On Mon, May 28, 2012 at 9:06 PM, Jeff King <peff@xxxxxxxx> wrote:
> On Mon, May 28, 2012 at 02:36:04PM +0200, Felipe Contreras wrote:
>
>> > What about a history with multiple branches?
>> >
>> > --X--A--B--C--D----E (master)
>> > \ /
>> > G--H--I---J (branch X)
>> > \ /
>> > K--L (branch Y)
>> [...]
>>
>> Yes, but then you would need to specify a second branch. I would avoid
>> that if possible.
>
> I agree that is less nice. But I don't think the operation is
> well-defined with a single branch. If you ask for "when did branch X
> split", then in the above graph it is unclear if you meant "split from
> master", or "split from Y".
If you look from the context that I explained in the first mail; it
would be from *any* branch; IOW; find the first commit from branch X
(G), and then find the parent. That would be the first commit where
branch X started.
> Maybe you could assume "master", or assume "git symbolic-ref HEAD" as
> the second branch?
No.
I think it would be easy to support this case if somehow there was a
way to find all the commits that comprise a branch;
% git log branch ^<any-other-branch>
I could swear I saw such an option, but I've been looking for days and
I can't find it.
IOW; all the commits were 'git branch --contains' would show 'branch'
and nothing else.
>> There's also another case that doesn't work:
>>
>> -- X -- A -- B (master)
>> \
>> \
>> C (branch A)
>>
>> Shouldn't be hard to add checks for those cases I think.
>
> Actually, I think that one extends naturally. They are never merged, so
> your rev-list never finds a merge commit, and you can just take the
> merge base of the branch tips.
Sure, I can _just_ do that, but I need to do it :)
So, here it is... I hope people can find ways to simplify it:
find_merge ()
{
local selection extra
test "$2" && extra=" into $2"
git rev-list --min-parents=2 --grep="Merge branch '$1'$extra"
--topo-order ${3:---all} | tail -1
}
branch_point ()
{
local first_merge second_merge merge
first_merge=$(find_merge $1 "" "$1 $2")
second_merge=$(find_merge $2 $1 $first_merge)
merge=${second_merge:-$first_merge}
if [ "$merge" ]; then
git merge-base $merge^1 $merge^2
else
git merge-base $1 $2
fi
}
And I've added tests:
https://raw.github.com/gist/2837595/0734e7f17a4597f81c5129e3cbfee09a183e93cd/branch-point
Seems to work :)
Cheers.
--
Felipe Contreras
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