merge-ort: basic outline for merge_switch_to_result()

This adds a basic implementation for merge_switch_to_result(), though
just in terms of a few new empty functions that will be defined in
subsequent commits.

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

merge-ort.c

@@ -971,13 +971,53 @@ static void process_entries(struct merge_options *opt,
 	string_list_clear(&dir_metadata.offsets, 0);
 }
 
+static int checkout(struct merge_options *opt,
+		    struct tree *prev,
+		    struct tree *next)
+{
+	die("Not yet implemented.");
+}
+
+static int record_conflicted_index_entries(struct merge_options *opt,
+					   struct index_state *index,
+					   struct strmap *paths,
+					   struct strmap *conflicted)
+{
+	if (strmap_empty(conflicted))
+		return 0;
+
+	die("Not yet implemented.");
+}
+
 void merge_switch_to_result(struct merge_options *opt,
 			    struct tree *head,
 			    struct merge_result *result,
 			    int update_worktree_and_index,
 			    int display_update_msgs)
 {
-	die("Not yet implemented");
+	assert(opt->priv == NULL);
+	if (result->clean >= 0 && update_worktree_and_index) {
+		struct merge_options_internal *opti = result->priv;
+
+		if (checkout(opt, head, result->tree)) {
+			/* failure to function */
+			result->clean = -1;
+			return;
+		}
+
+		if (record_conflicted_index_entries(opt, opt->repo->index,
+						    &opti->paths,
+						    &opti->conflicted)) {
+			/* failure to function */
+			result->clean = -1;
+			return;
+		}
+	}
+
+	if (display_update_msgs) {
+		/* TODO: print out CONFLICT and other informational messages. */
+	}
+
 	merge_finalize(opt, result);
 }