php recursive closure

php-recursive-closure

public function save()
	{
		// 
		// Find the root ID of the category to make selecting much easier
		//
		// Get all categories
		$all_categories = $this->all_categories();
		
		$parent_id = $this->get_parent_id();
		
		// A recursive closure to go up all the levels to root category and get its ID
		// We need to pass this closure to itself by reference and pass the array of all categories by reference
		$find_root_id = function ($parent_id) use (&$find_root_id, &$all_categories) {
			$parent_category = $all_categories[$parent_id]; // Get the parent category from the ID
			$id = $parent_category->get_id(); // Get the ID of the parent
			$parent_id = $parent_category->get_parent_id(); // Get the parents parent ID
		
			if ($parent_id == null)
			{
				// If parent ID is null we need to return its ID as it is the root category
				return $id;
			}
			else
			{
				// If parents ID is not null, we call this function again recursively
				return $find_root_id($parent_id);
			}
		};
		
		// Set the root ID of the object to the one found by the closure
		$this->set_root_id($find_root_id($parent_id));
		
		parent::save();
	}