/**
* Gets the underlying custom expression provider, the end developer is
* responsible for implementing IExpressionProvider if he choose for
*
* @return IExpressionProvider Instance of IExpressionProvider implementation.
*
*/
public function getExpressionProvider()
{
$expressionProvider = $this->queryProvider->getExpressionProvider();
if (is_null($expressionProvider)) {
throw ODataException::createInternalServerError(Messages::providersWrapperExpressionProviderMustNotBeNullOrEmpty());
}
if (!$expressionProvider instanceof IExpressionProvider) {
throw ODataException::createInternalServerError(Messages::providersWrapperInvalidExpressionProviderInstance());
}
return $expressionProvider;
}
