On Fri, Dec 04, 2020 at 02:05:12PM -0500, Taylor Blau wrote:
> > +static inline size_t oid_array_next_unique(struct oid_array *array, size_t cur)
> > +{
> > + do {
> > + cur++;
> > + } while (cur < array->nr &&
> > + oideq(array->oid + cur, array->oid + cur - 1));
>
> I don't love the pointer math here (would instead prefer
> oideq(&array->oid[cur]) and so on), but I don't think that it matters
> enough to make a difference.
I think it is a matter of preference. I actually prefer the arithmetic
(it's also what was in the code that we are replacing in
oid_array_for_each_unique(), but that is probably because I wrote that
one, too).
> I additionally had to make sure that cur - 1 >= 0 so that the second
> argument would always be valid, but it is, since we call cur++.
Yeah. I originally wrote it as:
cur++;
while (cur < array->nr) {
if (!oideq(...))
break;
cur++;
}
which maybe makes it more obvious that cur always gets implemented at
least once, but I found it harder to reason about the second increment.
I think the do-while expresses it pretty clearly, but we're not that
used to seeing them.
> You could check that cur++ doesn't overflow, but I think that that's
> mostly academic.
It can't overflow, because it can't ever go past array->nr (unless you
call it again after cur is already equal to array->nr, but that would be
a bug just like calling i++ after hitting the loop end would be).
-Peff
