diff options
Diffstat (limited to 'match-trees.c')
| -rw-r--r-- | match-trees.c | 69 |
1 files changed, 68 insertions, 1 deletions
diff --git a/match-trees.c b/match-trees.c index 0fd6df7..26f7ed1 100644 --- a/match-trees.c +++ b/match-trees.c @@ -185,7 +185,7 @@ static void match_trees(const unsigned char *hash1, * 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) { @@ -264,6 +264,13 @@ void shift_tree(const unsigned char *hash1, 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); @@ -301,3 +308,63 @@ void shift_tree(const unsigned char *hash1, 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); +} |