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 }