A new merge stragety 'subtree'.
[git/git.git] / merge-recursive.c
index 2b614b6..3096594 100644 (file)
 #include "path-list.h"
 #include "xdiff-interface.h"
 
+static int subtree_merge;
+
+static struct tree *shift_tree_object(struct tree *one, struct tree *two)
+{
+       unsigned char shifted[20];
+
+       /*
+        * NEEDSWORK: this limits the recursion depth to hardcoded
+        * value '2' to avoid excessive overhead.
+        */
+       shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
+       if (!hashcmp(two->object.sha1, shifted))
+               return two;
+       return lookup_tree(shifted);
+}
+
 /*
  * A virtual commit has
  * - (const char *)commit->util set to the name, and
@@ -1137,6 +1153,12 @@ static int merge_trees(struct tree *head,
                       struct tree **result)
 {
        int code, clean;
+
+       if (subtree_merge) {
+               merge = shift_tree_object(head, merge);
+               common = shift_tree_object(head, common);
+       }
+
        if (sha_eq(common->object.sha1, merge->object.sha1)) {
                output(0, "Already uptodate!");
                *result = head;
@@ -1342,6 +1364,13 @@ int main(int argc, char *argv[])
        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
        int index_fd;
 
+       if (argv[0]) {
+               int namelen = strlen(argv[0]);
+               if (8 < namelen &&
+                   !strcmp(argv[0] + namelen - 8, "-subtree"))
+                       subtree_merge = 1;
+       }
+
        git_config(merge_config);
        if (getenv("GIT_MERGE_VERBOSITY"))
                verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);