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447 lines
12 KiB
447 lines
12 KiB
<?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 Used to append additional content (passed by reference). |
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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 Used to append additional content (passed by reference). |
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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 Used to append additional content (passed by reference). |
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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 Used to append additional content (passed by reference). |
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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 (passed by reference). |
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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 Used to append additional content (passed by reference). |
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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'] = $this->has_children; // Back-compat. |
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} |
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$this->start_el( $output, $element, $depth, ...array_values( $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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$this->start_lvl( $output, $depth, ...array_values( $args ) ); |
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} |
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$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 ) && $newlevel ) { |
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//end the child delimiter |
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$this->end_lvl( $output, $depth, ...array_values( $args ) ); |
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} |
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//end this element |
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$this->end_el( $output, $element, $depth, ...array_values( $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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* $max_depth > 0 specifies the number of display levels. |
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* |
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* @since 2.1.0 |
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* @since 5.3.0 Formalized the existing `...$args` parameter by adding it |
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* to the function signature. |
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* |
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* @param array $elements An array of elements. |
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* @param int $max_depth The maximum hierarchical depth. |
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* @param mixed ...$args Optional additional arguments. |
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* @return string The hierarchical item output. |
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*/ |
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public function walk( $elements, $max_depth, ...$args ) { |
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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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} |
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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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/* |
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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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} |
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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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/* |
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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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} |
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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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* $max_depth > 0 specifies the number of display levels. |
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* |
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* @since 2.7.0 |
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* @since 5.3.0 Formalized the existing `...$args` parameter by adding it |
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* to the function signature. |
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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 $per_page |
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* @param mixed ...$args Optional additional arguments. |
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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, $per_page, ...$args ) { |
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if ( empty( $elements ) || $max_depth < -1 ) { |
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return ''; |
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} |
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$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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} |
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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 = $total_top; |
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} |
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$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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} |
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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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} |
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if ( $count >= $end ) { |
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break; |
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} |
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$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 ][] = $e; |
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} |
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} |
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$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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} |
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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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} |
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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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} |
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if ( $count < $start ) { |
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continue; |
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} |
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if ( $count >= $end ) { |
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break; |
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} |
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$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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} |
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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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} |
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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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} |
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} |
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unset( $children_elements[ $id ] ); |
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} |
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} // Walker
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