regex convert russian (cyrillic) to latin

regex-cyrillic-2-latin.php

<?php

//https://stackoverflow.com/a/6837426/1911609

function strtolatin($string){
    if (strpos($string = htmlentities($string, ENT_QUOTES, 'UTF-8'), '&') !== false){
        $string = html_entity_decode(preg_replace('~&([a-z]{1,2})(?:acute|cedil|circ|grave|lig|orn|ring|slash|tilde|uml);~i', '$1', $string), ENT_QUOTES, 'UTF-8');
    }
    return $string;
}