revision: introduce rev_walk_mode to clarify get_revision_1()

get_revision_1() dispatches to different walk strategies based on a
combination of rev_info flags: reflog_info, topo_walk_info, and
limited.  These conditions are checked in multiple places within
the function -- once to select the next commit, and again to decide
how to expand parents -- and the two chains must stay in sync.

Extract the mode selection into a rev_walk_mode enum and a small
get_walk_mode() helper, resolved once at the top of get_revision_1().
Both dispatch sites now switch on the same mode variable, making it
obvious that they agree and easier to verify that all modes are
handled.

No functional change.

Signed-off-by: Kristofer Karlsson <krka@spotify.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/revision.c b/revision.c
index e1970b9c5d34ed7b00cc6e753b0ed6ed1ae822de..9d0fc696d09937986bab559c77b8d738d167e396 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -4327,22 +4327,48 @@ static void track_linear(struct rev_info *revs, struct commit *commit)
        revs->previous_parents = commit_list_copy(commit->parents);
 }
 
+enum rev_walk_mode {
+       REV_WALK_REFLOG,
+       REV_WALK_TOPO,
+       REV_WALK_LIMITED,
+       REV_WALK_STREAMING,
+};
+
+static enum rev_walk_mode get_walk_mode(struct rev_info *revs)
+{
+       if (revs->reflog_info)
+               return REV_WALK_REFLOG;
+       if (revs->topo_walk_info)
+               return REV_WALK_TOPO;
+       if (revs->limited)
+               return REV_WALK_LIMITED;
+       return REV_WALK_STREAMING;
+}
+
 static struct commit *get_revision_1(struct rev_info *revs)
 {
+       enum rev_walk_mode mode = get_walk_mode(revs);
+
        while (1) {
                struct commit *commit;
 
-               if (revs->reflog_info)
+               switch (mode) {
+               case REV_WALK_REFLOG:
                        commit = next_reflog_entry(revs->reflog_info);
-               else if (revs->topo_walk_info)
+                       break;
+               case REV_WALK_TOPO:
                        commit = next_topo_commit(revs);
-               else
+                       break;
+               case REV_WALK_LIMITED:
+               case REV_WALK_STREAMING:
                        commit = pop_commit(&revs->commits);
+                       break;
+               }
 
                if (!commit)
                        return NULL;
 
-               if (revs->reflog_info)
+               if (mode == REV_WALK_REFLOG)
                        commit->object.flags &= ~(ADDED | SEEN | SHOWN);
 
                /*
@@ -4350,20 +4376,28 @@ static struct commit *get_revision_1(struct rev_info *revs)
                 * the parents here. We also need to do the date-based limiting
                 * that we'd otherwise have done in limit_list().
                 */
-               if (!revs->limited) {
-                       if (revs->max_age != -1 &&
-                           comparison_date(revs, commit) < revs->max_age)
-                               continue;
+               if (mode != REV_WALK_LIMITED &&
+                   revs->max_age != -1 &&
+                   comparison_date(revs, commit) < revs->max_age)
+                       continue;
 
-                       if (revs->reflog_info)
-                               try_to_simplify_commit(revs, commit);
-                       else if (revs->topo_walk_info)
-                               expand_topo_walk(revs, commit);
-                       else if (process_parents(revs, commit, &revs->commits, NULL) < 0) {
+               switch (mode) {
+               case REV_WALK_REFLOG:
+                       try_to_simplify_commit(revs, commit);
+                       break;
+               case REV_WALK_TOPO:
+                       expand_topo_walk(revs, commit);
+                       break;
+               case REV_WALK_STREAMING:
+                       if (process_parents(revs, commit,
+                                           &revs->commits, NULL) < 0) {
                                if (!revs->ignore_missing_links)
                                        die("Failed to traverse parents of commit %s",
-                                               oid_to_hex(&commit->object.oid));
+                                           oid_to_hex(&commit->object.oid));
                        }
+                       break;
+               case REV_WALK_LIMITED:
+                       break;
                }
 
                switch (simplify_commit(revs, commit)) {