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Diffstat (limited to 'wp-includes/class-wp-walker.php')
| -rw-r--r-- | wp-includes/class-wp-walker.php | 449 |
1 files changed, 449 insertions, 0 deletions
diff --git a/wp-includes/class-wp-walker.php b/wp-includes/class-wp-walker.php new file mode 100644 index 0000000..d8c00a3 --- /dev/null +++ b/wp-includes/class-wp-walker.php @@ -0,0 +1,449 @@ +<?php +/** + * A class for displaying various tree-like structures. + * + * Extend the Walker class to use it, see examples 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. + * + * @since 2.1.0 + * + * @package WordPress + * @abstract + */ +#[AllowDynamicProperties] +class Walker { + /** + * What the class handles. + * + * @since 2.1.0 + * @var string + */ + public $tree_type; + + /** + * DB fields to use. + * + * @since 2.1.0 + * @var string[] + */ + public $db_fields; + + /** + * Max number of pages walked by the paged walker. + * + * @since 2.7.0 + * @var int + */ + public $max_pages = 1; + + /** + * Whether the current element has children or not. + * + * To be used in start_el(). + * + * @since 4.0.0 + * @var bool + */ + public $has_children; + + /** + * Starts the list before the elements are added. + * + * 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 Used to append additional content (passed by reference). + * @param int $depth Depth of the item. + * @param array $args An array of additional arguments. + */ + public function start_lvl( &$output, $depth = 0, $args = array() ) {} + + /** + * Ends the list of after the elements are added. + * + * 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 Used to append additional content (passed by reference). + * @param int $depth Depth of the item. + * @param array $args An array of additional arguments. + */ + public function end_lvl( &$output, $depth = 0, $args = array() ) {} + + /** + * Starts the element output. + * + * The $args parameter holds additional values that may be used with the child + * class methods. Also includes the element output. + * + * @since 2.1.0 + * @since 5.9.0 Renamed `$object` (a PHP reserved keyword) to `$data_object` for PHP 8 named parameter support. + * @abstract + * + * @param string $output Used to append additional content (passed by reference). + * @param object $data_object The data object. + * @param int $depth Depth of the item. + * @param array $args An array of additional arguments. + * @param int $current_object_id Optional. ID of the current item. Default 0. + */ + public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {} + + /** + * Ends the element output, if needed. + * + * The $args parameter holds additional values that may be used with the child class methods. + * + * @since 2.1.0 + * @since 5.9.0 Renamed `$object` (a PHP reserved keyword) to `$data_object` for PHP 8 named parameter support. + * @abstract + * + * @param string $output Used to append additional content (passed by reference). + * @param object $data_object The data object. + * @param int $depth Depth of the item. + * @param array $args An array of additional arguments. + */ + public function end_el( &$output, $data_object, $depth = 0, $args = array() ) {} + + /** + * Traverses 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 should not 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 (passed by reference). + * @param int $max_depth Max depth to traverse. + * @param int $depth Depth of current element. + * @param array $args An array of arguments. + * @param string $output Used to append additional content (passed by reference). + */ + public function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) { + if ( ! $element ) { + return; + } + + $id_field = $this->db_fields['id']; + $id = $element->$id_field; + + // Display this element. + $this->has_children = ! empty( $children_elements[ $id ] ); + if ( isset( $args[0] ) && is_array( $args[0] ) ) { + $args[0]['has_children'] = $this->has_children; // Back-compat. + } + + $this->start_el( $output, $element, $depth, ...array_values( $args ) ); + + // Descend only when the depth is right and there are children for this element. + if ( ( 0 == $max_depth || $max_depth > $depth + 1 ) && isset( $children_elements[ $id ] ) ) { + + foreach ( $children_elements[ $id ] as $child ) { + + if ( ! isset( $newlevel ) ) { + $newlevel = true; + // Start the child delimiter. + $this->start_lvl( $output, $depth, ...array_values( $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. + $this->end_lvl( $output, $depth, ...array_values( $args ) ); + } + + // End this element. + $this->end_el( $output, $element, $depth, ...array_values( $args ) ); + } + + /** + * Displays array of elements hierarchically. + * + * Does not assume any existing order of elements. + * + * $max_depth = -1 means flatly display every element. + * $max_depth = 0 means display all levels. + * $max_depth > 0 specifies the number of display levels. + * + * @since 2.1.0 + * @since 5.3.0 Formalized the existing `...$args` parameter by adding it + * to the function signature. + * + * @param array $elements An array of elements. + * @param int $max_depth The maximum hierarchical depth. + * @param mixed ...$args Optional additional arguments. + * @return string The hierarchical item output. + */ + public function walk( $elements, $max_depth, ...$args ) { + $output = ''; + + // Invalid parameter or nothing to walk. + if ( $max_depth < -1 || empty( $elements ) ) { + return $output; + } + + $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. Example: + * Children_elements[10][] contains all sub-elements whose parent is 10. + */ + $top_level_elements = array(); + $children_elements = array(); + foreach ( $elements as $e ) { + if ( empty( $e->$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 ( ( 0 == $max_depth ) && 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; + } + + /** + * Produces 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. + * + * $max_depth = 0 means display all levels. + * $max_depth > 0 specifies the number of display levels. + * + * @since 2.7.0 + * @since 5.3.0 Formalized the existing `...$args` parameter by adding it + * to the function signature. + * + * @param array $elements An array of elements. + * @param int $max_depth The maximum hierarchical depth. + * @param int $page_num The specific page number, beginning with 1. + * @param int $per_page Number of elements per page. + * @param mixed ...$args Optional additional arguments. + * @return string XHTML of the specified page of elements. + */ + public function paged_walk( $elements, $max_depth, $page_num, $per_page, ...$args ) { + if ( empty( $elements ) || $max_depth < -1 ) { + return ''; + } + + $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 ( empty( $e->$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 + * + * @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 ( empty( $e->$parent_field ) ) { + ++$num; + } + } + return $num; + } + + /** + * Unsets all the children for a given top level element. + * + * @since 2.7.0 + * + * @param object $element The top level element. + * @param array $children_elements The children elements. + */ + public function unset_children( $element, &$children_elements ) { + if ( ! $element || ! $children_elements ) { + return; + } + + $id_field = $this->db_fields['id']; + $id = $element->$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 ] ); + } +} |