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          * 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                               int size, int i, int style,
 149                               xdmerge_t *m, char *dest, int marker_size)
 150 {
 151         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 152         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 153         int j;
 154
 155         if (marker_size <= 0)
 156                 marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 157
 158         /* Before conflicting part */
 159         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 160                               dest ? dest + size : NULL);
 161
 162         if (!dest) {
 163                 size += marker_size + 1 + marker1_size;
 164         } else {
 165                 for (j = 0; j < marker_size; j++)
 166                         dest[size++] = '<';
 167                 if (marker1_size) {
 168                         dest[size] = ' ';
 169                         memcpy(dest + size + 1, name1, marker1_size - 1);
 170                         size += marker1_size;
 171                 }
 172                 dest[size++] = '\n';
 173         }
 174
 175         /* Postimage from side #1 */
 176         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 177                               dest ? dest + size : NULL);
 178
 179         if (style == XDL_MERGE_DIFF3) {
 180                 /* Shared preimage */
 181                 if (!dest) {
 182                         size += marker_size + 1;
 183                 } else {
 184                         for (j = 0; j < marker_size; j++)
 185                                 dest[size++] = '|';
 186                         dest[size++] = '\n';
 187                 }
 188                 size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
 189                                       dest ? dest + size : NULL);
 190         }
 191
 192         if (!dest) {
 193                 size += marker_size + 1;
 194         } else {
 195                 for (j = 0; j < marker_size; j++)
 196                         dest[size++] = '=';
 197                 dest[size++] = '\n';
 198         }
 199
 200         /* Postimage from side #2 */
 201         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 202                               dest ? dest + size : NULL);
 203         if (!dest) {
 204                 size += marker_size + 1 + marker2_size;
 205         } else {
 206                 for (j = 0; j < marker_size; j++)
 207                         dest[size++] = '>';
 208                 if (marker2_size) {
 209                         dest[size] = ' ';
 210                         memcpy(dest + size + 1, name2, marker2_size - 1);
 211                         size += marker2_size;
 212                 }
 213                 dest[size++] = '\n';
 214         }
 215         return size;
 216 }
 217
 218 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 219                                  xdfenv_t *xe2, const char *name2,
 220                                  int favor,
 221                                  xdmerge_t *m, char *dest, int style,
 222                                  int marker_size)
 223 {
 224         int size, i;
 225
 226         for (size = i = 0; m; m = m->next) {
 227                 if (favor && !m->mode)
 228                         m->mode = favor;
 229
 230                 if (m->mode == 0)
 231                         size = fill_conflict_hunk(xe1, name1, xe2, name2,
 232                                                   size, i, style, m, dest,
 233                                                   marker_size);
 234                 else if (m->mode & 3) {
 235                         /* Before conflicting part */
 236                         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 237                                               dest ? dest + size : NULL);
 238                         /* Postimage from side #1 */
 239                         if (m->mode & 1)
 240                                 size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 241                                                       dest ? dest + size : NULL);
 242                         /* Postimage from side #2 */
 243                         if (m->mode & 2)
 244                                 size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 245                                                       dest ? dest + size : NULL);
 246                 } else
 247                         continue;
 248                 i = m->i1 + m->chg1;
 249         }
 250         size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 251                               dest ? dest + size : NULL);
 252         return size;
 253 }
 254
 255 /*
 256  * Sometimes, changes are not quite identical, but differ in only a few
 257  * lines. Try hard to show only these few lines as conflicting.
 258  */
 259 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 260                 xpparam_t const *xpp)
 261 {
 262         for (; m; m = m->next) {
 263                 mmfile_t t1, t2;
 264                 xdfenv_t xe;
 265                 xdchange_t *xscr, *x;
 266                 int i1 = m->i1, i2 = m->i2;
 267
 268                 /* let's handle just the conflicts */
 269                 if (m->mode)
 270                         continue;
 271
 272                 /* no sense refining a conflict when one side is empty */
 273                 if (m->chg1 == 0 || m->chg2 == 0)
 274                         continue;
 275
 276                 /*
 277                  * This probably does not work outside git, since
 278                  * we have a very simple mmfile structure.
 279                  */
 280                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 281                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 282                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 283                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 284                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 285                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 286                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 287                         return -1;
 288                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 289                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 290                     xdl_build_script(&xe, &xscr) < 0) {
 291                         xdl_free_env(&xe);
 292                         return -1;
 293                 }
 294                 if (!xscr) {
 295                         /* If this happens, the changes are identical. */
 296                         xdl_free_env(&xe);
 297                         m->mode = 4;
 298                         continue;
 299                 }
 300                 x = xscr;
 301                 m->i1 = xscr->i1 + i1;
 302                 m->chg1 = xscr->chg1;
 303                 m->i2 = xscr->i2 + i2;
 304                 m->chg2 = xscr->chg2;
 305                 while (xscr->next) {
 306                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 307                         if (!m2) {
 308                                 xdl_free_env(&xe);
 309                                 xdl_free_script(x);
 310                                 return -1;
 311                         }
 312                         xscr = xscr->next;
 313                         m2->next = m->next;
 314                         m->next = m2;
 315                         m = m2;
 316                         m->mode = 0;
 317                         m->i1 = xscr->i1 + i1;
 318                         m->chg1 = xscr->chg1;
 319                         m->i2 = xscr->i2 + i2;
 320                         m->chg2 = xscr->chg2;
 321                 }
 322                 xdl_free_env(&xe);
 323                 xdl_free_script(x);
 324         }
 325         return 0;
 326 }
 327
 328 static int line_contains_alnum(const char *ptr, long size)
 329 {
 330         while (size--)
 331                 if (isalnum(*(ptr++)))
 332                         return 1;
 333         return 0;
 334 }
 335
 336 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 337 {
 338         for (; chg; chg--, i++)
 339                 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 340                                 xe->xdf2.recs[i]->size))
 341                         return 1;
 342         return 0;
 343 }
 344
 345 /*
 346  * This function merges m and m->next, marking everything between those hunks
 347  * as conflicting, too.
 348  */
 349 static void xdl_merge_two_conflicts(xdmerge_t *m)
 350 {
 351         xdmerge_t *next_m = m->next;
 352         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 353         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 354         m->next = next_m->next;
 355         free(next_m);
 356 }
 357
 358 /*
 359  * If there are less than 3 non-conflicting lines between conflicts,
 360  * it appears simpler -- because it takes up less (or as many) lines --
 361  * if the lines are moved into the conflicts.
 362  */
 363 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 364                                       int simplify_if_no_alnum)
 365 {
 366         int result = 0;
 367
 368         if (!m)
 369                 return result;
 370         for (;;) {
 371                 xdmerge_t *next_m = m->next;
 372                 int begin, end;
 373
 374                 if (!next_m)
 375                         return result;
 376
 377                 begin = m->i1 + m->chg1;
 378                 end = next_m->i1;
 379
 380                 if (m->mode != 0 || next_m->mode != 0 ||
 381                     (end - begin > 3 &&
 382                      (!simplify_if_no_alnum ||
 383                       lines_contain_alnum(xe1, begin, end - begin)))) {
 384                         m = next_m;
 385                 } else {
 386                         result++;
 387                         xdl_merge_two_conflicts(m);
 388                 }
 389         }
 390 }
 391
 392 /*
 393  * level == 0: mark all overlapping changes as conflict
 394  * level == 1: mark overlapping changes as conflict only if not identical
 395  * level == 2: analyze non-identical changes for minimal conflict set
 396  * level == 3: analyze non-identical changes for minimal conflict set, but
 397  *             treat hunks not containing any letter or number as conflicting
 398  *
 399  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 400  */
 401 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 402                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 403                 int flags, xmparam_t const *xmp, mmbuffer_t *result) {
 404         xdmerge_t *changes, *c;
 405         xpparam_t const *xpp = &xmp->xpp;
 406         int i0, i1, i2, chg0, chg1, chg2;
 407         int level = flags & XDL_MERGE_LEVEL_MASK;
 408         int style = flags & XDL_MERGE_STYLE_MASK;
 409         int favor = XDL_MERGE_FAVOR(flags);
 410
 411         if (style == XDL_MERGE_DIFF3) {
 412                 /*
 413                  * "diff3 -m" output does not make sense for anything
 414                  * more aggressive than XDL_MERGE_EAGER.
 415                  */
 416                 if (XDL_MERGE_EAGER < level)
 417                         level = XDL_MERGE_EAGER;
 418         }
 419
 420         c = changes = NULL;
 421
 422         while (xscr1 && xscr2) {
 423                 if (!changes)
 424                         changes = c;
 425                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 426                         i0 = xscr1->i1;
 427                         i1 = xscr1->i2;
 428                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 429                         chg0 = xscr1->chg1;
 430                         chg1 = xscr1->chg2;
 431                         chg2 = xscr1->chg1;
 432                         if (xdl_append_merge(&c, 1,
 433                                              i0, chg0, i1, chg1, i2, chg2)) {
 434                                 xdl_cleanup_merge(changes);
 435                                 return -1;
 436                         }
 437                         xscr1 = xscr1->next;
 438                         continue;
 439                 }
 440                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 441                         i0 = xscr2->i1;
 442                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 443                         i2 = xscr2->i2;
 444                         chg0 = xscr2->chg1;
 445                         chg1 = xscr2->chg1;
 446                         chg2 = xscr2->chg2;
 447                         if (xdl_append_merge(&c, 2,
 448                                              i0, chg0, i1, chg1, i2, chg2)) {
 449                                 xdl_cleanup_merge(changes);
 450                                 return -1;
 451                         }
 452                         xscr2 = xscr2->next;
 453                         continue;
 454                 }
 455                 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 456                                 xscr1->chg1 != xscr2->chg1 ||
 457                                 xscr1->chg2 != xscr2->chg2 ||
 458                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 459                                         xe2, xscr2->i2,
 460                                         xscr1->chg2, xpp->flags)) {
 461                         /* conflict */
 462                         int off = xscr1->i1 - xscr2->i1;
 463                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 464
 465                         i0 = xscr1->i1;
 466                         i1 = xscr1->i2;
 467                         i2 = xscr2->i2;
 468                         if (off > 0) {
 469                                 i0 -= off;
 470                                 i1 -= off;
 471                         }
 472                         else
 473                                 i2 += off;
 474                         chg0 = xscr1->i1 + xscr1->chg1 - i0;
 475                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 476                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 477                         if (ffo < 0) {
 478                                 chg0 -= ffo;
 479                                 chg1 -= ffo;
 480                         } else
 481                                 chg2 += ffo;
 482                         if (xdl_append_merge(&c, 0,
 483                                              i0, chg0, i1, chg1, i2, chg2)) {
 484                                 xdl_cleanup_merge(changes);
 485                                 return -1;
 486                         }
 487                 }
 488
 489                 i1 = xscr1->i1 + xscr1->chg1;
 490                 i2 = xscr2->i1 + xscr2->chg1;
 491
 492                 if (i1 >= i2)
 493                         xscr2 = xscr2->next;
 494                 if (i2 >= i1)
 495                         xscr1 = xscr1->next;
 496         }
 497         while (xscr1) {
 498                 if (!changes)
 499                         changes = c;
 500                 i0 = xscr1->i1;
 501                 i1 = xscr1->i2;
 502                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 503                 chg0 = xscr1->chg1;
 504                 chg1 = xscr1->chg2;
 505                 chg2 = xscr1->chg1;
 506                 if (xdl_append_merge(&c, 1,
 507                                      i0, chg0, i1, chg1, i2, chg2)) {
 508                         xdl_cleanup_merge(changes);
 509                         return -1;
 510                 }
 511                 xscr1 = xscr1->next;
 512         }
 513         while (xscr2) {
 514                 if (!changes)
 515                         changes = c;
 516                 i0 = xscr2->i1;
 517                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 518                 i2 = xscr2->i2;
 519                 chg0 = xscr2->chg1;
 520                 chg1 = xscr2->chg1;
 521                 chg2 = xscr2->chg2;
 522                 if (xdl_append_merge(&c, 2,
 523                                      i0, chg0, i1, chg1, i2, chg2)) {
 524                         xdl_cleanup_merge(changes);
 525                         return -1;
 526                 }
 527                 xscr2 = xscr2->next;
 528         }
 529         if (!changes)
 530                 changes = c;
 531         /* refine conflicts */
 532         if (XDL_MERGE_ZEALOUS <= level &&
 533             (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 534              xdl_simplify_non_conflicts(xe1, changes,
 535                                         XDL_MERGE_ZEALOUS < level) < 0)) {
 536                 xdl_cleanup_merge(changes);
 537                 return -1;
 538         }
 539         /* output */
 540         if (result) {
 541                 int marker_size = xmp->marker_size;
 542                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 543                                                  favor, changes, NULL, style,
 544                                                  marker_size);
 545                 result->ptr = xdl_malloc(size);
 546                 if (!result->ptr) {
 547                         xdl_cleanup_merge(changes);
 548                         return -1;
 549                 }
 550                 result->size = size;
 551                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, favor, changes,
 552                                       result->ptr, style, marker_size);
 553         }
 554         return xdl_cleanup_merge(changes);
 555 }
 556
 557 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 558                 mmfile_t *mf2, const char *name2,
 559                 xmparam_t const *xmp, int flags, mmbuffer_t *result) {
 560         xdchange_t *xscr1, *xscr2;
 561         xdfenv_t xe1, xe2;
 562         int status;
 563         xpparam_t const *xpp = &xmp->xpp;
 564
 565         result->ptr = NULL;
 566         result->size = 0;
 567
 568         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 569                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 570                 return -1;
 571         }
 572         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 573             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 574             xdl_build_script(&xe1, &xscr1) < 0) {
 575                 xdl_free_env(&xe1);
 576                 return -1;
 577         }
 578         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 579             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 580             xdl_build_script(&xe2, &xscr2) < 0) {
 581                 xdl_free_env(&xe2);
 582                 return -1;
 583         }
 584         status = 0;
 585         if (!xscr1) {
 586                 result->ptr = xdl_malloc(mf2->size);
 587                 memcpy(result->ptr, mf2->ptr, mf2->size);
 588                 result->size = mf2->size;
 589         } else if (!xscr2) {
 590                 result->ptr = xdl_malloc(mf1->size);
 591                 memcpy(result->ptr, mf1->ptr, mf1->size);
 592                 result->size = mf1->size;
 593         } else {
 594                 status = xdl_do_merge(&xe1, xscr1, name1,
 595                                       &xe2, xscr2, name2,
 596                                       flags, xmp, result);
 597         }
 598         xdl_free_script(xscr1);
 599         xdl_free_script(xscr2);
 600
 601         xdl_free_env(&xe1);
 602         xdl_free_env(&xe2);
 603
 604         return status;
 605 }