2 * Copyright (C) 2005 Junio C Hamano
8 #include "count-delta.h"
10 /* Table of rename/copy destinations */
12 static struct diff_rename_dst {
13 struct diff_filespec *two;
14 struct diff_filepair *pair;
16 static int rename_dst_nr, rename_dst_alloc;
18 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
25 while (last > first) {
26 int next = (last + first) >> 1;
27 struct diff_rename_dst *dst = &(rename_dst[next]);
28 int cmp = strcmp(two->path, dst->two->path);
40 /* insert to make it at "first" */
41 if (rename_dst_alloc <= rename_dst_nr) {
42 rename_dst_alloc = alloc_nr(rename_dst_alloc);
43 rename_dst = xrealloc(rename_dst,
44 rename_dst_alloc * sizeof(*rename_dst));
47 if (first < rename_dst_nr)
48 memmove(rename_dst + first + 1, rename_dst + first,
49 (rename_dst_nr - first - 1) * sizeof(*rename_dst));
50 rename_dst[first].two = alloc_filespec(two->path);
51 fill_filespec(rename_dst[first].two, two->sha1, two->mode);
52 rename_dst[first].pair = NULL;
53 return &(rename_dst[first]);
56 /* Table of rename/copy src files */
57 static struct diff_rename_src {
58 struct diff_filespec *one;
59 unsigned src_path_left : 1;
61 static int rename_src_nr, rename_src_alloc;
63 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
70 while (last > first) {
71 int next = (last + first) >> 1;
72 struct diff_rename_src *src = &(rename_src[next]);
73 int cmp = strcmp(one->path, src->one->path);
83 /* insert to make it at "first" */
84 if (rename_src_alloc <= rename_src_nr) {
85 rename_src_alloc = alloc_nr(rename_src_alloc);
86 rename_src = xrealloc(rename_src,
87 rename_src_alloc * sizeof(*rename_src));
90 if (first < rename_src_nr)
91 memmove(rename_src + first + 1, rename_src + first,
92 (rename_src_nr - first - 1) * sizeof(*rename_src));
93 rename_src[first].one = one;
94 rename_src[first].src_path_left = src_path_left;
95 return &(rename_src[first]);
98 static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
100 if (src->sha1_valid && dst->sha1_valid &&
101 !memcmp(src->sha1, dst->sha1, 20))
103 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
105 if (src->size != dst->size)
107 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
109 if (src->size == dst->size &&
110 !memcmp(src->data, dst->data, src->size))
116 int src; /* index in rename_src */
117 int dst; /* index in rename_dst */
121 static int estimate_similarity(struct diff_filespec *src,
122 struct diff_filespec *dst,
125 /* src points at a file that existed in the original tree (or
126 * optionally a file in the destination tree) and dst points
127 * at a newly created file. They may be quite similar, in which
128 * case we want to say src is renamed to dst or src is copied into
129 * dst, and then some edit has been applied to dst.
131 * Compare them and return how similar they are, representing
132 * the score as an integer between 0 and MAX_SCORE.
134 * When there is an exact match, it is considered a better
135 * match than anything else; the destination does not even
136 * call into this function in that case.
139 unsigned long delta_size, base_size, src_copied, literal_added;
140 unsigned long delta_limit;
143 /* We deal only with regular files. Symlink renames are handled
144 * only when they are exact matches --- in other words, no edits
147 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
150 delta_size = ((src->size < dst->size) ?
151 (dst->size - src->size) : (src->size - dst->size));
152 base_size = ((src->size < dst->size) ? src->size : dst->size);
154 /* We would not consider edits that change the file size so
155 * drastically. delta_size must be smaller than
156 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
158 * Note that base_size == 0 case is handled here already
159 * and the final score computation below would not have a
160 * divide-by-zero issue.
162 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
165 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
166 return 0; /* error but caught downstream */
168 delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
169 delta = diff_delta(src->data, src->size,
170 dst->data, dst->size,
171 &delta_size, delta_limit);
173 /* If delta_limit is exceeded, we have too much differences */
176 /* A delta that has a lot of literal additions would have
177 * big delta_size no matter what else it does.
179 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
182 /* Estimate the edit size by interpreting delta. */
183 if (count_delta(delta, delta_size, &src_copied, &literal_added)) {
189 /* Extent of damage */
190 if (src->size + literal_added < src_copied)
193 delta_size = (src->size - src_copied) + literal_added;
196 * Now we will give some score to it. 100% edit gets 0 points
197 * and 0% edit gets MAX_SCORE points.
199 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
200 if (score < 0) return 0;
201 if (MAX_SCORE < score) return MAX_SCORE;
205 static void record_rename_pair(int dst_index, int src_index, int score)
207 struct diff_filespec *one, *two, *src, *dst;
208 struct diff_filepair *dp;
210 if (rename_dst[dst_index].pair)
211 die("internal error: dst already matched.");
213 src = rename_src[src_index].one;
214 one = alloc_filespec(src->path);
215 fill_filespec(one, src->sha1, src->mode);
217 dst = rename_dst[dst_index].two;
218 two = alloc_filespec(dst->path);
219 fill_filespec(two, dst->sha1, dst->mode);
221 dp = diff_queue(NULL, one, two);
223 dp->source_stays = rename_src[src_index].src_path_left;
224 rename_dst[dst_index].pair = dp;
228 * We sort the rename similarity matrix with the score, in descending
229 * order (the most similar first).
231 static int score_compare(const void *a_, const void *b_)
233 const struct diff_score *a = a_, *b = b_;
234 return b->score - a->score;
237 static int compute_stays(struct diff_queue_struct *q,
238 struct diff_filespec *one)
241 for (i = 0; i < q->nr; i++) {
242 struct diff_filepair *p = q->queue[i];
243 if (strcmp(one->path, p->two->path))
245 if (DIFF_PAIR_RENAME(p)) {
246 return 0; /* something else is renamed into this */
252 void diffcore_rename(int detect_rename, int minimum_score)
254 struct diff_queue_struct *q = &diff_queued_diff;
255 struct diff_queue_struct outq;
256 struct diff_score *mx;
257 int i, j, rename_count;
258 int num_create, num_src, dst_cnt;
261 minimum_score = DEFAULT_RENAME_SCORE;
264 for (i = 0; i < q->nr; i++) {
265 struct diff_filepair *p = q->queue[i];
266 if (!DIFF_FILE_VALID(p->one))
267 if (!DIFF_FILE_VALID(p->two))
268 continue; /* unmerged */
270 locate_rename_dst(p->two, 1);
271 else if (!DIFF_FILE_VALID(p->two)) {
272 /* If the source is a broken "delete", and
273 * they did not really want to get broken,
274 * that means the source actually stays.
276 int stays = (p->broken_pair && !p->score);
277 register_rename_src(p->one, stays);
279 else if (detect_rename == DIFF_DETECT_COPY)
280 register_rename_src(p->one, 1);
282 if (rename_dst_nr == 0)
283 goto cleanup; /* nothing to do */
285 /* We really want to cull the candidates list early
286 * with cheap tests in order to avoid doing deltas.
288 for (i = 0; i < rename_dst_nr; i++) {
289 struct diff_filespec *two = rename_dst[i].two;
290 for (j = 0; j < rename_src_nr; j++) {
291 struct diff_filespec *one = rename_src[j].one;
292 if (!is_exact_match(one, two))
294 record_rename_pair(i, j, MAX_SCORE);
296 break; /* we are done with this entry */
300 /* Have we run out the created file pool? If so we can avoid
301 * doing the delta matrix altogether.
303 if (rename_count == rename_dst_nr)
306 num_create = (rename_dst_nr - rename_count);
307 num_src = rename_src_nr;
308 mx = xmalloc(sizeof(*mx) * num_create * num_src);
309 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
310 int base = dst_cnt * num_src;
311 struct diff_filespec *two = rename_dst[i].two;
312 if (rename_dst[i].pair)
313 continue; /* dealt with exact match already. */
314 for (j = 0; j < rename_src_nr; j++) {
315 struct diff_filespec *one = rename_src[j].one;
316 struct diff_score *m = &mx[base+j];
319 m->score = estimate_similarity(one, two,
324 /* cost matrix sorted by most to least similar pair */
325 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
326 for (i = 0; i < num_create * num_src; i++) {
327 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
329 continue; /* already done, either exact or fuzzy. */
330 if (mx[i].score < minimum_score)
331 break; /* there is no more usable pair. */
332 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
338 /* At this point, we have found some renames and copies and they
339 * are recorded in rename_dst. The original list is still in *q.
342 outq.nr = outq.alloc = 0;
343 for (i = 0; i < q->nr; i++) {
344 struct diff_filepair *p = q->queue[i];
345 struct diff_filepair *pair_to_free = NULL;
347 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
351 * We would output this create record if it has
352 * not been turned into a rename/copy already.
354 struct diff_rename_dst *dst =
355 locate_rename_dst(p->two, 0);
356 if (dst && dst->pair) {
357 diff_q(&outq, dst->pair);
361 /* no matching rename/copy source, so
362 * record this as a creation.
366 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
370 * We would output this delete record if:
372 * (1) this is a broken delete and the counterpart
373 * broken create remains in the output; or
374 * (2) this is not a broken delete, and rename_dst
375 * does not have a rename/copy to move p->one->path
378 * Otherwise, the counterpart broken create
379 * has been turned into a rename-edit; or
380 * delete did not have a matching create to
383 if (DIFF_PAIR_BROKEN(p)) {
385 struct diff_rename_dst *dst =
386 locate_rename_dst(p->one, 0);
387 if (dst && dst->pair)
388 /* counterpart is now rename/copy */
392 for (j = 0; j < rename_dst_nr; j++) {
393 if (!rename_dst[j].pair)
395 if (strcmp(rename_dst[j].pair->
401 if (j < rename_dst_nr)
402 /* this path remains */
411 else if (!diff_unmodified_pair(p))
412 /* all the usual ones need to be kept */
415 /* no need to keep unmodified pairs */
419 diff_free_filepair(pair_to_free);
421 diff_debug_queue("done copying original", &outq);
425 diff_debug_queue("done collapsing", q);
427 /* We need to see which rename source really stays here;
428 * earlier we only checked if the path is left in the result,
429 * but even if a path remains in the result, if that is coming
430 * from copying something else on top of it, then the original
431 * source is lost and does not stay.
433 for (i = 0; i < q->nr; i++) {
434 struct diff_filepair *p = q->queue[i];
435 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
436 /* If one appears as the target of a rename-copy,
437 * then mark p->source_stays = 0; otherwise
440 p->source_stays = compute_stays(q, p->one);
444 for (i = 0; i < rename_dst_nr; i++) {
445 diff_free_filespec_data(rename_dst[i].two);
446 free(rename_dst[i].two);
451 rename_dst_nr = rename_dst_alloc = 0;
454 rename_src_nr = rename_src_alloc = 0;