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merge-recursive: Avoid excessive output for and reprocessing of renames
[git/dscho.git] / xdiff / xmerge.c
blob16dd9acd37b431f1e439d9ab051fe2436c54b45c
1 /*
2 * LibXDiff by Davide Libenzi ( File Differential Library )
3 * Copyright (C) 2003-2006 Davide Libenzi, Johannes E. Schindelin
4 *
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2.1 of the License, or (at your option) any later version.
9 *
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
19 * Davide Libenzi <davidel@xmailserver.org>
20 *
21 */
22
23 #include "xinclude.h"
24
25 typedef struct s_xdmerge {
26 struct s_xdmerge *next;
27 /*
28 * 0 = conflict,
29 * 1 = no conflict, take first,
30 * 2 = no conflict, take second.
31 * 3 = no conflict, take both.
32 */
33 int mode;
34 /*
35 * These point at the respective postimages. E.g. <i1,chg1> is
36 * how side #1 wants to change the common ancestor; if there is no
37 * overlap, lines before i1 in the postimage of side #1 appear
38 * in the merge result as a region touched by neither side.
39 */
40 long i1, i2;
41 long chg1, chg2;
42 /*
43 * These point at the preimage; of course there is just one
44 * preimage, that is from the shared common ancestor.
45 */
46 long i0;
47 long chg0;
48 } xdmerge_t;
49
50 static int xdl_append_merge(xdmerge_t **merge, int mode,
51 long i0, long chg0,
52 long i1, long chg1,
53 long i2, long chg2)
54 {
55 xdmerge_t *m = *merge;
56 if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
57 if (mode != m->mode)
58 m->mode = 0;
59 m->chg0 = i0 + chg0 - m->i0;
60 m->chg1 = i1 + chg1 - m->i1;
61 m->chg2 = i2 + chg2 - m->i2;
62 } else {
63 m = xdl_malloc(sizeof(xdmerge_t));
64 if (!m)
65 return -1;
66 m->next = NULL;
67 m->mode = mode;
68 m->i0 = i0;
69 m->chg0 = chg0;
70 m->i1 = i1;
71 m->chg1 = chg1;
72 m->i2 = i2;
73 m->chg2 = chg2;
74 if (*merge)
75 (*merge)->next = m;
76 *merge = m;
77 }
78 return 0;
79 }
80
81 static int xdl_cleanup_merge(xdmerge_t *c)
82 {
83 int count = 0;
84 xdmerge_t *next_c;
85
86 /* were there conflicts? */
87 for (; c; c = next_c) {
88 if (c->mode == 0)
89 count++;
90 next_c = c->next;
91 free(c);
92 }
93 return count;
94 }
95
96 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
97 int line_count, long flags)
98 {
99 int i;
100 xrecord_t **rec1 = xe1->xdf2.recs + i1;
101 xrecord_t **rec2 = xe2->xdf2.recs + i2;
102
103 for (i = 0; i < line_count; i++) {
104 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
105 rec2[i]->ptr, rec2[i]->size, flags);
106 if (!result)
107 return -1;
108 }
109 return 0;
110 }
111
112 static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int add_nl, char *dest)
113 {
114 xrecord_t **recs;
115 int size = 0;
116
117 recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
118
119 if (count < 1)
120 return 0;
121
122 for (i = 0; i < count; size += recs[i++]->size)
123 if (dest)
124 memcpy(dest + size, recs[i]->ptr, recs[i]->size);
125 if (add_nl) {
126 i = recs[count - 1]->size;
127 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
128 if (dest)
129 dest[size] = '\n';
130 size++;
131 }
132 }
133 return size;
134 }
135
136 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
137 {
138 return xdl_recs_copy_0(0, xe, i, count, add_nl, dest);
139 }
140
141 static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
142 {
143 return xdl_recs_copy_0(1, xe, i, count, add_nl, dest);
144 }
145
146 static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
147 xdfenv_t *xe2, const char *name2,
148 const char *name3,
149 int size, int i, int style,
150 xdmerge_t *m, char *dest, int marker_size)
151 {
152 int marker1_size = (name1 ? strlen(name1) + 1 : 0);
153 int marker2_size = (name2 ? strlen(name2) + 1 : 0);
154 int marker3_size = (name3 ? strlen(name3) + 1 : 0);
155 int j;
156
157 if (marker_size <= 0)
158 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
159
160 /* Before conflicting part */
161 size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
162 dest ? dest + size : NULL);
163
164 if (!dest) {
165 size += marker_size + 1 + marker1_size;
166 } else {
167 for (j = 0; j < marker_size; j++)
168 dest[size++] = '<';
169 if (marker1_size) {
170 dest[size] = ' ';
171 memcpy(dest + size + 1, name1, marker1_size - 1);
172 size += marker1_size;
173 }
174 dest[size++] = '\n';
175 }
176
177 /* Postimage from side #1 */
178 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
179 dest ? dest + size : NULL);
180
181 if (style == XDL_MERGE_DIFF3) {
182 /* Shared preimage */
183 if (!dest) {
184 size += marker_size + 1 + marker3_size;
185 } else {
186 for (j = 0; j < marker_size; j++)
187 dest[size++] = '|';
188 if (marker3_size) {
189 dest[size] = ' ';
190 memcpy(dest + size + 1, name3, marker3_size - 1);
191 size += marker3_size;
192 }
193 dest[size++] = '\n';
194 }
195 size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
196 dest ? dest + size : NULL);
197 }
198
199 if (!dest) {
200 size += marker_size + 1;
201 } else {
202 for (j = 0; j < marker_size; j++)
203 dest[size++] = '=';
204 dest[size++] = '\n';
205 }
206
207 /* Postimage from side #2 */
208 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
209 dest ? dest + size : NULL);
210 if (!dest) {
211 size += marker_size + 1 + marker2_size;
212 } else {
213 for (j = 0; j < marker_size; j++)
214 dest[size++] = '>';
215 if (marker2_size) {
216 dest[size] = ' ';
217 memcpy(dest + size + 1, name2, marker2_size - 1);
218 size += marker2_size;
219 }
220 dest[size++] = '\n';
221 }
222 return size;
223 }
224
225 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
226 xdfenv_t *xe2, const char *name2,
227 const char *ancestor_name,
228 int favor,
229 xdmerge_t *m, char *dest, int style,
230 int marker_size)
231 {
232 int size, i;
233
234 for (size = i = 0; m; m = m->next) {
235 if (favor && !m->mode)
236 m->mode = favor;
237
238 if (m->mode == 0)
239 size = fill_conflict_hunk(xe1, name1, xe2, name2,
240 ancestor_name,
241 size, i, style, m, dest,
242 marker_size);
243 else if (m->mode & 3) {
244 /* Before conflicting part */
245 size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
246 dest ? dest + size : NULL);
247 /* Postimage from side #1 */
248 if (m->mode & 1)
249 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
250 dest ? dest + size : NULL);
251 /* Postimage from side #2 */
252 if (m->mode & 2)
253 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
254 dest ? dest + size : NULL);
255 } else
256 continue;
257 i = m->i1 + m->chg1;
258 }
259 size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
260 dest ? dest + size : NULL);
261 return size;
262 }
263
264 /*
265 * Sometimes, changes are not quite identical, but differ in only a few
266 * lines. Try hard to show only these few lines as conflicting.
267 */
268 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
269 xpparam_t const *xpp)
270 {
271 for (; m; m = m->next) {
272 mmfile_t t1, t2;
273 xdfenv_t xe;
274 xdchange_t *xscr, *x;
275 int i1 = m->i1, i2 = m->i2;
276
277 /* let's handle just the conflicts */
278 if (m->mode)
279 continue;
280
281 /* no sense refining a conflict when one side is empty */
282 if (m->chg1 == 0 || m->chg2 == 0)
283 continue;
284
285 /*
286 * This probably does not work outside git, since
287 * we have a very simple mmfile structure.
288 */
289 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
290 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
291 + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
292 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
293 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
294 + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
295 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
296 return -1;
297 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
298 xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
299 xdl_build_script(&xe, &xscr) < 0) {
300 xdl_free_env(&xe);
301 return -1;
302 }
303 if (!xscr) {
304 /* If this happens, the changes are identical. */
305 xdl_free_env(&xe);
306 m->mode = 4;
307 continue;
308 }
309 x = xscr;
310 m->i1 = xscr->i1 + i1;
311 m->chg1 = xscr->chg1;
312 m->i2 = xscr->i2 + i2;
313 m->chg2 = xscr->chg2;
314 while (xscr->next) {
315 xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
316 if (!m2) {
317 xdl_free_env(&xe);
318 xdl_free_script(x);
319 return -1;
320 }
321 xscr = xscr->next;
322 m2->next = m->next;
323 m->next = m2;
324 m = m2;
325 m->mode = 0;
326 m->i1 = xscr->i1 + i1;
327 m->chg1 = xscr->chg1;
328 m->i2 = xscr->i2 + i2;
329 m->chg2 = xscr->chg2;
330 }
331 xdl_free_env(&xe);
332 xdl_free_script(x);
333 }
334 return 0;
335 }
336
337 static int line_contains_alnum(const char *ptr, long size)
338 {
339 while (size--)
340 if (isalnum(*(ptr++)))
341 return 1;
342 return 0;
343 }
344
345 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
346 {
347 for (; chg; chg--, i++)
348 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
349 xe->xdf2.recs[i]->size))
350 return 1;
351 return 0;
352 }
353
354 /*
355 * This function merges m and m->next, marking everything between those hunks
356 * as conflicting, too.
357 */
358 static void xdl_merge_two_conflicts(xdmerge_t *m)
359 {
360 xdmerge_t *next_m = m->next;
361 m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
362 m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
363 m->next = next_m->next;
364 free(next_m);
365 }
366
367 /*
368 * If there are less than 3 non-conflicting lines between conflicts,
369 * it appears simpler -- because it takes up less (or as many) lines --
370 * if the lines are moved into the conflicts.
371 */
372 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
373 int simplify_if_no_alnum)
374 {
375 int result = 0;
376
377 if (!m)
378 return result;
379 for (;;) {
380 xdmerge_t *next_m = m->next;
381 int begin, end;
382
383 if (!next_m)
384 return result;
385
386 begin = m->i1 + m->chg1;
387 end = next_m->i1;
388
389 if (m->mode != 0 || next_m->mode != 0 ||
390 (end - begin > 3 &&
391 (!simplify_if_no_alnum ||
392 lines_contain_alnum(xe1, begin, end - begin)))) {
393 m = next_m;
394 } else {
395 result++;
396 xdl_merge_two_conflicts(m);
397 }
398 }
399 }
400
401 /*
402 * level == 0: mark all overlapping changes as conflict
403 * level == 1: mark overlapping changes as conflict only if not identical
404 * level == 2: analyze non-identical changes for minimal conflict set
405 * level == 3: analyze non-identical changes for minimal conflict set, but
406 * treat hunks not containing any letter or number as conflicting
407 *
408 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
409 */
410 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
411 xdfenv_t *xe2, xdchange_t *xscr2,
412 xmparam_t const *xmp, mmbuffer_t *result)
413 {
414 xdmerge_t *changes, *c;
415 xpparam_t const *xpp = &xmp->xpp;
416 const char *const ancestor_name = xmp->ancestor;
417 const char *const name1 = xmp->file1;
418 const char *const name2 = xmp->file2;
419 int i0, i1, i2, chg0, chg1, chg2;
420 int level = xmp->level;
421 int style = xmp->style;
422 int favor = xmp->favor;
423
424 if (style == XDL_MERGE_DIFF3) {
425 /*
426 * "diff3 -m" output does not make sense for anything
427 * more aggressive than XDL_MERGE_EAGER.
428 */
429 if (XDL_MERGE_EAGER < level)
430 level = XDL_MERGE_EAGER;
431 }
432
433 c = changes = NULL;
434
435 while (xscr1 && xscr2) {
436 if (!changes)
437 changes = c;
438 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
439 i0 = xscr1->i1;
440 i1 = xscr1->i2;
441 i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
442 chg0 = xscr1->chg1;
443 chg1 = xscr1->chg2;
444 chg2 = xscr1->chg1;
445 if (xdl_append_merge(&c, 1,
446 i0, chg0, i1, chg1, i2, chg2)) {
447 xdl_cleanup_merge(changes);
448 return -1;
449 }
450 xscr1 = xscr1->next;
451 continue;
452 }
453 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
454 i0 = xscr2->i1;
455 i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
456 i2 = xscr2->i2;
457 chg0 = xscr2->chg1;
458 chg1 = xscr2->chg1;
459 chg2 = xscr2->chg2;
460 if (xdl_append_merge(&c, 2,
461 i0, chg0, i1, chg1, i2, chg2)) {
462 xdl_cleanup_merge(changes);
463 return -1;
464 }
465 xscr2 = xscr2->next;
466 continue;
467 }
468 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
469 xscr1->chg1 != xscr2->chg1 ||
470 xscr1->chg2 != xscr2->chg2 ||
471 xdl_merge_cmp_lines(xe1, xscr1->i2,
472 xe2, xscr2->i2,
473 xscr1->chg2, xpp->flags)) {
474 /* conflict */
475 int off = xscr1->i1 - xscr2->i1;
476 int ffo = off + xscr1->chg1 - xscr2->chg1;
477
478 i0 = xscr1->i1;
479 i1 = xscr1->i2;
480 i2 = xscr2->i2;
481 if (off > 0) {
482 i0 -= off;
483 i1 -= off;
484 }
485 else
486 i2 += off;
487 chg0 = xscr1->i1 + xscr1->chg1 - i0;
488 chg1 = xscr1->i2 + xscr1->chg2 - i1;
489 chg2 = xscr2->i2 + xscr2->chg2 - i2;
490 if (ffo < 0) {
491 chg0 -= ffo;
492 chg1 -= ffo;
493 } else
494 chg2 += ffo;
495 if (xdl_append_merge(&c, 0,
496 i0, chg0, i1, chg1, i2, chg2)) {
497 xdl_cleanup_merge(changes);
498 return -1;
499 }
500 }
501
502 i1 = xscr1->i1 + xscr1->chg1;
503 i2 = xscr2->i1 + xscr2->chg1;
504
505 if (i1 >= i2)
506 xscr2 = xscr2->next;
507 if (i2 >= i1)
508 xscr1 = xscr1->next;
509 }
510 while (xscr1) {
511 if (!changes)
512 changes = c;
513 i0 = xscr1->i1;
514 i1 = xscr1->i2;
515 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
516 chg0 = xscr1->chg1;
517 chg1 = xscr1->chg2;
518 chg2 = xscr1->chg1;
519 if (xdl_append_merge(&c, 1,
520 i0, chg0, i1, chg1, i2, chg2)) {
521 xdl_cleanup_merge(changes);
522 return -1;
523 }
524 xscr1 = xscr1->next;
525 }
526 while (xscr2) {
527 if (!changes)
528 changes = c;
529 i0 = xscr2->i1;
530 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
531 i2 = xscr2->i2;
532 chg0 = xscr2->chg1;
533 chg1 = xscr2->chg1;
534 chg2 = xscr2->chg2;
535 if (xdl_append_merge(&c, 2,
536 i0, chg0, i1, chg1, i2, chg2)) {
537 xdl_cleanup_merge(changes);
538 return -1;
539 }
540 xscr2 = xscr2->next;
541 }
542 if (!changes)
543 changes = c;
544 /* refine conflicts */
545 if (XDL_MERGE_ZEALOUS <= level &&
546 (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
547 xdl_simplify_non_conflicts(xe1, changes,
548 XDL_MERGE_ZEALOUS < level) < 0)) {
549 xdl_cleanup_merge(changes);
550 return -1;
551 }
552 /* output */
553 if (result) {
554 int marker_size = xmp->marker_size;
555 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
556 ancestor_name,
557 favor, changes, NULL, style,
558 marker_size);
559 result->ptr = xdl_malloc(size);
560 if (!result->ptr) {
561 xdl_cleanup_merge(changes);
562 return -1;
563 }
564 result->size = size;
565 xdl_fill_merge_buffer(xe1, name1, xe2, name2,
566 ancestor_name, favor, changes,
567 result->ptr, style, marker_size);
568 }
569 return xdl_cleanup_merge(changes);
570 }
571
572 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
573 xmparam_t const *xmp, mmbuffer_t *result)
574 {
575 xdchange_t *xscr1, *xscr2;
576 xdfenv_t xe1, xe2;
577 int status;
578 xpparam_t const *xpp = &xmp->xpp;
579
580 result->ptr = NULL;
581 result->size = 0;
582
583 if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
584 xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
585 return -1;
586 }
587 if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
588 xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
589 xdl_build_script(&xe1, &xscr1) < 0) {
590 xdl_free_env(&xe1);
591 return -1;
592 }
593 if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
594 xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
595 xdl_build_script(&xe2, &xscr2) < 0) {
596 xdl_free_env(&xe2);
597 return -1;
598 }
599 status = 0;
600 if (!xscr1) {
601 result->ptr = xdl_malloc(mf2->size);
602 memcpy(result->ptr, mf2->ptr, mf2->size);
603 result->size = mf2->size;
604 } else if (!xscr2) {
605 result->ptr = xdl_malloc(mf1->size);
606 memcpy(result->ptr, mf1->ptr, mf1->size);
607 result->size = mf1->size;
608 } else {
609 status = xdl_do_merge(&xe1, xscr1,
610 &xe2, xscr2,
611 xmp, result);
612 }
613 xdl_free_script(xscr1);
614 xdl_free_script(xscr2);
615
616 xdl_free_env(&xe1);
617 xdl_free_env(&xe2);
618
619 return status;
620 }
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