Allow rejection of input based on more complex criteria

[insin]

Use case in this Stack Overflow quesrtion:

http://stackoverflow.com/questions/34146273/how-do-i-make-a-masked-input-that-only-allows-specific-numers

[uap-dev]

Also encountering a similar constraint where it would be nice to validate based on the value of a previous character. Use case being a date input where mask = "11/11/1111" of format "MM/DD/YYYY". If user inputs "1", then the only acceptable values for that month would be "0, "1", or "2".

[andreasvirkus]

Any plans to implement this? Would love what @TroutZen suggested.