? /** * A class for displaying various tree-like structures. * * Extend the Walker class to use it, see examples at the below. Child classes * do not need to implement all of the abstract methods in the class. The child * only needs to implement the methods that are needed. Also, the methods are * not strictly abstract in that the parameter definition needs to be followed. * The child classes can have additional parameters. * * @package WordPress * @since 2.1.0 * @abstract */ class Walker { /** * What the class handles. * * @since 2.1.0 * @var string * @access public */ var $tree_type; /** * DB fields to use. * * @since 2.1.0 * @var array * @access protected */ var $db_fields; /** * Max number of pages walked by the paged walker * * @since 2.7.0 * @var int * @access protected */ var $max_pages = 1; /** * Starts the list before the elements are added. * * Additional parameters are used in child classes. The args parameter holds * additional values that may be used with the child class methods. This * method is called at the start of the output list. * * @since 2.1.0 * @abstract * * @param string $output Passed by reference. Used to append additional content. */ function start_lvl( &$output, $depth = 0, $args = array() ) {} /** * Ends the list of after the elements are added. * * Additional parameters are used in child classes. The args parameter holds * additional values that may be used with the child class methods. This * method finishes the list at the end of output of the elements. * * @since 2.1.0 * @abstract * * @param string $output Passed by reference. Used to append additional content. */ function end_lvl( &$output, $depth = 0, $args = array() ) {} /** * Start the element output. * * Additional parameters are used in child classes. The args parameter holds * additional values that may be used with the child class methods. Includes * the element output also. * * @since 2.1.0 * @abstract * * @param string $output Passed by reference. Used to append additional content. */ function start_el( &$output, $object, $depth = 0, $args = array(), $current_object_id = 0 ) {} /** * Ends the element output, if needed. * * Additional parameters are used in child classes. The args parameter holds * additional values that may be used with the child class methods. * * @since 2.1.0 * @abstract * * @param string $output Passed by reference. Used to append additional content. */ function end_el( &$output, $object, $depth = 0, $args = array() ) {} /** * Traverse elements to create list from elements. * * Display one element if the element doesn't have any children otherwise, * display the element and its children. Will only traverse up to the max * depth and no ignore elements under that depth. It is possible to set the * max depth to include all depths, see walk() method. * * This method shouldn't be called directly, use the walk() method instead. * * @since 2.5.0 * * @param object $element Data object * @param array $children_elements List of elements to continue traversing. * @param int $max_depth Max depth to traverse. * @param int $depth Depth of current element. * @param array $args * @param string $output Passed by reference. Used to append additional content. * @return null Null on failure with no changes to parameters. */ function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) { if ( !$element ) return; $id_field = $this->db_fields['id']; //display this element if ( isset( $args[0] ) && is_array( $args[0] ) ) $args[0]['has_children'] = ! empty( $children_elements[$element->$id_field] ); $cb_args = array_merge( array(&$output, $element, $depth), $args); call_user_func_array(array($this, 'start_el'), $cb_args); $id = $element->$id_field; // descend only when the depth is right and there are childrens for this element if ( ($max_depth == 0 || $max_depth > $depth+1 ) && isset( $children_elements[$id]) ) { foreach( $children_elements[ $id ] as $child ){ if ( !isset($newlevel) ) { $newlevel = true; //start the child delimiter $cb_args = array_merge( array(&$output, $depth), $args); call_user_func_array(array($this, 'start_lvl'), $cb_args); } $this->display_element( $child, $children_elements, $max_depth, $depth + 1, $args, $output ); } unset( $children_elements[ $id ] ); } if ( isset($newlevel) && $newlevel ){ //end the child delimiter $cb_args = array_merge( array(&$output, $depth), $args); call_user_func_array(array($this, 'end_lvl'), $cb_args); } //end this element $cb_args = array_merge( array(&$output, $element, $depth), $args); call_user_func_array(array($this, 'end_el'), $cb_args); } /** * Display array of elements hierarchically. * * It is a generic function which does not assume any existing order of * elements. max_depth = -1 means flatly display every element. max_depth = * 0 means display all levels. max_depth > 0 specifies the number of * display levels. * * @since 2.1.0 * * @param array $elements * @param int $max_depth * @return string */ function walk( $elements, $max_depth) { $args = array_slice(func_get_args(), 2); $output = ''; if ($max_depth < -1) //invalid parameter return $output; if (empty($elements)) //nothing to walk return $output; $id_field = $this->db_fields['id']; $parent_field = $this->db_fields['parent']; // flat display if ( -1 == $max_depth ) { $empty_array = array(); foreach ( $elements as $e ) $this->display_element( $e, $empty_array, 1, 0, $args, $output ); return $output; } /* * need to display in hierarchical order * separate elements into two buckets: top level and children elements * children_elements is two dimensional array, eg. * 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 ][] = $e; } /* * when none of the elements is top level * assume the first one must be root of the sub elements */ if ( empty($top_level_elements) ) { $first = array_slice( $elements, 0, 1 ); $root = $first[0]; $top_level_elements = array(); $children_elements = array(); foreach ( $elements as $e) { if ( $root->$parent_field == $e->$parent_field ) $top_level_elements[] = $e; else $children_elements[ $e->$parent_field ][] = $e; } } foreach ( $top_level_elements as $e ) $this->display_element( $e, $children_elements, $max_depth, 0, $args, $output ); /* * if we are displaying all levels, and remaining children_elements is not empty, * then we got orphans, which should be displayed regardless */ if ( ( $max_depth == 0 ) && 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; } /** * paged_walk() - produce a page of nested elements * * Given an array of hierarchical elements, the maximum depth, a specific page number, * and number of elements per page, this function first determines all top level root elements * belonging to that page, then lists them and all of their children in hierarchical order. * * @package WordPress * @since 2.7 * @param int $max_depth = 0 means display all levels; $max_depth > 0 specifies the number of display levels. * @param int $page_num the specific page number, beginning with 1. * @return XHTML of the specified page of elements */ function paged_walk( $elements, $max_depth, $page_num, $per_page ) { /* sanity check */ if ( empty($elements) || $max_depth < -1 ) return ''; $args = array_slice( func_get_args(), 4 ); $output = ''; $id_field = $this->db_fields['id']; $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, eg. * 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; } 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 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, $children_elements ); if ( isset($children_elements[$id]) ) unset( $children_elements[$id] ); } }
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