merge-ort: add outline of get_provisional_directory_renames()

This function is based on merge-recursive.c's get_directory_renames(),
except that the first half has been split out into a not-yet-implemented
compute_rename_counts().  The primary difference here is our lack of the
non_unique_new_dir boolean in our strmap.  The lack of that field will
at first cause us to fail testcase 2b of t6423; however, future
optimizations will obviate the need for that ugly field so we have just
left it out.

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

diff --git a/merge-ort.c b/merge-ort.c
index b4c1fe28a5c8bfdd18b1e1229be0503742e41cc3..2a1c62c533b514fee0406d3f32062a1aba79ca59 100644 (file)
--- a/merge-ort.c
+++ b/merge-ort.c
@@ -721,11 +721,66 @@ static int handle_content_merge(struct merge_options *opt,
 
 /*** Function Grouping: functions related to directory rename detection ***/
 
+static void compute_rename_counts(struct diff_queue_struct *pairs,
+                                 struct strmap *dir_rename_count,
+                                 struct strset *dirs_removed)
+{
+       die("Not yet implemented!");
+}
+
 static void get_provisional_directory_renames(struct merge_options *opt,
                                              unsigned side,
                                              int *clean)
 {
-       die("Not yet implemented!");
+       struct hashmap_iter iter;
+       struct strmap_entry *entry;
+       struct rename_info *renames = &opt->priv->renames;
+
+       compute_rename_counts(&renames->pairs[side],
+                             &renames->dir_rename_count[side],
+                             &renames->dirs_removed[side]);
+       /*
+        * Collapse
+        *    dir_rename_count: old_directory -> {new_directory -> count}
+        * down to
+        *    dir_renames: old_directory -> best_new_directory
+        * where best_new_directory is the one with the unique highest count.
+        */
+       strmap_for_each_entry(&renames->dir_rename_count[side], &iter, entry) {
+               const char *source_dir = entry->key;
+               struct strintmap *counts = entry->value;
+               struct hashmap_iter count_iter;
+               struct strmap_entry *count_entry;
+               int max = 0;
+               int bad_max = 0;
+               const char *best = NULL;
+
+               strintmap_for_each_entry(counts, &count_iter, count_entry) {
+                       const char *target_dir = count_entry->key;
+                       intptr_t count = (intptr_t)count_entry->value;
+
+                       if (count == max)
+                               bad_max = max;
+                       else if (count > max) {
+                               max = count;
+                               best = target_dir;
+                       }
+               }
+
+               if (bad_max == max) {
+                       path_msg(opt, source_dir, 0,
+                              _("CONFLICT (directory rename split): "
+                                "Unclear where to rename %s to; it was "
+                                "renamed to multiple other directories, with "
+                                "no destination getting a majority of the "
+                                "files."),
+                              source_dir);
+                       *clean = 0;
+               } else {
+                       strmap_put(&renames->dir_renames[side],
+                                  source_dir, (void*)best);
+               }
+       }
 }
 
 static void handle_directory_level_conflicts(struct merge_options *opt)