[PATCH v12 2/7] revision: add next_commit_to_show()

[Pablo Sabater <pabloosabaterr@gmail.com>]

get_revision() gets its commits from two sources depending on the mode:

1. Normally it gets the commits from get_revision_internal().

2. --max-count-oldest which was introduced at bb4ce23284 (revision.c:
   implement --max-count-oldest, 2026-05-19) gets the commits by popping
   from a saved list at revs->commits marking SHOWN and CHILD_SHOWN on
   each popped commit.

Extract the choice logic into a helper, next_commit_to_show(), which
returns the next commit regardless of the source it comes from.

This has no change in behavior. The helper is needed in a subsequent
commit that pre-fetches two commits into a buffer for lookahead purposes
and needs to pre-fetch from the same source.

The --reverse branch keeps its own pop loop. Using the helper for
--reverse would additionally set SHOWN and CHILD_SHOWN which is not
desired and a behavior change.

Signed-off-by: Pablo Sabater <pabloosabaterr@gmail.com>
---
 revision.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/revision.c b/revision.c
index 0c95edef59..288935943f 100644
--- a/revision.c
+++ b/revision.c
@@ -4658,12 +4658,34 @@ static void retrieve_oldest_commits(struct rev_info *revs,
 		commit_list_insert(c, queue);
 }
 
+/*
+ * Returns the next commit that will be shown, regardless of whether it comes
+ * directly from the revision walk or from the list saved by the staged output
+ * of --max-count-oldest.
+ */
+static struct commit *next_commit_to_show(struct rev_info *revs)
+{
+	struct commit *c;
+	struct commit_list *p;
+
+	if (!revs->max_count_stage)
+		return get_revision_internal(revs);
+
+	c = pop_commit(&revs->commits);
+	if (c) {
+		c->object.flags |= SHOWN;
+		if (!(c->object.flags & BOUNDARY))
+			for (p = c->parents; p; p = p->next)
+				p->item->object.flags |= CHILD_SHOWN;
+	}
+	return c;
+}
+
 struct commit *get_revision(struct rev_info *revs)
 {
 	struct commit *c;
 	struct commit_list *reversed;
 	struct commit_list *queue = NULL;
-	struct commit_list *p;
 
 	if (revs->max_count_type == 1 && !revs->max_count_stage) {
 		retrieve_oldest_commits(revs, &queue);
@@ -4693,17 +4715,7 @@ struct commit *get_revision(struct rev_info *revs)
 		return c;
 	}
 
-	if (revs->max_count_stage) {
-		c = pop_commit(&revs->commits);
-		if (c) {
-			c->object.flags |= SHOWN;
-			if (!(c->object.flags & BOUNDARY))
-				for (p = c->parents; p; p = p->next)
-					p->item->object.flags |= CHILD_SHOWN;
-		}
-	} else {
-		c = get_revision_internal(revs);
-	}
+	c = next_commit_to_show(revs);
 
 	if (c && revs->graph)
 		graph_update(revs->graph, c);

-- 
2.54.0