We are looking to implement upper() / lower() for non-ASCII characters. The current Gandiva implementation handles upper() / lower() only for standard ASCII characters.
For the implementation in Gandiva, I went through a few articles and answers on StackOverflow and the top answer to this question <https://stackoverflow.com/questions/36897781/how-to-uppercase-lowercase-utf-8-characters-in-c> suggests that there is no standard way to do Unicode case conversion in C/C++ and that an external library like ICU <https://unicode-org.github.io/icu-docs/#/icu4c/> is necessary to ensure guaranteed Unicode case conversion. So, I just wanted to know that while adding any external library in Gandiva, what are the issues that we need to take care of in order to ensure that we do not break existing code and not sacrifice on performance as well? Is there any existing library that we can make use of to go about solving this problem? Any suggestions would be welcome. Regards, Sagnik
