The benefit is quite clear on EofminGoldenTest.java which has states and doesn't have a single token for the EOF status.

@lsf37 Am I missing something? Can a client of the scanner know whether the scanner has reached EOF in a generic way?

@lsf37 I chose name zzAtEof() to be consistent with the field name, but why a zz prefix? It could also be yyAtEof() or just isAtEof(). What do you prefer?

The zz prefix means that something is internal, i.e. not part of the API. If we make it a getter method that we want people to use, it should therefore be yyAtEOF(). We could also rename the field, but it makes sense to leave that internal, because we might change the mechanism by which we figure out the end of file.

I don't fully remember any more wether relying on zzAtEOF is always safe. Will investigate.

The whole yy and zz naming scheme is from the JLex days (at least yy is, and then I think I used zz to distinguish). The idea was to avoid conflicts with names that users might want to pick. For the actually internal parts that makes sense, but the API would probably look less strange if it didn't have a prefix. In any case, for new things we should stay consistent.

Ok, after looking through the emitter and skeleton code, yyAtEOF() should be fine to export as API. I have vague memories of not doing that initially, because usually the scanner should return a token to indicate that it is done instead of the caller looking at scanner state, but that is really more a matter of taste, so no reason not to export. (Debug and standalone scanners used zzAtEOF because it was hard to figure out what the spec uses as EOF token).

We should probably add it to the manual as well. I can do that if you like (happy for you to merge first).

Oops, last comment was for the wrong thread. I'm still investigating, but it looks like it's fine so far. Would only change zzAtEof() to yyAtEOF().

Renamed to yyatEOF() (lower case 'a' to be consistent with the rest) in commit ba9a74c.

We should probably add it to the manual as well. I can do that if you like (happy for you to merge first).

Documentation should be added with code. Done in 4405977.