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Lexing IS regular expressipn matching (except for some esoteric features like Haskell's nrsted comments).

Difference is in the handling.

As a matter of fact, Visual Studio uses semantic analysis - classes show differently than other identifiers.



It can be, it can also be a context free grammar, which is 'higher' than a state machine (or regular expression)


But there are also higher complexity bounds on CFGs (since they include regular expressions, they certainly can't be lower).

In any case, I've never heard of someone using non-regular expression CFGs for lexing. Are there cases?


I mentioned Haskell above. It has nested block comments which should be balanced. Thus CFG.




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