On 25/08/19 05:12AM, Denton Liu wrote:
> Before, can_fast_forward was written with an if-else statement. However,
> in the future, we may be adding more termination cases which would lead
> to deeply nested if statements.
>
> Refactor to use a goto tower so that future cases can be easily
> inserted.
>
> Signed-off-by: Denton Liu <liu.denton@xxxxxxxxx>
> ---
> builtin/rebase.c | 24 +++++++++++++++---------
> 1 file changed, 15 insertions(+), 9 deletions(-)
>
> diff --git a/builtin/rebase.c b/builtin/rebase.c
> index 670096c065..22c4f1ff93 100644
> --- a/builtin/rebase.c
> +++ b/builtin/rebase.c
> @@ -1264,21 +1264,27 @@ static int can_fast_forward(struct commit *onto, struct object_id *head_oid,
> struct object_id *merge_base)
> {
> struct commit *head = lookup_commit(the_repository, head_oid);
> - struct commit_list *merge_bases;
> - int res;
> + struct commit_list *merge_bases = NULL;
> + int res = 0;
>
> if (!head)
> - return 0;
> + goto done;
>
> merge_bases = get_merge_bases(onto, head);
> - if (merge_bases && !merge_bases->next) {
> - oidcpy(merge_base, &merge_bases->item->object.oid);
> - res = oideq(merge_base, &onto->object.oid);
> - } else {
> + if (!merge_bases || merge_bases->next) {
> oidcpy(merge_base, &null_oid);
> - res = 0;
> + goto done;
> }
> - free_commit_list(merge_bases);
> +
> + oidcpy(merge_base, &merge_bases->item->object.oid);
> + if (!oideq(merge_base, &onto->object.oid))
> + goto done;
> +
> + res = 1;
> +
> +done:
> + if (merge_bases)
> + free_commit_list(merge_bases);
free_commit_list() returns immediately when a NULL pointer is passed in,
so I'm not sure if this check is really necessary. I think it is a
reasonable assumption to make that free* functions work well with NULL
inputs.
> return res && is_linear_history(onto, head);
> }
>
Out of curiosity, since you are going with a goto tower, why not do
something like:
done_merge_bases:
free_commit_list(merge_bases);
done:
return res && is_linear_history(onto, head);
You jump to done_merge_bases after you have initialized merge_bases, and
directly to done before initializing it.
I'm not advocating for either way, just curious if there is a specific
reason to do it your way. Anyway, if you drop the if (merge_bases), then
it doesn't really matter I suppose.
--
Regards,
Pratyush Yadav
