Source

File: wp-admin/includes/class-wp-posts-list-table.php

private function _page_rows( &$children_pages, &$count, $parent, $level, $pagenum, $per_page, &$to_display ) {
		if ( ! isset( $children_pages[ $parent ] ) ) {
			return;
		}

		$start = ( $pagenum - 1 ) * $per_page;
		$end   = $start + $per_page;

		foreach ( $children_pages[ $parent ] as $page ) {
			if ( $count >= $end ) {
				break;
			}

			// If the page starts in a subtree, print the parents.
			if ( $count == $start && $page->post_parent > 0 ) {
				$my_parents = array();
				$my_parent  = $page->post_parent;
				while ( $my_parent ) {
					// Get the ID from the list or the attribute if my_parent is an object.
					$parent_id = $my_parent;
					if ( is_object( $my_parent ) ) {
						$parent_id = $my_parent->ID;
					}

					$my_parent    = get_post( $parent_id );
					$my_parents[] = $my_parent;
					if ( ! $my_parent->post_parent ) {
						break;
					}
					$my_parent = $my_parent->post_parent;
				}
				$num_parents = count( $my_parents );
				while ( $my_parent = array_pop( $my_parents ) ) {
					$to_display[ $my_parent->ID ] = $level - $num_parents;
					$num_parents--;
				}
			}

			if ( $count >= $start ) {
				$to_display[ $page->ID ] = $level;
			}

			$count++;

			$this->_page_rows( $children_pages, $count, $page->ID, $level + 1, $pagenum, $per_page, $to_display );
		}

		unset( $children_pages[ $parent ] ); // Required in order to keep track of orphans.
	}