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         long i1, i2;
  34         long chg1, chg2;
  35 } xdmerge_t;
  36
  37 static int xdl_append_merge(xdmerge_t **merge, int mode,
  38                 long i1, long chg1, long i2, long chg2)
  39 {
  40         xdmerge_t *m = *merge;
  41         if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
  42                 if (mode != m->mode)
  43                         m->mode = 0;
  44                 m->chg1 = i1 + chg1 - m->i1;
  45                 m->chg2 = i2 + chg2 - m->i2;
  46         } else {
  47                 m = xdl_malloc(sizeof(xdmerge_t));
  48                 if (!m)
  49                         return -1;
  50                 m->next = NULL;
  51                 m->mode = mode;
  52                 m->i1 = i1;
  53                 m->chg1 = chg1;
  54                 m->i2 = i2;
  55                 m->chg2 = chg2;
  56                 if (*merge)
  57                         (*merge)->next = m;
  58                 *merge = m;
  59         }
  60         return 0;
  61 }
  62
  63 static int xdl_cleanup_merge(xdmerge_t *c)
  64 {
  65         int count = 0;
  66         xdmerge_t *next_c;
  67
  68         /* were there conflicts? */
  69         for (; c; c = next_c) {
  70                 if (c->mode == 0)
  71                         count++;
  72                 next_c = c->next;
  73                 free(c);
  74         }
  75         return count;
  76 }
  77
  78 static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  79                 int line_count, long flags)
  80 {
  81         int i;
  82         xrecord_t **rec1 = xe1->xdf2.recs + i1;
  83         xrecord_t **rec2 = xe2->xdf2.recs + i2;
  84
  85         for (i = 0; i < line_count; i++) {
  86                 int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
  87                         rec2[i]->ptr, rec2[i]->size, flags);
  88                 if (!result)
  89                         return -1;
  90         }
  91         return 0;
  92 }
  93
  94 static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
  95 {
  96         xrecord_t **recs = xe->xdf2.recs + i;
  97         int size = 0;
  98
  99         if (count < 1)
 100                 return 0;
 101
 102         for (i = 0; i < count; size += recs[i++]->size)
 103                 if (dest)
 104                         memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 105         if (add_nl) {
 106                 i = recs[count - 1]->size;
 107                 if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 108                         if (dest)
 109                                 dest[size] = '\n';
 110                         size++;
 111                 }
 112         }
 113         return size;
 114 }
 115
 116 static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 117                               xdfenv_t *xe2, const char *name2,
 118                               int size, int i,
 119                               xdmerge_t *m, char *dest)
 120 {
 121         const int marker_size = 7;
 122         int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 123         int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 124         int j;
 125
 126         /* Before conflicting part */
 127         size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 128                               dest ? dest + size : NULL);
 129
 130         if (!dest) {
 131                 size += marker_size + 1 + marker1_size;
 132         } else {
 133                 for (j = 0; j < marker_size; j++)
 134                         dest[size++] = '<';
 135                 if (marker1_size) {
 136                         dest[size] = ' ';
 137                         memcpy(dest + size + 1, name1, marker1_size - 1);
 138                         size += marker1_size;
 139                 }
 140                 dest[size++] = '\n';
 141         }
 142
 143         /* Postimage from side #1 */
 144         size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 145                               dest ? dest + size : NULL);
 146         if (!dest) {
 147                 size += marker_size + 1;
 148         } else {
 149                 for (j = 0; j < marker_size; j++)
 150                         dest[size++] = '=';
 151                 dest[size++] = '\n';
 152         }
 153
 154         /* Postimage from side #2 */
 155         size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 156                               dest ? dest + size : NULL);
 157         if (!dest) {
 158                 size += marker_size + 1 + marker2_size;
 159         } else {
 160                 for (j = 0; j < marker_size; j++)
 161                         dest[size++] = '>';
 162                 if (marker2_size) {
 163                         dest[size] = ' ';
 164                         memcpy(dest + size + 1, name2, marker2_size - 1);
 165                         size += marker2_size;
 166                 }
 167                 dest[size++] = '\n';
 168         }
 169         return size;
 170 }
 171
 172 static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 173                 xdfenv_t *xe2, const char *name2, xdmerge_t *m, char *dest)
 174 {
 175         int size, i;
 176
 177         for (size = i = 0; m; m = m->next) {
 178                 if (m->mode == 0)
 179                         size = fill_conflict_hunk(xe1, name1, xe2, name2,
 180                                                   size, i, m, dest);
 181                 else if (m->mode == 1)
 182                         size += xdl_recs_copy(xe1, i, m->i1 + m->chg1 - i, 0,
 183                                               dest ? dest + size : NULL);
 184                 else if (m->mode == 2)
 185                         size += xdl_recs_copy(xe2, m->i2 - m->i1 + i,
 186                                               m->i1 + m->chg2 - i, 0,
 187                                               dest ? dest + size : NULL);
 188                 else
 189                         continue;
 190                 i = m->i1 + m->chg1;
 191         }
 192         size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 193                               dest ? dest + size : NULL);
 194         return size;
 195 }
 196
 197 /*
 198  * Sometimes, changes are not quite identical, but differ in only a few
 199  * lines. Try hard to show only these few lines as conflicting.
 200  */
 201 static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 202                 xpparam_t const *xpp)
 203 {
 204         for (; m; m = m->next) {
 205                 mmfile_t t1, t2;
 206                 xdfenv_t xe;
 207                 xdchange_t *xscr, *x;
 208                 int i1 = m->i1, i2 = m->i2;
 209
 210                 /* let's handle just the conflicts */
 211                 if (m->mode)
 212                         continue;
 213
 214                 /* no sense refining a conflict when one side is empty */
 215                 if (m->chg1 == 0 || m->chg2 == 0)
 216                         continue;
 217
 218                 /*
 219                  * This probably does not work outside git, since
 220                  * we have a very simple mmfile structure.
 221                  */
 222                 t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 223                 t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 224                         + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 225                 t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 226                 t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 227                         + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 228                 if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 229                         return -1;
 230                 if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 231                     xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 232                     xdl_build_script(&xe, &xscr) < 0) {
 233                         xdl_free_env(&xe);
 234                         return -1;
 235                 }
 236                 if (!xscr) {
 237                         /* If this happens, the changes are identical. */
 238                         xdl_free_env(&xe);
 239                         m->mode = 4;
 240                         continue;
 241                 }
 242                 x = xscr;
 243                 m->i1 = xscr->i1 + i1;
 244                 m->chg1 = xscr->chg1;
 245                 m->i2 = xscr->i2 + i2;
 246                 m->chg2 = xscr->chg2;
 247                 while (xscr->next) {
 248                         xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 249                         if (!m2) {
 250                                 xdl_free_env(&xe);
 251                                 xdl_free_script(x);
 252                                 return -1;
 253                         }
 254                         xscr = xscr->next;
 255                         m2->next = m->next;
 256                         m->next = m2;
 257                         m = m2;
 258                         m->mode = 0;
 259                         m->i1 = xscr->i1 + i1;
 260                         m->chg1 = xscr->chg1;
 261                         m->i2 = xscr->i2 + i2;
 262                         m->chg2 = xscr->chg2;
 263                 }
 264                 xdl_free_env(&xe);
 265                 xdl_free_script(x);
 266         }
 267         return 0;
 268 }
 269
 270 static int line_contains_alnum(const char *ptr, long size)
 271 {
 272         while (size--)
 273                 if (isalnum(*(ptr++)))
 274                         return 1;
 275         return 0;
 276 }
 277
 278 static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 279 {
 280         for (; chg; chg--, i++)
 281                 if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 282                                 xe->xdf2.recs[i]->size))
 283                         return 1;
 284         return 0;
 285 }
 286
 287 /*
 288  * This function merges m and m->next, marking everything between those hunks
 289  * as conflicting, too.
 290  */
 291 static void xdl_merge_two_conflicts(xdmerge_t *m)
 292 {
 293         xdmerge_t *next_m = m->next;
 294         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 295         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 296         m->next = next_m->next;
 297         free(next_m);
 298 }
 299
 300 /*
 301  * If there are less than 3 non-conflicting lines between conflicts,
 302  * it appears simpler -- because it takes up less (or as many) lines --
 303  * if the lines are moved into the conflicts.
 304  */
 305 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 306                                       int simplify_if_no_alnum)
 307 {
 308         int result = 0;
 309
 310         if (!m)
 311                 return result;
 312         for (;;) {
 313                 xdmerge_t *next_m = m->next;
 314                 int begin, end;
 315
 316                 if (!next_m)
 317                         return result;
 318
 319                 begin = m->i1 + m->chg1;
 320                 end = next_m->i1;
 321
 322                 if (m->mode != 0 || next_m->mode != 0 ||
 323                     (end - begin > 3 &&
 324                      (!simplify_if_no_alnum ||
 325                       lines_contain_alnum(xe1, begin, end - begin)))) {
 326                         m = next_m;
 327                 } else {
 328                         result++;
 329                         xdl_merge_two_conflicts(m);
 330                 }
 331         }
 332 }
 333
 334 /*
 335  * level == 0: mark all overlapping changes as conflict
 336  * level == 1: mark overlapping changes as conflict only if not identical
 337  * level == 2: analyze non-identical changes for minimal conflict set
 338  * level == 3: analyze non-identical changes for minimal conflict set, but
 339  *             treat hunks not containing any letter or number as conflicting
 340  *
 341  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 342  */
 343 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 344                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 345                 int level, xpparam_t const *xpp, mmbuffer_t *result) {
 346         xdmerge_t *changes, *c;
 347         int i1, i2, chg1, chg2;
 348
 349         c = changes = NULL;
 350
 351         while (xscr1 && xscr2) {
 352                 if (!changes)
 353                         changes = c;
 354                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 355                         i1 = xscr1->i2;
 356                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 357                         chg1 = xscr1->chg2;
 358                         chg2 = xscr1->chg1;
 359                         if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 360                                 xdl_cleanup_merge(changes);
 361                                 return -1;
 362                         }
 363                         xscr1 = xscr1->next;
 364                         continue;
 365                 }
 366                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 367                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 368                         i2 = xscr2->i2;
 369                         chg1 = xscr2->chg1;
 370                         chg2 = xscr2->chg2;
 371                         if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 372                                 xdl_cleanup_merge(changes);
 373                                 return -1;
 374                         }
 375                         xscr2 = xscr2->next;
 376                         continue;
 377                 }
 378                 if (level < 1 || xscr1->i1 != xscr2->i1 ||
 379                                 xscr1->chg1 != xscr2->chg1 ||
 380                                 xscr1->chg2 != xscr2->chg2 ||
 381                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 382                                         xe2, xscr2->i2,
 383                                         xscr1->chg2, xpp->flags)) {
 384                         /* conflict */
 385                         int off = xscr1->i1 - xscr2->i1;
 386                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 387
 388                         i1 = xscr1->i2;
 389                         i2 = xscr2->i2;
 390                         if (off > 0)
 391                                 i1 -= off;
 392                         else
 393                                 i2 += off;
 394                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 395                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 396                         if (ffo > 0)
 397                                 chg2 += ffo;
 398                         else
 399                                 chg1 -= ffo;
 400                         if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 401                                 xdl_cleanup_merge(changes);
 402                                 return -1;
 403                         }
 404                 }
 405
 406                 i1 = xscr1->i1 + xscr1->chg1;
 407                 i2 = xscr2->i1 + xscr2->chg1;
 408
 409                 if (i1 >= i2)
 410                         xscr2 = xscr2->next;
 411                 if (i2 >= i1)
 412                         xscr1 = xscr1->next;
 413         }
 414         while (xscr1) {
 415                 if (!changes)
 416                         changes = c;
 417                 i1 = xscr1->i2;
 418                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 419                 chg1 = xscr1->chg2;
 420                 chg2 = xscr1->chg1;
 421                 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 422                         xdl_cleanup_merge(changes);
 423                         return -1;
 424                 }
 425                 xscr1 = xscr1->next;
 426         }
 427         while (xscr2) {
 428                 if (!changes)
 429                         changes = c;
 430                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 431                 i2 = xscr2->i2;
 432                 chg1 = xscr2->chg1;
 433                 chg2 = xscr2->chg2;
 434                 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 435                         xdl_cleanup_merge(changes);
 436                         return -1;
 437                 }
 438                 xscr2 = xscr2->next;
 439         }
 440         if (!changes)
 441                 changes = c;
 442         /* refine conflicts */
 443         if (level > 1 &&
 444             (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 445              xdl_simplify_non_conflicts(xe1, changes, level > 2) < 0)) {
 446                 xdl_cleanup_merge(changes);
 447                 return -1;
 448         }
 449         /* output */
 450         if (result) {
 451                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 452                         changes, NULL);
 453                 result->ptr = xdl_malloc(size);
 454                 if (!result->ptr) {
 455                         xdl_cleanup_merge(changes);
 456                         return -1;
 457                 }
 458                 result->size = size;
 459                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 460                                 result->ptr);
 461         }
 462         return xdl_cleanup_merge(changes);
 463 }
 464
 465 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 466                 mmfile_t *mf2, const char *name2,
 467                 xpparam_t const *xpp, int level, mmbuffer_t *result) {
 468         xdchange_t *xscr1, *xscr2;
 469         xdfenv_t xe1, xe2;
 470         int status;
 471
 472         result->ptr = NULL;
 473         result->size = 0;
 474
 475         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 476                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 477                 return -1;
 478         }
 479         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 480             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 481             xdl_build_script(&xe1, &xscr1) < 0) {
 482                 xdl_free_env(&xe1);
 483                 return -1;
 484         }
 485         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 486             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 487             xdl_build_script(&xe2, &xscr2) < 0) {
 488                 xdl_free_env(&xe2);
 489                 return -1;
 490         }
 491         status = 0;
 492         if (xscr1 || xscr2) {
 493                 if (!xscr1) {
 494                         result->ptr = xdl_malloc(mf2->size);
 495                         memcpy(result->ptr, mf2->ptr, mf2->size);
 496                         result->size = mf2->size;
 497                 } else if (!xscr2) {
 498                         result->ptr = xdl_malloc(mf1->size);
 499                         memcpy(result->ptr, mf1->ptr, mf1->size);
 500                         result->size = mf1->size;
 501                 } else {
 502                         status = xdl_do_merge(&xe1, xscr1, name1,
 503                                               &xe2, xscr2, name2,
 504                                               level, xpp, result);
 505                 }
 506                 xdl_free_script(xscr1);
 507                 xdl_free_script(xscr2);
 508         }
 509         xdl_free_env(&xe1);
 510         xdl_free_env(&xe2);
 511
 512         return status;
 513 }