merge-ort: add initial outline for basic rename detection

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

merge-ort.c

@@ -644,20 +644,72 @@ static int handle_content_merge(struct merge_options *opt,
 
 /*** Function Grouping: functions related to regular rename detection ***/
 
+static int process_renames(struct merge_options *opt,
+			   struct diff_queue_struct *renames)
+{
+	die("Not yet implemented.");
+}
+
+static int compare_pairs(const void *a_, const void *b_)
+{
+	die("Not yet implemented.");
+}
+
+/* Call diffcore_rename() to compute which files have changed on given side */
+static void detect_regular_renames(struct merge_options *opt,
+				   struct tree *merge_base,
+				   struct tree *side,
+				   unsigned side_index)
+{
+	die("Not yet implemented.");
+}
+
+/*
+ * Get information of all renames which occurred in 'side_pairs', discarding
+ * non-renames.
+ */
+static int collect_renames(struct merge_options *opt,
+			   struct diff_queue_struct *result,
+			   unsigned side_index)
+{
+	die("Not yet implemented.");
+}
+
 static int detect_and_process_renames(struct merge_options *opt,
 				      struct tree *merge_base,
 				      struct tree *side1,
 				      struct tree *side2)
 {
-	int clean = 1;
+	struct diff_queue_struct combined;
+	struct rename_info *renames = &opt->priv->renames;
+	int s, clean = 1;
+
+	memset(&combined, 0, sizeof(combined));
+
+	detect_regular_renames(opt, merge_base, side1, MERGE_SIDE1);
+	detect_regular_renames(opt, merge_base, side2, MERGE_SIDE2);
+
+	ALLOC_GROW(combined.queue,
+		   renames->pairs[1].nr + renames->pairs[2].nr,
+		   combined.alloc);
+	clean &= collect_renames(opt, &combined, MERGE_SIDE1);
+	clean &= collect_renames(opt, &combined, MERGE_SIDE2);
+	QSORT(combined.queue, combined.nr, compare_pairs);
+
+	clean &= process_renames(opt, &combined);
+
+	/* Free memory for renames->pairs[] and combined */
+	for (s = MERGE_SIDE1; s <= MERGE_SIDE2; s++) {
+		free(renames->pairs[s].queue);
+		DIFF_QUEUE_CLEAR(&renames->pairs[s]);
+	}
+	if (combined.nr) {
+		int i;
+		for (i = 0; i < combined.nr; i++)
+			diff_free_filepair(combined.queue[i]);
+		free(combined.queue);
+	}
 
-	/*
-	 * Rename detection works by detecting file similarity.  Here we use
-	 * a really easy-to-implement scheme: files are similar IFF they have
-	 * the same filename.  Therefore, by this scheme, there are no renames.
-	 *
-	 * TODO: Actually implement a real rename detection scheme.
-	 */
 	return clean;
 }