Fix longstanding mismerge of ALL_CFLAGS vs BASIC_CFLAGS
[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 = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
176         if (diffcore_count_changes(src->data, src->size,
177                                    dst->data, dst->size,
178                                    &src->cnt_data, &dst->cnt_data,
179                                    delta_limit,
180                                    &src_copied, &literal_added))
181                 return 0;
182
183         /* How similar are they?
184          * what percentage of material in dst are from source?
185          */
186         if (!dst->size)
187                 score = 0; /* should not happen */
188         else
189                 score = src_copied * MAX_SCORE / max_size;
190         return score;
191 }
192
193 static void record_rename_pair(int dst_index, int src_index, int score)
194 {
195         struct diff_filespec *one, *two, *src, *dst;
196         struct diff_filepair *dp;
197
198         if (rename_dst[dst_index].pair)
199                 die("internal error: dst already matched.");
200
201         src = rename_src[src_index].one;
202         one = alloc_filespec(src->path);
203         fill_filespec(one, src->sha1, src->mode);
204
205         dst = rename_dst[dst_index].two;
206         two = alloc_filespec(dst->path);
207         fill_filespec(two, dst->sha1, dst->mode);
208
209         dp = diff_queue(NULL, one, two);
210         dp->renamed_pair = 1;
211         if (!strcmp(src->path, dst->path))
212                 dp->score = rename_src[src_index].score;
213         else
214                 dp->score = score;
215         dp->source_stays = rename_src[src_index].src_path_left;
216         rename_dst[dst_index].pair = dp;
217 }
218
219 /*
220  * We sort the rename similarity matrix with the score, in descending
221  * order (the most similar first).
222  */
223 static int score_compare(const void *a_, const void *b_)
224 {
225         const struct diff_score *a = a_, *b = b_;
226         return b->score - a->score;
227 }
228
229 static int compute_stays(struct diff_queue_struct *q,
230                          struct diff_filespec *one)
231 {
232         int i;
233         for (i = 0; i < q->nr; i++) {
234                 struct diff_filepair *p = q->queue[i];
235                 if (strcmp(one->path, p->two->path))
236                         continue;
237                 if (DIFF_PAIR_RENAME(p)) {
238                         return 0; /* something else is renamed into this */
239                 }
240         }
241         return 1;
242 }
243
244 void diffcore_rename(struct diff_options *options)
245 {
246         int detect_rename = options->detect_rename;
247         int minimum_score = options->rename_score;
248         int rename_limit = options->rename_limit;
249         struct diff_queue_struct *q = &diff_queued_diff;
250         struct diff_queue_struct outq;
251         struct diff_score *mx;
252         int i, j, rename_count, contents_too;
253         int num_create, num_src, dst_cnt;
254
255         if (!minimum_score)
256                 minimum_score = DEFAULT_RENAME_SCORE;
257         rename_count = 0;
258
259         for (i = 0; i < q->nr; i++) {
260                 struct diff_filepair *p = q->queue[i];
261                 if (!DIFF_FILE_VALID(p->one)) {
262                         if (!DIFF_FILE_VALID(p->two))
263                                 continue; /* unmerged */
264                         else if (options->single_follow &&
265                                  strcmp(options->single_follow, p->two->path))
266                                 continue; /* not interested */
267                         else
268                                 locate_rename_dst(p->two, 1);
269                 }
270                 else if (!DIFF_FILE_VALID(p->two)) {
271                         /* If the source is a broken "delete", and
272                          * they did not really want to get broken,
273                          * that means the source actually stays.
274                          */
275                         int stays = (p->broken_pair && !p->score);
276                         register_rename_src(p->one, stays, p->score);
277                 }
278                 else if (detect_rename == DIFF_DETECT_COPY)
279                         register_rename_src(p->one, 1, p->score);
280         }
281         if (rename_dst_nr == 0 || rename_src_nr == 0 ||
282             (0 < rename_limit && rename_limit < rename_dst_nr))
283                 goto cleanup; /* nothing to do */
284
285         /* We really want to cull the candidates list early
286          * with cheap tests in order to avoid doing deltas.
287          * The first round matches up the up-to-date entries,
288          * and then during the second round we try to match
289          * cache-dirty entries as well.
290          */
291         for (contents_too = 0; contents_too < 2; contents_too++) {
292                 for (i = 0; i < rename_dst_nr; i++) {
293                         struct diff_filespec *two = rename_dst[i].two;
294                         if (rename_dst[i].pair)
295                                 continue; /* dealt with an earlier round */
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, contents_too))
299                                         continue;
300                                 record_rename_pair(i, j, MAX_SCORE);
301                                 rename_count++;
302                                 break; /* we are done with this entry */
303                         }
304                 }
305         }
306
307         /* Have we run out the created file pool?  If so we can avoid
308          * doing the delta matrix altogether.
309          */
310         if (rename_count == rename_dst_nr)
311                 goto cleanup;
312
313         if (minimum_score == MAX_SCORE)
314                 goto cleanup;
315
316         num_create = (rename_dst_nr - rename_count);
317         num_src = rename_src_nr;
318         mx = xmalloc(sizeof(*mx) * num_create * num_src);
319         for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
320                 int base = dst_cnt * num_src;
321                 struct diff_filespec *two = rename_dst[i].two;
322                 if (rename_dst[i].pair)
323                         continue; /* dealt with exact match already. */
324                 for (j = 0; j < rename_src_nr; j++) {
325                         struct diff_filespec *one = rename_src[j].one;
326                         struct diff_score *m = &mx[base+j];
327                         m->src = j;
328                         m->dst = i;
329                         m->score = estimate_similarity(one, two,
330                                                        minimum_score);
331                 }
332                 /* We do not need the text anymore */
333                 diff_free_filespec_data(two);
334                 dst_cnt++;
335         }
336         /* cost matrix sorted by most to least similar pair */
337         qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
338         for (i = 0; i < num_create * num_src; i++) {
339                 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
340                 if (dst->pair)
341                         continue; /* already done, either exact or fuzzy. */
342                 if (mx[i].score < minimum_score)
343                         break; /* there is no more usable pair. */
344                 record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
345                 rename_count++;
346         }
347         free(mx);
348
349  cleanup:
350         /* At this point, we have found some renames and copies and they
351          * are recorded in rename_dst.  The original list is still in *q.
352          */
353         outq.queue = NULL;
354         outq.nr = outq.alloc = 0;
355         for (i = 0; i < q->nr; i++) {
356                 struct diff_filepair *p = q->queue[i];
357                 struct diff_filepair *pair_to_free = NULL;
358
359                 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
360                         /*
361                          * Creation
362                          *
363                          * We would output this create record if it has
364                          * not been turned into a rename/copy already.
365                          */
366                         struct diff_rename_dst *dst =
367                                 locate_rename_dst(p->two, 0);
368                         if (dst && dst->pair) {
369                                 diff_q(&outq, dst->pair);
370                                 pair_to_free = p;
371                         }
372                         else
373                                 /* no matching rename/copy source, so
374                                  * record this as a creation.
375                                  */
376                                 diff_q(&outq, p);
377                 }
378                 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
379                         /*
380                          * Deletion
381                          *
382                          * We would output this delete record if:
383                          *
384                          * (1) this is a broken delete and the counterpart
385                          *     broken create remains in the output; or
386                          * (2) this is not a broken delete, and rename_dst
387                          *     does not have a rename/copy to move p->one->path
388                          *     out of existence.
389                          *
390                          * Otherwise, the counterpart broken create
391                          * has been turned into a rename-edit; or
392                          * delete did not have a matching create to
393                          * begin with.
394                          */
395                         if (DIFF_PAIR_BROKEN(p)) {
396                                 /* broken delete */
397                                 struct diff_rename_dst *dst =
398                                         locate_rename_dst(p->one, 0);
399                                 if (dst && dst->pair)
400                                         /* counterpart is now rename/copy */
401                                         pair_to_free = p;
402                         }
403                         else {
404                                 for (j = 0; j < rename_dst_nr; j++) {
405                                         if (!rename_dst[j].pair)
406                                                 continue;
407                                         if (strcmp(rename_dst[j].pair->
408                                                    one->path,
409                                                    p->one->path))
410                                                 continue;
411                                         break;
412                                 }
413                                 if (j < rename_dst_nr)
414                                         /* this path remains */
415                                         pair_to_free = p;
416                         }
417
418                         if (pair_to_free)
419                                 ;
420                         else
421                                 diff_q(&outq, p);
422                 }
423                 else if (!diff_unmodified_pair(p))
424                         /* all the usual ones need to be kept */
425                         diff_q(&outq, p);
426                 else
427                         /* no need to keep unmodified pairs */
428                         pair_to_free = p;
429
430                 if (pair_to_free)
431                         diff_free_filepair(pair_to_free);
432         }
433         diff_debug_queue("done copying original", &outq);
434
435         free(q->queue);
436         *q = outq;
437         diff_debug_queue("done collapsing", q);
438
439         /* We need to see which rename source really stays here;
440          * earlier we only checked if the path is left in the result,
441          * but even if a path remains in the result, if that is coming
442          * from copying something else on top of it, then the original
443          * source is lost and does not stay.
444          */
445         for (i = 0; i < q->nr; i++) {
446                 struct diff_filepair *p = q->queue[i];
447                 if (DIFF_PAIR_RENAME(p) && p->source_stays) {
448                         /* If one appears as the target of a rename-copy,
449                          * then mark p->source_stays = 0; otherwise
450                          * leave it as is.
451                          */
452                         p->source_stays = compute_stays(q, p->one);
453                 }
454         }
455
456         for (i = 0; i < rename_dst_nr; i++) {
457                 diff_free_filespec_data(rename_dst[i].two);
458                 free(rename_dst[i].two);
459         }
460
461         free(rename_dst);
462         rename_dst = NULL;
463         rename_dst_nr = rename_dst_alloc = 0;
464         free(rename_src);
465         rename_src = NULL;
466         rename_src_nr = rename_src_alloc = 0;
467         return;
468 }