Andrew's git / gitweb.git / xdiff/xmerge.c
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xdiff / xmerge.con commit git-am: add am.threeWay config variable (e97a5e7)
   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
  25typedef 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         * 3 = no conflict, take both.
  32         */
  33        int mode;
  34        /*
  35         * These point at the respective postimages.  E.g. <i1,chg1> is
  36         * how side #1 wants to change the common ancestor; if there is no
  37         * overlap, lines before i1 in the postimage of side #1 appear
  38         * in the merge result as a region touched by neither side.
  39         */
  40        long i1, i2;
  41        long chg1, chg2;
  42        /*
  43         * These point at the preimage; of course there is just one
  44         * preimage, that is from the shared common ancestor.
  45         */
  46        long i0;
  47        long chg0;
  48} xdmerge_t;
  49
  50static int xdl_append_merge(xdmerge_t **merge, int mode,
  51                            long i0, long chg0,
  52                            long i1, long chg1,
  53                            long i2, long chg2)
  54{
  55        xdmerge_t *m = *merge;
  56        if (m && (i1 <= m->i1 + m->chg1 || i2 <= m->i2 + m->chg2)) {
  57                if (mode != m->mode)
  58                        m->mode = 0;
  59                m->chg0 = i0 + chg0 - m->i0;
  60                m->chg1 = i1 + chg1 - m->i1;
  61                m->chg2 = i2 + chg2 - m->i2;
  62        } else {
  63                m = xdl_malloc(sizeof(xdmerge_t));
  64                if (!m)
  65                        return -1;
  66                m->next = NULL;
  67                m->mode = mode;
  68                m->i0 = i0;
  69                m->chg0 = chg0;
  70                m->i1 = i1;
  71                m->chg1 = chg1;
  72                m->i2 = i2;
  73                m->chg2 = chg2;
  74                if (*merge)
  75                        (*merge)->next = m;
  76                *merge = m;
  77        }
  78        return 0;
  79}
  80
  81static int xdl_cleanup_merge(xdmerge_t *c)
  82{
  83        int count = 0;
  84        xdmerge_t *next_c;
  85
  86        /* were there conflicts? */
  87        for (; c; c = next_c) {
  88                if (c->mode == 0)
  89                        count++;
  90                next_c = c->next;
  91                free(c);
  92        }
  93        return count;
  94}
  95
  96static int xdl_merge_cmp_lines(xdfenv_t *xe1, int i1, xdfenv_t *xe2, int i2,
  97                int line_count, long flags)
  98{
  99        int i;
 100        xrecord_t **rec1 = xe1->xdf2.recs + i1;
 101        xrecord_t **rec2 = xe2->xdf2.recs + i2;
 102
 103        for (i = 0; i < line_count; i++) {
 104                int result = xdl_recmatch(rec1[i]->ptr, rec1[i]->size,
 105                        rec2[i]->ptr, rec2[i]->size, flags);
 106                if (!result)
 107                        return -1;
 108        }
 109        return 0;
 110}
 111
 112static int xdl_recs_copy_0(int use_orig, xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 113{
 114        xrecord_t **recs;
 115        int size = 0;
 116
 117        recs = (use_orig ? xe->xdf1.recs : xe->xdf2.recs) + i;
 118
 119        if (count < 1)
 120                return 0;
 121
 122        for (i = 0; i < count; size += recs[i++]->size)
 123                if (dest)
 124                        memcpy(dest + size, recs[i]->ptr, recs[i]->size);
 125        if (add_nl) {
 126                i = recs[count - 1]->size;
 127                if (i == 0 || recs[count - 1]->ptr[i - 1] != '\n') {
 128                        if (dest)
 129                                dest[size] = '\n';
 130                        size++;
 131                }
 132        }
 133        return size;
 134}
 135
 136static int xdl_recs_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 137{
 138        return xdl_recs_copy_0(0, xe, i, count, add_nl, dest);
 139}
 140
 141static int xdl_orig_copy(xdfenv_t *xe, int i, int count, int add_nl, char *dest)
 142{
 143        return xdl_recs_copy_0(1, xe, i, count, add_nl, dest);
 144}
 145
 146static int fill_conflict_hunk(xdfenv_t *xe1, const char *name1,
 147                              xdfenv_t *xe2, const char *name2,
 148                              const char *name3,
 149                              int size, int i, int style,
 150                              xdmerge_t *m, char *dest, int marker_size)
 151{
 152        int marker1_size = (name1 ? strlen(name1) + 1 : 0);
 153        int marker2_size = (name2 ? strlen(name2) + 1 : 0);
 154        int marker3_size = (name3 ? strlen(name3) + 1 : 0);
 155
 156        if (marker_size <= 0)
 157                marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 158
 159        /* Before conflicting part */
 160        size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 161                              dest ? dest + size : NULL);
 162
 163        if (!dest) {
 164                size += marker_size + 1 + marker1_size;
 165        } else {
 166                memset(dest + size, '<', marker_size);
 167                size += marker_size;
 168                if (marker1_size) {
 169                        dest[size] = ' ';
 170                        memcpy(dest + size + 1, name1, marker1_size - 1);
 171                        size += marker1_size;
 172                }
 173                dest[size++] = '\n';
 174        }
 175
 176        /* Postimage from side #1 */
 177        size += xdl_recs_copy(xe1, m->i1, m->chg1, 1,
 178                              dest ? dest + size : NULL);
 179
 180        if (style == XDL_MERGE_DIFF3) {
 181                /* Shared preimage */
 182                if (!dest) {
 183                        size += marker_size + 1 + marker3_size;
 184                } else {
 185                        memset(dest + size, '|', marker_size);
 186                        size += marker_size;
 187                        if (marker3_size) {
 188                                dest[size] = ' ';
 189                                memcpy(dest + size + 1, name3, marker3_size - 1);
 190                                size += marker3_size;
 191                        }
 192                        dest[size++] = '\n';
 193                }
 194                size += xdl_orig_copy(xe1, m->i0, m->chg0, 1,
 195                                      dest ? dest + size : NULL);
 196        }
 197
 198        if (!dest) {
 199                size += marker_size + 1;
 200        } else {
 201                memset(dest + size, '=', marker_size);
 202                size += marker_size;
 203                dest[size++] = '\n';
 204        }
 205
 206        /* Postimage from side #2 */
 207        size += xdl_recs_copy(xe2, m->i2, m->chg2, 1,
 208                              dest ? dest + size : NULL);
 209        if (!dest) {
 210                size += marker_size + 1 + marker2_size;
 211        } else {
 212                memset(dest + size, '>', marker_size);
 213                size += marker_size;
 214                if (marker2_size) {
 215                        dest[size] = ' ';
 216                        memcpy(dest + size + 1, name2, marker2_size - 1);
 217                        size += marker2_size;
 218                }
 219                dest[size++] = '\n';
 220        }
 221        return size;
 222}
 223
 224static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
 225                                 xdfenv_t *xe2, const char *name2,
 226                                 const char *ancestor_name,
 227                                 int favor,
 228                                 xdmerge_t *m, char *dest, int style,
 229                                 int marker_size)
 230{
 231        int size, i;
 232
 233        for (size = i = 0; m; m = m->next) {
 234                if (favor && !m->mode)
 235                        m->mode = favor;
 236
 237                if (m->mode == 0)
 238                        size = fill_conflict_hunk(xe1, name1, xe2, name2,
 239                                                  ancestor_name,
 240                                                  size, i, style, m, dest,
 241                                                  marker_size);
 242                else if (m->mode & 3) {
 243                        /* Before conflicting part */
 244                        size += xdl_recs_copy(xe1, i, m->i1 - i, 0,
 245                                              dest ? dest + size : NULL);
 246                        /* Postimage from side #1 */
 247                        if (m->mode & 1)
 248                                size += xdl_recs_copy(xe1, m->i1, m->chg1, (m->mode & 2),
 249                                                      dest ? dest + size : NULL);
 250                        /* Postimage from side #2 */
 251                        if (m->mode & 2)
 252                                size += xdl_recs_copy(xe2, m->i2, m->chg2, 0,
 253                                                      dest ? dest + size : NULL);
 254                } else
 255                        continue;
 256                i = m->i1 + m->chg1;
 257        }
 258        size += xdl_recs_copy(xe1, i, xe1->xdf2.nrec - i, 0,
 259                              dest ? dest + size : NULL);
 260        return size;
 261}
 262
 263/*
 264 * Sometimes, changes are not quite identical, but differ in only a few
 265 * lines. Try hard to show only these few lines as conflicting.
 266 */
 267static int xdl_refine_conflicts(xdfenv_t *xe1, xdfenv_t *xe2, xdmerge_t *m,
 268                xpparam_t const *xpp)
 269{
 270        for (; m; m = m->next) {
 271                mmfile_t t1, t2;
 272                xdfenv_t xe;
 273                xdchange_t *xscr, *x;
 274                int i1 = m->i1, i2 = m->i2;
 275
 276                /* let's handle just the conflicts */
 277                if (m->mode)
 278                        continue;
 279
 280                /* no sense refining a conflict when one side is empty */
 281                if (m->chg1 == 0 || m->chg2 == 0)
 282                        continue;
 283
 284                /*
 285                 * This probably does not work outside git, since
 286                 * we have a very simple mmfile structure.
 287                 */
 288                t1.ptr = (char *)xe1->xdf2.recs[m->i1]->ptr;
 289                t1.size = xe1->xdf2.recs[m->i1 + m->chg1 - 1]->ptr
 290                        + xe1->xdf2.recs[m->i1 + m->chg1 - 1]->size - t1.ptr;
 291                t2.ptr = (char *)xe2->xdf2.recs[m->i2]->ptr;
 292                t2.size = xe2->xdf2.recs[m->i2 + m->chg2 - 1]->ptr
 293                        + xe2->xdf2.recs[m->i2 + m->chg2 - 1]->size - t2.ptr;
 294                if (xdl_do_diff(&t1, &t2, xpp, &xe) < 0)
 295                        return -1;
 296                if (xdl_change_compact(&xe.xdf1, &xe.xdf2, xpp->flags) < 0 ||
 297                    xdl_change_compact(&xe.xdf2, &xe.xdf1, xpp->flags) < 0 ||
 298                    xdl_build_script(&xe, &xscr) < 0) {
 299                        xdl_free_env(&xe);
 300                        return -1;
 301                }
 302                if (!xscr) {
 303                        /* If this happens, the changes are identical. */
 304                        xdl_free_env(&xe);
 305                        m->mode = 4;
 306                        continue;
 307                }
 308                x = xscr;
 309                m->i1 = xscr->i1 + i1;
 310                m->chg1 = xscr->chg1;
 311                m->i2 = xscr->i2 + i2;
 312                m->chg2 = xscr->chg2;
 313                while (xscr->next) {
 314                        xdmerge_t *m2 = xdl_malloc(sizeof(xdmerge_t));
 315                        if (!m2) {
 316                                xdl_free_env(&xe);
 317                                xdl_free_script(x);
 318                                return -1;
 319                        }
 320                        xscr = xscr->next;
 321                        m2->next = m->next;
 322                        m->next = m2;
 323                        m = m2;
 324                        m->mode = 0;
 325                        m->i1 = xscr->i1 + i1;
 326                        m->chg1 = xscr->chg1;
 327                        m->i2 = xscr->i2 + i2;
 328                        m->chg2 = xscr->chg2;
 329                }
 330                xdl_free_env(&xe);
 331                xdl_free_script(x);
 332        }
 333        return 0;
 334}
 335
 336static int line_contains_alnum(const char *ptr, long size)
 337{
 338        while (size--)
 339                if (isalnum((unsigned char)*(ptr++)))
 340                        return 1;
 341        return 0;
 342}
 343
 344static int lines_contain_alnum(xdfenv_t *xe, int i, int chg)
 345{
 346        for (; chg; chg--, i++)
 347                if (line_contains_alnum(xe->xdf2.recs[i]->ptr,
 348                                xe->xdf2.recs[i]->size))
 349                        return 1;
 350        return 0;
 351}
 352
 353/*
 354 * This function merges m and m->next, marking everything between those hunks
 355 * as conflicting, too.
 356 */
 357static void xdl_merge_two_conflicts(xdmerge_t *m)
 358{
 359        xdmerge_t *next_m = m->next;
 360        m->chg1 = next_m->i1 + next_m->chg1 - m->i1;
 361        m->chg2 = next_m->i2 + next_m->chg2 - m->i2;
 362        m->next = next_m->next;
 363        free(next_m);
 364}
 365
 366/*
 367 * If there are less than 3 non-conflicting lines between conflicts,
 368 * it appears simpler -- because it takes up less (or as many) lines --
 369 * if the lines are moved into the conflicts.
 370 */
 371static int xdl_simplify_non_conflicts(xdfenv_t *xe1, xdmerge_t *m,
 372                                      int simplify_if_no_alnum)
 373{
 374        int result = 0;
 375
 376        if (!m)
 377                return result;
 378        for (;;) {
 379                xdmerge_t *next_m = m->next;
 380                int begin, end;
 381
 382                if (!next_m)
 383                        return result;
 384
 385                begin = m->i1 + m->chg1;
 386                end = next_m->i1;
 387
 388                if (m->mode != 0 || next_m->mode != 0 ||
 389                    (end - begin > 3 &&
 390                     (!simplify_if_no_alnum ||
 391                      lines_contain_alnum(xe1, begin, end - begin)))) {
 392                        m = next_m;
 393                } else {
 394                        result++;
 395                        xdl_merge_two_conflicts(m);
 396                }
 397        }
 398}
 399
 400/*
 401 * level == 0: mark all overlapping changes as conflict
 402 * level == 1: mark overlapping changes as conflict only if not identical
 403 * level == 2: analyze non-identical changes for minimal conflict set
 404 * level == 3: analyze non-identical changes for minimal conflict set, but
 405 *             treat hunks not containing any letter or number as conflicting
 406 *
 407 * returns < 0 on error, == 0 for no conflicts, else number of conflicts
 408 */
 409static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
 410                xdfenv_t *xe2, xdchange_t *xscr2,
 411                xmparam_t const *xmp, mmbuffer_t *result)
 412{
 413        xdmerge_t *changes, *c;
 414        xpparam_t const *xpp = &xmp->xpp;
 415        const char *const ancestor_name = xmp->ancestor;
 416        const char *const name1 = xmp->file1;
 417        const char *const name2 = xmp->file2;
 418        int i0, i1, i2, chg0, chg1, chg2;
 419        int level = xmp->level;
 420        int style = xmp->style;
 421        int favor = xmp->favor;
 422
 423        if (style == XDL_MERGE_DIFF3) {
 424                /*
 425                 * "diff3 -m" output does not make sense for anything
 426                 * more aggressive than XDL_MERGE_EAGER.
 427                 */
 428                if (XDL_MERGE_EAGER < level)
 429                        level = XDL_MERGE_EAGER;
 430        }
 431
 432        c = changes = NULL;
 433
 434        while (xscr1 && xscr2) {
 435                if (!changes)
 436                        changes = c;
 437                if (xscr1->i1 + xscr1->chg1 < xscr2->i1) {
 438                        i0 = xscr1->i1;
 439                        i1 = xscr1->i2;
 440                        i2 = xscr2->i2 - xscr2->i1 + xscr1->i1;
 441                        chg0 = xscr1->chg1;
 442                        chg1 = xscr1->chg2;
 443                        chg2 = xscr1->chg1;
 444                        if (xdl_append_merge(&c, 1,
 445                                             i0, chg0, i1, chg1, i2, chg2)) {
 446                                xdl_cleanup_merge(changes);
 447                                return -1;
 448                        }
 449                        xscr1 = xscr1->next;
 450                        continue;
 451                }
 452                if (xscr2->i1 + xscr2->chg1 < xscr1->i1) {
 453                        i0 = xscr2->i1;
 454                        i1 = xscr1->i2 - xscr1->i1 + xscr2->i1;
 455                        i2 = xscr2->i2;
 456                        chg0 = xscr2->chg1;
 457                        chg1 = xscr2->chg1;
 458                        chg2 = xscr2->chg2;
 459                        if (xdl_append_merge(&c, 2,
 460                                             i0, chg0, i1, chg1, i2, chg2)) {
 461                                xdl_cleanup_merge(changes);
 462                                return -1;
 463                        }
 464                        xscr2 = xscr2->next;
 465                        continue;
 466                }
 467                if (level == XDL_MERGE_MINIMAL || xscr1->i1 != xscr2->i1 ||
 468                                xscr1->chg1 != xscr2->chg1 ||
 469                                xscr1->chg2 != xscr2->chg2 ||
 470                                xdl_merge_cmp_lines(xe1, xscr1->i2,
 471                                        xe2, xscr2->i2,
 472                                        xscr1->chg2, xpp->flags)) {
 473                        /* conflict */
 474                        int off = xscr1->i1 - xscr2->i1;
 475                        int ffo = off + xscr1->chg1 - xscr2->chg1;
 476
 477                        i0 = xscr1->i1;
 478                        i1 = xscr1->i2;
 479                        i2 = xscr2->i2;
 480                        if (off > 0) {
 481                                i0 -= off;
 482                                i1 -= off;
 483                        }
 484                        else
 485                                i2 += off;
 486                        chg0 = xscr1->i1 + xscr1->chg1 - i0;
 487                        chg1 = xscr1->i2 + xscr1->chg2 - i1;
 488                        chg2 = xscr2->i2 + xscr2->chg2 - i2;
 489                        if (ffo < 0) {
 490                                chg0 -= ffo;
 491                                chg1 -= ffo;
 492                        } else
 493                                chg2 += ffo;
 494                        if (xdl_append_merge(&c, 0,
 495                                             i0, chg0, i1, chg1, i2, chg2)) {
 496                                xdl_cleanup_merge(changes);
 497                                return -1;
 498                        }
 499                }
 500
 501                i1 = xscr1->i1 + xscr1->chg1;
 502                i2 = xscr2->i1 + xscr2->chg1;
 503
 504                if (i1 >= i2)
 505                        xscr2 = xscr2->next;
 506                if (i2 >= i1)
 507                        xscr1 = xscr1->next;
 508        }
 509        while (xscr1) {
 510                if (!changes)
 511                        changes = c;
 512                i0 = xscr1->i1;
 513                i1 = xscr1->i2;
 514                i2 = xscr1->i1 + xe2->xdf2.nrec - xe2->xdf1.nrec;
 515                chg0 = xscr1->chg1;
 516                chg1 = xscr1->chg2;
 517                chg2 = xscr1->chg1;
 518                if (xdl_append_merge(&c, 1,
 519                                     i0, chg0, i1, chg1, i2, chg2)) {
 520                        xdl_cleanup_merge(changes);
 521                        return -1;
 522                }
 523                xscr1 = xscr1->next;
 524        }
 525        while (xscr2) {
 526                if (!changes)
 527                        changes = c;
 528                i0 = xscr2->i1;
 529                i1 = xscr2->i1 + xe1->xdf2.nrec - xe1->xdf1.nrec;
 530                i2 = xscr2->i2;
 531                chg0 = xscr2->chg1;
 532                chg1 = xscr2->chg1;
 533                chg2 = xscr2->chg2;
 534                if (xdl_append_merge(&c, 2,
 535                                     i0, chg0, i1, chg1, i2, chg2)) {
 536                        xdl_cleanup_merge(changes);
 537                        return -1;
 538                }
 539                xscr2 = xscr2->next;
 540        }
 541        if (!changes)
 542                changes = c;
 543        /* refine conflicts */
 544        if (XDL_MERGE_ZEALOUS <= level &&
 545            (xdl_refine_conflicts(xe1, xe2, changes, xpp) < 0 ||
 546             xdl_simplify_non_conflicts(xe1, changes,
 547                                        XDL_MERGE_ZEALOUS < level) < 0)) {
 548                xdl_cleanup_merge(changes);
 549                return -1;
 550        }
 551        /* output */
 552        if (result) {
 553                int marker_size = xmp->marker_size;
 554                int size = xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 555                                                 ancestor_name,
 556                                                 favor, changes, NULL, style,
 557                                                 marker_size);
 558                result->ptr = xdl_malloc(size);
 559                if (!result->ptr) {
 560                        xdl_cleanup_merge(changes);
 561                        return -1;
 562                }
 563                result->size = size;
 564                xdl_fill_merge_buffer(xe1, name1, xe2, name2,
 565                                      ancestor_name, favor, changes,
 566                                      result->ptr, style, marker_size);
 567        }
 568        return xdl_cleanup_merge(changes);
 569}
 570
 571int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 572                xmparam_t const *xmp, mmbuffer_t *result)
 573{
 574        xdchange_t *xscr1, *xscr2;
 575        xdfenv_t xe1, xe2;
 576        int status;
 577        xpparam_t const *xpp = &xmp->xpp;
 578
 579        result->ptr = NULL;
 580        result->size = 0;
 581
 582        if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0 ||
 583                        xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
 584                return -1;
 585        }
 586        if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 587            xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
 588            xdl_build_script(&xe1, &xscr1) < 0) {
 589                xdl_free_env(&xe1);
 590                return -1;
 591        }
 592        if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 593            xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
 594            xdl_build_script(&xe2, &xscr2) < 0) {
 595                xdl_free_env(&xe2);
 596                return -1;
 597        }
 598        status = 0;
 599        if (!xscr1) {
 600                result->ptr = xdl_malloc(mf2->size);
 601                memcpy(result->ptr, mf2->ptr, mf2->size);
 602                result->size = mf2->size;
 603        } else if (!xscr2) {
 604                result->ptr = xdl_malloc(mf1->size);
 605                memcpy(result->ptr, mf1->ptr, mf1->size);
 606                result->size = mf1->size;
 607        } else {
 608                status = xdl_do_merge(&xe1, xscr1,
 609                                      &xe2, xscr2,
 610                                      xmp, result);
 611        }
 612        xdl_free_script(xscr1);
 613        xdl_free_script(xscr2);
 614
 615        xdl_free_env(&xe1);
 616        xdl_free_env(&xe2);
 617
 618        return status;
 619}