[antlr-interest] ANTLR or ANTLR Eclipse plugin bug

[Martin Olsson]

Hi,

I've been trying for quite a while now to get my lexer to handle unknown
chars (report error, ignore char, resume lexing for new token). I've now
managed to implement something that achieves this but I had to resort to a
little semi-ugly hack.

For the record, I'm using the latest version of the ANTLR plugin for
Eclipse. Atleast when I use the Eclipse update site feature it says I
already got the latest version. I couldn't really tell exactly which
version this is, but this is what the version info in Eclipse look like
currently:

  http://mnemo.minimum.se/screens/version_box.png

Anyway, back to the matter at hand. From the ANTLR docs, it seemed like
the default error handling would do exactly what I needed. Which I assume
also means that defaultErrorHandler is implicitly set to true when not
specified, correct? Anyway, I looked at the lexer source and saw that the
lexer did NOT do what the docs said, instead it did raise an exception
which when propagated to the parser would cause the entire lex/parse
process to stop. So I tried to set defaultErrorHandler to true in the
lexer options, generated the lexer and parser and boom, now the lexer was
full of errors. It said "missing method recover()". Now the error handling
started to look more like what I actually wanted, it reported and error
and then called recover() just like in the parser. So my hack was to add a
dummy method called recover() with the right params, and then have this
method so nothing at all. This silenced the errors and the code works, but
it feels rather ugly.

Unfortunately my current code is closed-source proprietary so I cannot
attach the .g file here even though I understand that this would help
reproduce the error etc.

So, the big question is; why does ANTLR generate broken code? Is this
fixed in cvs? Or, is it not an ANTLR problem at all? Maybe it's a problem
with the Eclipse ANTLR plugin?

I've tried to contact the ANTLR Eclipse plugin author too (hi again if
you're on this list too ;D).

What do you make of this?




Regards,
martin