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[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
8 /* Table of rename/copy destinations */
9
10 static struct diff_rename_dst {
11 struct diff_filespec *two;
12 struct diff_filepair *pair;
13 } *rename_dst;
14 static int rename_dst_nr, rename_dst_alloc;
15
16 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
17 int insert_ok)
18 {
19 int first, last;
20
21 first = 0;
22 last = rename_dst_nr;
23 while (last > first) {
24 int next = (last + first) >> 1;
25 struct diff_rename_dst *dst = &(rename_dst[next]);
26 int cmp = strcmp(two->path, dst->two->path);
27 if (!cmp)
28 return dst;
29 if (cmp < 0) {
30 last = next;
31 continue;
32 }
33 first = next+1;
34 }
35 /* not found */
36 if (!insert_ok)
37 return NULL;
38 /* insert to make it at "first" */
39 if (rename_dst_alloc <= rename_dst_nr) {
40 rename_dst_alloc = alloc_nr(rename_dst_alloc);
41 rename_dst = xrealloc(rename_dst,
42 rename_dst_alloc * sizeof(*rename_dst));
43 }
44 rename_dst_nr++;
45 if (first < rename_dst_nr)
46 memmove(rename_dst + first + 1, rename_dst + first,
47 (rename_dst_nr - first - 1) * sizeof(*rename_dst));
48 rename_dst[first].two = alloc_filespec(two->path);
49 fill_filespec(rename_dst[first].two, two->sha1, two->mode);
50 rename_dst[first].pair = NULL;
51 return &(rename_dst[first]);
52 }
53
54 /* Table of rename/copy src files */
55 static struct diff_rename_src {
56 struct diff_filespec *one;
57 unsigned short score; /* to remember the break score */
58 unsigned src_path_left : 1;
59 } *rename_src;
60 static int rename_src_nr, rename_src_alloc;
61
62 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63 int src_path_left,
64 unsigned short score)
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].score = score;
95 rename_src[first].src_path_left = src_path_left;
96 return &(rename_src[first]);
97 }
98
99 static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
100 {
101 if (src->sha1_valid && dst->sha1_valid &&
102 !memcmp(src->sha1, dst->sha1, 20))
103 return 1;
104 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
105 return 0;
106 if (src->size != dst->size)
107 return 0;
108 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
109 return 0;
110 if (src->size == dst->size &&
111 !memcmp(src->data, dst->data, src->size))
112 return 1;
113 return 0;
114 }
115
116 struct diff_score {
117 int src; /* index in rename_src */
118 int dst; /* index in rename_dst */
119 int score;
120 };
121
122 static int estimate_similarity(struct diff_filespec *src,
123 struct diff_filespec *dst,
124 int minimum_score)
125 {
126 /* src points at a file that existed in the original tree (or
127 * optionally a file in the destination tree) and dst points
128 * at a newly created file. They may be quite similar, in which
129 * case we want to say src is renamed to dst or src is copied into
130 * dst, and then some edit has been applied to dst.
131 *
132 * Compare them and return how similar they are, representing
133 * the score as an integer between 0 and MAX_SCORE.
134 *
135 * When there is an exact match, it is considered a better
136 * match than anything else; the destination does not even
137 * call into this function in that case.
138 */
139 unsigned long max_size, 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 max_size = ((src->size > dst->size) ? src->size : dst->size);
151 base_size = ((src->size < dst->size) ? src->size : dst->size);
152 delta_size = max_size - base_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
169 delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
170 if (diffcore_count_changes(src->data, src->size,
171 dst->data, dst->size,
172 &src->cnt_data, &dst->cnt_data,
173 delta_limit,
174 &src_copied, &literal_added))
175 return 0;
176
177 /* How similar are they?
178 * what percentage of material in dst are from source?
179 */
180 if (!dst->size)
181 score = 0; /* should not happen */
182 else
183 score = src_copied * MAX_SCORE / max_size;
184 return score;
185 }
186
187 static void record_rename_pair(int dst_index, int src_index, int score)
188 {
189 struct diff_filespec *one, *two, *src, *dst;
190 struct diff_filepair *dp;
191
192 if (rename_dst[dst_index].pair)
193 die("internal error: dst already matched.");
194
195 src = rename_src[src_index].one;
196 one = alloc_filespec(src->path);
197 fill_filespec(one, src->sha1, src->mode);
198
199 dst = rename_dst[dst_index].two;
200 two = alloc_filespec(dst->path);
201 fill_filespec(two, dst->sha1, dst->mode);
202
203 dp = diff_queue(NULL, one, two);
204 if (!strcmp(src->path, dst->path))
205 dp->score = rename_src[src_index].score;
206 else
207 dp->score = score;
208 dp->source_stays = rename_src[src_index].src_path_left;
209 rename_dst[dst_index].pair = dp;
210 }
211
212 /*
213 * We sort the rename similarity matrix with the score, in descending
214 * order (the most similar first).
215 */
216 static int score_compare(const void *a_, const void *b_)
217 {
218 const struct diff_score *a = a_, *b = b_;
219 return b->score - a->score;
220 }
221
222 static int compute_stays(struct diff_queue_struct *q,
223 struct diff_filespec *one)
224 {
225 int i;
226 for (i = 0; i < q->nr; i++) {
227 struct diff_filepair *p = q->queue[i];
228 if (strcmp(one->path, p->two->path))
229 continue;
230 if (DIFF_PAIR_RENAME(p)) {
231 return 0; /* something else is renamed into this */
232 }
233 }
234 return 1;
235 }
236
237 void diffcore_rename(struct diff_options *options)
238 {
239 int detect_rename = options->detect_rename;
240 int minimum_score = options->rename_score;
241 int rename_limit = options->rename_limit;
242 struct diff_queue_struct *q = &diff_queued_diff;
243 struct diff_queue_struct outq;
244 struct diff_score *mx;
245 int i, j, rename_count;
246 int num_create, num_src, dst_cnt;
247
248 if (!minimum_score)
249 minimum_score = DEFAULT_RENAME_SCORE;
250 rename_count = 0;
251
252 for (i = 0; i < q->nr; i++) {
253 struct diff_filepair *p = q->queue[i];
254 if (!DIFF_FILE_VALID(p->one))
255 if (!DIFF_FILE_VALID(p->two))
256 continue; /* unmerged */
257 else
258 locate_rename_dst(p->two, 1);
259 else if (!DIFF_FILE_VALID(p->two)) {
260 /* If the source is a broken "delete", and
261 * they did not really want to get broken,
262 * that means the source actually stays.
263 */
264 int stays = (p->broken_pair && !p->score);
265 register_rename_src(p->one, stays, p->score);
266 }
267 else if (detect_rename == DIFF_DETECT_COPY)
268 register_rename_src(p->one, 1, p->score);
269 }
270 if (rename_dst_nr == 0 || rename_src_nr == 0 ||
271 (0 < rename_limit && rename_limit < rename_dst_nr))
272 goto cleanup; /* nothing to do */
273
274 /* We really want to cull the candidates list early
275 * with cheap tests in order to avoid doing deltas.
276 */
277 for (i = 0; i < rename_dst_nr; i++) {
278 struct diff_filespec *two = rename_dst[i].two;
279 for (j = 0; j < rename_src_nr; j++) {
280 struct diff_filespec *one = rename_src[j].one;
281 if (!is_exact_match(one, two))
282 continue;
283 record_rename_pair(i, j, MAX_SCORE);
284 rename_count++;
285 break; /* we are done with this entry */
286 }
287 }
288
289 /* Have we run out the created file pool? If so we can avoid
290 * doing the delta matrix altogether.
291 */
292 if (rename_count == rename_dst_nr)
293 goto cleanup;
294
295 if (minimum_score == MAX_SCORE)
296 goto cleanup;
297
298 num_create = (rename_dst_nr - rename_count);
299 num_src = rename_src_nr;
300 mx = xmalloc(sizeof(*mx) * num_create * num_src);
301 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
302 int base = dst_cnt * num_src;
303 struct diff_filespec *two = rename_dst[i].two;
304 if (rename_dst[i].pair)
305 continue; /* dealt with exact match already. */
306 for (j = 0; j < rename_src_nr; j++) {
307 struct diff_filespec *one = rename_src[j].one;
308 struct diff_score *m = &mx[base+j];
309 m->src = j;
310 m->dst = i;
311 m->score = estimate_similarity(one, two,
312 minimum_score);
313 }
314 /* We do not need the text anymore */
315 diff_free_filespec_data(two);
316 dst_cnt++;
317 }
318 /* cost matrix sorted by most to least similar pair */
319 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
320 for (i = 0; i < num_create * num_src; i++) {
321 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
322 if (dst->pair)
323 continue; /* already done, either exact or fuzzy. */
324 if (mx[i].score < minimum_score)
325 break; /* there is no more usable pair. */
326 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
327 rename_count++;
328 }
329 free(mx);
330
331 cleanup:
332 /* At this point, we have found some renames and copies and they
333 * are recorded in rename_dst. The original list is still in *q.
334 */
335 outq.queue = NULL;
336 outq.nr = outq.alloc = 0;
337 for (i = 0; i < q->nr; i++) {
338 struct diff_filepair *p = q->queue[i];
339 struct diff_filepair *pair_to_free = NULL;
340
341 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
342 /*
343 * Creation
344 *
345 * We would output this create record if it has
346 * not been turned into a rename/copy already.
347 */
348 struct diff_rename_dst *dst =
349 locate_rename_dst(p->two, 0);
350 if (dst && dst->pair) {
351 diff_q(&outq, dst->pair);
352 pair_to_free = p;
353 }
354 else
355 /* no matching rename/copy source, so
356 * record this as a creation.
357 */
358 diff_q(&outq, p);
359 }
360 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
361 /*
362 * Deletion
363 *
364 * We would output this delete record if:
365 *
366 * (1) this is a broken delete and the counterpart
367 * broken create remains in the output; or
368 * (2) this is not a broken delete, and rename_dst
369 * does not have a rename/copy to move p->one->path
370 * out of existence.
371 *
372 * Otherwise, the counterpart broken create
373 * has been turned into a rename-edit; or
374 * delete did not have a matching create to
375 * begin with.
376 */
377 if (DIFF_PAIR_BROKEN(p)) {
378 /* broken delete */
379 struct diff_rename_dst *dst =
380 locate_rename_dst(p->one, 0);
381 if (dst && dst->pair)
382 /* counterpart is now rename/copy */
383 pair_to_free = p;
384 }
385 else {
386 for (j = 0; j < rename_dst_nr; j++) {
387 if (!rename_dst[j].pair)
388 continue;
389 if (strcmp(rename_dst[j].pair->
390 one->path,
391 p->one->path))
392 continue;
393 break;
394 }
395 if (j < rename_dst_nr)
396 /* this path remains */
397 pair_to_free = p;
398 }
399
400 if (pair_to_free)
401 ;
402 else
403 diff_q(&outq, p);
404 }
405 else if (!diff_unmodified_pair(p))
406 /* all the usual ones need to be kept */
407 diff_q(&outq, p);
408 else
409 /* no need to keep unmodified pairs */
410 pair_to_free = p;
411
412 if (pair_to_free)
413 diff_free_filepair(pair_to_free);
414 }
415 diff_debug_queue("done copying original", &outq);
416
417 free(q->queue);
418 *q = outq;
419 diff_debug_queue("done collapsing", q);
420
421 /* We need to see which rename source really stays here;
422 * earlier we only checked if the path is left in the result,
423 * but even if a path remains in the result, if that is coming
424 * from copying something else on top of it, then the original
425 * source is lost and does not stay.
426 */
427 for (i = 0; i < q->nr; i++) {
428 struct diff_filepair *p = q->queue[i];
429 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
430 /* If one appears as the target of a rename-copy,
431 * then mark p->source_stays = 0; otherwise
432 * leave it as is.
433 */
434 p->source_stays = compute_stays(q, p->one);
435 }
436 }
437
438 for (i = 0; i < rename_dst_nr; i++) {
439 diff_free_filespec_data(rename_dst[i].two);
440 free(rename_dst[i].two);
441 }
442
443 free(rename_dst);
444 rename_dst = NULL;
445 rename_dst_nr = rename_dst_alloc = 0;
446 free(rename_src);
447 rename_src = NULL;
448 rename_src_nr = rename_src_alloc = 0;
449 return;
450 }