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)
 149 {
 150         const int marker_size = 7;
 151         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 152         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 153         int j;
 154
 155         /* Before conflicting part */
 156         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 157                               dest ? dest + size : NULL);
 158
 159         if (!dest) {
 160                 size += marker_size + 1 + marker1_size;
 161         } else {
 162                 for (j = 0; j < marker_size; j++)
 163                         dest[size++] = '<';
 164                 if (marker1_size) {
 165                         dest[size] = ' ';
 166                         memcpy(dest + size + 1, name1, marker1_size - 1);
 167                         size += marker1_size;
 168                 }
 169                 dest[size++] = '\n';
 170         }
 171
 172         /* Postimage from side #1 */
 173         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 174                               dest ? dest + size : NULL);
 175
 176         if (style == XDL_MERGE_DIFF3) {
 177                 /* Shared preimage */
 178                 if (!dest) {
 179                         size += marker_size + 1;
 180                 } else {
 181                         for (j = 0; j < marker_size; j++)
 182                                 dest[size++] = '|';
 183                         dest[size++] = '\n';
 184                 }
 185                 size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
 186                                       dest ? dest + size : NULL);
 187         }
 188
 189         if (!dest) {
 190                 size += marker_size + 1;
 191         } else {
 192                 for (j = 0; j < marker_size; j++)
 193                         dest[size++] = '=';
 194                 dest[size++] = '\n';
 195         }
 196
 197         /* Postimage from side #2 */
 198         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 199                               dest ? dest + size : NULL);
 200         if (!dest) {
 201                 size += marker_size + 1 + marker2_size;
 202         } else {
 203                 for (j = 0; j < marker_size; j++)
 204                         dest[size++] = '>';
 205                 if (marker2_size) {
 206                         dest[size] = ' ';
 207                         memcpy(dest + size + 1, name2, marker2_size - 1);
 208                         size += marker2_size;
 209                 }
 210                 dest[size++] = '\n';
 211         }
 212         return size;
 213 }
 214
 215 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 216                                  xdfenv_t *xe2, const char *name2,
 217                                  xdmerge_t *m, char *dest, int style)
 218 {
 219         int size, i;
 220
 221         for (size = i = 0; m; m = m->next) {
 222                 if (m->mode == 0)
 223                         size = fill_conflict_hunk(xe1, name1, xe2, name2,
 224                                                   size, i, style, m, dest);
 225                 else if (m->mode == 1)
 226                         size += xdl_recs_copy(xe1, i, m->i1 + m->chg1 - i, 0,
 227                                               dest ? dest + size : NULL);
 228                 else if (m->mode == 2)
 229                         size += xdl_recs_copy(xe2, m->i2 - m->i1 + i,
 230                                               m->i1 + m->chg2 - i, 0,
 231                                               dest ? dest + size : NULL);
 232                 else
 233                         continue;
 234                 i = m->i1 + m->chg1;
 235         }
 236         size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 237                               dest ? dest + size : NULL);
 238         return size;
 239 }
 240
 241 /*
 242  * Sometimes, changes are not quite identical, but differ in only a few
 243  * lines. Try hard to show only these few lines as conflicting.
 244  */
 245 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 246                 xpparam_t const *xpp)
 247 {
 248         for (; m; m = m->next) {
 249                 mmfile_t t1, t2;
 250                 xdfenv_t xe;
 251                 xdchange_t *xscr, *x;
 252                 int i1 = m->i1, i2 = m->i2;
 253
 254                 /* let's handle just the conflicts */
 255                 if (m->mode)
 256                         continue;
 257
 258                 /* no sense refining a conflict when one side is empty */
 259                 if (m->chg1 == 0 || m->chg2 == 0)
 260                         continue;
 261
 262                 /*
 263                  * This probably does not work outside git, since
 264                  * we have a very simple mmfile structure.
 265                  */
 266                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 267                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 268                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 269                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 270                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 271                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 272                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 273                         return -1;
 274                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 275                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 276                     xdl_build_script(&xe, &xscr) < 0) {
 277                         xdl_free_env(&xe);
 278                         return -1;
 279                 }
 280                 if (!xscr) {
 281                         /* If this happens, the changes are identical. */
 282                         xdl_free_env(&xe);
 283                         m->mode = 4;
 284                         continue;
 285                 }
 286                 x = xscr;
 287                 m->i1 = xscr->i1 + i1;
 288                 m->chg1 = xscr->chg1;
 289                 m->i2 = xscr->i2 + i2;
 290                 m->chg2 = xscr->chg2;
 291                 while (xscr->next) {
 292                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 293                         if (!m2) {
 294                                 xdl_free_env(&xe);
 295                                 xdl_free_script(x);
 296                                 return -1;
 297                         }
 298                         xscr = xscr->next;
 299                         m2->next = m->next;
 300                         m->next = m2;
 301                         m = m2;
 302                         m->mode = 0;
 303                         m->i1 = xscr->i1 + i1;
 304                         m->chg1 = xscr->chg1;
 305                         m->i2 = xscr->i2 + i2;
 306                         m->chg2 = xscr->chg2;
 307                 }
 308                 xdl_free_env(&xe);
 309                 xdl_free_script(x);
 310         }
 311         return 0;
 312 }
 313
 314 static int line_contains_alnum(const char *ptr, long size)
 315 {
 316         while (size--)
 317                 if (isalnum(*(ptr++)))
 318                         return 1;
 319         return 0;
 320 }
 321
 322 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 323 {
 324         for (; chg; chg--, i++)
 325                 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 326                                 xe->xdf2.recs[i]->size))
 327                         return 1;
 328         return 0;
 329 }
 330
 331 /*
 332  * This function merges m and m->next, marking everything between those hunks
 333  * as conflicting, too.
 334  */
 335 static void xdl_merge_two_conflicts(xdmerge_t *m)
 336 {
 337         xdmerge_t *next_m = m->next;
 338         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 339         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 340         m->next = next_m->next;
 341         free(next_m);
 342 }
 343
 344 /*
 345  * If there are less than 3 non-conflicting lines between conflicts,
 346  * it appears simpler -- because it takes up less (or as many) lines --
 347  * if the lines are moved into the conflicts.
 348  */
 349 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 350                                       int simplify_if_no_alnum)
 351 {
 352         int result = 0;
 353
 354         if (!m)
 355                 return result;
 356         for (;;) {
 357                 xdmerge_t *next_m = m->next;
 358                 int begin, end;
 359
 360                 if (!next_m)
 361                         return result;
 362
 363                 begin = m->i1 + m->chg1;
 364                 end = next_m->i1;
 365
 366                 if (m->mode != 0 || next_m->mode != 0 ||
 367                     (end - begin > 3 &&
 368                      (!simplify_if_no_alnum ||
 369                       lines_contain_alnum(xe1, begin, end - begin)))) {
 370                         m = next_m;
 371                 } else {
 372                         result++;
 373                         xdl_merge_two_conflicts(m);
 374                 }
 375         }
 376 }
 377
 378 /*
 379  * level == 0: mark all overlapping changes as conflict
 380  * level == 1: mark overlapping changes as conflict only if not identical
 381  * level == 2: analyze non-identical changes for minimal conflict set
 382  * level == 3: analyze non-identical changes for minimal conflict set, but
 383  *             treat hunks not containing any letter or number as conflicting
 384  *
 385  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 386  */
 387 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 388                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 389                 int flags, xpparam_t const *xpp, mmbuffer_t *result) {
 390         xdmerge_t *changes, *c;
 391         int i0, i1, i2, chg0, chg1, chg2;
 392         int level = flags & XDL_MERGE_LEVEL_MASK;
 393         int style = flags & XDL_MERGE_STYLE_MASK;
 394
 395         if (style == XDL_MERGE_DIFF3) {
 396                 /*
 397                  * "diff3 -m" output does not make sense for anything
 398                  * more aggressive than XDL_MERGE_EAGER.
 399                  */
 400                 if (XDL_MERGE_EAGER < level)
 401                         level = XDL_MERGE_EAGER;
 402         }
 403
 404         c = changes = NULL;
 405
 406         while (xscr1 && xscr2) {
 407                 if (!changes)
 408                         changes = c;
 409                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 410                         i0 = xscr1->i1;
 411                         i1 = xscr1->i2;
 412                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 413                         chg0 = xscr1->chg1;
 414                         chg1 = xscr1->chg2;
 415                         chg2 = xscr1->chg1;
 416                         if (xdl_append_merge(&c, 1,
 417                                              i0, chg0, i1, chg1, i2, chg2)) {
 418                                 xdl_cleanup_merge(changes);
 419                                 return -1;
 420                         }
 421                         xscr1 = xscr1->next;
 422                         continue;
 423                 }
 424                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 425                         i0 = xscr2->i1;
 426                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 427                         i2 = xscr2->i2;
 428                         chg0 = xscr2->chg1;
 429                         chg1 = xscr2->chg1;
 430                         chg2 = xscr2->chg2;
 431                         if (xdl_append_merge(&c, 2,
 432                                              i0, chg0, i1, chg1, i2, chg2)) {
 433                                 xdl_cleanup_merge(changes);
 434                                 return -1;
 435                         }
 436                         xscr2 = xscr2->next;
 437                         continue;
 438                 }
 439                 if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 440                                 xscr1->chg1 != xscr2->chg1 ||
 441                                 xscr1->chg2 != xscr2->chg2 ||
 442                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 443                                         xe2, xscr2->i2,
 444                                         xscr1->chg2, xpp->flags)) {
 445                         /* conflict */
 446                         int off = xscr1->i1 - xscr2->i1;
 447                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 448
 449                         i0 = xscr1->i1;
 450                         i1 = xscr1->i2;
 451                         i2 = xscr2->i2;
 452                         if (off > 0) {
 453                                 i0 -= off;
 454                                 i1 -= off;
 455                         }
 456                         else
 457                                 i2 += off;
 458                         chg0 = xscr1->i1 + xscr1->chg1 - i0;
 459                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 460                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 461                         if (ffo < 0) {
 462                                 chg0 -= ffo;
 463                                 chg1 -= ffo;
 464                         } else
 465                                 chg2 += ffo;
 466                         if (xdl_append_merge(&c, 0,
 467                                              i0, chg0, i1, chg1, i2, chg2)) {
 468                                 xdl_cleanup_merge(changes);
 469                                 return -1;
 470                         }
 471                 }
 472
 473                 i1 = xscr1->i1 + xscr1->chg1;
 474                 i2 = xscr2->i1 + xscr2->chg1;
 475
 476                 if (i1 >= i2)
 477                         xscr2 = xscr2->next;
 478                 if (i2 >= i1)
 479                         xscr1 = xscr1->next;
 480         }
 481         while (xscr1) {
 482                 if (!changes)
 483                         changes = c;
 484                 i0 = xscr1->i1;
 485                 i1 = xscr1->i2;
 486                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 487                 chg0 = xscr1->chg1;
 488                 chg1 = xscr1->chg2;
 489                 chg2 = xscr1->chg1;
 490                 if (xdl_append_merge(&c, 1,
 491                                      i0, chg0, i1, chg1, i2, chg2)) {
 492                         xdl_cleanup_merge(changes);
 493                         return -1;
 494                 }
 495                 xscr1 = xscr1->next;
 496         }
 497         while (xscr2) {
 498                 if (!changes)
 499                         changes = c;
 500                 i0 = xscr2->i1;
 501                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 502                 i2 = xscr2->i2;
 503                 chg0 = xscr2->chg1;
 504                 chg1 = xscr2->chg1;
 505                 chg2 = xscr2->chg2;
 506                 if (xdl_append_merge(&c, 2,
 507                                      i0, chg0, i1, chg1, i2, chg2)) {
 508                         xdl_cleanup_merge(changes);
 509                         return -1;
 510                 }
 511                 xscr2 = xscr2->next;
 512         }
 513         if (!changes)
 514                 changes = c;
 515         /* refine conflicts */
 516         if (XDL_MERGE_ZEALOUS <= level &&
 517             (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 518              xdl_simplify_non_conflicts(xe1, changes,
 519                                         XDL_MERGE_ZEALOUS < level) < 0)) {
 520                 xdl_cleanup_merge(changes);
 521                 return -1;
 522         }
 523         /* output */
 524         if (result) {
 525                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 526                         changes, NULL, style);
 527                 result->ptr = xdl_malloc(size);
 528                 if (!result->ptr) {
 529                         xdl_cleanup_merge(changes);
 530                         return -1;
 531                 }
 532                 result->size = size;
 533                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 534                                       result->ptr, style);
 535         }
 536         return xdl_cleanup_merge(changes);
 537 }
 538
 539 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 540                 mmfile_t *mf2, const char *name2,
 541                 xpparam_t const *xpp, int flags, mmbuffer_t *result) {
 542         xdchange_t *xscr1, *xscr2;
 543         xdfenv_t xe1, xe2;
 544         int status;
 545
 546         result->ptr = NULL;
 547         result->size = 0;
 548
 549         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 550                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 551                 return -1;
 552         }
 553         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 554             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 555             xdl_build_script(&xe1, &xscr1) < 0) {
 556                 xdl_free_env(&xe1);
 557                 return -1;
 558         }
 559         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 560             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 561             xdl_build_script(&xe2, &xscr2) < 0) {
 562                 xdl_free_env(&xe2);
 563                 return -1;
 564         }
 565         status = 0;
 566         if (!xscr1) {
 567                 result->ptr = xdl_malloc(mf2->size);
 568                 memcpy(result->ptr, mf2->ptr, mf2->size);
 569                 result->size = mf2->size;
 570         } else if (!xscr2) {
 571                 result->ptr = xdl_malloc(mf1->size);
 572                 memcpy(result->ptr, mf1->ptr, mf1->size);
 573                 result->size = mf1->size;
 574         } else {
 575                 status = xdl_do_merge(&xe1, xscr1, name1,
 576                                       &xe2, xscr2, name2,
 577                                       flags, xpp, result);
 578         }
 579         xdl_free_script(xscr1);
 580         xdl_free_script(xscr2);
 581
 582         xdl_free_env(&xe1);
 583         xdl_free_env(&xe2);
 584
 585         return status;
 586 }