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