Re: Splitting a rev list into 2 sets

From: Thomas Rast <trast@inf.ethz.ch>
Date: Jun 24, 2013, 09:59 UTC
Message-ID: <87mwqf3k3n.fsf@linux-k42r.v.cablecom.net>
In-Reply-To: <CAC9WiBgb18ZX0vr8V79tCEUStrDRhRiSh44nH6+3B_Kf8rypYg@mail.gmail.com>

Francis Moreau <francis.moro@gmail.com> writes:

Show 16 quoted lines

> On Thu, Jun 20, 2013 at 3:20 PM, Thomas Rast <trast@inf.ethz.ch> wrote:
>>   positive=$(git rev-parse "$@" | grep -v '^\^')
>>   negative=$(git rev-parse "$@" | grep '^\^')
>>   boundary=$(git rev-list --boundary $positive ^master | sed -n 's/^-//p')
>>   # the intersection is
>>   git rev-list $boundary $negative
>
> I think there's a minor issue here, when boundary is empty. Please
> correct me if I'm wrong but I think it can only happen if positive is
> simply master or a subset of master. In that case I think the solution
> is just make boundary equal to positive:
>
>      # the intersection is
>      git rev-list ${boundary:-$positive} $negative
>
> Now I'm going to see if that solution is faster than the initial one.

Jan "jast" Krüger pointed out on #git that

  git log $(git merge-base --all A B)

is exactly the set of commits reachable from both A and B; so there's your intersection operator :-)

So it would seem that a much simpler approach is

  git rev-list $(git merge-base --all master $positive) --not $negative

avoiding the boundary handling and special-case. It relies on the (weird?) property that $(git merge-base --all A B1 B2 ...) shows the merge bases of A with a hypothetical merge of B1, B2, ..., which is just what you need here.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch