171		$atts['href']         = get_permalink( $page->ID );172		$atts['aria-current'] = ( $page->ID === (int) $current_page_id ) ? 'page' : '';173 174		/**175		 * Filters the HTML attributes applied to a page menu item's anchor element.176		 *177		 * @since 4.8.0178		 *179		 * @param array $atts {180		 *     The HTML attributes applied to the menu item's `<a>` element, empty strings are ignored.181		 *182		 *     @type string $href         The href attribute.183		 *     @type string $aria-current The aria-current attribute.184		 * }

Changelog

Introduced in 2.1.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/class-walker-page.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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