/**
* @see Filter::supports()
* @param $input mixed
* @param $output mixed
* @param $fromString boolean true if the filter accepts a string as input.
* @param $toString boolean true if the filter produces a string as output.
* @return boolean
*/
function supports(&$input, &$output)
{
// Do the normal type check first.
if (!parent::supports($input, $output)) {
return false;
}
// Additional checks that cannot be done via type checks.
// 1) Check that the given publication type is supported by this filter
// If no publication type is given then we'll support the description
// by default.
if (is_a($this->getInputType(), 'MetadataTypeDescription')) {
$publicationType = $input->getStatement('[@publication-type]');
if (!empty($publicationType) && !in_array($publicationType, $this->getSupportedPublicationTypes())) {
return false;
}
}
// 2) Check that the output actually contains data and is not an empty
// description.
if (!is_null($output) && is_a($output, 'MetadataDescription')) {
$statements =& $output->getStatements();
if (empty($statements)) {
return false;
}
}
return true;
}