diff -r 2f6f6f7551ca -r 32102edaa81b web/wp-includes/class-wp-walker.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/wp-includes/class-wp-walker.php	Mon Nov 19 18:26:13 2012 +0100
@@ -0,0 +1,397 @@
+<?php
+/**
+ * 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, $args, $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=0, $args, &$output ) {
+
+		if ( !$element )
+			return;
+
+		$id_field = $this->db_fields['id'];
+
+		//display this element
+		if ( 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] );
+
+	}
+}