category.php

См. документацию.

<?php
namespace Bitrix\Report\VisualConstructor\Helper;

class Category
{
    public static function getOptionsTree($categories, $options = array(), $depth = 0)
    {
 
        $prefix = str_repeat('-', $depth);
        $depth++;
 
        foreach ($categories as $category)
        {
            $options[$category->getKey()] = $prefix . $category->getLabel();
            $options = self::getOptionsTree($category->children, $options, $depth);
        }
 
        return $options;
    }
}