Re: [PATCH] dir: fix negative pathspecs in 'git ls-files' and 'git add'

[Junio C Hamano <gitster@pobox.com>]

Diogo Castro <diogo.filipe.acastro@gmail.com> writes:

> My point was that computing the common prefix across both positive
> *and* negative pathspecs would not improve performance, and might
> actually make it worse.

OK.  Then that points at the right solution.  Ignore negative ones
when finding what the common prefix is, strip it only from positive
ones to reduce the width of the traversal to come up with the list
of possible match candidates, and match them as full paths against
the negative ones to cull "within the positive set but is excluded"
paths, and the posted patch looks good.

I still wonder if we need different implementation when we have many
more negative patterns than the positive ones.  In such a case, the
stage to filter paths that matched one positive pattern by finding
matches with a negative pattern among many of them, which may
benefit from having a similar common prefix (among negative
patterns) optimization, but that is a separate topic.

Thanks.