rebase: refactor can_fast_forward into goto tower

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@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rebase.c b/builtin/rebase.c
index 670096c065f5f5fa8cb57c642cd759111b010988..1ddad4612640e09dda9b81174974802eaf8ee71d 100644 (file)
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1264,20 +1264,25 @@ 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;
        }
+
+       oidcpy(merge_base, &merge_bases->item->object.oid);
+       if (!oideq(merge_base, &onto->object.oid))
+               goto done;
+
+       res = 1;
+
+done:
        free_commit_list(merge_bases);
        return res && is_linear_history(onto, head);
 }