user-manual: update references discussion
[git/mingw.git] / diffcore-rename.c
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1 /*
2 * Copyright (C) 2005 Junio C Hamano
3 */
4 #include "cache.h"
5 #include "diff.h"
6 #include "diffcore.h"
8 /* Table of rename/copy destinations */
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;
16 static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
17 int insert_ok)
19 int first, last;
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;
33 first = next+1;
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));
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]);
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;
62 static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63 int src_path_left,
64 unsigned short score)
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;
80 first = next+1;
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));
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]);
99 static int is_exact_match(struct diff_filespec *src,
100 struct diff_filespec *dst,
101 int contents_too)
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;
122 struct diff_score {
123 int src; /* index in rename_src */
124 int dst; /* index in rename_dst */
125 int score;
128 static int estimate_similarity(struct diff_filespec *src,
129 struct diff_filespec *dst,
130 int minimum_score)
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.
138 * Compare them and return how similar they are, representing
139 * the score as an integer between 0 and MAX_SCORE.
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.
145 unsigned long max_size, delta_size, base_size, src_copied, literal_added;
146 unsigned long delta_limit;
147 int score;
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.
153 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
154 return 0;
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;
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).
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.
168 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
169 return 0;
171 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
172 return 0; /* error but caught downstream */
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;
183 /* How similar are they?
184 * what percentage of material in dst are from source?
186 if (!dst->size)
187 score = 0; /* should not happen */
188 else
189 score = src_copied * MAX_SCORE / max_size;
190 return score;
193 static void record_rename_pair(int dst_index, int src_index, int score)
195 struct diff_filespec *one, *two, *src, *dst;
196 struct diff_filepair *dp;
198 if (rename_dst[dst_index].pair)
199 die("internal error: dst already matched.");
201 src = rename_src[src_index].one;
202 one = alloc_filespec(src->path);
203 fill_filespec(one, src->sha1, src->mode);
205 dst = rename_dst[dst_index].two;
206 two = alloc_filespec(dst->path);
207 fill_filespec(two, dst->sha1, dst->mode);
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;
220 * We sort the rename similarity matrix with the score, in descending
221 * order (the most similar first).
223 static int score_compare(const void *a_, const void *b_)
225 const struct diff_score *a = a_, *b = b_;
226 return b->score - a->score;
229 static int compute_stays(struct diff_queue_struct *q,
230 struct diff_filespec *one)
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 */
241 return 1;
244 void diffcore_rename(struct diff_options *options)
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;
255 if (!minimum_score)
256 minimum_score = DEFAULT_RENAME_SCORE;
257 rename_count = 0;
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);
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.
275 int stays = (p->broken_pair && !p->score);
276 register_rename_src(p->one, stays, p->score);
278 else if (detect_rename == DIFF_DETECT_COPY)
279 register_rename_src(p->one, 1, p->score);
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 */
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.
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 */
307 /* Have we run out the created file pool? If so we can avoid
308 * doing the delta matrix altogether.
310 if (rename_count == rename_dst_nr)
311 goto cleanup;
313 if (minimum_score == MAX_SCORE)
314 goto cleanup;
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);
332 /* We do not need the text anymore */
333 diff_free_filespec_data(two);
334 dst_cnt++;
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++;
347 free(mx);
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.
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;
359 if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
361 * Creation
363 * We would output this create record if it has
364 * not been turned into a rename/copy already.
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;
372 else
373 /* no matching rename/copy source, so
374 * record this as a creation.
376 diff_q(&outq, p);
378 else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
380 * Deletion
382 * We would output this delete record if:
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.
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.
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;
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;
413 if (j < rename_dst_nr)
414 /* this path remains */
415 pair_to_free = p;
418 if (pair_to_free)
420 else
421 diff_q(&outq, p);
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;
430 if (pair_to_free)
431 diff_free_filepair(pair_to_free);
433 diff_debug_queue("done copying original", &outq);
435 free(q->queue);
436 *q = outq;
437 diff_debug_queue("done collapsing", q);
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.
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.
452 p->source_stays = compute_stays(q, p->one);
456 for (i = 0; i < rename_dst_nr; i++) {
457 diff_free_filespec_data(rename_dst[i].two);
458 free(rename_dst[i].two);
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;