Convert to "nice" URLs (replace special characters)

<?php

// Source: http://prohardver.hu/tema/php_kerdesek_2/hsz_9694-9694.html

/**
 *
 * $url = new url("helló világ ez az első szép url-em");
 * var_dump($url->_output);
 *
 * string(34) "hello-vilag-ez-az-elso-szep-url-em"
 */
class url
{
    public $_output;
    private $_str;
    private $_separator;
    /**
     *
     * @param string $str - nyers url
     * @param string $separator - szoelvalaszto karakter
     */
    public function __construct($str, $separator = "dash")
    {
        $this->_str       = $str;
        $this->_separator = $separator;
        $this->url_title();
    }
    /**
     * szep url generalas
     * @return string
     */
    protected function url_title()
    {
        if ($this->_separator == 'dash') {
            $search  = '_';
            $replace = '-';
        } else {
            $search  = '-';
            $replace = '_';
        }
        $str    = strtolower($this->_str);
        $before = array(
            "á",
            "é",
            "ő",
            "ö",
            "ó",
            "ú",
            "ű",
            "ü",
            "í"
        );
        $after  = array(
            "a",
            "e",
            "o",
            "o",
            "o",
            "u",
            "u",
            "u",
            "i"
        );
        $str    = str_replace($before, $after, $str);
        $trans  = array(
            '&\#\d+?;' => '',
            '&\S+?;' => '',
            '\s+' => $replace,
            '[^a-z0-9\-\._]' => '',
            $replace . '+' => $replace,
            $replace . '$' => $replace,
            '^' . $replace => $replace,
            '\.+$' => ''
        );
        $str    = strip_tags($str);
        foreach ($trans as $key => $val) {
            $str = preg_replace("#" . $key . "#i", $val, $str);
        }
        return $this->_output = strtolower(trim(trim(stripslashes($str)), $replace));
    }
}