Re: [PATCH 2/2] graph: fix collapse of multiple edges

From: Jeff King <peff@peff.net>
Date: Jan 8, 2020, 13:49 UTC
Message-ID: <20200108134945.GA3390419@coredump.intra.peff.net>
In-Reply-To: <7a0e4637-85de-589f-df31-915b4603e45a@gmail.com>

On Wed, Jan 08, 2020 at 08:40:26AM -0500, Derrick Stolee wrote:

Show 23 quoted lines

> > Hmm. Your description and your diagrams make sense to me. But one
> > curious thing is that the earlier test you added for 6_* does not need
> > modified. Because it continues to show:
> > 
> >           | | | | * 6_F
> >           | |_|_|/|
> >           |/| | |/
> >           | | |/|
> >           | |/| |
> >           | * | | 6_D
> > 
> > rather than adding a horizontal component to the second-parent line.
> > That seems inconsistent.
> 
> The issue here is that there is not enough room for a second horizontal
> line. The horizontal line can only start after the previous has completely
> terminated, that is
> 
>            | | | | * 6_F
>            | |_|_|/|
>            |/| | |/
> 
> at this point, the first horizontal line has terminated.

Ahhh, OK, that makes perfect sense. I didn't quite realize how the rules for "going horizontal" worked.

Show 8 quoted lines

> If there was one more row to the example, then we would have:
> 
>            | | | | | * 6_F
>            | |_|_|_|/|
>            |/| | | |/
>            | | |_|/|
>            | |/| | |
>            | * | | | 6_D

Right, that makes sense. Thanks for explaining. And the patch otherwise looked good to me; your explanation convinced me that this is the right thing to do.

-Peff