> On 16 Dec 2018, at 15:48, Frank Heckenbach <f.heckenb...@fh-soft.de> wrote: > > Hans Åberg wrote: > >> The idea would be that rather than returning the token value, >> something that does not need translation. I don't know if that >> helps up the static approach, though. > > Not sure what you mean here. Please elaborate.
I couldn't see the details when I looked at it. I don't use the typed parser, but might if it is safe. >>>> Personally, I am already at C++17, so I have no reason for using a >>>> simpler variant. Having the type stored just adds a size_t, and >>>> that is used a lot in other circumstances, so no overhead to worry >>>> about. >>> >>> Well, we had this discussion recently (as far as Bison is >>> concerned). >> >> Indeed, but that was where it seemed not requiring the type being >> stored in the variant. This situation might be different in that >> respect. >> >> Here, not making sure the type is properly returned may bomb the >> program, so preventing that seems higher than a rather small >> overhead. > > I think Akim made it clear enough that he doesn't like the overhead. > (I don't mind so much, as I used std::variant in my implementation, > but I only have a few parsers to care about.) In that case, my impression was that he thought he could do without it. > One might validly say that preventing it is the job of the lexer > (and my lexer does so), not Bison's, just like other kinds of > undefined or wrong behaviour outside of the generated code, also > dynamic token types are a somewhat special usage anyway, so Bison > can just do nothing about it, that's fine. I use the same thing, returning the token value found on a lookup table, but I would not want to use the typed parser if I would have to add translations for every possibility. The information about it is in Bison, therefore it should not be put on the writing of the lexer. > I also suggested an approach in my previous mail with a few more > generated functions that help runtime checking. I'd prefer Bison to > add them, and then we'd have runtime checking as good as we'd have > with std::variant in this respect. Maybe an option. Akim perhaps haven't used this dynamic token lookup. Those that do might prefer not risking the program to bomb.
