public function addUrl(Url $loc, DateTime $lastmod = null, $changefreq = null, $priority = null)
{
// check length
$url = $loc->getUrl();
if (strlen($url) >= 2048) {
throw new Exception('Location value must be less than 2048 characters');
}
$this->writer->startElement('url');
$this->writer->writeElement('loc', $url);
if ($lastmod !== null) {
$this->writer->writeElement('lastmod', $lastmod->format(DateTime::W3C));
}
if ($changefreq !== null) {
if (in_array($changefreq, self::$freq)) {
$this->writer->writeElement('changefreq', $changefreq);
} else {
throw new Exception('Invalid change frequence must be one of ' . implode(', ', self::$freq));
}
}
if ($priority !== null) {
$priority = (double) $priority;
if ($priority >= 0.0 && $priority <= 1.0) {
$this->writer->writeElement('priority', $priority);
} else {
throw new Exception('Invalid priority must be between 0.0 and 0.1');
}
}
$this->writer->endElement();
}
