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Merge branch 'master' of git://repo.or.cz/alt-git
[git/dscho.git] / xdiff / xmerge.c
blob8cbe45e6755487dbe3759398375a11d05f6d91bc
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 */
32 int mode;
33 /*
34 * These point at the respective postimages. E.g. <i1,chg1> is
35 * how side #1 wants to change the common ancestor; if there is no
36 * overlap, lines before i1 in the postimage of side #1 appear
37 * in the merge result as a region touched by neither side.
38 */
39 long i1, i2;
40 long chg1, chg2;
41 /*
42 * These point at the preimage; of course there is just one
43 * preimage, that is from the shared common ancestor.
44 */
45 long i0;
46 long chg0;
47 } xdmerge_t;
48
49 static int xdl_append_merge(xdmerge_t **merge, int mode,
50 long i0, long chg0,
51 long i1, long chg1,
52 long i2, long chg2)
53 {
54 xdmerge_t *m = *merge;
55 if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
56 if (mode != m->mode)
57 m->mode = 0;
58 m->chg0 = i0 + chg0 - m->i0;
59 m->chg1 = i1 + chg1 - m->i1;
60 m->chg2 = i2 + chg2 - m->i2;
61 } else {
62 m = xdl_malloc(sizeof(xdmerge_t));
63 if (!m)
64 return -1;
65 m->next = NULL;
66 m->mode = mode;
67 m->i0 = i0;
68 m->chg0 = chg0;
69 m->i1 = i1;
70 m->chg1 = chg1;
71 m->i2 = i2;
72 m->chg2 = chg2;
73 if (*merge)
74 (*merge)->next = m;
75 *merge = m;
76 }
77 return 0;
78 }
79
80 static int xdl_cleanup_merge(xdmerge_t *c)
81 {
82 int count = 0;
83 xdmerge_t *next_c;
84
85 /* were there conflicts? */
86 for (; c; c = next_c) {
87 if (c->mode == 0)
88 count++;
89 next_c = c->next;
90 free(c);
91 }
92 return count;
93 }
94
95 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
96 int line_count, long flags)
97 {
98 int i;
99 xrecord_t **rec1 = xe1->xdf2.recs + i1;
100 xrecord_t **rec2 = xe2->xdf2.recs + i2;
101
102 for (i = 0; i < line_count; i++) {
103 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
104 rec2[i]->ptr, rec2[i]->size, flags);
105 if (!result)
106 return -1;
107 }
108 return 0;
109 }
110
111 static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int add_nl, char *dest)
112 {
113 xrecord_t **recs;
114 int size = 0;
115
116 recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
117
118 if (count < 1)
119 return 0;
120
121 for (i = 0; i < count; size += recs[i++]->size)
122 if (dest)
123 memcpy(dest + size, recs[i]->ptr, recs[i]->size);
124 if (add_nl) {
125 i = recs[count - 1]->size;
126 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
127 if (dest)
128 dest[size] = '\n';
129 size++;
130 }
131 }
132 return size;
133 }
134
135 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
136 {
137 return xdl_recs_copy_0(0, xe, i, count, add_nl, dest);
138 }
139
140 static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
141 {
142 return xdl_recs_copy_0(1, xe, i, count, add_nl, dest);
143 }
144
145 static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
146 xdfenv_t *xe2, const char *name2,
147 int size, int i, int style,
148 xdmerge_t *m, char *dest, int marker_size)
149 {
150 int marker1_size = (name1 ? strlen(name1) + 1 : 0);
151 int marker2_size = (name2 ? strlen(name2) + 1 : 0);
152 int j;
153
154 if (marker_size <= 0)
155 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
156
157 /* Before conflicting part */
158 size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
159 dest ? dest + size : NULL);
160
161 if (!dest) {
162 size += marker_size + 1 + marker1_size;
163 } else {
164 for (j = 0; j < marker_size; j++)
165 dest[size++] = '<';
166 if (marker1_size) {
167 dest[size] = ' ';
168 memcpy(dest + size + 1, name1, marker1_size - 1);
169 size += marker1_size;
170 }
171 dest[size++] = '\n';
172 }
173
174 /* Postimage from side #1 */
175 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
176 dest ? dest + size : NULL);
177
178 if (style == XDL_MERGE_DIFF3) {
179 /* Shared preimage */
180 if (!dest) {
181 size += marker_size + 1;
182 } else {
183 for (j = 0; j < marker_size; j++)
184 dest[size++] = '|';
185 dest[size++] = '\n';
186 }
187 size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
188 dest ? dest + size : NULL);
189 }
190
191 if (!dest) {
192 size += marker_size + 1;
193 } else {
194 for (j = 0; j < marker_size; j++)
195 dest[size++] = '=';
196 dest[size++] = '\n';
197 }
198
199 /* Postimage from side #2 */
200 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
201 dest ? dest + size : NULL);
202 if (!dest) {
203 size += marker_size + 1 + marker2_size;
204 } else {
205 for (j = 0; j < marker_size; j++)
206 dest[size++] = '>';
207 if (marker2_size) {
208 dest[size] = ' ';
209 memcpy(dest + size + 1, name2, marker2_size - 1);
210 size += marker2_size;
211 }
212 dest[size++] = '\n';
213 }
214 return size;
215 }
216
217 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
218 xdfenv_t *xe2, const char *name2,
219 int favor,
220 xdmerge_t *m, char *dest, int style,
221 int marker_size)
222 {
223 int size, i;
224
225 for (size = i = 0; m; m = m->next) {
226 if (favor && !m->mode)
227 m->mode = favor;
228
229 if (m->mode == 0)
230 size = fill_conflict_hunk(xe1, name1, xe2, name2,
231 size, i, style, m, dest,
232 marker_size);
233 else if (m->mode == 1)
234 size += xdl_recs_copy(xe1, i, m->i1 + m->chg1 - i, 0,
235 dest ? dest + size : NULL);
236 else if (m->mode == 2)
237 size += xdl_recs_copy(xe2, m->i2 - m->i1 + i,
238 m->i1 + m->chg2 - i, 0,
239 dest ? dest + size : NULL);
240 else
241 continue;
242 i = m->i1 + m->chg1;
243 }
244 size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
245 dest ? dest + size : NULL);
246 return size;
247 }
248
249 /*
250 * Sometimes, changes are not quite identical, but differ in only a few
251 * lines. Try hard to show only these few lines as conflicting.
252 */
253 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
254 xpparam_t const *xpp)
255 {
256 for (; m; m = m->next) {
257 mmfile_t t1, t2;
258 xdfenv_t xe;
259 xdchange_t *xscr, *x;
260 int i1 = m->i1, i2 = m->i2;
261
262 /* let's handle just the conflicts */
263 if (m->mode)
264 continue;
265
266 /* no sense refining a conflict when one side is empty */
267 if (m->chg1 == 0 || m->chg2 == 0)
268 continue;
269
270 /*
271 * This probably does not work outside git, since
272 * we have a very simple mmfile structure.
273 */
274 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
275 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
276 + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
277 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
278 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
279 + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
280 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
281 return -1;
282 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
283 xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
284 xdl_build_script(&xe, &xscr) < 0) {
285 xdl_free_env(&xe);
286 return -1;
287 }
288 if (!xscr) {
289 /* If this happens, the changes are identical. */
290 xdl_free_env(&xe);
291 m->mode = 4;
292 continue;
293 }
294 x = xscr;
295 m->i1 = xscr->i1 + i1;
296 m->chg1 = xscr->chg1;
297 m->i2 = xscr->i2 + i2;
298 m->chg2 = xscr->chg2;
299 while (xscr->next) {
300 xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
301 if (!m2) {
302 xdl_free_env(&xe);
303 xdl_free_script(x);
304 return -1;
305 }
306 xscr = xscr->next;
307 m2->next = m->next;
308 m->next = m2;
309 m = m2;
310 m->mode = 0;
311 m->i1 = xscr->i1 + i1;
312 m->chg1 = xscr->chg1;
313 m->i2 = xscr->i2 + i2;
314 m->chg2 = xscr->chg2;
315 }
316 xdl_free_env(&xe);
317 xdl_free_script(x);
318 }
319 return 0;
320 }
321
322 static int line_contains_alnum(const char *ptr, long size)
323 {
324 while (size--)
325 if (isalnum(*(ptr++)))
326 return 1;
327 return 0;
328 }
329
330 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
331 {
332 for (; chg; chg--, i++)
333 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
334 xe->xdf2.recs[i]->size))
335 return 1;
336 return 0;
337 }
338
339 /*
340 * This function merges m and m->next, marking everything between those hunks
341 * as conflicting, too.
342 */
343 static void xdl_merge_two_conflicts(xdmerge_t *m)
344 {
345 xdmerge_t *next_m = m->next;
346 m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
347 m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
348 m->next = next_m->next;
349 free(next_m);
350 }
351
352 /*
353 * If there are less than 3 non-conflicting lines between conflicts,
354 * it appears simpler -- because it takes up less (or as many) lines --
355 * if the lines are moved into the conflicts.
356 */
357 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
358 int simplify_if_no_alnum)
359 {
360 int result = 0;
361
362 if (!m)
363 return result;
364 for (;;) {
365 xdmerge_t *next_m = m->next;
366 int begin, end;
367
368 if (!next_m)
369 return result;
370
371 begin = m->i1 + m->chg1;
372 end = next_m->i1;
373
374 if (m->mode != 0 || next_m->mode != 0 ||
375 (end - begin > 3 &&
376 (!simplify_if_no_alnum ||
377 lines_contain_alnum(xe1, begin, end - begin)))) {
378 m = next_m;
379 } else {
380 result++;
381 xdl_merge_two_conflicts(m);
382 }
383 }
384 }
385
386 /*
387 * level == 0: mark all overlapping changes as conflict
388 * level == 1: mark overlapping changes as conflict only if not identical
389 * level == 2: analyze non-identical changes for minimal conflict set
390 * level == 3: analyze non-identical changes for minimal conflict set, but
391 * treat hunks not containing any letter or number as conflicting
392 *
393 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
394 */
395 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
396 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
397 int flags, xmparam_t const *xmp, mmbuffer_t *result) {
398 xdmerge_t *changes, *c;
399 xpparam_t const *xpp = &xmp->xpp;
400 int i0, i1, i2, chg0, chg1, chg2;
401 int level = flags & XDL_MERGE_LEVEL_MASK;
402 int style = flags & XDL_MERGE_STYLE_MASK;
403 int favor = XDL_MERGE_FAVOR(flags);
404
405 if (style == XDL_MERGE_DIFF3) {
406 /*
407 * "diff3 -m" output does not make sense for anything
408 * more aggressive than XDL_MERGE_EAGER.
409 */
410 if (XDL_MERGE_EAGER < level)
411 level = XDL_MERGE_EAGER;
412 }
413
414 c = changes = NULL;
415
416 while (xscr1 && xscr2) {
417 if (!changes)
418 changes = c;
419 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
420 i0 = xscr1->i1;
421 i1 = xscr1->i2;
422 i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
423 chg0 = xscr1->chg1;
424 chg1 = xscr1->chg2;
425 chg2 = xscr1->chg1;
426 if (xdl_append_merge(&c, 1,
427 i0, chg0, i1, chg1, i2, chg2)) {
428 xdl_cleanup_merge(changes);
429 return -1;
430 }
431 xscr1 = xscr1->next;
432 continue;
433 }
434 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
435 i0 = xscr2->i1;
436 i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
437 i2 = xscr2->i2;
438 chg0 = xscr2->chg1;
439 chg1 = xscr2->chg1;
440 chg2 = xscr2->chg2;
441 if (xdl_append_merge(&c, 2,
442 i0, chg0, i1, chg1, i2, chg2)) {
443 xdl_cleanup_merge(changes);
444 return -1;
445 }
446 xscr2 = xscr2->next;
447 continue;
448 }
449 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
450 xscr1->chg1 != xscr2->chg1 ||
451 xscr1->chg2 != xscr2->chg2 ||
452 xdl_merge_cmp_lines(xe1, xscr1->i2,
453 xe2, xscr2->i2,
454 xscr1->chg2, xpp->flags)) {
455 /* conflict */
456 int off = xscr1->i1 - xscr2->i1;
457 int ffo = off + xscr1->chg1 - xscr2->chg1;
458
459 i0 = xscr1->i1;
460 i1 = xscr1->i2;
461 i2 = xscr2->i2;
462 if (off > 0) {
463 i0 -= off;
464 i1 -= off;
465 }
466 else
467 i2 += off;
468 chg0 = xscr1->i1 + xscr1->chg1 - i0;
469 chg1 = xscr1->i2 + xscr1->chg2 - i1;
470 chg2 = xscr2->i2 + xscr2->chg2 - i2;
471 if (ffo < 0) {
472 chg0 -= ffo;
473 chg1 -= ffo;
474 } else
475 chg2 += ffo;
476 if (xdl_append_merge(&c, 0,
477 i0, chg0, i1, chg1, i2, chg2)) {
478 xdl_cleanup_merge(changes);
479 return -1;
480 }
481 }
482
483 i1 = xscr1->i1 + xscr1->chg1;
484 i2 = xscr2->i1 + xscr2->chg1;
485
486 if (i1 >= i2)
487 xscr2 = xscr2->next;
488 if (i2 >= i1)
489 xscr1 = xscr1->next;
490 }
491 while (xscr1) {
492 if (!changes)
493 changes = c;
494 i0 = xscr1->i1;
495 i1 = xscr1->i2;
496 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
497 chg0 = xscr1->chg1;
498 chg1 = xscr1->chg2;
499 chg2 = xscr1->chg1;
500 if (xdl_append_merge(&c, 1,
501 i0, chg0, i1, chg1, i2, chg2)) {
502 xdl_cleanup_merge(changes);
503 return -1;
504 }
505 xscr1 = xscr1->next;
506 }
507 while (xscr2) {
508 if (!changes)
509 changes = c;
510 i0 = xscr2->i1;
511 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
512 i2 = xscr2->i2;
513 chg0 = xscr2->chg1;
514 chg1 = xscr2->chg1;
515 chg2 = xscr2->chg2;
516 if (xdl_append_merge(&c, 2,
517 i0, chg0, i1, chg1, i2, chg2)) {
518 xdl_cleanup_merge(changes);
519 return -1;
520 }
521 xscr2 = xscr2->next;
522 }
523 if (!changes)
524 changes = c;
525 /* refine conflicts */
526 if (XDL_MERGE_ZEALOUS <= level &&
527 (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
528 xdl_simplify_non_conflicts(xe1, changes,
529 XDL_MERGE_ZEALOUS < level) < 0)) {
530 xdl_cleanup_merge(changes);
531 return -1;
532 }
533 /* output */
534 if (result) {
535 int marker_size = xmp->marker_size;
536 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
537 favor, changes, NULL, style,
538 marker_size);
539 result->ptr = xdl_malloc(size);
540 if (!result->ptr) {
541 xdl_cleanup_merge(changes);
542 return -1;
543 }
544 result->size = size;
545 xdl_fill_merge_buffer(xe1, name1, xe2, name2, favor, changes,
546 result->ptr, style, marker_size);
547 }
548 return xdl_cleanup_merge(changes);
549 }
550
551 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
552 mmfile_t *mf2, const char *name2,
553 xmparam_t const *xmp, int flags, mmbuffer_t *result) {
554 xdchange_t *xscr1, *xscr2;
555 xdfenv_t xe1, xe2;
556 int status;
557 xpparam_t const *xpp = &xmp->xpp;
558
559 result->ptr = NULL;
560 result->size = 0;
561
562 if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
563 xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
564 return -1;
565 }
566 if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
567 xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
568 xdl_build_script(&xe1, &xscr1) < 0) {
569 xdl_free_env(&xe1);
570 return -1;
571 }
572 if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
573 xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
574 xdl_build_script(&xe2, &xscr2) < 0) {
575 xdl_free_env(&xe2);
576 return -1;
577 }
578 status = 0;
579 if (!xscr1) {
580 result->ptr = xdl_malloc(mf2->size);
581 memcpy(result->ptr, mf2->ptr, mf2->size);
582 result->size = mf2->size;
583 } else if (!xscr2) {
584 result->ptr = xdl_malloc(mf1->size);
585 memcpy(result->ptr, mf1->ptr, mf1->size);
586 result->size = mf1->size;
587 } else {
588 status = xdl_do_merge(&xe1, xscr1, name1,
589 &xe2, xscr2, name2,
590 flags, xmp, result);
591 }
592 xdl_free_script(xscr1);
593 xdl_free_script(xscr2);
594
595 xdl_free_env(&xe1);
596 xdl_free_env(&xe2);
597
598 return status;
599 }
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