Re: Splitting a rev list into 2 sets

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