[PATCH] Move pathspec to the beginning of the diffcore chain.
[git/git.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"
7#include "delta.h"
85976974 8#include "count-delta.h"
427dcb4b 9
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10/* Table of rename/copy destinations */
11
12static struct diff_rename_dst {
13 struct diff_filespec *two;
14 struct diff_filepair *pair;
15} *rename_dst;
16static int rename_dst_nr, rename_dst_alloc;
427dcb4b 17
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18static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
19 int insert_ok)
427dcb4b 20{
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21 int first, last;
22
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 = two;
51 rename_dst[first].pair = NULL;
52 return &(rename_dst[first]);
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53}
54
15d061b4 55/* Table of rename/copy src files */
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56static struct diff_rename_src {
57 struct diff_filespec *one;
15d061b4 58 unsigned src_stays : 1;
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59} *rename_src;
60static int rename_src_nr, rename_src_alloc;
427dcb4b 61
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62static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
63 int src_stays)
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64{
65 int first, last;
66
67 first = 0;
68 last = rename_src_nr;
69 while (last > first) {
70 int next = (last + first) >> 1;
71 struct diff_rename_src *src = &(rename_src[next]);
72 int cmp = strcmp(one->path, src->one->path);
73 if (!cmp)
74 return src;
75 if (cmp < 0) {
76 last = next;
77 continue;
78 }
79 first = next+1;
80 }
15d061b4 81
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82 /* insert to make it at "first" */
83 if (rename_src_alloc <= rename_src_nr) {
84 rename_src_alloc = alloc_nr(rename_src_alloc);
85 rename_src = xrealloc(rename_src,
86 rename_src_alloc * sizeof(*rename_src));
427dcb4b 87 }
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88 rename_src_nr++;
89 if (first < rename_src_nr)
90 memmove(rename_src + first + 1, rename_src + first,
91 (rename_src_nr - first - 1) * sizeof(*rename_src));
92 rename_src[first].one = one;
15d061b4 93 rename_src[first].src_stays = src_stays;
25d5ea41 94 return &(rename_src[first]);
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95}
96
97static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
98{
99 if (src->sha1_valid && dst->sha1_valid &&
100 !memcmp(src->sha1, dst->sha1, 20))
101 return 1;
102 if (diff_populate_filespec(src) || diff_populate_filespec(dst))
103 /* this is an error but will be caught downstream */
104 return 0;
105 if (src->size == dst->size &&
106 !memcmp(src->data, dst->data, src->size))
107 return 1;
108 return 0;
109}
110
111struct diff_score {
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112 int src; /* index in rename_src */
113 int dst; /* index in rename_dst */
427dcb4b 114 int score;
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115};
116
117static int estimate_similarity(struct diff_filespec *src,
118 struct diff_filespec *dst,
119 int minimum_score)
120{
121 /* src points at a file that existed in the original tree (or
122 * optionally a file in the destination tree) and dst points
123 * at a newly created file. They may be quite similar, in which
124 * case we want to say src is renamed to dst or src is copied into
125 * dst, and then some edit has been applied to dst.
126 *
127 * Compare them and return how similar they are, representing
128 * the score as an integer between 0 and 10000, except
129 * where they match exactly it is considered better than anything
130 * else.
131 */
132 void *delta;
58b103f5 133 unsigned long delta_size, base_size;
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134 int score;
135
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136 /* We deal only with regular files. Symlink renames are handled
137 * only when they are exact matches --- in other words, no edits
138 * after renaming.
139 */
140 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
141 return 0;
142
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143 delta_size = ((src->size < dst->size) ?
144 (dst->size - src->size) : (src->size - dst->size));
58b103f5 145 base_size = ((src->size < dst->size) ? src->size : dst->size);
427dcb4b 146
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147 /* We would not consider edits that change the file size so
148 * drastically. delta_size must be smaller than
cd1870ed 149 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
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150 * Note that base_size == 0 case is handled here already
151 * and the final score computation below would not have a
152 * divide-by-zero issue.
427dcb4b 153 */
cd1870ed 154 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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155 return 0;
156
157 delta = diff_delta(src->data, src->size,
158 dst->data, dst->size,
159 &delta_size);
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160
161 /* A delta that has a lot of literal additions would have
162 * big delta_size no matter what else it does.
58b103f5 163 */
a00d7d10 164 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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165 return 0;
166
167 /* Estimate the edit size by interpreting delta. */
168 delta_size = count_delta(delta, delta_size);
427dcb4b 169 free(delta);
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170 if (delta_size == UINT_MAX)
171 return 0;
427dcb4b 172
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173 /*
174 * Now we will give some score to it. 100% edit gets 0 points
175 * and 0% edit gets MAX_SCORE points.
427dcb4b 176 */
58b103f5 177 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
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178 if (score < 0) return 0;
179 if (MAX_SCORE < score) return MAX_SCORE;
180 return score;
181}
182
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183static void record_rename_pair(struct diff_queue_struct *renq,
184 int dst_index, int src_index, int score)
427dcb4b 185{
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186 struct diff_filespec *one, *two, *src, *dst;
187 struct diff_filepair *dp;
f7c1512a 188
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189 if (rename_dst[dst_index].pair)
190 die("internal error: dst already matched.");
427dcb4b 191
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192 src = rename_src[src_index].one;
193 one = alloc_filespec(src->path);
194 fill_filespec(one, src->sha1, src->mode);
427dcb4b 195
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196 dst = rename_dst[dst_index].two;
197 two = alloc_filespec(dst->path);
198 fill_filespec(two, dst->sha1, dst->mode);
427dcb4b 199
25d5ea41 200 dp = diff_queue(renq, one, two);
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201 dp->score = score ? : 1; /* make sure it is at least 1 */
202 dp->source_stays = rename_src[src_index].src_stays;
25d5ea41 203 rename_dst[dst_index].pair = dp;
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204}
205
206/*
207 * We sort the rename similarity matrix with the score, in descending
15d061b4 208 * order (the most similar first).
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209 */
210static int score_compare(const void *a_, const void *b_)
211{
212 const struct diff_score *a = a_, *b = b_;
213 return b->score - a->score;
214}
215
6b14d7fa
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216int diff_scoreopt_parse(const char *opt)
217{
218 int diglen, num, scale, i;
219 if (opt[0] != '-' || (opt[1] != 'M' && opt[1] != 'C'))
220 return -1; /* that is not a -M nor -C option */
221 diglen = strspn(opt+2, "0123456789");
222 if (diglen == 0 || strlen(opt+2) != diglen)
223 return 0; /* use default */
224 sscanf(opt+2, "%d", &num);
225 for (i = 0, scale = 1; i < diglen; i++)
226 scale *= 10;
227
228 /* user says num divided by scale and we say internally that
229 * is MAX_SCORE * num / scale.
230 */
231 return MAX_SCORE * num / scale;
232}
233
234void diffcore_rename(int detect_rename, int minimum_score)
427dcb4b 235{
38c6f780 236 struct diff_queue_struct *q = &diff_queued_diff;
25d5ea41 237 struct diff_queue_struct renq, outq;
427dcb4b 238 struct diff_score *mx;
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239 int i, j;
240 int num_create, num_src, dst_cnt;
427dcb4b 241
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242 if (!minimum_score)
243 minimum_score = DEFAULT_MINIMUM_SCORE;
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244 renq.queue = NULL;
245 renq.nr = renq.alloc = 0;
427dcb4b 246
427dcb4b 247 for (i = 0; i < q->nr; i++) {
52e95789 248 struct diff_filepair *p = q->queue[i];
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249 if (!DIFF_FILE_VALID(p->one))
250 if (!DIFF_FILE_VALID(p->two))
60896c7b 251 continue; /* unmerged */
427dcb4b 252 else
25d5ea41 253 locate_rename_dst(p->two, 1);
81e50eab 254 else if (!DIFF_FILE_VALID(p->two))
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255 register_rename_src(p->one, 0);
256 else if (detect_rename == DIFF_DETECT_COPY)
257 register_rename_src(p->one, 1);
427dcb4b 258 }
25d5ea41 259 if (rename_dst_nr == 0)
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260 goto cleanup; /* nothing to do */
261
262 /* We really want to cull the candidates list early
263 * with cheap tests in order to avoid doing deltas.
427dcb4b 264 */
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265 for (i = 0; i < rename_dst_nr; i++) {
266 struct diff_filespec *two = rename_dst[i].two;
267 for (j = 0; j < rename_src_nr; j++) {
268 struct diff_filespec *one = rename_src[j].one;
269 if (!is_exact_match(one, two))
270 continue;
271 record_rename_pair(&renq, i, j, MAX_SCORE);
272 break; /* we are done with this entry */
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273 }
274 }
25d5ea41 275 diff_debug_queue("done detecting exact", &renq);
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276
277 /* Have we run out the created file pool? If so we can avoid
278 * doing the delta matrix altogether.
279 */
25d5ea41 280 if (renq.nr == rename_dst_nr)
15d061b4 281 goto cleanup;
427dcb4b 282
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283 num_create = (rename_dst_nr - renq.nr);
284 num_src = rename_src_nr;
427dcb4b 285 mx = xmalloc(sizeof(*mx) * num_create * num_src);
25d5ea41 286 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
427dcb4b 287 int base = dst_cnt * num_src;
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288 struct diff_filespec *two = rename_dst[i].two;
289 if (rename_dst[i].pair)
427dcb4b 290 continue; /* dealt with exact match already. */
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291 for (j = 0; j < rename_src_nr; j++) {
292 struct diff_filespec *one = rename_src[j].one;
293 struct diff_score *m = &mx[base+j];
294 m->src = j;
295 m->dst = i;
296 m->score = estimate_similarity(one, two,
297 minimum_score);
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298 }
299 dst_cnt++;
300 }
301 /* cost matrix sorted by most to least similar pair */
302 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
303 for (i = 0; i < num_create * num_src; i++) {
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304 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
305 if (dst->pair)
306 continue; /* already done, either exact or fuzzy. */
427dcb4b 307 if (mx[i].score < minimum_score)
15d061b4 308 break; /* there is no more usable pair. */
25d5ea41 309 record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score);
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310 }
311 free(mx);
25d5ea41 312 diff_debug_queue("done detecting fuzzy", &renq);
427dcb4b 313
15d061b4 314 cleanup:
427dcb4b 315 /* At this point, we have found some renames and copies and they
25d5ea41 316 * are kept in renq. The original list is still in *q.
427dcb4b 317 */
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318 outq.queue = NULL;
319 outq.nr = outq.alloc = 0;
427dcb4b 320 for (i = 0; i < q->nr; i++) {
25d5ea41 321 struct diff_filepair *p = q->queue[i];
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322 struct diff_rename_dst *dst = locate_rename_dst(p->two, 0);
323 struct diff_filepair *pair_to_free = NULL;
324
325 if (dst) {
326 /* creation */
327 if (dst->pair) {
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328 /* renq has rename/copy to produce
329 * this file already, so we do not
330 * emit the creation record in the
331 * output.
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332 */
333 diff_q(&outq, dst->pair);
334 pair_to_free = p;
335 }
336 else
337 /* no matching rename/copy source, so record
338 * this as a creation.
339 */
340 diff_q(&outq, p);
427dcb4b 341 }
25d5ea41 342 else if (!diff_unmodified_pair(p))
15d061b4 343 /* all the usual ones need to be kept */
25d5ea41 344 diff_q(&outq, p);
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345 else
346 /* no need to keep unmodified pairs */
347 pair_to_free = p;
348
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349 if (pair_to_free)
350 diff_free_filepair(pair_to_free);
427dcb4b 351 }
25d5ea41 352 diff_debug_queue("done copying original", &outq);
427dcb4b 353
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354 free(renq.queue);
355 free(q->queue);
356 *q = outq;
357 diff_debug_queue("done collapsing", q);
427dcb4b 358
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359 free(rename_dst);
360 rename_dst = NULL;
361 rename_dst_nr = rename_dst_alloc = 0;
362 free(rename_src);
363 rename_src = NULL;
364 rename_src_nr = rename_src_alloc = 0;
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365 return;
366}