der. * * $max_depth = 0 means display all levels. * $max_depth > 0 specifies the number of display levels. * * @since 2.7.0 * * @param array $elements * @param int $max_depth The maximum hierarchical depth. * @param int $page_num The specific page number, beginning with 1. * @param int $per_page * @return string XHTML of the specified page of elements */ public function paged_walk( $elements, $max_depth, $page_num, $per_page ) { if ( empty( $elements ) || $max_depth < -1 ) { return ''; } $args = array_slice( func_get_args(), 4 ); $output = ''; $parent_field = $this->db_fields['parent']; $count = -1; if ( -1 == $max_depth ) $total_top = count( $elements ); if ( $page_num < 1 || $per_page < 0 ) { // No paging $paging = false; $start = 0; if ( -1 == $max_depth ) $end = $total_top; $this->max_pages = 1; } else { $paging = true; $start = ( (int)$page_num - 1 ) * (int)$per_page; $end = $start + $per_page; if ( -1 == $max_depth ) $this->max_pages = ceil($total_top / $per_page); } // flat display if ( -1 == $max_depth ) { if ( !empty($args[0]['reverse_top_level']) ) { $elements = array_reverse( $elements ); $oldstart = $start; $start = $total_top - $end; $end = $total_top - $oldstart; } $empty_array = array(); foreach ( $elements as $e ) { $count++; if ( $count < $start ) continue; if ( $count >= $end ) break; $this->display_element( $e, $empty_array, 1, 0, $args, $output ); } return $output; } /* * Separate elements into two buckets: top level and children elements. * Children_elements is two dimensional array, e.g. * $children_elements[10][] contains all sub-elements whose parent is 10. */ $top_level_elements = array(); $children_elements = array(); foreach ( $elements as $e) { if ( 0 == $e->$parent_field ) $top_level_elements[] = $e; else $children_elements[ $e->$parent_field ][] = $e; } $total_top = count( $top_level_elements ); if ( $paging ) $this->max_pages = ceil($total_top / $per_page); else $end = $total_top; if ( !empty($args[0]['reverse_top_level']) ) { $top_level_elements = array_reverse( $top_level_elements ); $oldstart = $start; $start = $total_top - $end; $end = $total_top - $oldstart; } if ( !empty($args[0]['reverse_children']) ) { foreach ( $children_elements as $parent => $children ) $children_elements[$parent] = array_reverse( $children ); } foreach ( $top_level_elements as $e ) { $count++; // For the last page, need to unset earlier children in order to keep track of orphans. if ( $end >= $total_top && $count < $start ) $this->unset_children( $e, $children_elements ); if ( $count < $start ) continue; if ( $count >= $end ) break; $this->display_element( $e, $children_elements, $max_depth, 0, $args, $output ); } if ( $end >= $total_top && count( $children_elements ) > 0 ) { $empty_array = array(); foreach ( $children_elements as $orphans ) foreach ( $orphans as $op ) $this->display_element( $op, $empty_array, 1, 0, $args, $output ); } return $output; } /** * Calculates the total number of root elements. * * @since 2.7.0 * @access public * * @param array $elements Elements to list. * @return int Number of root elements. */ public function get_number_of_root_elements( $elements ){ $num = 0; $parent_field = $this->db_fields['parent']; foreach ( $elements as $e) { if ( 0 == $e->$parent_field ) $num++; } return $num; } /** * Unset all the children for a given top level element. * * @param object $e * @param array $children_elements */ public function unset_children( $e, &$children_elements ){ if ( ! $e || ! $children_elements ) { return; } $id_field = $this->db_fields['id']; $id = $e->$id_field; if ( !empty($children_elements[$id]) && is_array($children_elements[$id]) ) foreach ( (array) $children_elements[$id] as $child ) $this->unset_children( $child, $children_elements ); unset( $children_elements[ $id ] ); } } // Walker