Re: master ea93326: Add `union' and `intersection' to rx (bug#37849)

[Mattias Engdegård]

15 dec. 2019 kl. 15.53 skrev Stefan Monnier <address@hidden>:

>> A bit overkill just for matching a set of constant strings, don't you think?
> 
> I think there's a lot of implicit assumptions here.
> Yes, there are cases where you may want the "longest match" rule and
> where `posix-string-match` can be too costly, but the ones I can think
> of seem to be fairly contrived.

Perhaps I should have underlined that it is only literal strings that is of 
immediate concern, since that is what regexp-opt is used for. It is not a 
contrived situation to have a set of strings -- keywords, for instance -- not 
necessarily anchored by something else at the end. Unless it is known that no 
string is a prefix of another, the longest match is naturally desired.