Merge "Move 'builtin-*' into a 'builtin/' subdirectory"
[git] / xdiff / xmerge.c
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 }