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0860bb2771
Prior to about 2013, many class methods lacked even access modifiers which made the `@access` notations that much more useful. Now that we've gotten to a point where the codebase is more mature from a maintenance perspective and we can finally remove these notations. Notable exceptions to this change include standalone functions notated as private as well as some classes still considered to represent "private" APIs. See #41452. Built from https://develop.svn.wordpress.org/trunk@41162 git-svn-id: http://core.svn.wordpress.org/trunk@41002 1a063a9b-81f0-0310-95a4-ce76da25c4cd
426 lines
12 KiB
PHP
426 lines
12 KiB
PHP
<?php
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/**
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* A class for displaying various tree-like structures.
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*
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* Extend the Walker class to use it, see examples below. Child classes
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* do not need to implement all of the abstract methods in the class. The child
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* only needs to implement the methods that are needed.
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*
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* @since 2.1.0
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*
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* @package WordPress
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* @abstract
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*/
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class Walker {
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/**
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* What the class handles.
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*
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* @since 2.1.0
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* @var string
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*/
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public $tree_type;
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/**
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* DB fields to use.
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*
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* @since 2.1.0
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* @var array
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*/
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public $db_fields;
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/**
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* Max number of pages walked by the paged walker
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*
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* @since 2.7.0
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* @var int
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*/
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public $max_pages = 1;
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/**
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* Whether the current element has children or not.
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*
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* To be used in start_el().
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*
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* @since 4.0.0
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* @var bool
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*/
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public $has_children;
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/**
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* Starts the list before the elements are added.
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*
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* The $args parameter holds additional values that may be used with the child
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* class methods. This method is called at the start of the output list.
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*
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* @since 2.1.0
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* @abstract
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*
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* @param string $output Passed by reference. Used to append additional content.
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* @param int $depth Depth of the item.
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* @param array $args An array of additional arguments.
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*/
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public function start_lvl( &$output, $depth = 0, $args = array() ) {}
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/**
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* Ends the list of after the elements are added.
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*
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* The $args parameter holds additional values that may be used with the child
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* class methods. This method finishes the list at the end of output of the elements.
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*
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* @since 2.1.0
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* @abstract
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*
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* @param string $output Passed by reference. Used to append additional content.
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* @param int $depth Depth of the item.
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* @param array $args An array of additional arguments.
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*/
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public function end_lvl( &$output, $depth = 0, $args = array() ) {}
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/**
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* Start the element output.
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*
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* The $args parameter holds additional values that may be used with the child
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* class methods. Includes the element output also.
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*
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* @since 2.1.0
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* @abstract
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*
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* @param string $output Passed by reference. Used to append additional content.
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* @param object $object The data object.
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* @param int $depth Depth of the item.
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* @param array $args An array of additional arguments.
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* @param int $current_object_id ID of the current item.
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*/
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public function start_el( &$output, $object, $depth = 0, $args = array(), $current_object_id = 0 ) {}
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/**
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* Ends the element output, if needed.
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*
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* The $args parameter holds additional values that may be used with the child class methods.
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*
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* @since 2.1.0
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* @abstract
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*
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* @param string $output Passed by reference. Used to append additional content.
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* @param object $object The data object.
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* @param int $depth Depth of the item.
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* @param array $args An array of additional arguments.
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*/
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public function end_el( &$output, $object, $depth = 0, $args = array() ) {}
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/**
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* Traverse elements to create list from elements.
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*
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* Display one element if the element doesn't have any children otherwise,
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* display the element and its children. Will only traverse up to the max
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* depth and no ignore elements under that depth. It is possible to set the
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* max depth to include all depths, see walk() method.
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*
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* This method should not be called directly, use the walk() method instead.
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*
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* @since 2.5.0
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*
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* @param object $element Data object.
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* @param array $children_elements List of elements to continue traversing.
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* @param int $max_depth Max depth to traverse.
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* @param int $depth Depth of current element.
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* @param array $args An array of arguments.
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* @param string $output Passed by reference. Used to append additional content.
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*/
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public function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) {
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if ( ! $element ) {
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return;
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}
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$id_field = $this->db_fields['id'];
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$id = $element->$id_field;
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//display this element
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$this->has_children = ! empty( $children_elements[ $id ] );
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if ( isset( $args[0] ) && is_array( $args[0] ) ) {
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$args[0]['has_children'] = $this->has_children; // Back-compat.
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}
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$cb_args = array_merge( array(&$output, $element, $depth), $args);
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call_user_func_array(array($this, 'start_el'), $cb_args);
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// descend only when the depth is right and there are childrens for this element
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if ( ($max_depth == 0 || $max_depth > $depth+1 ) && isset( $children_elements[$id]) ) {
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foreach ( $children_elements[ $id ] as $child ){
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if ( !isset($newlevel) ) {
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$newlevel = true;
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//start the child delimiter
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$cb_args = array_merge( array(&$output, $depth), $args);
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call_user_func_array(array($this, 'start_lvl'), $cb_args);
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}
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$this->display_element( $child, $children_elements, $max_depth, $depth + 1, $args, $output );
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}
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unset( $children_elements[ $id ] );
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}
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if ( isset($newlevel) && $newlevel ){
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//end the child delimiter
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$cb_args = array_merge( array(&$output, $depth), $args);
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call_user_func_array(array($this, 'end_lvl'), $cb_args);
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}
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//end this element
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$cb_args = array_merge( array(&$output, $element, $depth), $args);
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call_user_func_array(array($this, 'end_el'), $cb_args);
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}
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/**
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* Display array of elements hierarchically.
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*
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* Does not assume any existing order of elements.
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*
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* $max_depth = -1 means flatly display every element.
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* $max_depth = 0 means display all levels.
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* $max_depth > 0 specifies the number of display levels.
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*
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* @since 2.1.0
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*
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* @param array $elements An array of elements.
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* @param int $max_depth The maximum hierarchical depth.
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* @return string The hierarchical item output.
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*/
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public function walk( $elements, $max_depth ) {
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$args = array_slice(func_get_args(), 2);
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$output = '';
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//invalid parameter or nothing to walk
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if ( $max_depth < -1 || empty( $elements ) ) {
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return $output;
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}
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$parent_field = $this->db_fields['parent'];
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// flat display
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if ( -1 == $max_depth ) {
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$empty_array = array();
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foreach ( $elements as $e )
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$this->display_element( $e, $empty_array, 1, 0, $args, $output );
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return $output;
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}
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/*
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* Need to display in hierarchical order.
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* Separate elements into two buckets: top level and children elements.
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* Children_elements is two dimensional array, eg.
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* Children_elements[10][] contains all sub-elements whose parent is 10.
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*/
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$top_level_elements = array();
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$children_elements = array();
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foreach ( $elements as $e) {
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if ( empty( $e->$parent_field ) )
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$top_level_elements[] = $e;
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else
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$children_elements[ $e->$parent_field ][] = $e;
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}
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/*
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* When none of the elements is top level.
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* Assume the first one must be root of the sub elements.
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*/
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if ( empty($top_level_elements) ) {
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$first = array_slice( $elements, 0, 1 );
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$root = $first[0];
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$top_level_elements = array();
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$children_elements = array();
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foreach ( $elements as $e) {
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if ( $root->$parent_field == $e->$parent_field )
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$top_level_elements[] = $e;
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else
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$children_elements[ $e->$parent_field ][] = $e;
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}
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}
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foreach ( $top_level_elements as $e )
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$this->display_element( $e, $children_elements, $max_depth, 0, $args, $output );
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/*
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* If we are displaying all levels, and remaining children_elements is not empty,
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* then we got orphans, which should be displayed regardless.
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*/
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if ( ( $max_depth == 0 ) && count( $children_elements ) > 0 ) {
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$empty_array = array();
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foreach ( $children_elements as $orphans )
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foreach ( $orphans as $op )
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$this->display_element( $op, $empty_array, 1, 0, $args, $output );
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}
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return $output;
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}
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/**
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* paged_walk() - produce a page of nested elements
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*
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* Given an array of hierarchical elements, the maximum depth, a specific page number,
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* and number of elements per page, this function first determines all top level root elements
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* belonging to that page, then lists them and all of their children in hierarchical order.
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*
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* $max_depth = 0 means display all levels.
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* $max_depth > 0 specifies the number of display levels.
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*
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* @since 2.7.0
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*
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* @param array $elements
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* @param int $max_depth The maximum hierarchical depth.
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* @param int $page_num The specific page number, beginning with 1.
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* @param int $per_page
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* @return string XHTML of the specified page of elements
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*/
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public function paged_walk( $elements, $max_depth, $page_num, $per_page ) {
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if ( empty( $elements ) || $max_depth < -1 ) {
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return '';
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}
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$args = array_slice( func_get_args(), 4 );
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$output = '';
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$parent_field = $this->db_fields['parent'];
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$count = -1;
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if ( -1 == $max_depth )
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$total_top = count( $elements );
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if ( $page_num < 1 || $per_page < 0 ) {
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// No paging
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$paging = false;
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$start = 0;
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if ( -1 == $max_depth )
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$end = $total_top;
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$this->max_pages = 1;
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} else {
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$paging = true;
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$start = ( (int)$page_num - 1 ) * (int)$per_page;
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$end = $start + $per_page;
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if ( -1 == $max_depth )
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$this->max_pages = ceil($total_top / $per_page);
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}
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// flat display
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if ( -1 == $max_depth ) {
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if ( !empty($args[0]['reverse_top_level']) ) {
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$elements = array_reverse( $elements );
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$oldstart = $start;
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$start = $total_top - $end;
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$end = $total_top - $oldstart;
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}
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$empty_array = array();
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foreach ( $elements as $e ) {
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$count++;
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if ( $count < $start )
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continue;
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if ( $count >= $end )
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break;
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$this->display_element( $e, $empty_array, 1, 0, $args, $output );
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}
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return $output;
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}
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/*
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* Separate elements into two buckets: top level and children elements.
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* Children_elements is two dimensional array, e.g.
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* $children_elements[10][] contains all sub-elements whose parent is 10.
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*/
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$top_level_elements = array();
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$children_elements = array();
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foreach ( $elements as $e) {
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if ( 0 == $e->$parent_field )
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$top_level_elements[] = $e;
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else
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$children_elements[ $e->$parent_field ][] = $e;
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}
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$total_top = count( $top_level_elements );
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if ( $paging )
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$this->max_pages = ceil($total_top / $per_page);
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else
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$end = $total_top;
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if ( !empty($args[0]['reverse_top_level']) ) {
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$top_level_elements = array_reverse( $top_level_elements );
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$oldstart = $start;
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$start = $total_top - $end;
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$end = $total_top - $oldstart;
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}
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if ( !empty($args[0]['reverse_children']) ) {
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foreach ( $children_elements as $parent => $children )
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$children_elements[$parent] = array_reverse( $children );
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}
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foreach ( $top_level_elements as $e ) {
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$count++;
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// For the last page, need to unset earlier children in order to keep track of orphans.
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if ( $end >= $total_top && $count < $start )
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$this->unset_children( $e, $children_elements );
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if ( $count < $start )
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continue;
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if ( $count >= $end )
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break;
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$this->display_element( $e, $children_elements, $max_depth, 0, $args, $output );
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}
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if ( $end >= $total_top && count( $children_elements ) > 0 ) {
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$empty_array = array();
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foreach ( $children_elements as $orphans )
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foreach ( $orphans as $op )
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$this->display_element( $op, $empty_array, 1, 0, $args, $output );
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}
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return $output;
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}
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/**
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* Calculates the total number of root elements.
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*
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* @since 2.7.0
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*
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* @param array $elements Elements to list.
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* @return int Number of root elements.
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*/
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public function get_number_of_root_elements( $elements ){
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$num = 0;
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$parent_field = $this->db_fields['parent'];
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foreach ( $elements as $e) {
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if ( 0 == $e->$parent_field )
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$num++;
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}
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return $num;
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}
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/**
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* Unset all the children for a given top level element.
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*
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* @since 2.7.0
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*
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* @param object $e
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* @param array $children_elements
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*/
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public function unset_children( $e, &$children_elements ){
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if ( ! $e || ! $children_elements ) {
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return;
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}
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$id_field = $this->db_fields['id'];
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$id = $e->$id_field;
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if ( !empty($children_elements[$id]) && is_array($children_elements[$id]) )
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foreach ( (array) $children_elements[$id] as $child )
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$this->unset_children( $child, $children_elements );
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unset( $children_elements[ $id ] );
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}
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} // Walker
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