Re: [Grep-devel] Proposed patch: remove DFA_CASE_FOLD

[arnold]

So Paul and I seem to be on the same page here. :-)

I'll let you two reach a decision, I already made the change in gawk.

Paul - yes, resolving the dfasyntax thing would be nice. I believe I
sent an updated patch as to what I actually put into gawk; if not you
can see it in gawk's master these days.

Thanks,

Arnold

Paul Eggert <address@hidden> wrote:

> address@hidden wrote:
> >> This change would enable a small simplification in each definition of
> >> "dfaopts." However, it does that at the cost of changing the public
> >> API of the dfa module and making it dependent on the regex one. I.e.,
> >> it would change the value of DFA_EOL_NUL (I would object even if this
> >> value were left unchanged)
> > So insert a DFA_UNUSED_1 value there. OK with me.
>
> Currently the DFA API require the regex API, and the DFA code uses 
> reg_syntax_t 
> and a bunch of its values (RE_CHAR_CLASSES, RE_BACKSLASH_ESCAPE_IN_LISTS, 
> etc.). 
> If we were to completely decouple the DFA code from regex.h we'd have to 
> reinvent all those wheels, which sounds like a nonstarter. So if I'm right, 
> the 
> DFA API will continue to depend on the regex API.
>
> Given all that, I'm puzzled as to why there is a DFA_CASE_FOLD. Surely it 
> doesn't make sense to have the DFA_CASE_FOLD bit disagree with the RE_ICASE 
> bit, 
> so why give applications the option?
>
> I don't see why changing the public API would be a problem. Any application 
> that 
> uses dfa.c must set DFA_CASE_FOLD to be consistent with RE_ICASE (otherwise, 
> the 
> code doesn't work anyway). Gnulib is not like an ordinary library; API and 
> ABI 
> changes are OK in Gnulib, as long as we put something in NEWS. If someone 
> uses a 
> new dfa.h (with Arnold's change) but forgets to update their app accordingly, 
> they'll get a compile-time error that is obvious and easy to fix. That's all 
> we 
> need for Gnulib.
>
> This reminds me of other unfinished business we have, namely, reworking 
> dfasyntax so that DFAs can be reused/restarted more efficiently.  I'll see if 
> I 
> can squeeze some time free to look into that again. This will be another API 
> change.