Query::isFieldPrivate

static function isFieldPrivate($field)
{
	if ($field instanceof ScalarField)
	{
		return $field->isPrivate();
	}
	elseif ($field instanceof ExpressionField)
	{
		foreach ($field->getBuildFromChains() as $chain)
		{
			if (static::isFieldPrivate($chain->getLastElement()->getValue()))
			{
				return  true;
			}
		}
	}

	return false;
}