Merge branch 'fk/blame' into next
[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 src_path_left : 1;
58 } *rename_src;
59 static int rename_src_nr, rename_src_alloc;
60
61 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
62                                                    int src_path_left)
63 {
64         int first, last;
65
66         first = 0;
67         last = rename_src_nr;
68         while (last > first) {
69                 int next = (last + first) >> 1;
70                 struct diff_rename_src *src = &(rename_src[next]);
71                 int cmp = strcmp(one->path, src->one->path);
72                 if (!cmp)
73                         return src;
74                 if (cmp < 0) {
75                         last = next;
76                         continue;
77                 }
78                 first = next+1;
79         }
80
81         /* insert to make it at "first" */
82         if (rename_src_alloc <= rename_src_nr) {
83                 rename_src_alloc = alloc_nr(rename_src_alloc);
84                 rename_src = xrealloc(rename_src,
85                                       rename_src_alloc * sizeof(*rename_src));
86         }
87         rename_src_nr++;
88         if (first < rename_src_nr)
89                 memmove(rename_src + first + 1, rename_src + first,
90                         (rename_src_nr - first - 1) * sizeof(*rename_src));
91         rename_src[first].one = one;
92         rename_src[first].src_path_left = src_path_left;
93         return &(rename_src[first]);
94 }
95
96 static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
97 {
98         if (src->sha1_valid && dst->sha1_valid &&
99             !memcmp(src->sha1, dst->sha1, 20))
100                 return 1;
101         if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
102                 return 0;
103         if (src->size != dst->size)
104                 return 0;
105         if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
106                 return 0;
107         if (src->size == dst->size &&
108             !memcmp(src->data, dst->data, src->size))
109                 return 1;
110         return 0;
111 }
112
113 struct diff_score {
114         int src; /* index in rename_src */
115         int dst; /* index in rename_dst */
116         int score;
117 };
118
119 static int estimate_similarity(struct diff_filespec *src,
120                                struct diff_filespec *dst,
121                                int minimum_score)
122 {
123         /* src points at a file that existed in the original tree (or
124          * optionally a file in the destination tree) and dst points
125          * at a newly created file.  They may be quite similar, in which
126          * case we want to say src is renamed to dst or src is copied into
127          * dst, and then some edit has been applied to dst.
128          *
129          * Compare them and return how similar they are, representing
130          * the score as an integer between 0 and MAX_SCORE.
131          *
132          * When there is an exact match, it is considered a better
133          * match than anything else; the destination does not even
134          * call into this function in that case.
135          */
136         unsigned long delta_size, base_size, src_copied, literal_added;
137         unsigned long delta_limit;
138         int score;
139
140         /* We deal only with regular files.  Symlink renames are handled
141          * only when they are exact matches --- in other words, no edits
142          * after renaming.
143          */
144         if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
145                 return 0;
146
147         delta_size = ((src->size < dst->size) ?
148                       (dst->size - src->size) : (src->size - dst->size));
149         base_size = ((src->size < dst->size) ? src->size : dst->size);
150
151         /* We would not consider edits that change the file size so
152          * drastically.  delta_size must be smaller than
153          * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
154          *
155          * Note that base_size == 0 case is handled here already
156          * and the final score computation below would not have a
157          * divide-by-zero issue.
158          */
159         if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
160                 return 0;
161
162         if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
163                 return 0; /* error but caught downstream */
164
165
166         delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
167         if (diffcore_count_changes(src->data, src->size,
168                                    dst->data, dst->size,
169                                    delta_limit,
170                                    &src_copied, &literal_added))
171                 return 0;
172
173         /* How similar are they?
174          * what percentage of material in dst are from source?
175          */
176         if (dst->size < src_copied)
177                 score = MAX_SCORE;
178         else if (!dst->size)
179                 score = 0; /* should not happen */
180         else
181                 score = src_copied * MAX_SCORE / dst->size;
182         return score;
183 }
184
185 static void record_rename_pair(int dst_index, int src_index, int score)
186 {
187         struct diff_filespec *one, *two, *src, *dst;
188         struct diff_filepair *dp;
189
190         if (rename_dst[dst_index].pair)
191                 die("internal error: dst already matched.");
192
193         src = rename_src[src_index].one;
194         one = alloc_filespec(src->path);
195         fill_filespec(one, src->sha1, src->mode);
196
197         dst = rename_dst[dst_index].two;
198         two = alloc_filespec(dst->path);
199         fill_filespec(two, dst->sha1, dst->mode);
200
201         dp = diff_queue(NULL, one, two);
202         dp->score = score;
203         dp->source_stays = rename_src[src_index].src_path_left;
204         rename_dst[dst_index].pair = dp;
205 }
206
207 /*
208  * We sort the rename similarity matrix with the score, in descending
209  * order (the most similar first).
210  */
211 static int score_compare(const void *a_, const void *b_)
212 {
213         const struct diff_score *a = a_, *b = b_;
214         return b->score - a->score;
215 }
216
217 static int compute_stays(struct diff_queue_struct *q,
218                          struct diff_filespec *one)
219 {
220         int i;
221         for (i = 0; i < q->nr; i++) {
222                 struct diff_filepair *p = q->queue[i];
223                 if (strcmp(one->path, p->two->path))
224                         continue;
225                 if (DIFF_PAIR_RENAME(p)) {
226                         return 0; /* something else is renamed into this */
227                 }
228         }
229         return 1;
230 }
231
232 void diffcore_rename(struct diff_options *options)
233 {
234         int detect_rename = options->detect_rename;
235         int minimum_score = options->rename_score;
236         int rename_limit = options->rename_limit;
237         struct diff_queue_struct *q = &diff_queued_diff;
238         struct diff_queue_struct outq;
239         struct diff_score *mx;
240         int i, j, rename_count;
241         int num_create, num_src, dst_cnt;
242
243         if (!minimum_score)
244                 minimum_score = DEFAULT_RENAME_SCORE;
245         rename_count = 0;
246
247         for (i = 0; i < q->nr; i++) {
248                 struct diff_filepair *p = q->queue[i];
249                 if (!DIFF_FILE_VALID(p->one))
250                         if (!DIFF_FILE_VALID(p->two))
251                                 continue; /* unmerged */
252                         else
253                                 locate_rename_dst(p->two, 1);
254                 else if (!DIFF_FILE_VALID(p->two)) {
255                         /* If the source is a broken "delete", and
256                          * they did not really want to get broken,
257                          * that means the source actually stays.
258                          */
259                         int stays = (p->broken_pair && !p->score);
260                         register_rename_src(p->one, stays);
261                 }
262                 else if (detect_rename == DIFF_DETECT_COPY)
263                         register_rename_src(p->one, 1);
264         }
265         if (rename_dst_nr == 0 || rename_src_nr == 0 ||
266             (0 < rename_limit && rename_limit < rename_dst_nr))
267                 goto cleanup; /* nothing to do */
268
269         /* We really want to cull the candidates list early
270          * with cheap tests in order to avoid doing deltas.
271          */
272         for (i = 0; i < rename_dst_nr; i++) {
273                 struct diff_filespec *two = rename_dst[i].two;
274                 for (j = 0; j < rename_src_nr; j++) {
275                         struct diff_filespec *one = rename_src[j].one;
276                         if (!is_exact_match(one, two))
277                                 continue;
278                         record_rename_pair(i, j, MAX_SCORE);
279                         rename_count++;
280                         break; /* we are done with this entry */
281                 }
282         }
283
284         /* Have we run out the created file pool?  If so we can avoid
285          * doing the delta matrix altogether.
286          */
287         if (rename_count == rename_dst_nr)
288                 goto cleanup;
289
290         if (minimum_score == MAX_SCORE)
291                 goto cleanup;
292
293         num_create = (rename_dst_nr - rename_count);
294         num_src = rename_src_nr;
295         mx = xmalloc(sizeof(*mx) * num_create * num_src);
296         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
297                 int base = dst_cnt * num_src;
298                 struct diff_filespec *two = rename_dst[i].two;
299                 if (rename_dst[i].pair)
300                         continue; /* dealt with exact match already. */
301                 for (j = 0; j < rename_src_nr; j++) {
302                         struct diff_filespec *one = rename_src[j].one;
303                         struct diff_score *m = &mx[base+j];
304                         m->src = j;
305                         m->dst = i;
306                         m->score = estimate_similarity(one, two,
307                                                        minimum_score);
308                 }
309                 dst_cnt++;
310         }
311         /* cost matrix sorted by most to least similar pair */
312         qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
313         for (i = 0; i < num_create * num_src; i++) {
314                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
315                 if (dst->pair)
316                         continue; /* already done, either exact or fuzzy. */
317                 if (mx[i].score < minimum_score)
318                         break; /* there is no more usable pair. */
319                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
320                 rename_count++;
321         }
322         free(mx);
323
324  cleanup:
325         /* At this point, we have found some renames and copies and they
326          * are recorded in rename_dst.  The original list is still in *q.
327          */
328         outq.queue = NULL;
329         outq.nr = outq.alloc = 0;
330         for (i = 0; i < q->nr; i++) {
331                 struct diff_filepair *p = q->queue[i];
332                 struct diff_filepair *pair_to_free = NULL;
333
334                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
335                         /*
336                          * Creation
337                          *
338                          * We would output this create record if it has
339                          * not been turned into a rename/copy already.
340                          */
341                         struct diff_rename_dst *dst =
342                                 locate_rename_dst(p->two, 0);
343                         if (dst && dst->pair) {
344                                 diff_q(&outq, dst->pair);
345                                 pair_to_free = p;
346                         }
347                         else
348                                 /* no matching rename/copy source, so
349                                  * record this as a creation.
350                                  */
351                                 diff_q(&outq, p);
352                 }
353                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
354                         /*
355                          * Deletion
356                          *
357                          * We would output this delete record if:
358                          *
359                          * (1) this is a broken delete and the counterpart
360                          *     broken create remains in the output; or
361                          * (2) this is not a broken delete, and rename_dst
362                          *     does not have a rename/copy to move p->one->path
363                          *     out of existence.
364                          *
365                          * Otherwise, the counterpart broken create
366                          * has been turned into a rename-edit; or
367                          * delete did not have a matching create to
368                          * begin with.
369                          */
370                         if (DIFF_PAIR_BROKEN(p)) {
371                                 /* broken delete */
372                                 struct diff_rename_dst *dst =
373                                         locate_rename_dst(p->one, 0);
374                                 if (dst && dst->pair)
375                                         /* counterpart is now rename/copy */
376                                         pair_to_free = p;
377                         }
378                         else {
379                                 for (j = 0; j < rename_dst_nr; j++) {
380                                         if (!rename_dst[j].pair)
381                                                 continue;
382                                         if (strcmp(rename_dst[j].pair->
383                                                    one->path,
384                                                    p->one->path))
385                                                 continue;
386                                         break;
387                                 }
388                                 if (j < rename_dst_nr)
389                                         /* this path remains */
390                                         pair_to_free = p;
391                         }
392
393                         if (pair_to_free)
394                                 ;
395                         else
396                                 diff_q(&outq, p);
397                 }
398                 else if (!diff_unmodified_pair(p))
399                         /* all the usual ones need to be kept */
400                         diff_q(&outq, p);
401                 else
402                         /* no need to keep unmodified pairs */
403                         pair_to_free = p;
404
405                 if (pair_to_free)
406                         diff_free_filepair(pair_to_free);
407         }
408         diff_debug_queue("done copying original", &outq);
409
410         free(q->queue);
411         *q = outq;
412         diff_debug_queue("done collapsing", q);
413
414         /* We need to see which rename source really stays here;
415          * earlier we only checked if the path is left in the result,
416          * but even if a path remains in the result, if that is coming
417          * from copying something else on top of it, then the original
418          * source is lost and does not stay.
419          */
420         for (i = 0; i < q->nr; i++) {
421                 struct diff_filepair *p = q->queue[i];
422                 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
423                         /* If one appears as the target of a rename-copy,
424                          * then mark p->source_stays = 0; otherwise
425                          * leave it as is.
426                          */
427                         p->source_stays = compute_stays(q, p->one);
428                 }
429         }
430
431         for (i = 0; i < rename_dst_nr; i++) {
432                 diff_free_filespec_data(rename_dst[i].two);
433                 free(rename_dst[i].two);
434         }
435
436         free(rename_dst);
437         rename_dst = NULL;
438         rename_dst_nr = rename_dst_alloc = 0;
439         free(rename_src);
440         rename_src = NULL;
441         rename_src_nr = rename_src_alloc = 0;
442         return;
443 }