Thanks Stack for pinging me about the Filter Language!
1. Todd, I think your test failed because the way I wrote my code, the arguments needed to be enclosed in single quotes. I know it is in the documentation I sent out, however, it may not have been highlighted. I don't see how I would parse the filterString if the entire filterString is enclosed in double quotes and some of the arguments are enclosed in double quotes too?
2. Regarding the incorrect order of arguments specified in the documentation for SingleColumnValueFilter, I apologize about that - the filter language went through several iterations and I may have overlooked updating the documentation in one place. I can take a look at it over the weekend and check the documentation again
3. Better error messages? - I can try and improve this. Are there any specific points I can address to improve what is already there?
4. Writing the filter parsing using antlr or javacc, I doubt I will have time to do that during the school semester. It's something I could potentially look into during the winter break. However, I leave this to your discretion.
Hope the Filter Language is benefiting the community!