The inability to inject tokens and expressions into the lexer and
parser is another limitation on what can be done from extensions in
terms of syntax level features. Yes, I know this is more of a problem
with bison and flex than with the design of ZE, but that doesn't make
it any less bothersome.
Do other compiler tools allow this?
I've heard second hand that lemon does. But I'm quite certain that rewriting the lexer/parser is not at the top of the list of productive ways to advance the language.