diff-tree: don't print multiple headers for merges when silent.
[git/git.git] / diffcore-rename.c
CommitLineData
427dcb4b
JH
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
9struct diff_rename_pool {
10 struct diff_filespec **s;
11 int nr, alloc;
12};
13
14static void diff_rename_pool_clear(struct diff_rename_pool *pool)
15{
16 pool->s = NULL; pool->nr = pool->alloc = 0;
17}
18
19static void diff_rename_pool_add(struct diff_rename_pool *pool,
20 struct diff_filespec *s)
21{
22 if (S_ISDIR(s->mode))
23 return; /* rename/copy patch for tree does not make sense. */
24
25 if (pool->alloc <= pool->nr) {
26 pool->alloc = alloc_nr(pool->alloc);
27 pool->s = xrealloc(pool->s,
28 sizeof(*(pool->s)) * pool->alloc);
29 }
30 pool->s[pool->nr] = s;
31 pool->nr++;
32}
33
34static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
35{
36 if (src->sha1_valid && dst->sha1_valid &&
37 !memcmp(src->sha1, dst->sha1, 20))
38 return 1;
39 if (diff_populate_filespec(src) || diff_populate_filespec(dst))
40 /* this is an error but will be caught downstream */
41 return 0;
42 if (src->size == dst->size &&
43 !memcmp(src->data, dst->data, src->size))
44 return 1;
45 return 0;
46}
47
48struct diff_score {
49 struct diff_filespec *src;
50 struct diff_filespec *dst;
51 int score;
52 int rank;
53};
54
55static int estimate_similarity(struct diff_filespec *src,
56 struct diff_filespec *dst,
57 int minimum_score)
58{
59 /* src points at a file that existed in the original tree (or
60 * optionally a file in the destination tree) and dst points
61 * at a newly created file. They may be quite similar, in which
62 * case we want to say src is renamed to dst or src is copied into
63 * dst, and then some edit has been applied to dst.
64 *
65 * Compare them and return how similar they are, representing
66 * the score as an integer between 0 and 10000, except
67 * where they match exactly it is considered better than anything
68 * else.
69 */
70 void *delta;
71 unsigned long delta_size;
72 int score;
73
74 delta_size = ((src->size < dst->size) ?
75 (dst->size - src->size) : (src->size - dst->size));
76
77 /* We would not consider rename followed by more than
78 * minimum_score/MAX_SCORE edits; that is, delta_size must be smaller
79 * than (src->size + dst->size)/2 * minimum_score/MAX_SCORE,
80 * which means...
81 */
82
83 if ((src->size+dst->size)*minimum_score < delta_size*MAX_SCORE*2)
84 return 0;
85
86 delta = diff_delta(src->data, src->size,
87 dst->data, dst->size,
88 &delta_size);
89 free(delta);
90
91 /* This "delta" is really xdiff with adler32 and all the
92 * overheads but it is a quick and dirty approximation.
93 *
94 * Now we will give some score to it. 100% edit gets
95 * 0 points and 0% edit gets MAX_SCORE points. That is, every
96 * 1/MAX_SCORE edit gets 1 point penalty. The amount of penalty is:
97 *
98 * (delta_size * 2 / (src->size + dst->size)) * MAX_SCORE
99 *
100 */
101 score = MAX_SCORE-(MAX_SCORE*2*delta_size/(src->size+dst->size));
102 if (score < 0) return 0;
103 if (MAX_SCORE < score) return MAX_SCORE;
104 return score;
105}
106
107static void record_rename_pair(struct diff_queue_struct *outq,
108 struct diff_filespec *src,
109 struct diff_filespec *dst,
110 int rank,
111 int score)
112{
113 /* The rank is used to sort the final output, because there
114 * are certain dependencies.
115 *
116 * - rank #0 depends on deleted ones.
117 * - rank #1 depends on kept files before they are modified.
118 * - rank #2 depends on kept files after they are modified;
119 * currently not used.
120 *
121 * Therefore, the final output order should be:
122 *
123 * 1. rank #0 rename/copy diffs.
124 * 2. deletions in the original.
125 * 3. rank #1 rename/copy diffs.
126 * 4. additions and modifications in the original.
127 * 5. rank #2 rename/copy diffs; currently not used.
128 *
129 * To achieve this sort order, we give xform_work the number
130 * above.
131 */
52e95789 132 struct diff_filepair *dp = diff_queue(outq, src, dst);
427dcb4b
JH
133 dp->xfrm_work = (rank * 2 + 1) | (score<<RENAME_SCORE_SHIFT);
134 dst->xfrm_flags |= RENAME_DST_MATCHED;
135}
136
137#if 0
138static void debug_filespec(struct diff_filespec *s, int x, const char *one)
139{
140 fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
141 x, one,
142 s->path,
143 s->file_valid ? "valid" : "invalid",
144 s->mode,
145 s->sha1_valid ? sha1_to_hex(s->sha1) : "");
146 fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
147 x, one,
148 s->size, s->xfrm_flags);
149}
150
52e95789 151static void debug_filepair(const struct diff_filepair *p, int i)
427dcb4b
JH
152{
153 debug_filespec(p->one, i, "one");
154 debug_filespec(p->two, i, "two");
155 fprintf(stderr, "pair flags %d, orig order %d, score %d\n",
156 (p->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1)),
157 p->orig_order,
158 (p->xfrm_work >> RENAME_SCORE_SHIFT));
159}
160
161static void debug_queue(const char *msg, struct diff_queue_struct *q)
162{
163 int i;
164 if (msg)
165 fprintf(stderr, "%s\n", msg);
166 fprintf(stderr, "q->nr = %d\n", q->nr);
167 for (i = 0; i < q->nr; i++) {
52e95789 168 struct diff_filepair *p = q->queue[i];
427dcb4b
JH
169 debug_filepair(p, i);
170 }
171}
172#else
173#define debug_queue(a,b) do { ; /*nothing*/ } while(0)
174#endif
175
176/*
177 * We sort the outstanding diff entries according to the rank (see
178 * comment at the beginning of record_rename_pair) and tiebreak with
179 * the order in the original input.
180 */
181static int rank_compare(const void *a_, const void *b_)
182{
52e95789
JH
183 const struct diff_filepair *a = *(const struct diff_filepair **)a_;
184 const struct diff_filepair *b = *(const struct diff_filepair **)b_;
427dcb4b
JH
185 int a_rank = a->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1);
186 int b_rank = b->xfrm_work & ((1<<RENAME_SCORE_SHIFT) - 1);
187
188 if (a_rank != b_rank)
189 return a_rank - b_rank;
190 return a->orig_order - b->orig_order;
191}
192
193/*
194 * We sort the rename similarity matrix with the score, in descending
195 * order (more similar first).
196 */
197static int score_compare(const void *a_, const void *b_)
198{
199 const struct diff_score *a = a_, *b = b_;
200 return b->score - a->score;
201}
202
203static int needs_to_stay(struct diff_queue_struct *q, int i,
204 struct diff_filespec *it)
205{
206 /* If it will be used in later entry (either stay or used
207 * as the source of rename/copy), we need to copy, not rename.
208 */
209 while (i < q->nr) {
52e95789 210 struct diff_filepair *p = q->queue[i++];
427dcb4b
JH
211 if (!p->two->file_valid)
212 continue; /* removed is fine */
213 if (strcmp(p->one->path, it->path))
214 continue; /* not relevant */
215
216 /* p has its src set to *it and it is not a delete;
217 * it will be used for in-place change or rename/copy,
218 * so we cannot rename it out.
219 */
220 return 1;
221 }
222 return 0;
223}
224
225void diff_detect_rename(struct diff_queue_struct *q,
226 int detect_rename,
227 int minimum_score)
228{
229 struct diff_queue_struct outq;
230 struct diff_rename_pool created, deleted, stay;
231 struct diff_rename_pool *(srcs[2]);
232 struct diff_score *mx;
233 int h, i, j;
234 int num_create, num_src, dst_cnt, src_cnt;
235
236 outq.queue = NULL;
237 outq.nr = outq.alloc = 0;
238
239 diff_rename_pool_clear(&created);
240 diff_rename_pool_clear(&deleted);
241 diff_rename_pool_clear(&stay);
242
243 srcs[0] = &deleted;
244 srcs[1] = &stay;
245
427dcb4b 246 for (i = 0; i < q->nr; i++) {
52e95789 247 struct diff_filepair *p = q->queue[i];
427dcb4b
JH
248 if (!p->one->file_valid)
249 if (!p->two->file_valid)
250 continue; /* ignore nonsense */
251 else
252 diff_rename_pool_add(&created, p->two);
253 else if (!p->two->file_valid)
254 diff_rename_pool_add(&deleted, p->one);
255 else if (1 < detect_rename) /* find copy, too */
256 diff_rename_pool_add(&stay, p->one);
257 }
258 if (created.nr == 0)
259 goto cleanup; /* nothing to do */
260
261 /* We really want to cull the candidates list early
262 * with cheap tests in order to avoid doing deltas.
263 *
264 * With the current callers, we should not have already
265 * matched entries at this point, but it is nonetheless
266 * checked for sanity.
267 */
268 for (i = 0; i < created.nr; i++) {
269 if (created.s[i]->xfrm_flags & RENAME_DST_MATCHED)
270 continue; /* we have matched exactly already */
271 for (h = 0; h < sizeof(srcs)/sizeof(srcs[0]); h++) {
272 struct diff_rename_pool *p = srcs[h];
273 for (j = 0; j < p->nr; j++) {
274 if (!is_exact_match(p->s[j], created.s[i]))
275 continue;
276 record_rename_pair(&outq,
277 p->s[j], created.s[i], h,
278 MAX_SCORE);
279 break; /* we are done with this entry */
280 }
281 }
282 }
283 debug_queue("done detecting exact", &outq);
284
285 /* Have we run out the created file pool? If so we can avoid
286 * doing the delta matrix altogether.
287 */
288 if (outq.nr == created.nr)
289 goto flush_rest;
290
291 num_create = (created.nr - outq.nr);
292 num_src = deleted.nr + stay.nr;
293 mx = xmalloc(sizeof(*mx) * num_create * num_src);
294 for (dst_cnt = i = 0; i < created.nr; i++) {
295 int base = dst_cnt * num_src;
296 if (created.s[i]->xfrm_flags & RENAME_DST_MATCHED)
297 continue; /* dealt with exact match already. */
298 for (src_cnt = h = 0; h < sizeof(srcs)/sizeof(srcs[0]); h++) {
299 struct diff_rename_pool *p = srcs[h];
300 for (j = 0; j < p->nr; j++, src_cnt++) {
301 struct diff_score *m = &mx[base + src_cnt];
302 m->src = p->s[j];
303 m->dst = created.s[i];
304 m->score = estimate_similarity(m->src, m->dst,
305 minimum_score);
306 m->rank = h;
307 }
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 if (mx[i].dst->xfrm_flags & RENAME_DST_MATCHED)
315 continue; /* alreayd done, either exact or fuzzy. */
316 if (mx[i].score < minimum_score)
317 continue;
318 record_rename_pair(&outq,
319 mx[i].src, mx[i].dst, mx[i].rank,
320 mx[i].score);
321 }
322 free(mx);
323 debug_queue("done detecting fuzzy", &outq);
324
325 flush_rest:
326 /* At this point, we have found some renames and copies and they
327 * are kept in outq. The original list is still in *q.
328 *
329 * Scan the original list and move them into the outq; we will sort
330 * outq and swap it into the queue supplied to pass that to
331 * downstream, so we assign the sort keys in this loop.
332 *
333 * See comments at the top of record_rename_pair for numbers used
334 * to assign xfrm_work.
335 *
52e95789 336 * Note that we have not annotated the diff_filepair with any comment
427dcb4b
JH
337 * so there is nothing other than p to free.
338 */
339 for (i = 0; i < q->nr; i++) {
52e95789 340 struct diff_filepair *dp, *p = q->queue[i];
427dcb4b
JH
341 if (!p->one->file_valid) {
342 if (p->two->file_valid) {
343 /* creation */
344 dp = diff_queue(&outq, p->one, p->two);
345 dp->xfrm_work = 4;
346 }
347 /* otherwise it is a nonsense; just ignore it */
348 }
349 else if (!p->two->file_valid) {
350 /* deletion */
351 dp = diff_queue(&outq, p->one, p->two);
352 dp->xfrm_work = 2;
353 }
354 else {
355 /* modification, or stay as is */
356 dp = diff_queue(&outq, p->one, p->two);
357 dp->xfrm_work = 4;
358 }
359 free(p);
360 }
361 debug_queue("done copying original", &outq);
362
363 /* Sort outq */
364 qsort(outq.queue, outq.nr, sizeof(outq.queue[0]), rank_compare);
365
366 debug_queue("done sorting", &outq);
367
368 free(q->queue);
369 q->nr = q->alloc = 0;
370 q->queue = NULL;
371
372 /* Copy it out to q, removing duplicates. */
373 for (i = 0; i < outq.nr; i++) {
52e95789 374 struct diff_filepair *p = outq.queue[i];
427dcb4b
JH
375 if (!p->one->file_valid) {
376 /* created */
377 if (p->two->xfrm_flags & RENAME_DST_MATCHED)
378 ; /* rename/copy created it already */
379 else
380 diff_queue(q, p->one, p->two);
381 }
382 else if (!p->two->file_valid) {
383 /* deleted */
384 if (p->one->xfrm_flags & RENAME_SRC_GONE)
385 ; /* rename/copy deleted it already */
386 else
387 diff_queue(q, p->one, p->two);
388 }
389 else if (strcmp(p->one->path, p->two->path)) {
390 /* rename or copy */
52e95789 391 struct diff_filepair *dp =
427dcb4b
JH
392 diff_queue(q, p->one, p->two);
393 int msglen = (strlen(p->one->path) +
394 strlen(p->two->path) + 100);
395 int score = (p->xfrm_work >> RENAME_SCORE_SHIFT);
396 dp->xfrm_msg = xmalloc(msglen);
397
398 /* if we have a later entry that is a rename/copy
399 * that depends on p->one, then we copy here.
400 * otherwise we rename it.
401 */
402 if (needs_to_stay(&outq, i+1, p->one)) {
403 /* copy it */
404 sprintf(dp->xfrm_msg,
405 "similarity index %d%%\n"
406 "copy from %s\n"
407 "copy to %s\n",
408 (int)(0.5 + score * 100 / MAX_SCORE),
409 p->one->path, p->two->path);
410 }
411 else {
412 /* rename it, and mark it as gone. */
413 p->one->xfrm_flags |= RENAME_SRC_GONE;
414 sprintf(dp->xfrm_msg,
415 "similarity index %d%%\n"
416 "rename old %s\n"
417 "rename new %s\n",
418 (int)(0.5 + score * 100 / MAX_SCORE),
419 p->one->path, p->two->path);
420 }
421 }
422 else
423 /* otherwise it is a modified (or stayed) entry */
424 diff_queue(q, p->one, p->two);
425 free(p);
426 }
427
428 free(outq.queue);
429 debug_queue("done collapsing", q);
430
431 cleanup:
432 free(created.s);
433 free(deleted.s);
434 free(stay.s);
435 return;
436}