On 1/8/2020 2:25 AM, Jeff King wrote:
> On Wed, Jan 08, 2020 at 04:27:55AM +0000, Derrick Stolee via GitGitGadget wrote:
>
>> Before this change:
>>
>> | | | | | | *
>> | |_|_|_|_|/|\
>> |/| | | | |/ /
>> | | | | |/| /
>> | | | |/| |/
>> | | |/| |/|
>> | |/| |/| |
>> | | |/| | |
>>
>> By adding the logic for "filling" a horizontal edge between the
>> target column and the current column, we are able to resolve the
>> issue.
>>
>> After this change:
>>
>> | | | | | | *
>> | |_|_|_|_|/|\
>> |/| | | | |/ /
>> | | |_|_|/| /
>> | |/| | | |/
>> | | | |_|/|
>> | | |/| | |
>
> 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.
| | |/|
| |/| |
The remaining movement for the second line has no room for a horizontal
edge. The logic that I added is hit, but the for loop (over j) terminates
immediately without a single execution of the loop body.
If there was one more row to the example, then we would have:
| | | | | * 6_F
| |_|_|_|/|
|/| | | |/
| | |_|/|
| |/| | |
| * | | | 6_D
Thanks,
-Stolee
