private function prepareSource($source, $contentType, $options)
{
$loaded = FALSE;
$this->_useDocumentContext = TRUE;
if ($source instanceof Nodes) {
$loaded = $source->getDocument();
} elseif ($source instanceof \DOMDocument) {
$loaded = $source;
} elseif ($source instanceof \DOMNode) {
$loaded = $source->ownerDocument;
$this->_nodes = array($source);
$this->_useDocumentContext = FALSE;
} elseif ($this->loaders()->supports($contentType)) {
$loaded = $this->loaders()->load($source, $contentType, $options);
$this->_loadingContext = ['contentType' => $contentType, 'options' => $options];
}
return $loaded;
}