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 /*
 252  * This function merges m and m->next, marking everything between those hunks
 253  * as conflicting, too.
 254  */
 255 static void xdl_merge_two_conflicts(xdmerge_t *m)
 256 {
 257         xdmerge_t *next_m = m->next;
 258         m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 259         m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 260         m->next = next_m->next;
 261         free(next_m);
 262 }
 263
 264 /*
 265  * If there are less than 3 non-conflicting lines between conflicts,
 266  * it appears simpler -- because it takes up less (or as many) lines --
 267  * if the lines are moved into the conflicts.
 268  */
 269 static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m)
 270 {
 271         int result = 0;
 272
 273         if (!m)
 274                 return result;
 275         for (;;) {
 276                 xdmerge_t *next_m = m->next;
 277                 int begin, end;
 278
 279                 if (!next_m)
 280                         return result;
 281
 282                 begin = m->i1 + m->chg1;
 283                 end = next_m->i1;
 284
 285                 if (m->mode != 0 || next_m->mode != 0 || end - begin > 3)
 286                         m = next_m;
 287                 else {
 288                         result++;
 289                         xdl_merge_two_conflicts(m);
 290                 }
 291         }
 292 }
 293
 294 /*
 295  * level == 0: mark all overlapping changes as conflict
 296  * level == 1: mark overlapping changes as conflict only if not identical
 297  * level == 2: analyze non-identical changes for minimal conflict set
 298  *
 299  * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 300  */
 301 static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1, const char *name1,
 302                 xdfenv_t *xe2, xdchange_t *xscr2, const char *name2,
 303                 int level, xpparam_t const *xpp, mmbuffer_t *result) {
 304         xdmerge_t *changes, *c;
 305         int i1, i2, chg1, chg2;
 306
 307         c = changes = NULL;
 308
 309         while (xscr1 && xscr2) {
 310                 if (!changes)
 311                         changes = c;
 312                 if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 313                         i1 = xscr1->i2;
 314                         i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 315                         chg1 = xscr1->chg2;
 316                         chg2 = xscr1->chg1;
 317                         if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 318                                 xdl_cleanup_merge(changes);
 319                                 return -1;
 320                         }
 321                         xscr1 = xscr1->next;
 322                         continue;
 323                 }
 324                 if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 325                         i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 326                         i2 = xscr2->i2;
 327                         chg1 = xscr2->chg1;
 328                         chg2 = xscr2->chg2;
 329                         if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 330                                 xdl_cleanup_merge(changes);
 331                                 return -1;
 332                         }
 333                         xscr2 = xscr2->next;
 334                         continue;
 335                 }
 336                 if (level < 1 || xscr1->i1 != xscr2->i1 ||
 337                                 xscr1->chg1 != xscr2->chg1 ||
 338                                 xscr1->chg2 != xscr2->chg2 ||
 339                                 xdl_merge_cmp_lines(xe1, xscr1->i2,
 340                                         xe2, xscr2->i2,
 341                                         xscr1->chg2, xpp->flags)) {
 342                         /* conflict */
 343                         int off = xscr1->i1 - xscr2->i1;
 344                         int ffo = off + xscr1->chg1 - xscr2->chg1;
 345
 346                         i1 = xscr1->i2;
 347                         i2 = xscr2->i2;
 348                         if (off > 0)
 349                                 i1 -= off;
 350                         else
 351                                 i2 += off;
 352                         chg1 = xscr1->i2 + xscr1->chg2 - i1;
 353                         chg2 = xscr2->i2 + xscr2->chg2 - i2;
 354                         if (ffo > 0)
 355                                 chg2 += ffo;
 356                         else
 357                                 chg1 -= ffo;
 358                         if (xdl_append_merge(&c, 0, i1, chg1, i2, chg2)) {
 359                                 xdl_cleanup_merge(changes);
 360                                 return -1;
 361                         }
 362                 }
 363
 364                 i1 = xscr1->i1 + xscr1->chg1;
 365                 i2 = xscr2->i1 + xscr2->chg1;
 366
 367                 if (i1 >= i2)
 368                         xscr2 = xscr2->next;
 369                 if (i2 >= i1)
 370                         xscr1 = xscr1->next;
 371         }
 372         while (xscr1) {
 373                 if (!changes)
 374                         changes = c;
 375                 i1 = xscr1->i2;
 376                 i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 377                 chg1 = xscr1->chg2;
 378                 chg2 = xscr1->chg1;
 379                 if (xdl_append_merge(&c, 1, i1, chg1, i2, chg2)) {
 380                         xdl_cleanup_merge(changes);
 381                         return -1;
 382                 }
 383                 xscr1 = xscr1->next;
 384         }
 385         while (xscr2) {
 386                 if (!changes)
 387                         changes = c;
 388                 i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 389                 i2 = xscr2->i2;
 390                 chg1 = xscr2->chg1;
 391                 chg2 = xscr2->chg2;
 392                 if (xdl_append_merge(&c, 2, i1, chg1, i2, chg2)) {
 393                         xdl_cleanup_merge(changes);
 394                         return -1;
 395                 }
 396                 xscr2 = xscr2->next;
 397         }
 398         if (!changes)
 399                 changes = c;
 400         /* refine conflicts */
 401         if (level > 1 &&
 402             (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 403              xdl_simplify_non_conflicts(xe1, changes) < 0)) {
 404                 xdl_cleanup_merge(changes);
 405                 return -1;
 406         }
 407         /* output */
 408         if (result) {
 409                 int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 410                         changes, NULL);
 411                 result->ptr = xdl_malloc(size);
 412                 if (!result->ptr) {
 413                         xdl_cleanup_merge(changes);
 414                         return -1;
 415                 }
 416                 result->size = size;
 417                 xdl_fill_merge_buffer(xe1, name1, xe2, name2, changes,
 418                                 result->ptr);
 419         }
 420         return xdl_cleanup_merge(changes);
 421 }
 422
 423 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, const char *name1,
 424                 mmfile_t *mf2, const char *name2,
 425                 xpparam_t const *xpp, int level, mmbuffer_t *result) {
 426         xdchange_t *xscr1, *xscr2;
 427         xdfenv_t xe1, xe2;
 428         int status;
 429
 430         result->ptr = NULL;
 431         result->size = 0;
 432
 433         if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 434                         xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 435                 return -1;
 436         }
 437         if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 438             xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 439             xdl_build_script(&xe1, &xscr1) < 0) {
 440                 xdl_free_env(&xe1);
 441                 return -1;
 442         }
 443         if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 444             xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 445             xdl_build_script(&xe2, &xscr2) < 0) {
 446                 xdl_free_env(&xe2);
 447                 return -1;
 448         }
 449         status = 0;
 450         if (xscr1 || xscr2) {
 451                 if (!xscr1) {
 452                         result->ptr = xdl_malloc(mf2->size);
 453                         memcpy(result->ptr, mf2->ptr, mf2->size);
 454                         result->size = mf2->size;
 455                 } else if (!xscr2) {
 456                         result->ptr = xdl_malloc(mf1->size);
 457                         memcpy(result->ptr, mf1->ptr, mf1->size);
 458                         result->size = mf1->size;
 459                 } else {
 460                         status = xdl_do_merge(&xe1, xscr1, name1,
 461                                               &xe2, xscr2, name2,
 462                                               level, xpp, result);
 463                 }
 464                 xdl_free_script(xscr1);
 465                 xdl_free_script(xscr2);
 466         }
 467         xdl_free_env(&xe1);
 468         xdl_free_env(&xe2);
 469
 470         return status;
 471 }