[PATCH] diff: further cleanup.
[git/git.git] / diffcore-rename.c
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427dcb4b
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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;
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102 if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
103 return 0;
104 if (src->size != dst->size)
105 return 0;
106 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
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107 return 0;
108 if (src->size == dst->size &&
109 !memcmp(src->data, dst->data, src->size))
110 return 1;
111 return 0;
112}
113
114struct diff_score {
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115 int src; /* index in rename_src */
116 int dst; /* index in rename_dst */
427dcb4b 117 int score;
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118};
119
120static int estimate_similarity(struct diff_filespec *src,
121 struct diff_filespec *dst,
122 int minimum_score)
123{
124 /* src points at a file that existed in the original tree (or
125 * optionally a file in the destination tree) and dst points
126 * at a newly created file. They may be quite similar, in which
127 * case we want to say src is renamed to dst or src is copied into
128 * dst, and then some edit has been applied to dst.
129 *
130 * Compare them and return how similar they are, representing
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131 * the score as an integer between 0 and MAX_SCORE.
132 *
133 * When there is an exact match, it is considered a better
134 * match than anything else; the destination does not even
135 * call into this function in that case.
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136 */
137 void *delta;
58b103f5 138 unsigned long delta_size, base_size;
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139 int score;
140
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141 /* We deal only with regular files. Symlink renames are handled
142 * only when they are exact matches --- in other words, no edits
143 * after renaming.
144 */
145 if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
146 return 0;
147
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148 delta_size = ((src->size < dst->size) ?
149 (dst->size - src->size) : (src->size - dst->size));
58b103f5 150 base_size = ((src->size < dst->size) ? src->size : dst->size);
427dcb4b 151
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152 /* We would not consider edits that change the file size so
153 * drastically. delta_size must be smaller than
cd1870ed 154 * (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
f0c6b2a2 155 *
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156 * Note that base_size == 0 case is handled here already
157 * and the final score computation below would not have a
158 * divide-by-zero issue.
427dcb4b 159 */
cd1870ed 160 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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161 return 0;
162
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163 if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
164 return 0; /* error but caught downstream */
165
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166 delta = diff_delta(src->data, src->size,
167 dst->data, dst->size,
168 &delta_size);
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169
170 /* A delta that has a lot of literal additions would have
171 * big delta_size no matter what else it does.
58b103f5 172 */
a00d7d10 173 if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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174 return 0;
175
176 /* Estimate the edit size by interpreting delta. */
177 delta_size = count_delta(delta, delta_size);
427dcb4b 178 free(delta);
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179 if (delta_size == UINT_MAX)
180 return 0;
427dcb4b 181
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182 /*
183 * Now we will give some score to it. 100% edit gets 0 points
184 * and 0% edit gets MAX_SCORE points.
427dcb4b 185 */
58b103f5 186 score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
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187 if (score < 0) return 0;
188 if (MAX_SCORE < score) return MAX_SCORE;
189 return score;
190}
191
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192static void record_rename_pair(struct diff_queue_struct *renq,
193 int dst_index, int src_index, int score)
427dcb4b 194{
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195 struct diff_filespec *one, *two, *src, *dst;
196 struct diff_filepair *dp;
f7c1512a 197
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198 if (rename_dst[dst_index].pair)
199 die("internal error: dst already matched.");
427dcb4b 200
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201 src = rename_src[src_index].one;
202 one = alloc_filespec(src->path);
203 fill_filespec(one, src->sha1, src->mode);
427dcb4b 204
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205 dst = rename_dst[dst_index].two;
206 two = alloc_filespec(dst->path);
207 fill_filespec(two, dst->sha1, dst->mode);
427dcb4b 208
25d5ea41 209 dp = diff_queue(renq, one, two);
01c4e70f 210 dp->score = score;
15d061b4 211 dp->source_stays = rename_src[src_index].src_stays;
25d5ea41 212 rename_dst[dst_index].pair = dp;
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213}
214
215/*
216 * We sort the rename similarity matrix with the score, in descending
15d061b4 217 * order (the most similar first).
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218 */
219static int score_compare(const void *a_, const void *b_)
220{
221 const struct diff_score *a = a_, *b = b_;
222 return b->score - a->score;
223}
224
6b14d7fa
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225int diff_scoreopt_parse(const char *opt)
226{
227 int diglen, num, scale, i;
228 if (opt[0] != '-' || (opt[1] != 'M' && opt[1] != 'C'))
229 return -1; /* that is not a -M nor -C option */
230 diglen = strspn(opt+2, "0123456789");
231 if (diglen == 0 || strlen(opt+2) != diglen)
232 return 0; /* use default */
233 sscanf(opt+2, "%d", &num);
234 for (i = 0, scale = 1; i < diglen; i++)
235 scale *= 10;
236
237 /* user says num divided by scale and we say internally that
238 * is MAX_SCORE * num / scale.
239 */
240 return MAX_SCORE * num / scale;
241}
242
243void diffcore_rename(int detect_rename, int minimum_score)
427dcb4b 244{
38c6f780 245 struct diff_queue_struct *q = &diff_queued_diff;
25d5ea41 246 struct diff_queue_struct renq, outq;
427dcb4b 247 struct diff_score *mx;
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248 int i, j;
249 int num_create, num_src, dst_cnt;
427dcb4b 250
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251 if (!minimum_score)
252 minimum_score = DEFAULT_MINIMUM_SCORE;
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253 renq.queue = NULL;
254 renq.nr = renq.alloc = 0;
427dcb4b 255
427dcb4b 256 for (i = 0; i < q->nr; i++) {
52e95789 257 struct diff_filepair *p = q->queue[i];
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258 if (!DIFF_FILE_VALID(p->one))
259 if (!DIFF_FILE_VALID(p->two))
60896c7b 260 continue; /* unmerged */
427dcb4b 261 else
25d5ea41 262 locate_rename_dst(p->two, 1);
81e50eab 263 else if (!DIFF_FILE_VALID(p->two))
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264 register_rename_src(p->one, 0);
265 else if (detect_rename == DIFF_DETECT_COPY)
266 register_rename_src(p->one, 1);
427dcb4b 267 }
25d5ea41 268 if (rename_dst_nr == 0)
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269 goto cleanup; /* nothing to do */
270
271 /* We really want to cull the candidates list early
272 * with cheap tests in order to avoid doing deltas.
427dcb4b 273 */
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274 for (i = 0; i < rename_dst_nr; i++) {
275 struct diff_filespec *two = rename_dst[i].two;
276 for (j = 0; j < rename_src_nr; j++) {
277 struct diff_filespec *one = rename_src[j].one;
278 if (!is_exact_match(one, two))
279 continue;
280 record_rename_pair(&renq, i, j, MAX_SCORE);
281 break; /* we are done with this entry */
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282 }
283 }
25d5ea41 284 diff_debug_queue("done detecting exact", &renq);
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285
286 /* Have we run out the created file pool? If so we can avoid
287 * doing the delta matrix altogether.
288 */
25d5ea41 289 if (renq.nr == rename_dst_nr)
15d061b4 290 goto cleanup;
427dcb4b 291
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292 num_create = (rename_dst_nr - renq.nr);
293 num_src = rename_src_nr;
427dcb4b 294 mx = xmalloc(sizeof(*mx) * num_create * num_src);
25d5ea41 295 for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
427dcb4b 296 int base = dst_cnt * num_src;
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297 struct diff_filespec *two = rename_dst[i].two;
298 if (rename_dst[i].pair)
427dcb4b 299 continue; /* dealt with exact match already. */
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300 for (j = 0; j < rename_src_nr; j++) {
301 struct diff_filespec *one = rename_src[j].one;
302 struct diff_score *m = &mx[base+j];
303 m->src = j;
304 m->dst = i;
305 m->score = estimate_similarity(one, two,
306 minimum_score);
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307 }
308 dst_cnt++;
309 }
310 /* cost matrix sorted by most to least similar pair */
311 qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
312 for (i = 0; i < num_create * num_src; i++) {
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313 struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
314 if (dst->pair)
315 continue; /* already done, either exact or fuzzy. */
427dcb4b 316 if (mx[i].score < minimum_score)
15d061b4 317 break; /* there is no more usable pair. */
25d5ea41 318 record_rename_pair(&renq, mx[i].dst, mx[i].src, mx[i].score);
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319 }
320 free(mx);
25d5ea41 321 diff_debug_queue("done detecting fuzzy", &renq);
427dcb4b 322
15d061b4 323 cleanup:
427dcb4b 324 /* At this point, we have found some renames and copies and they
25d5ea41 325 * are kept in renq. The original list is still in *q.
427dcb4b 326 */
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327 outq.queue = NULL;
328 outq.nr = outq.alloc = 0;
427dcb4b 329 for (i = 0; i < q->nr; i++) {
25d5ea41 330 struct diff_filepair *p = q->queue[i];
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331 struct diff_rename_dst *dst = locate_rename_dst(p->two, 0);
332 struct diff_filepair *pair_to_free = NULL;
333
334 if (dst) {
335 /* creation */
336 if (dst->pair) {
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337 /* renq has rename/copy to produce
338 * this file already, so we do not
339 * emit the creation record in the
340 * output.
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341 */
342 diff_q(&outq, dst->pair);
343 pair_to_free = p;
344 }
345 else
346 /* no matching rename/copy source, so record
347 * this as a creation.
348 */
349 diff_q(&outq, p);
427dcb4b 350 }
25d5ea41 351 else if (!diff_unmodified_pair(p))
15d061b4 352 /* all the usual ones need to be kept */
25d5ea41 353 diff_q(&outq, p);
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354 else
355 /* no need to keep unmodified pairs */
356 pair_to_free = p;
357
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358 if (pair_to_free)
359 diff_free_filepair(pair_to_free);
427dcb4b 360 }
25d5ea41 361 diff_debug_queue("done copying original", &outq);
427dcb4b 362
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363 free(renq.queue);
364 free(q->queue);
365 *q = outq;
366 diff_debug_queue("done collapsing", q);
427dcb4b 367
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368 free(rename_dst);
369 rename_dst = NULL;
370 rename_dst_nr = rename_dst_alloc = 0;
371 free(rename_src);
372 rename_src = NULL;
373 rename_src_nr = rename_src_alloc = 0;
427dcb4b
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374 return;
375}