<?php

class DibiExtensions extends Nette\Object
{

    public static function fetchTree(DibiObject $obj, $id, $parent_id)
    {
    if ($obj instanceof DibiFluent) {
        $result = $obj->execute();

    } elseif ($obj instanceof DibiResult) {
        $result = $obj;

    } else {
        throw new Nette\MemberAccessException("fetchTree cant be called on " . get_class($obj));
    }

    // nahradit $obj za $result

        $obj->seek(0);
        $row = $obj->fetch(FALSE);
        if (!$row)
            return array();  // empty resultset

            $refs = array();
        $data = NULL;

        if (!array_key_exists($id, $row) ||
                !array_key_exists($parent_id, $row)) {
            throw new InvalidArgumentException("Column '$id' or '$parent_id' is not in record");
        }

        do {
            $ref = &$refs[$row[$id]];

            $ref[$parent_id] = $row[$parent_id];
            $ref = array_merge($ref, $row);

            if ($row[$parent_id] == NULL) {
                $data[$row[$id]] = &$ref;
            } else {
                $refs[$row[$parent_id]]['children'][$row[$id]] = &$ref;
            }
        } while ($row = $obj->fetch(FALSE));

        unset($ref);
        unset($refs);
        return $data;
    }


    public static function register()
    {
    DibiObject::extensionMethod(...
    }

}