dba965c0b4006251b1da04465d319c5fe9997ea4
[git/git.git] / diffcore-rename.c
1 /*
2 * Copyright (C) 2005 Junio C Hamano
3 */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
7 #include "delta.h"
8 #include "count-delta.h"
9
10 /* Table of rename/copy destinations */
11
12 static struct diff_rename_dst {
13 struct diff_filespec *two;
14 struct diff_filepair *pair;
15 } *rename_dst;
16 static int rename_dst_nr, rename_dst_alloc;
17
18 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
19 int insert_ok)
20 {
21 int first, last;
22
23 first = 0;
24 last = rename_dst_nr;
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);
29 if (!cmp)
30 return dst;
31 if (cmp < 0) {
32 last = next;
33 continue;
34 }
35 first = next+1;
36 }
37 /* not found */
38 if (!insert_ok)
39 return NULL;
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));
45 }
46 rename_dst_nr++;
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]);
54 }
55
56 /* Table of rename/copy src files */
57 static struct diff_rename_src {
58 struct diff_filespec *one;
59 unsigned src_path_left : 1;
60 } *rename_src;
61 static int rename_src_nr, rename_src_alloc;
62
63 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
64 int src_path_left)
65 {
66 int first, last;
67
68 first = 0;
69 last = rename_src_nr;
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);
74 if (!cmp)
75 return src;
76 if (cmp < 0) {
77 last = next;
78 continue;
79 }
80 first = next+1;
81 }
82
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));
88 }
89 rename_src_nr++;
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]);
96 }
97
98 static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
99 {
100 if (src->sha1_valid && dst->sha1_valid &&
101 !memcmp(src->sha1, dst->sha1, 20))
102 return 1;
103 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
104 return 0;
105 if (src->size != dst->size)
106 return 0;
107 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
108 return 0;
109 if (src->size == dst->size &&
110 !memcmp(src->data, dst->data, src->size))
111 return 1;
112 return 0;
113 }
114
115 struct diff_score {
116 int src; /* index in rename_src */
117 int dst; /* index in rename_dst */
118 int score;
119 };
120
121 static int estimate_similarity(struct diff_filespec *src,
122 struct diff_filespec *dst,
123 int minimum_score)
124 {
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.
130 *
131 * Compare them and return how similar they are, representing
132 * the score as an integer between 0 and MAX_SCORE.
133 *
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.
137 */
138 void *delta;
139 unsigned long delta_size, base_size, src_copied, literal_added;
140 unsigned long delta_limit;
141 int score;
142
143 /* We deal only with regular files. Symlink renames are handled
144 * only when they are exact matches --- in other words, no edits
145 * after renaming.
146 */
147 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
148 return 0;
149
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);
153
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).
157 *
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.
161 */
162 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
163 return 0;
164
165 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
166 return 0; /* error but caught downstream */
167
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);
172 if (!delta)
173 /* If delta_limit is exceeded, we have too much differences */
174 return 0;
175
176 /* A delta that has a lot of literal additions would have
177 * big delta_size no matter what else it does.
178 */
179 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
180 return 0;
181
182 /* Estimate the edit size by interpreting delta. */
183 if (count_delta(delta, delta_size, &src_copied, &literal_added)) {
184 free(delta);
185 return 0;
186 }
187 free(delta);
188
189 /* Extent of damage */
190 if (src->size + literal_added < src_copied)
191 delta_size = 0;
192 else
193 delta_size = (src->size - src_copied) + literal_added;
194
195 /*
196 * Now we will give some score to it. 100% edit gets 0 points
197 * and 0% edit gets MAX_SCORE points.
198 */
199 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
200 if (score < 0) return 0;
201 if (MAX_SCORE < score) return MAX_SCORE;
202 return score;
203 }
204
205 static void record_rename_pair(int dst_index, int src_index, int score)
206 {
207 struct diff_filespec *one, *two, *src, *dst;
208 struct diff_filepair *dp;
209
210 if (rename_dst[dst_index].pair)
211 die("internal error: dst already matched.");
212
213 src = rename_src[src_index].one;
214 one = alloc_filespec(src->path);
215 fill_filespec(one, src->sha1, src->mode);
216
217 dst = rename_dst[dst_index].two;
218 two = alloc_filespec(dst->path);
219 fill_filespec(two, dst->sha1, dst->mode);
220
221 dp = diff_queue(NULL, one, two);
222 dp->score = score;
223 dp->source_stays = rename_src[src_index].src_path_left;
224 rename_dst[dst_index].pair = dp;
225 }
226
227 /*
228 * We sort the rename similarity matrix with the score, in descending
229 * order (the most similar first).
230 */
231 static int score_compare(const void *a_, const void *b_)
232 {
233 const struct diff_score *a = a_, *b = b_;
234 return b->score - a->score;
235 }
236
237 static int compute_stays(struct diff_queue_struct *q,
238 struct diff_filespec *one)
239 {
240 int i;
241 for (i = 0; i < q->nr; i++) {
242 struct diff_filepair *p = q->queue[i];
243 if (strcmp(one->path, p->two->path))
244 continue;
245 if (DIFF_PAIR_RENAME(p)) {
246 return 0; /* something else is renamed into this */
247 }
248 }
249 return 1;
250 }
251
252 void diffcore_rename(struct diff_options *options)
253 {
254 int detect_rename = options->detect_rename;
255 int minimum_score = options->rename_score;
256 int rename_limit = options->rename_limit;
257 struct diff_queue_struct *q = &diff_queued_diff;
258 struct diff_queue_struct outq;
259 struct diff_score *mx;
260 int i, j, rename_count;
261 int num_create, num_src, dst_cnt;
262
263 if (!minimum_score)
264 minimum_score = DEFAULT_RENAME_SCORE;
265 rename_count = 0;
266
267 for (i = 0; i < q->nr; i++) {
268 struct diff_filepair *p = q->queue[i];
269 if (!DIFF_FILE_VALID(p->one))
270 if (!DIFF_FILE_VALID(p->two))
271 continue; /* unmerged */
272 else
273 locate_rename_dst(p->two, 1);
274 else if (!DIFF_FILE_VALID(p->two)) {
275 /* If the source is a broken "delete", and
276 * they did not really want to get broken,
277 * that means the source actually stays.
278 */
279 int stays = (p->broken_pair && !p->score);
280 register_rename_src(p->one, stays);
281 }
282 else if (detect_rename == DIFF_DETECT_COPY)
283 register_rename_src(p->one, 1);
284 }
285 if (rename_dst_nr == 0 ||
286 (0 < rename_limit && rename_limit < rename_dst_nr))
287 goto cleanup; /* nothing to do */
288
289 /* We really want to cull the candidates list early
290 * with cheap tests in order to avoid doing deltas.
291 */
292 for (i = 0; i < rename_dst_nr; i++) {
293 struct diff_filespec *two = rename_dst[i].two;
294 for (j = 0; j < rename_src_nr; j++) {
295 struct diff_filespec *one = rename_src[j].one;
296 if (!is_exact_match(one, two))
297 continue;
298 record_rename_pair(i, j, MAX_SCORE);
299 rename_count++;
300 break; /* we are done with this entry */
301 }
302 }
303
304 /* Have we run out the created file pool? If so we can avoid
305 * doing the delta matrix altogether.
306 */
307 if (rename_count == rename_dst_nr)
308 goto cleanup;
309
310 if (minimum_score == MAX_SCORE)
311 goto cleanup;
312
313 num_create = (rename_dst_nr - rename_count);
314 num_src = rename_src_nr;
315 mx = xmalloc(sizeof(*mx) * num_create * num_src);
316 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
317 int base = dst_cnt * num_src;
318 struct diff_filespec *two = rename_dst[i].two;
319 if (rename_dst[i].pair)
320 continue; /* dealt with exact match already. */
321 for (j = 0; j < rename_src_nr; j++) {
322 struct diff_filespec *one = rename_src[j].one;
323 struct diff_score *m = &mx[base+j];
324 m->src = j;
325 m->dst = i;
326 m->score = estimate_similarity(one, two,
327 minimum_score);
328 }
329 dst_cnt++;
330 }
331 /* cost matrix sorted by most to least similar pair */
332 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
333 for (i = 0; i < num_create * num_src; i++) {
334 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
335 if (dst->pair)
336 continue; /* already done, either exact or fuzzy. */
337 if (mx[i].score < minimum_score)
338 break; /* there is no more usable pair. */
339 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
340 rename_count++;
341 }
342 free(mx);
343
344 cleanup:
345 /* At this point, we have found some renames and copies and they
346 * are recorded in rename_dst. The original list is still in *q.
347 */
348 outq.queue = NULL;
349 outq.nr = outq.alloc = 0;
350 for (i = 0; i < q->nr; i++) {
351 struct diff_filepair *p = q->queue[i];
352 struct diff_filepair *pair_to_free = NULL;
353
354 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
355 /*
356 * Creation
357 *
358 * We would output this create record if it has
359 * not been turned into a rename/copy already.
360 */
361 struct diff_rename_dst *dst =
362 locate_rename_dst(p->two, 0);
363 if (dst && dst->pair) {
364 diff_q(&outq, dst->pair);
365 pair_to_free = p;
366 }
367 else
368 /* no matching rename/copy source, so
369 * record this as a creation.
370 */
371 diff_q(&outq, p);
372 }
373 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
374 /*
375 * Deletion
376 *
377 * We would output this delete record if:
378 *
379 * (1) this is a broken delete and the counterpart
380 * broken create remains in the output; or
381 * (2) this is not a broken delete, and rename_dst
382 * does not have a rename/copy to move p->one->path
383 * out of existence.
384 *
385 * Otherwise, the counterpart broken create
386 * has been turned into a rename-edit; or
387 * delete did not have a matching create to
388 * begin with.
389 */
390 if (DIFF_PAIR_BROKEN(p)) {
391 /* broken delete */
392 struct diff_rename_dst *dst =
393 locate_rename_dst(p->one, 0);
394 if (dst && dst->pair)
395 /* counterpart is now rename/copy */
396 pair_to_free = p;
397 }
398 else {
399 for (j = 0; j < rename_dst_nr; j++) {
400 if (!rename_dst[j].pair)
401 continue;
402 if (strcmp(rename_dst[j].pair->
403 one->path,
404 p->one->path))
405 continue;
406 break;
407 }
408 if (j < rename_dst_nr)
409 /* this path remains */
410 pair_to_free = p;
411 }
412
413 if (pair_to_free)
414 ;
415 else
416 diff_q(&outq, p);
417 }
418 else if (!diff_unmodified_pair(p))
419 /* all the usual ones need to be kept */
420 diff_q(&outq, p);
421 else
422 /* no need to keep unmodified pairs */
423 pair_to_free = p;
424
425 if (pair_to_free)
426 diff_free_filepair(pair_to_free);
427 }
428 diff_debug_queue("done copying original", &outq);
429
430 free(q->queue);
431 *q = outq;
432 diff_debug_queue("done collapsing", q);
433
434 /* We need to see which rename source really stays here;
435 * earlier we only checked if the path is left in the result,
436 * but even if a path remains in the result, if that is coming
437 * from copying something else on top of it, then the original
438 * source is lost and does not stay.
439 */
440 for (i = 0; i < q->nr; i++) {
441 struct diff_filepair *p = q->queue[i];
442 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
443 /* If one appears as the target of a rename-copy,
444 * then mark p->source_stays = 0; otherwise
445 * leave it as is.
446 */
447 p->source_stays = compute_stays(q, p->one);
448 }
449 }
450
451 for (i = 0; i < rename_dst_nr; i++) {
452 diff_free_filespec_data(rename_dst[i].two);
453 free(rename_dst[i].two);
454 }
455
456 free(rename_dst);
457 rename_dst = NULL;
458 rename_dst_nr = rename_dst_alloc = 0;
459 free(rename_src);
460 rename_src = NULL;
461 rename_src_nr = rename_src_alloc = 0;
462 return;
463 }