/**
* Implements corresponding isValidXX logic.
*
* @param string $context Please see corresponding isValidXX description.
* @param string $input Please see corresponding isValidXX description.
* @param int $format Please see corresponding isValidXX description.
* @param bool $allowNull Please see corresponding isValidXX description.
*
* @return does not return a value.
* @throws ValidationException thrown if input is invalid.
* @throws IntrusionException thrown if intrusion is detected.
*/
private function _assertValidDate($context, $input, $format, $allowNull)
{
$dvr = new DateValidationRule('DateValidator', $this->_encoder, $format);
$dvr->setAllowNull($allowNull);
$dvr->assertValid($context, $input);
return null;
}
