Merge branch 'maint'
[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,
100                           struct diff_filespec *dst,
101                           int contents_too)
102 {
103         if (src->sha1_valid && dst->sha1_valid &&
104             !hashcmp(src->sha1, dst->sha1))
105                 return 1;
106         if (!contents_too)
107                 return 0;
108         if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
109                 return 0;
110         if (src->size != dst->size)
111                 return 0;
112         if (src->sha1_valid && dst->sha1_valid)
113             return !hashcmp(src->sha1, dst->sha1);
114         if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
115                 return 0;
116         if (src->size == dst->size &&
117             !memcmp(src->data, dst->data, src->size))
118                 return 1;
119         return 0;
120 }
121
122 struct diff_score {
123         int src; /* index in rename_src */
124         int dst; /* index in rename_dst */
125         int score;
126 };
127
128 static int estimate_similarity(struct diff_filespec *src,
129                                struct diff_filespec *dst,
130                                int minimum_score)
131 {
132         /* src points at a file that existed in the original tree (or
133          * optionally a file in the destination tree) and dst points
134          * at a newly created file.  They may be quite similar, in which
135          * case we want to say src is renamed to dst or src is copied into
136          * dst, and then some edit has been applied to dst.
137          *
138          * Compare them and return how similar they are, representing
139          * the score as an integer between 0 and MAX_SCORE.
140          *
141          * When there is an exact match, it is considered a better
142          * match than anything else; the destination does not even
143          * call into this function in that case.
144          */
145         unsigned long max_size, delta_size, base_size, src_copied, literal_added;
146         unsigned long delta_limit;
147         int score;
148
149         /* We deal only with regular files.  Symlink renames are handled
150          * only when they are exact matches --- in other words, no edits
151          * after renaming.
152          */
153         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
154                 return 0;
155
156         max_size = ((src->size > dst->size) ? src->size : dst->size);
157         base_size = ((src->size < dst->size) ? src->size : dst->size);
158         delta_size = max_size - base_size;
159
160         /* We would not consider edits that change the file size so
161          * drastically.  delta_size must be smaller than
162          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
163          *
164          * Note that base_size == 0 case is handled here already
165          * and the final score computation below would not have a
166          * divide-by-zero issue.
167          */
168         if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
169                 return 0;
170
171         if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
172                 return 0; /* error but caught downstream */
173
174
175         delta_limit = (unsigned long)
176                 (base_size * (MAX_SCORE-minimum_score) / MAX_SCORE);
177         if (diffcore_count_changes(src->data, src->size,
178                                    dst->data, dst->size,
179                                    &src->cnt_data, &dst->cnt_data,
180                                    delta_limit,
181                                    &src_copied, &literal_added))
182                 return 0;
183
184         /* How similar are they?
185          * what percentage of material in dst are from source?
186          */
187         if (!dst->size)
188                 score = 0; /* should not happen */
189         else
190                 score = (int)(src_copied * MAX_SCORE / max_size);
191         return score;
192 }
193
194 static void record_rename_pair(int dst_index, int src_index, int score)
195 {
196         struct diff_filespec *one, *two, *src, *dst;
197         struct diff_filepair *dp;
198
199         if (rename_dst[dst_index].pair)
200                 die("internal error: dst already matched.");
201
202         src = rename_src[src_index].one;
203         one = alloc_filespec(src->path);
204         fill_filespec(one, src->sha1, src->mode);
205
206         dst = rename_dst[dst_index].two;
207         two = alloc_filespec(dst->path);
208         fill_filespec(two, dst->sha1, dst->mode);
209
210         dp = diff_queue(NULL, one, two);
211         dp->renamed_pair = 1;
212         if (!strcmp(src->path, dst->path))
213                 dp->score = rename_src[src_index].score;
214         else
215                 dp->score = score;
216         dp->source_stays = rename_src[src_index].src_path_left;
217         rename_dst[dst_index].pair = dp;
218 }
219
220 /*
221  * We sort the rename similarity matrix with the score, in descending
222  * order (the most similar first).
223  */
224 static int score_compare(const void *a_, const void *b_)
225 {
226         const struct diff_score *a = a_, *b = b_;
227         return b->score - a->score;
228 }
229
230 static int compute_stays(struct diff_queue_struct *q,
231                          struct diff_filespec *one)
232 {
233         int i;
234         for (i = 0; i < q->nr; i++) {
235                 struct diff_filepair *p = q->queue[i];
236                 if (strcmp(one->path, p->two->path))
237                         continue;
238                 if (DIFF_PAIR_RENAME(p)) {
239                         return 0; /* something else is renamed into this */
240                 }
241         }
242         return 1;
243 }
244
245 void diffcore_rename(struct diff_options *options)
246 {
247         int detect_rename = options->detect_rename;
248         int minimum_score = options->rename_score;
249         int rename_limit = options->rename_limit;
250         struct diff_queue_struct *q = &diff_queued_diff;
251         struct diff_queue_struct outq;
252         struct diff_score *mx;
253         int i, j, rename_count, contents_too;
254         int num_create, num_src, dst_cnt;
255
256         if (!minimum_score)
257                 minimum_score = DEFAULT_RENAME_SCORE;
258         rename_count = 0;
259
260         for (i = 0; i < q->nr; i++) {
261                 struct diff_filepair *p = q->queue[i];
262                 if (!DIFF_FILE_VALID(p->one)) {
263                         if (!DIFF_FILE_VALID(p->two))
264                                 continue; /* unmerged */
265                         else if (options->single_follow &&
266                                  strcmp(options->single_follow, p->two->path))
267                                 continue; /* not interested */
268                         else
269                                 locate_rename_dst(p->two, 1);
270                 }
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.
275                          */
276                         int stays = (p->broken_pair && !p->score);
277                         register_rename_src(p->one, stays, p->score);
278                 }
279                 else if (detect_rename == DIFF_DETECT_COPY)
280                         register_rename_src(p->one, 1, p->score);
281         }
282         if (rename_dst_nr == 0 || rename_src_nr == 0 ||
283             (0 < rename_limit && rename_limit < rename_dst_nr))
284                 goto cleanup; /* nothing to do */
285
286         /* We really want to cull the candidates list early
287          * with cheap tests in order to avoid doing deltas.
288          * The first round matches up the up-to-date entries,
289          * and then during the second round we try to match
290          * cache-dirty entries as well.
291          */
292         for (contents_too = 0; contents_too < 2; contents_too++) {
293                 for (i = 0; i < rename_dst_nr; i++) {
294                         struct diff_filespec *two = rename_dst[i].two;
295                         if (rename_dst[i].pair)
296                                 continue; /* dealt with an earlier round */
297                         for (j = 0; j < rename_src_nr; j++) {
298                                 struct diff_filespec *one = rename_src[j].one;
299                                 if (!is_exact_match(one, two, contents_too))
300                                         continue;
301                                 record_rename_pair(i, j, (int)MAX_SCORE);
302                                 rename_count++;
303                                 break; /* we are done with this entry */
304                         }
305                 }
306         }
307
308         /* Have we run out the created file pool?  If so we can avoid
309          * doing the delta matrix altogether.
310          */
311         if (rename_count == rename_dst_nr)
312                 goto cleanup;
313
314         if (minimum_score == MAX_SCORE)
315                 goto cleanup;
316
317         num_create = (rename_dst_nr - rename_count);
318         num_src = rename_src_nr;
319         mx = xmalloc(sizeof(*mx) * num_create * num_src);
320         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
321                 int base = dst_cnt * num_src;
322                 struct diff_filespec *two = rename_dst[i].two;
323                 if (rename_dst[i].pair)
324                         continue; /* dealt with exact match already. */
325                 for (j = 0; j < rename_src_nr; j++) {
326                         struct diff_filespec *one = rename_src[j].one;
327                         struct diff_score *m = &mx[base+j];
328                         m->src = j;
329                         m->dst = i;
330                         m->score = estimate_similarity(one, two,
331                                                        minimum_score);
332                         diff_free_filespec_data(one);
333                 }
334                 /* We do not need the text anymore */
335                 diff_free_filespec_data(two);
336                 dst_cnt++;
337         }
338         /* cost matrix sorted by most to least similar pair */
339         qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
340         for (i = 0; i < num_create * num_src; i++) {
341                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
342                 if (dst->pair)
343                         continue; /* already done, either exact or fuzzy. */
344                 if (mx[i].score < minimum_score)
345                         break; /* there is no more usable pair. */
346                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
347                 rename_count++;
348         }
349         free(mx);
350
351  cleanup:
352         /* At this point, we have found some renames and copies and they
353          * are recorded in rename_dst.  The original list is still in *q.
354          */
355         outq.queue = NULL;
356         outq.nr = outq.alloc = 0;
357         for (i = 0; i < q->nr; i++) {
358                 struct diff_filepair *p = q->queue[i];
359                 struct diff_filepair *pair_to_free = NULL;
360
361                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
362                         /*
363                          * Creation
364                          *
365                          * We would output this create record if it has
366                          * not been turned into a rename/copy already.
367                          */
368                         struct diff_rename_dst *dst =
369                                 locate_rename_dst(p->two, 0);
370                         if (dst && dst->pair) {
371                                 diff_q(&outq, dst->pair);
372                                 pair_to_free = p;
373                         }
374                         else
375                                 /* no matching rename/copy source, so
376                                  * record this as a creation.
377                                  */
378                                 diff_q(&outq, p);
379                 }
380                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
381                         /*
382                          * Deletion
383                          *
384                          * We would output this delete record if:
385                          *
386                          * (1) this is a broken delete and the counterpart
387                          *     broken create remains in the output; or
388                          * (2) this is not a broken delete, and rename_dst
389                          *     does not have a rename/copy to move p->one->path
390                          *     out of existence.
391                          *
392                          * Otherwise, the counterpart broken create
393                          * has been turned into a rename-edit; or
394                          * delete did not have a matching create to
395                          * begin with.
396                          */
397                         if (DIFF_PAIR_BROKEN(p)) {
398                                 /* broken delete */
399                                 struct diff_rename_dst *dst =
400                                         locate_rename_dst(p->one, 0);
401                                 if (dst && dst->pair)
402                                         /* counterpart is now rename/copy */
403                                         pair_to_free = p;
404                         }
405                         else {
406                                 for (j = 0; j < rename_dst_nr; j++) {
407                                         if (!rename_dst[j].pair)
408                                                 continue;
409                                         if (strcmp(rename_dst[j].pair->
410                                                    one->path,
411                                                    p->one->path))
412                                                 continue;
413                                         break;
414                                 }
415                                 if (j < rename_dst_nr)
416                                         /* this path remains */
417                                         pair_to_free = p;
418                         }
419
420                         if (pair_to_free)
421                                 ;
422                         else
423                                 diff_q(&outq, p);
424                 }
425                 else if (!diff_unmodified_pair(p))
426                         /* all the usual ones need to be kept */
427                         diff_q(&outq, p);
428                 else
429                         /* no need to keep unmodified pairs */
430                         pair_to_free = p;
431
432                 if (pair_to_free)
433                         diff_free_filepair(pair_to_free);
434         }
435         diff_debug_queue("done copying original", &outq);
436
437         free(q->queue);
438         *q = outq;
439         diff_debug_queue("done collapsing", q);
440
441         /* We need to see which rename source really stays here;
442          * earlier we only checked if the path is left in the result,
443          * but even if a path remains in the result, if that is coming
444          * from copying something else on top of it, then the original
445          * source is lost and does not stay.
446          */
447         for (i = 0; i < q->nr; i++) {
448                 struct diff_filepair *p = q->queue[i];
449                 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
450                         /* If one appears as the target of a rename-copy,
451                          * then mark p->source_stays = 0; otherwise
452                          * leave it as is.
453                          */
454                         p->source_stays = compute_stays(q, p->one);
455                 }
456         }
457
458         for (i = 0; i < rename_dst_nr; i++) {
459                 diff_free_filespec_data(rename_dst[i].two);
460                 free(rename_dst[i].two);
461         }
462
463         free(rename_dst);
464         rename_dst = NULL;
465         rename_dst_nr = rename_dst_alloc = 0;
466         free(rename_src);
467         rename_src = NULL;
468         rename_src_nr = rename_src_alloc = 0;
469         return;
470 }