This populates a list of directory renames for us.  The list of
directory renames is not yet used, but will be in subsequent commits.

Signed-off-by: Elijah Newren <new...@gmail.com>
---
 merge-recursive.c | 155 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 152 insertions(+), 3 deletions(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index c5932d5c57..6aef357e78 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1384,6 +1384,138 @@ static struct diff_queue_struct *get_diffpairs(struct 
merge_options *o,
        return ret;
 }
 
+static void get_renamed_dir_portion(const char *old_path, const char *new_path,
+                                   char **old_dir, char **new_dir)
+{
+       char *end_of_old, *end_of_new;
+       int old_len, new_len;
+
+       *old_dir = NULL;
+       *new_dir = NULL;
+
+       /* For
+        *    "a/b/c/d/foo.c" -> "a/b/something-else/d/foo.c"
+        * the "d/foo.c" part is the same, we just want to know that
+        *    "a/b/c" was renamed to "a/b/something-else"
+        * so, for this example, this function returns "a/b/c" in
+        * *old_dir and "a/b/something-else" in *new_dir.
+        *
+        * Also, if the basename of the file changed, we don't care.  We
+        * want to know which portion of the directory, if any, changed.
+        */
+       end_of_old = strrchr(old_path, '/');
+       end_of_new = strrchr(new_path, '/');
+
+       if (end_of_old == NULL || end_of_new == NULL)
+               return;
+       while (*--end_of_new == *--end_of_old &&
+              end_of_old != old_path &&
+              end_of_new != new_path)
+               ; /* Do nothing; all in the while loop */
+       /*
+        * We've found the first non-matching character in the directory
+        * paths.  That means the current directory we were comparing
+        * represents the rename.  Move end_of_old and end_of_new back
+        * to the full directory name.
+        */
+       if (*end_of_old == '/')
+               end_of_old++;
+       if (*end_of_old != '/')
+               end_of_new++;
+       end_of_old = strchr(end_of_old, '/');
+       end_of_new = strchr(end_of_new, '/');
+
+       /*
+        * It may have been the case that old_path and new_path were the same
+        * directory all along.  Don't claim a rename if they're the same.
+        */
+       old_len = end_of_old - old_path;
+       new_len = end_of_new - new_path;
+
+       if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
+               *old_dir = xstrndup(old_path, old_len);
+               *new_dir = xstrndup(new_path, new_len);
+       }
+}
+
+static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
+                                            struct tree *tree)
+{
+       struct hashmap *dir_renames;
+       struct hashmap_iter iter;
+       struct dir_rename_entry *entry;
+       int i;
+
+       dir_renames = malloc(sizeof(struct hashmap));
+       dir_rename_init(dir_renames);
+       for (i = 0; i < pairs->nr; ++i) {
+               struct string_list_item *item;
+               int *count;
+               struct diff_filepair *pair = pairs->queue[i];
+               char *old_dir, *new_dir;
+
+               /* File not part of directory rename if it wasn't renamed */
+               if (pair->status != 'R')
+                       continue;
+
+               get_renamed_dir_portion(pair->one->path, pair->two->path,
+                                       &old_dir,        &new_dir);
+               if (!old_dir)
+                       /* Directory didn't change at all; ignore this one. */
+                       continue;
+
+               entry = dir_rename_find_entry(dir_renames, old_dir);
+               if (!entry) {
+                       entry = xmalloc(sizeof(struct dir_rename_entry));
+                       dir_rename_entry_init(entry, old_dir);
+                       hashmap_put(dir_renames, entry);
+               } else {
+                       free(old_dir);
+               }
+               item = string_list_lookup(&entry->possible_new_dirs, new_dir);
+               if (!item) {
+                       item = string_list_insert(&entry->possible_new_dirs,
+                                                 new_dir);
+                       item->util = xcalloc(1, sizeof(int));
+               } else {
+                       free(new_dir);
+               }
+               count = item->util;
+               *count += 1;
+       }
+
+       hashmap_iter_init(dir_renames, &iter);
+       while ((entry = hashmap_iter_next(&iter))) {
+               int max = 0;
+               int bad_max = 0;
+               char *best = NULL;
+
+               for (i = 0; i < entry->possible_new_dirs.nr; i++) {
+                       int *count = entry->possible_new_dirs.items[i].util;
+
+                       if (*count == max)
+                               bad_max = max;
+                       else if (*count > max) {
+                               max = *count;
+                               best = entry->possible_new_dirs.items[i].string;
+                       }
+               }
+               if (bad_max == max)
+                       entry->non_unique_new_dir = 1;
+               else {
+                       assert(entry->new_dir.len == 0);
+                       strbuf_addstr(&entry->new_dir, best);
+               }
+               /* Strings were xstrndup'ed before inserting into string-list,
+                * so ask string_list to remove the entries for us.
+                */
+               entry->possible_new_dirs.strdup_strings = 1;
+               string_list_clear(&entry->possible_new_dirs, 1);
+       }
+
+       return dir_renames;
+}
+
 /*
  * Get information of all renames which occurred in 'pairs', making use of
  * any implicit directory renames inferred from the other side of history.
@@ -1695,8 +1827,21 @@ struct rename_info {
        struct string_list *merge_renames;
 };
 
-static void initial_cleanup_rename(struct diff_queue_struct *pairs)
+static void initial_cleanup_rename(struct diff_queue_struct *pairs,
+                                  struct hashmap *dir_renames)
 {
+       struct hashmap_iter iter;
+       struct dir_rename_entry *e;
+
+       hashmap_iter_init(dir_renames, &iter);
+       while ((e = hashmap_iter_next(&iter))) {
+               free(e->dir);
+               strbuf_release(&e->new_dir);
+               /* possible_new_dirs already cleared in get_directory_renames */
+       }
+       hashmap_free(dir_renames, 1);
+       free(dir_renames);
+
        free(pairs->queue);
        free(pairs);
 }
@@ -1709,6 +1854,7 @@ static int handle_renames(struct merge_options *o,
                          struct rename_info *ri)
 {
        struct diff_queue_struct *head_pairs, *merge_pairs;
+       struct hashmap *dir_re_head, *dir_re_merge;
        int clean;
 
        ri->head_renames = NULL;
@@ -1720,6 +1866,9 @@ static int handle_renames(struct merge_options *o,
        head_pairs = get_diffpairs(o, common, head);
        merge_pairs = get_diffpairs(o, common, merge);
 
+       dir_re_head = get_directory_renames(head_pairs, head);
+       dir_re_merge = get_directory_renames(merge_pairs, merge);
+
        ri->head_renames  = get_renames(o, head_pairs, head,
                                         common, head, merge, entries);
        ri->merge_renames = get_renames(o, merge_pairs, merge,
@@ -1731,8 +1880,8 @@ static int handle_renames(struct merge_options *o,
         * data structures are still needed and referenced in
         * process_entry().  But there are a few things we can free now.
         */
-       initial_cleanup_rename(head_pairs);
-       initial_cleanup_rename(merge_pairs);
+       initial_cleanup_rename(head_pairs, dir_re_head);
+       initial_cleanup_rename(merge_pairs, dir_re_merge);
 
        return clean;
 }
-- 
2.15.0.408.g850bc54b15

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