Code

git-fetch: print the new and old ref when fast-forwarding
[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"
10 /* Table of rename/copy destinations */
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;
18 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
19                                                  int insert_ok)
20 {
21         int first, last;
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 }
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;
63 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
64                                                    int src_path_left)
65 {
66         int first, last;
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         }
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 }
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;
115 struct diff_score {
116         int src; /* index in rename_src */
117         int dst; /* index in rename_dst */
118         int score;
119 };
121 static int estimate_similarity(struct diff_filespec *src,
122                                struct diff_filespec *dst,
123                                int minimum_score)
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;
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;
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).
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;
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);
172         if (!delta)
173                 /* If delta_limit is exceeded, we have too much differences */
174                 return 0;
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                 free(delta);
181                 return 0;
182         }
184         /* Estimate the edit size by interpreting delta. */
185         if (count_delta(delta, delta_size, &src_copied, &literal_added)) {
186                 free(delta);
187                 return 0;
188         }
189         free(delta);
191         /* Extent of damage */
192         if (src->size + literal_added < src_copied)
193                 delta_size = 0;
194         else
195                 delta_size = (src->size - src_copied) + literal_added;
197         /*
198          * Now we will give some score to it.  100% edit gets 0 points
199          * and 0% edit gets MAX_SCORE points.
200          */
201         score = MAX_SCORE - (MAX_SCORE * delta_size / base_size); 
202         if (score < 0) return 0;
203         if (MAX_SCORE < score) return MAX_SCORE;
204         return score;
207 static void record_rename_pair(int dst_index, int src_index, int score)
209         struct diff_filespec *one, *two, *src, *dst;
210         struct diff_filepair *dp;
212         if (rename_dst[dst_index].pair)
213                 die("internal error: dst already matched.");
215         src = rename_src[src_index].one;
216         one = alloc_filespec(src->path);
217         fill_filespec(one, src->sha1, src->mode);
219         dst = rename_dst[dst_index].two;
220         two = alloc_filespec(dst->path);
221         fill_filespec(two, dst->sha1, dst->mode);
223         dp = diff_queue(NULL, one, two);
224         dp->score = score;
225         dp->source_stays = rename_src[src_index].src_path_left;
226         rename_dst[dst_index].pair = dp;
229 /*
230  * We sort the rename similarity matrix with the score, in descending
231  * order (the most similar first).
232  */
233 static int score_compare(const void *a_, const void *b_)
235         const struct diff_score *a = a_, *b = b_;
236         return b->score - a->score;
239 static int compute_stays(struct diff_queue_struct *q,
240                          struct diff_filespec *one)
242         int i;
243         for (i = 0; i < q->nr; i++) {
244                 struct diff_filepair *p = q->queue[i];
245                 if (strcmp(one->path, p->two->path))
246                         continue;
247                 if (DIFF_PAIR_RENAME(p)) {
248                         return 0; /* something else is renamed into this */
249                 }
250         }
251         return 1;
254 void diffcore_rename(struct diff_options *options)
256         int detect_rename = options->detect_rename;
257         int minimum_score = options->rename_score;
258         int rename_limit = options->rename_limit;
259         struct diff_queue_struct *q = &diff_queued_diff;
260         struct diff_queue_struct outq;
261         struct diff_score *mx;
262         int i, j, rename_count;
263         int num_create, num_src, dst_cnt;
265         if (!minimum_score)
266                 minimum_score = DEFAULT_RENAME_SCORE;
267         rename_count = 0;
269         for (i = 0; i < q->nr; i++) {
270                 struct diff_filepair *p = q->queue[i];
271                 if (!DIFF_FILE_VALID(p->one))
272                         if (!DIFF_FILE_VALID(p->two))
273                                 continue; /* unmerged */
274                         else
275                                 locate_rename_dst(p->two, 1);
276                 else if (!DIFF_FILE_VALID(p->two)) {
277                         /* If the source is a broken "delete", and
278                          * they did not really want to get broken,
279                          * that means the source actually stays.
280                          */
281                         int stays = (p->broken_pair && !p->score);
282                         register_rename_src(p->one, stays);
283                 }
284                 else if (detect_rename == DIFF_DETECT_COPY)
285                         register_rename_src(p->one, 1);
286         }
287         if (rename_dst_nr == 0 || rename_src_nr == 0 ||
288             (0 < rename_limit && rename_limit < rename_dst_nr))
289                 goto cleanup; /* nothing to do */
291         /* We really want to cull the candidates list early
292          * with cheap tests in order to avoid doing deltas.
293          */
294         for (i = 0; i < rename_dst_nr; i++) {
295                 struct diff_filespec *two = rename_dst[i].two;
296                 for (j = 0; j < rename_src_nr; j++) {
297                         struct diff_filespec *one = rename_src[j].one;
298                         if (!is_exact_match(one, two))
299                                 continue;
300                         record_rename_pair(i, j, MAX_SCORE);
301                         rename_count++;
302                         break; /* we are done with this entry */
303                 }
304         }
306         /* Have we run out the created file pool?  If so we can avoid
307          * doing the delta matrix altogether.
308          */
309         if (rename_count == rename_dst_nr)
310                 goto cleanup;
312         if (minimum_score == MAX_SCORE)
313                 goto cleanup;
315         num_create = (rename_dst_nr - rename_count);
316         num_src = rename_src_nr;
317         mx = xmalloc(sizeof(*mx) * num_create * num_src);
318         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
319                 int base = dst_cnt * num_src;
320                 struct diff_filespec *two = rename_dst[i].two;
321                 if (rename_dst[i].pair)
322                         continue; /* dealt with exact match already. */
323                 for (j = 0; j < rename_src_nr; j++) {
324                         struct diff_filespec *one = rename_src[j].one;
325                         struct diff_score *m = &mx[base+j];
326                         m->src = j;
327                         m->dst = i;
328                         m->score = estimate_similarity(one, two,
329                                                        minimum_score);
330                 }
331                 dst_cnt++;
332         }
333         /* cost matrix sorted by most to least similar pair */
334         qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
335         for (i = 0; i < num_create * num_src; i++) {
336                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
337                 if (dst->pair)
338                         continue; /* already done, either exact or fuzzy. */
339                 if (mx[i].score < minimum_score)
340                         break; /* there is no more usable pair. */
341                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
342                 rename_count++;
343         }
344         free(mx);
346  cleanup:
347         /* At this point, we have found some renames and copies and they
348          * are recorded in rename_dst.  The original list is still in *q.
349          */
350         outq.queue = NULL;
351         outq.nr = outq.alloc = 0;
352         for (i = 0; i < q->nr; i++) {
353                 struct diff_filepair *p = q->queue[i];
354                 struct diff_filepair *pair_to_free = NULL;
356                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
357                         /*
358                          * Creation
359                          *
360                          * We would output this create record if it has
361                          * not been turned into a rename/copy already.
362                          */
363                         struct diff_rename_dst *dst =
364                                 locate_rename_dst(p->two, 0);
365                         if (dst && dst->pair) {
366                                 diff_q(&outq, dst->pair);
367                                 pair_to_free = p;
368                         }
369                         else
370                                 /* no matching rename/copy source, so
371                                  * record this as a creation.
372                                  */
373                                 diff_q(&outq, p);
374                 }
375                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
376                         /*
377                          * Deletion
378                          *
379                          * We would output this delete record if:
380                          *
381                          * (1) this is a broken delete and the counterpart
382                          *     broken create remains in the output; or
383                          * (2) this is not a broken delete, and rename_dst
384                          *     does not have a rename/copy to move p->one->path
385                          *     out of existence.
386                          *
387                          * Otherwise, the counterpart broken create
388                          * has been turned into a rename-edit; or
389                          * delete did not have a matching create to
390                          * begin with.
391                          */
392                         if (DIFF_PAIR_BROKEN(p)) {
393                                 /* broken delete */
394                                 struct diff_rename_dst *dst =
395                                         locate_rename_dst(p->one, 0);
396                                 if (dst && dst->pair)
397                                         /* counterpart is now rename/copy */
398                                         pair_to_free = p;
399                         }
400                         else {
401                                 for (j = 0; j < rename_dst_nr; j++) {
402                                         if (!rename_dst[j].pair)
403                                                 continue;
404                                         if (strcmp(rename_dst[j].pair->
405                                                    one->path,
406                                                    p->one->path))
407                                                 continue;
408                                         break;
409                                 }
410                                 if (j < rename_dst_nr)
411                                         /* this path remains */
412                                         pair_to_free = p;
413                         }
415                         if (pair_to_free)
416                                 ;
417                         else
418                                 diff_q(&outq, p);
419                 }
420                 else if (!diff_unmodified_pair(p))
421                         /* all the usual ones need to be kept */
422                         diff_q(&outq, p);
423                 else
424                         /* no need to keep unmodified pairs */
425                         pair_to_free = p;
427                 if (pair_to_free)
428                         diff_free_filepair(pair_to_free);
429         }
430         diff_debug_queue("done copying original", &outq);
432         free(q->queue);
433         *q = outq;
434         diff_debug_queue("done collapsing", q);
436         /* We need to see which rename source really stays here;
437          * earlier we only checked if the path is left in the result,
438          * but even if a path remains in the result, if that is coming
439          * from copying something else on top of it, then the original
440          * source is lost and does not stay.
441          */
442         for (i = 0; i < q->nr; i++) {
443                 struct diff_filepair *p = q->queue[i];
444                 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
445                         /* If one appears as the target of a rename-copy,
446                          * then mark p->source_stays = 0; otherwise
447                          * leave it as is.
448                          */
449                         p->source_stays = compute_stays(q, p->one);
450                 }
451         }
453         for (i = 0; i < rename_dst_nr; i++) {
454                 diff_free_filespec_data(rename_dst[i].two);
455                 free(rename_dst[i].two);
456         }
458         free(rename_dst);
459         rename_dst = NULL;
460         rename_dst_nr = rename_dst_alloc = 0;
461         free(rename_src);
462         rename_src = NULL;
463         rename_src_nr = rename_src_alloc = 0;
464         return;