return score;
}
+static int base_name_entries_compare(const struct name_entry *a,
+ const struct name_entry *b)
+{
+ return base_name_compare(a->path, tree_entry_len(a), a->mode,
+ b->path, tree_entry_len(b), b->mode);
+}
+
/*
* Inspect two trees, and give a score that tells how similar they are.
*/
if (type != OBJ_TREE)
die("%s is not a tree", sha1_to_hex(hash2));
init_tree_desc(&two, two_buf, size);
- while (one.size | two.size) {
- const unsigned char *elem1 = elem1;
- const unsigned char *elem2 = elem2;
- const char *path1 = path1;
- const char *path2 = path2;
- unsigned mode1 = mode1;
- unsigned mode2 = mode2;
+ for (;;) {
+ struct name_entry e1, e2;
+ int got_entry_from_one = tree_entry(&one, &e1);
+ int got_entry_from_two = tree_entry(&two, &e2);
int cmp;
- if (one.size)
- elem1 = tree_entry_extract(&one, &path1, &mode1);
- if (two.size)
- elem2 = tree_entry_extract(&two, &path2, &mode2);
-
- if (!one.size) {
- /* two has more entries */
- score += score_missing(mode2, path2);
- update_tree_entry(&two);
- continue;
- }
- if (!two.size) {
+ if (got_entry_from_one && got_entry_from_two)
+ cmp = base_name_entries_compare(&e1, &e2);
+ else if (got_entry_from_one)
/* two lacks this entry */
- score += score_missing(mode1, path1);
- update_tree_entry(&one);
- continue;
- }
- cmp = base_name_compare(path1, strlen(path1), mode1,
- path2, strlen(path2), mode2);
- if (cmp < 0) {
+ cmp = -1;
+ else if (got_entry_from_two)
+ /* two has more entries */
+ cmp = 1;
+ else
+ break;
+
+ if (cmp < 0)
/* path1 does not appear in two */
- score += score_missing(mode1, path1);
- update_tree_entry(&one);
- continue;
- }
- else if (cmp > 0) {
+ score += score_missing(e1.mode, e1.path);
+ else if (cmp > 0)
/* path2 does not appear in one */
- score += score_missing(mode2, path2);
- update_tree_entry(&two);
- continue;
- }
- else if (hashcmp(elem1, elem2))
+ score += score_missing(e2.mode, e2.path);
+ else if (hashcmp(e1.sha1, e2.sha1))
/* they are different */
- score += score_differs(mode1, mode2, path1);
+ score += score_differs(e1.mode, e2.mode, e1.path);
else
/* same subtree or blob */
- score += score_matches(mode1, mode2, path1);
- update_tree_entry(&one);
- update_tree_entry(&two);
+ score += score_matches(e1.mode, e2.mode, e1.path);
}
free(one_buf);
free(two_buf);
* tree object by replacing it with another tree "hash2".
*/
static int splice_tree(const unsigned char *hash1,
- char *prefix,
+ const char *prefix,
const unsigned char *hash2,
unsigned char *result)
{
char *del_prefix;
int add_score, del_score;
+ /*
+ * NEEDSWORK: this limits the recursion depth to hardcoded
+ * value '2' to avoid excessive overhead.
+ */
+ if (!depth_limit)
+ depth_limit = 2;
+
add_score = del_score = score_trees(hash1, hash2);
add_prefix = xcalloc(1, 1);
del_prefix = xcalloc(1, 1);
splice_tree(hash1, add_prefix, hash2, shifted);
}
+
+/*
+ * The user says the trees will be shifted by this much.
+ * Unfortunately we cannot fundamentally tell which one to
+ * be prefixed, as recursive merge can work in either direction.
+ */
+void shift_tree_by(const unsigned char *hash1,
+ const unsigned char *hash2,
+ unsigned char *shifted,
+ const char *shift_prefix)
+{
+ unsigned char sub1[20], sub2[20];
+ unsigned mode1, mode2;
+ unsigned candidate = 0;
+
+ /* Can hash2 be a tree at shift_prefix in tree hash1? */
+ if (!get_tree_entry(hash1, shift_prefix, sub1, &mode1) &&
+ S_ISDIR(mode1))
+ candidate |= 1;
+
+ /* Can hash1 be a tree at shift_prefix in tree hash2? */
+ if (!get_tree_entry(hash2, shift_prefix, sub2, &mode2) &&
+ S_ISDIR(mode2))
+ candidate |= 2;
+
+ if (candidate == 3) {
+ /* Both are plausible -- we need to evaluate the score */
+ int best_score = score_trees(hash1, hash2);
+ int score;
+
+ candidate = 0;
+ score = score_trees(sub1, hash2);
+ if (score > best_score) {
+ candidate = 1;
+ best_score = score;
+ }
+ score = score_trees(sub2, hash1);
+ if (score > best_score)
+ candidate = 2;
+ }
+
+ if (!candidate) {
+ /* Neither is plausible -- do not shift */
+ hashcpy(shifted, hash2);
+ return;
+ }
+
+ if (candidate == 1)
+ /*
+ * shift tree2 down by adding shift_prefix above it
+ * to match tree1.
+ */
+ splice_tree(hash1, shift_prefix, hash2, shifted);
+ else
+ /*
+ * shift tree2 up by removing shift_prefix from it
+ * to match tree1.
+ */
+ hashcpy(shifted, sub2);
+}