includes/diff/DairikiDiff.php

   1 <?php
   2 /**
   3  * A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
   4  *
   5  * Copyright © 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
   6  * You may copy this code freely under the conditions of the GPL.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  21  * http://www.gnu.org/copyleft/gpl.html
  22  *
  23  * @file
  24  * @ingroup DifferenceEngine
  25  * @defgroup DifferenceEngine DifferenceEngine
  26  */
  27
  28 /**
  29  * @todo document
  30  * @private
  31  * @ingroup DifferenceEngine
  32  */
  33 abstract class DiffOp {
  34         public $type;
  35         public $orig;
  36         public $closing;
  37
  38         abstract public function reverse();
  39
  40         /**
  41          * @return int
  42          */
  43         function norig() {
  44                 return $this->orig ? count( $this->orig ) : 0;
  45         }
  46
  47         /**
  48          * @return int
  49          */
  50         function nclosing() {
  51                 return $this->closing ? count( $this->closing ) : 0;
  52         }
  53 }
  54
  55 /**
  56  * @todo document
  57  * @private
  58  * @ingroup DifferenceEngine
  59  */
  60 class DiffOpCopy extends DiffOp {
  61         public $type = 'copy';
  62
  63         function __construct( $orig, $closing = false ) {
  64                 if ( !is_array( $closing ) ) {
  65                         $closing = $orig;
  66                 }
  67                 $this->orig = $orig;
  68                 $this->closing = $closing;
  69         }
  70
  71         /**
  72          * @return DiffOpCopy
  73          */
  74         function reverse() {
  75                 return new DiffOpCopy( $this->closing, $this->orig );
  76         }
  77 }
  78
  79 /**
  80  * @todo document
  81  * @private
  82  * @ingroup DifferenceEngine
  83  */
  84 class DiffOpDelete extends DiffOp {
  85         public $type = 'delete';
  86
  87         function __construct( $lines ) {
  88                 $this->orig = $lines;
  89                 $this->closing = false;
  90         }
  91
  92         /**
  93          * @return DiffOpAdd
  94          */
  95         function reverse() {
  96                 return new DiffOpAdd( $this->orig );
  97         }
  98 }
  99
 100 /**
 101  * @todo document
 102  * @private
 103  * @ingroup DifferenceEngine
 104  */
 105 class DiffOpAdd extends DiffOp {
 106         public $type = 'add';
 107
 108         function __construct( $lines ) {
 109                 $this->closing = $lines;
 110                 $this->orig = false;
 111         }
 112
 113         /**
 114          * @return DiffOpDelete
 115          */
 116         function reverse() {
 117                 return new DiffOpDelete( $this->closing );
 118         }
 119 }
 120
 121 /**
 122  * @todo document
 123  * @private
 124  * @ingroup DifferenceEngine
 125  */
 126 class DiffOpChange extends DiffOp {
 127         public $type = 'change';
 128
 129         function __construct( $orig, $closing ) {
 130                 $this->orig = $orig;
 131                 $this->closing = $closing;
 132         }
 133
 134         /**
 135          * @return DiffOpChange
 136          */
 137         function reverse() {
 138                 return new DiffOpChange( $this->closing, $this->orig );
 139         }
 140 }
 141
 142 /**
 143  * Class used internally by Diff to actually compute the diffs.
 144  *
 145  * The algorithm used here is mostly lifted from the perl module
 146  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 147  *     http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 148  *
 149  * More ideas are taken from:
 150  *     http://www.ics.uci.edu/~eppstein/161/960229.html
 151  *
 152  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 153  * diffutils-2.7, which can be found at:
 154  *     ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 155  *
 156  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 157  * are my own.
 158  *
 159  * Line length limits for robustness added by Tim Starling, 2005-08-31
 160  * Alternative implementation added by Guy Van den Broeck, 2008-07-30
 161  *
 162  * @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
 163  * @private
 164  * @ingroup DifferenceEngine
 165  */
 166 class DiffEngine {
 167         const MAX_XREF_LENGTH = 10000;
 168
 169         protected $xchanged, $ychanged;
 170
 171         protected $xv = array(), $yv = array();
 172         protected $xind = array(), $yind = array();
 173
 174         protected $seq = array(), $in_seq = array();
 175
 176         protected $lcs = 0;
 177
 178         /**
 179          * @param $from_lines
 180          * @param $to_lines
 181          * @return array
 182          */
 183         function diff( $from_lines, $to_lines ) {
 184                 wfProfileIn( __METHOD__ );
 185
 186                 // Diff and store locally
 187                 $this->diffLocal( $from_lines, $to_lines );
 188
 189                 // Merge edits when possible
 190                 $this->shiftBoundaries( $from_lines, $this->xchanged, $this->ychanged );
 191                 $this->shiftBoundaries( $to_lines, $this->ychanged, $this->xchanged );
 192
 193                 // Compute the edit operations.
 194                 $n_from = count( $from_lines );
 195                 $n_to = count( $to_lines );
 196
 197                 $edits = array();
 198                 $xi = $yi = 0;
 199                 while ( $xi < $n_from || $yi < $n_to ) {
 200                         assert( '$yi < $n_to || $this->xchanged[$xi]' );
 201                         assert( '$xi < $n_from || $this->ychanged[$yi]' );
 202
 203                         // Skip matching "snake".
 204                         $copy = array();
 205                         while ( $xi < $n_from && $yi < $n_to
 206                                 && !$this->xchanged[$xi] && !$this->ychanged[$yi]
 207                         ) {
 208                                 $copy[] = $from_lines[$xi++];
 209                                 ++$yi;
 210                         }
 211                         if ( $copy ) {
 212                                 $edits[] = new DiffOpCopy( $copy );
 213                         }
 214
 215                         // Find deletes & adds.
 216                         $delete = array();
 217                         while ( $xi < $n_from && $this->xchanged[$xi] ) {
 218                                 $delete[] = $from_lines[$xi++];
 219                         }
 220
 221                         $add = array();
 222                         while ( $yi < $n_to && $this->ychanged[$yi] ) {
 223                                 $add[] = $to_lines[$yi++];
 224                         }
 225
 226                         if ( $delete && $add ) {
 227                                 $edits[] = new DiffOpChange( $delete, $add );
 228                         } elseif ( $delete ) {
 229                                 $edits[] = new DiffOpDelete( $delete );
 230                         } elseif ( $add ) {
 231                                 $edits[] = new DiffOpAdd( $add );
 232                         }
 233                 }
 234                 wfProfileOut( __METHOD__ );
 235
 236                 return $edits;
 237         }
 238
 239         /**
 240          * @param $from_lines
 241          * @param $to_lines
 242          */
 243         private function diffLocal( $from_lines, $to_lines ) {
 244                 global $wgExternalDiffEngine;
 245                 wfProfileIn( __METHOD__ );
 246
 247                 if ( $wgExternalDiffEngine == 'wikidiff3' ) {
 248                         // wikidiff3
 249                         $wikidiff3 = new WikiDiff3();
 250                         $wikidiff3->diff( $from_lines, $to_lines );
 251                         $this->xchanged = $wikidiff3->removed;
 252                         $this->ychanged = $wikidiff3->added;
 253                         unset( $wikidiff3 );
 254                 } else {
 255                         // old diff
 256                         $n_from = count( $from_lines );
 257                         $n_to = count( $to_lines );
 258                         $this->xchanged = $this->ychanged = array();
 259                         $this->xv = $this->yv = array();
 260                         $this->xind = $this->yind = array();
 261                         unset( $this->seq );
 262                         unset( $this->in_seq );
 263                         unset( $this->lcs );
 264
 265                         // Skip leading common lines.
 266                         for ( $skip = 0; $skip < $n_from && $skip < $n_to; $skip++ ) {
 267                                 if ( $from_lines[$skip] !== $to_lines[$skip] ) {
 268                                         break;
 269                                 }
 270                                 $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 271                         }
 272                         // Skip trailing common lines.
 273                         $xi = $n_from;
 274                         $yi = $n_to;
 275                         for ( $endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++ ) {
 276                                 if ( $from_lines[$xi] !== $to_lines[$yi] ) {
 277                                         break;
 278                                 }
 279                                 $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 280                         }
 281
 282                         // Ignore lines which do not exist in both files.
 283                         for ( $xi = $skip; $xi < $n_from - $endskip; $xi++ ) {
 284                                 $xhash[$this->lineHash( $from_lines[$xi] )] = 1;
 285                         }
 286
 287                         for ( $yi = $skip; $yi < $n_to - $endskip; $yi++ ) {
 288                                 $line = $to_lines[$yi];
 289                                 if ( ( $this->ychanged[$yi] = empty( $xhash[$this->lineHash( $line )] ) ) ) {
 290                                         continue;
 291                                 }
 292                                 $yhash[$this->lineHash( $line )] = 1;
 293                                 $this->yv[] = $line;
 294                                 $this->yind[] = $yi;
 295                         }
 296                         for ( $xi = $skip; $xi < $n_from - $endskip; $xi++ ) {
 297                                 $line = $from_lines[$xi];
 298                                 if ( ( $this->xchanged[$xi] = empty( $yhash[$this->lineHash( $line )] ) ) ) {
 299                                         continue;
 300                                 }
 301                                 $this->xv[] = $line;
 302                                 $this->xind[] = $xi;
 303                         }
 304
 305                         // Find the LCS.
 306                         $this->compareSeq( 0, count( $this->xv ), 0, count( $this->yv ) );
 307                 }
 308                 wfProfileOut( __METHOD__ );
 309         }
 310
 311         /**
 312          * Returns the whole line if it's small enough, or the MD5 hash otherwise
 313          * @param $line string
 314          * @return string
 315          */
 316         private function lineHash( $line ) {
 317                 if ( strlen( $line ) > self::MAX_XREF_LENGTH ) {
 318                         return md5( $line );
 319                 } else {
 320                         return $line;
 321                 }
 322         }
 323
 324         /**
 325          * Divide the Largest Common Subsequence (LCS) of the sequences
 326          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 327          * sized segments.
 328          *
 329          * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an
 330          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 331          * sub sequences.  The first sub-sequence is contained in [X0, X1),
 332          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 333          * that (X0, Y0) == (XOFF, YOFF) and
 334          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 335          *
 336          * This function assumes that the first lines of the specified portions
 337          * of the two files do not match, and likewise that the last lines do not
 338          * match.  The caller must trim matching lines from the beginning and end
 339          * of the portions it is going to specify.
 340          * @param $xoff
 341          * @param $xlim
 342          * @param $yoff
 343          * @param $ylim
 344          * @param $nchunks
 345          * @return array
 346          */
 347         private function diag( $xoff, $xlim, $yoff, $ylim, $nchunks ) {
 348                 $flip = false;
 349
 350                 if ( $xlim - $xoff > $ylim - $yoff ) {
 351                         // Things seems faster (I'm not sure I understand why)
 352                         // when the shortest sequence in X.
 353                         $flip = true;
 354                         list( $xoff, $xlim, $yoff, $ylim ) = array( $yoff, $ylim, $xoff, $xlim );
 355                 }
 356
 357                 if ( $flip ) {
 358                         for ( $i = $ylim - 1; $i >= $yoff; $i-- ) {
 359                                 $ymatches[$this->xv[$i]][] = $i;
 360                         }
 361                 } else {
 362                         for ( $i = $ylim - 1; $i >= $yoff; $i-- ) {
 363                                 $ymatches[$this->yv[$i]][] = $i;
 364                         }
 365                 }
 366
 367                 $this->lcs = 0;
 368                 $this->seq[0] = $yoff - 1;
 369                 $this->in_seq = array();
 370                 $ymids[0] = array();
 371
 372                 $numer = $xlim - $xoff + $nchunks - 1;
 373                 $x = $xoff;
 374                 for ( $chunk = 0; $chunk < $nchunks; $chunk++ ) {
 375                         if ( $chunk > 0 ) {
 376                                 for ( $i = 0; $i <= $this->lcs; $i++ ) {
 377                                         $ymids[$i][$chunk - 1] = $this->seq[$i];
 378                                 }
 379                         }
 380
 381                         $x1 = $xoff + (int)( ( $numer + ( $xlim - $xoff ) * $chunk ) / $nchunks );
 382                         for ( ; $x < $x1; $x++ ) {
 383                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 384                                 if ( empty( $ymatches[$line] ) ) {
 385                                         continue;
 386                                 }
 387
 388                                 $k = 0;
 389                                 $matches = $ymatches[$line];
 390                                 reset( $matches );
 391                                 while ( list( , $y ) = each( $matches ) ) {
 392                                         if ( empty( $this->in_seq[$y] ) ) {
 393                                                 $k = $this->lcsPos( $y );
 394                                                 assert( '$k > 0' );
 395                                                 $ymids[$k] = $ymids[$k - 1];
 396                                                 break;
 397                                         }
 398                                 }
 399
 400                                 while ( list( , $y ) = each( $matches ) ) {
 401                                         if ( $y > $this->seq[$k - 1] ) {
 402                                                 assert( '$y < $this->seq[$k]' );
 403                                                 // Optimization: this is a common case:
 404                                                 //      next match is just replacing previous match.
 405                                                 $this->in_seq[$this->seq[$k]] = false;
 406                                                 $this->seq[$k] = $y;
 407                                                 $this->in_seq[$y] = 1;
 408                                         } elseif ( empty( $this->in_seq[$y] ) ) {
 409                                                 $k = $this->lcsPos( $y );
 410                                                 assert( '$k > 0' );
 411                                                 $ymids[$k] = $ymids[$k - 1];
 412                                         }
 413                                 }
 414                         }
 415                 }
 416
 417                 $seps[] = $flip ? array( $yoff, $xoff ) : array( $xoff, $yoff );
 418                 $ymid = $ymids[$this->lcs];
 419                 for ( $n = 0; $n < $nchunks - 1; $n++ ) {
 420                         $x1 = $xoff + (int)( ( $numer + ( $xlim - $xoff ) * $n ) / $nchunks );
 421                         $y1 = $ymid[$n] + 1;
 422                         $seps[] = $flip ? array( $y1, $x1 ) : array( $x1, $y1 );
 423                 }
 424                 $seps[] = $flip ? array( $ylim, $xlim ) : array( $xlim, $ylim );
 425
 426                 return array( $this->lcs, $seps );
 427         }
 428
 429         /**
 430          * @param $ypos
 431          * @return int
 432          */
 433         private function lcsPos( $ypos ) {
 434                 $end = $this->lcs;
 435                 if ( $end == 0 || $ypos > $this->seq[$end] ) {
 436                         $this->seq[++$this->lcs] = $ypos;
 437                         $this->in_seq[$ypos] = 1;
 438
 439                         return $this->lcs;
 440                 }
 441
 442                 $beg = 1;
 443                 while ( $beg < $end ) {
 444                         $mid = (int)( ( $beg + $end ) / 2 );
 445                         if ( $ypos > $this->seq[$mid] ) {
 446                                 $beg = $mid + 1;
 447                         } else {
 448                                 $end = $mid;
 449                         }
 450                 }
 451
 452                 assert( '$ypos != $this->seq[$end]' );
 453
 454                 $this->in_seq[$this->seq[$end]] = false;
 455                 $this->seq[$end] = $ypos;
 456                 $this->in_seq[$ypos] = 1;
 457
 458                 return $end;
 459         }
 460
 461         /**
 462          * Find LCS of two sequences.
 463          *
 464          * The results are recorded in the vectors $this->{x,y}changed[], by
 465          * storing a 1 in the element for each line that is an insertion
 466          * or deletion (ie. is not in the LCS).
 467          *
 468          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
 469          *
 470          * Note that XLIM, YLIM are exclusive bounds.
 471          * All line numbers are origin-0 and discarded lines are not counted.
 472          * @param $xoff
 473          * @param $xlim
 474          * @param $yoff
 475          * @param $ylim
 476          */
 477         private function compareSeq( $xoff, $xlim, $yoff, $ylim ) {
 478                 // Slide down the bottom initial diagonal.
 479                 while ( $xoff < $xlim && $yoff < $ylim && $this->xv[$xoff] == $this->yv[$yoff] ) {
 480                         ++$xoff;
 481                         ++$yoff;
 482                 }
 483
 484                 // Slide up the top initial diagonal.
 485                 while ( $xlim > $xoff && $ylim > $yoff
 486                         && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]
 487                 ) {
 488                         --$xlim;
 489                         --$ylim;
 490                 }
 491
 492                 if ( $xoff == $xlim || $yoff == $ylim ) {
 493                         $lcs = 0;
 494                 } else {
 495                         // This is ad hoc but seems to work well.
 496                         // $nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
 497                         // $nchunks = max(2,min(8,(int)$nchunks));
 498                         $nchunks = min( 7, $xlim - $xoff, $ylim - $yoff ) + 1;
 499                         list( $lcs, $seps ) = $this->diag( $xoff, $xlim, $yoff, $ylim, $nchunks );
 500                 }
 501
 502                 if ( $lcs == 0 ) {
 503                         // X and Y sequences have no common subsequence:
 504                         // mark all changed.
 505                         while ( $yoff < $ylim ) {
 506                                 $this->ychanged[$this->yind[$yoff++]] = 1;
 507                         }
 508                         while ( $xoff < $xlim ) {
 509                                 $this->xchanged[$this->xind[$xoff++]] = 1;
 510                         }
 511                 } else {
 512                         // Use the partitions to split this problem into subproblems.
 513                         reset( $seps );
 514                         $pt1 = $seps[0];
 515                         while ( $pt2 = next( $seps ) ) {
 516                                 $this->compareSeq( $pt1[0], $pt2[0], $pt1[1], $pt2[1] );
 517                                 $pt1 = $pt2;
 518                         }
 519                 }
 520         }
 521
 522         /**
 523          * Adjust inserts/deletes of identical lines to join changes
 524          * as much as possible.
 525          *
 526          * We do something when a run of changed lines include a
 527          * line at one end and has an excluded, identical line at the other.
 528          * We are free to choose which identical line is included.
 529          * `compareseq' usually chooses the one at the beginning,
 530          * but usually it is cleaner to consider the following identical line
 531          * to be the "change".
 532          *
 533          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
 534          */
 535         private function shiftBoundaries( $lines, &$changed, $other_changed ) {
 536                 wfProfileIn( __METHOD__ );
 537                 $i = 0;
 538                 $j = 0;
 539
 540                 assert( 'count($lines) == count($changed)' );
 541                 $len = count( $lines );
 542                 $other_len = count( $other_changed );
 543
 544                 while ( 1 ) {
 545                         /*
 546                          * Scan forwards to find beginning of another run of changes.
 547                          * Also keep track of the corresponding point in the other file.
 548                          *
 549                          * Throughout this code, $i and $j are adjusted together so that
 550                          * the first $i elements of $changed and the first $j elements
 551                          * of $other_changed both contain the same number of zeros
 552                          * (unchanged lines).
 553                          * Furthermore, $j is always kept so that $j == $other_len or
 554                          * $other_changed[$j] == false.
 555                          */
 556                         while ( $j < $other_len && $other_changed[$j] ) {
 557                                 $j++;
 558                         }
 559
 560                         while ( $i < $len && !$changed[$i] ) {
 561                                 assert( '$j < $other_len && ! $other_changed[$j]' );
 562                                 $i++;
 563                                 $j++;
 564                                 while ( $j < $other_len && $other_changed[$j] ) {
 565                                         $j++;
 566                                 }
 567                         }
 568
 569                         if ( $i == $len ) {
 570                                 break;
 571                         }
 572
 573                         $start = $i;
 574
 575                         // Find the end of this run of changes.
 576                         while ( ++$i < $len && $changed[$i] ) {
 577                                 continue;
 578                         }
 579
 580                         do {
 581                                 /*
 582                                  * Record the length of this run of changes, so that
 583                                  * we can later determine whether the run has grown.
 584                                  */
 585                                 $runlength = $i - $start;
 586
 587                                 /*
 588                                  * Move the changed region back, so long as the
 589                                  * previous unchanged line matches the last changed one.
 590                                  * This merges with previous changed regions.
 591                                  */
 592                                 while ( $start > 0 && $lines[$start - 1] == $lines[$i - 1] ) {
 593                                         $changed[--$start] = 1;
 594                                         $changed[--$i] = false;
 595                                         while ( $start > 0 && $changed[$start - 1] ) {
 596                                                 $start--;
 597                                         }
 598                                         assert( '$j > 0' );
 599                                         while ( $other_changed[--$j] ) {
 600                                                 continue;
 601                                         }
 602                                         assert( '$j >= 0 && !$other_changed[$j]' );
 603                                 }
 604
 605                                 /*
 606                                  * Set CORRESPONDING to the end of the changed run, at the last
 607                                  * point where it corresponds to a changed run in the other file.
 608                                  * CORRESPONDING == LEN means no such point has been found.
 609                                  */
 610                                 $corresponding = $j < $other_len ? $i : $len;
 611
 612                                 /*
 613                                  * Move the changed region forward, so long as the
 614                                  * first changed line matches the following unchanged one.
 615                                  * This merges with following changed regions.
 616                                  * Do this second, so that if there are no merges,
 617                                  * the changed region is moved forward as far as possible.
 618                                  */
 619                                 while ( $i < $len && $lines[$start] == $lines[$i] ) {
 620                                         $changed[$start++] = false;
 621                                         $changed[$i++] = 1;
 622                                         while ( $i < $len && $changed[$i] ) {
 623                                                 $i++;
 624                                         }
 625
 626                                         assert( '$j < $other_len && ! $other_changed[$j]' );
 627                                         $j++;
 628                                         if ( $j < $other_len && $other_changed[$j] ) {
 629                                                 $corresponding = $i;
 630                                                 while ( $j < $other_len && $other_changed[$j] ) {
 631                                                         $j++;
 632                                                 }
 633                                         }
 634                                 }
 635                         } while ( $runlength != $i - $start );
 636
 637                         /*
 638                          * If possible, move the fully-merged run of changes
 639                          * back to a corresponding run in the other file.
 640                          */
 641                         while ( $corresponding < $i ) {
 642                                 $changed[--$start] = 1;
 643                                 $changed[--$i] = 0;
 644                                 assert( '$j > 0' );
 645                                 while ( $other_changed[--$j] ) {
 646                                         continue;
 647                                 }
 648                                 assert( '$j >= 0 && !$other_changed[$j]' );
 649                         }
 650                 }
 651                 wfProfileOut( __METHOD__ );
 652         }
 653 }
 654
 655 /**
 656  * Class representing a 'diff' between two sequences of strings.
 657  * @todo document
 658  * @private
 659  * @ingroup DifferenceEngine
 660  */
 661 class Diff {
 662         public $edits;
 663
 664         /**
 665          * Constructor.
 666          * Computes diff between sequences of strings.
 667          *
 668          * @param $from_lines array An array of strings.
 669          *   Typically these are lines from a file.
 670          * @param $to_lines array An array of strings.
 671          */
 672         function __construct( $from_lines, $to_lines ) {
 673                 $eng = new DiffEngine;
 674                 $this->edits = $eng->diff( $from_lines, $to_lines );
 675         }
 676
 677         /**
 678          * Compute reversed Diff.
 679          *
 680          * SYNOPSIS:
 681          *
 682          *    $diff = new Diff($lines1, $lines2);
 683          *    $rev = $diff->reverse();
 684          * @return Object A Diff object representing the inverse of the
 685          *   original diff.
 686          */
 687         function reverse() {
 688                 $rev = $this;
 689                 $rev->edits = array();
 690                 /** @var DiffOp $edit */
 691                 foreach ( $this->edits as $edit ) {
 692                         $rev->edits[] = $edit->reverse();
 693                 }
 694
 695                 return $rev;
 696         }
 697
 698         /**
 699          * Check for empty diff.
 700          *
 701          * @return bool True if two sequences were identical.
 702          */
 703         function isEmpty() {
 704                 foreach ( $this->edits as $edit ) {
 705                         if ( $edit->type != 'copy' ) {
 706                                 return false;
 707                         }
 708                 }
 709
 710                 return true;
 711         }
 712
 713         /**
 714          * Compute the length of the Longest Common Subsequence (LCS).
 715          *
 716          * This is mostly for diagnostic purposed.
 717          *
 718          * @return int The length of the LCS.
 719          */
 720         function lcs() {
 721                 $lcs = 0;
 722                 foreach ( $this->edits as $edit ) {
 723                         if ( $edit->type == 'copy' ) {
 724                                 $lcs += count( $edit->orig );
 725                         }
 726                 }
 727
 728                 return $lcs;
 729         }
 730
 731         /**
 732          * Get the original set of lines.
 733          *
 734          * This reconstructs the $from_lines parameter passed to the
 735          * constructor.
 736          *
 737          * @return array The original sequence of strings.
 738          */
 739         function orig() {
 740                 $lines = array();
 741
 742                 foreach ( $this->edits as $edit ) {
 743                         if ( $edit->orig ) {
 744                                 array_splice( $lines, count( $lines ), 0, $edit->orig );
 745                         }
 746                 }
 747
 748                 return $lines;
 749         }
 750
 751         /**
 752          * Get the closing set of lines.
 753          *
 754          * This reconstructs the $to_lines parameter passed to the
 755          * constructor.
 756          *
 757          * @return array The sequence of strings.
 758          */
 759         function closing() {
 760                 $lines = array();
 761
 762                 foreach ( $this->edits as $edit ) {
 763                         if ( $edit->closing ) {
 764                                 array_splice( $lines, count( $lines ), 0, $edit->closing );
 765                         }
 766                 }
 767
 768                 return $lines;
 769         }
 770 }
 771
 772 /**
 773  * @todo document, bad name.
 774  * @private
 775  * @ingroup DifferenceEngine
 776  */
 777 class MappedDiff extends Diff {
 778         /**
 779          * Constructor.
 780          *
 781          * Computes diff between sequences of strings.
 782          *
 783          * This can be used to compute things like
 784          * case-insensitve diffs, or diffs which ignore
 785          * changes in white-space.
 786          *
 787          * @param $from_lines array An array of strings.
 788          *   Typically these are lines from a file.
 789          *
 790          * @param $to_lines array An array of strings.
 791          *
 792          * @param $mapped_from_lines array This array should
 793          *   have the same size number of elements as $from_lines.
 794          *   The elements in $mapped_from_lines and
 795          *   $mapped_to_lines are what is actually compared
 796          *   when computing the diff.
 797          *
 798          * @param $mapped_to_lines array This array should
 799          *   have the same number of elements as $to_lines.
 800          */
 801         function __construct( $from_lines, $to_lines,
 802                 $mapped_from_lines, $mapped_to_lines ) {
 803                 wfProfileIn( __METHOD__ );
 804
 805                 assert( 'count( $from_lines ) == count( $mapped_from_lines )' );
 806                 assert( 'count( $to_lines ) == count( $mapped_to_lines )' );
 807
 808                 parent::__construct( $mapped_from_lines, $mapped_to_lines );
 809
 810                 $xi = $yi = 0;
 811                 $editCount = count( $this->edits );
 812                 for ( $i = 0; $i < $editCount; $i++ ) {
 813                         $orig = &$this->edits[$i]->orig;
 814                         if ( is_array( $orig ) ) {
 815                                 $orig = array_slice( $from_lines, $xi, count( $orig ) );
 816                                 $xi += count( $orig );
 817                         }
 818
 819                         $closing = &$this->edits[$i]->closing;
 820                         if ( is_array( $closing ) ) {
 821                                 $closing = array_slice( $to_lines, $yi, count( $closing ) );
 822                                 $yi += count( $closing );
 823                         }
 824                 }
 825                 wfProfileOut( __METHOD__ );
 826         }
 827 }
 828
 829 /**
 830  * Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
 831  */
 832
 833 /**
 834  * @todo document
 835  * @private
 836  * @ingroup DifferenceEngine
 837  */
 838 class HWLDFWordAccumulator {
 839         public $insClass = ' class="diffchange diffchange-inline"';
 840         public $delClass = ' class="diffchange diffchange-inline"';
 841
 842         private $lines = array();
 843         private $line = '';
 844         private $group = '';
 845         private $tag = '';
 846
 847         /**
 848          * @param $new_tag
 849          */
 850         private function flushGroup( $new_tag ) {
 851                 if ( $this->group !== '' ) {
 852                         if ( $this->tag == 'ins' ) {
 853                                 $this->line .= "<ins{$this->insClass}>" .
 854                                         htmlspecialchars( $this->group ) . '</ins>';
 855                         } elseif ( $this->tag == 'del' ) {
 856                                 $this->line .= "<del{$this->delClass}>" .
 857                                         htmlspecialchars( $this->group ) . '</del>';
 858                         } else {
 859                                 $this->line .= htmlspecialchars( $this->group );
 860                         }
 861                 }
 862                 $this->group = '';
 863                 $this->tag = $new_tag;
 864         }
 865
 866         /**
 867          * @param $new_tag
 868          */
 869         private function flushLine( $new_tag ) {
 870                 $this->flushGroup( $new_tag );
 871                 if ( $this->line != '' ) {
 872                         array_push( $this->lines, $this->line );
 873                 } else {
 874                         # make empty lines visible by inserting an NBSP
 875                         array_push( $this->lines, '&#160;' );
 876                 }
 877                 $this->line = '';
 878         }
 879
 880         /**
 881          * @param $words
 882          * @param $tag string
 883          */
 884         public function addWords( $words, $tag = '' ) {
 885                 if ( $tag != $this->tag ) {
 886                         $this->flushGroup( $tag );
 887                 }
 888
 889                 foreach ( $words as $word ) {
 890                         // new-line should only come as first char of word.
 891                         if ( $word == '' ) {
 892                                 continue;
 893                         }
 894                         if ( $word[0] == "\n" ) {
 895                                 $this->flushLine( $tag );
 896                                 $word = substr( $word, 1 );
 897                         }
 898                         assert( '!strstr( $word, "\n" )' );
 899                         $this->group .= $word;
 900                 }
 901         }
 902
 903         /**
 904          * @return array
 905          */
 906         public function getLines() {
 907                 $this->flushLine( '~done' );
 908
 909                 return $this->lines;
 910         }
 911 }
 912
 913 /**
 914  * @todo document
 915  * @private
 916  * @ingroup DifferenceEngine
 917  */
 918 class WordLevelDiff extends MappedDiff {
 919         const MAX_LINE_LENGTH = 10000;
 920
 921         /**
 922          * @param $orig_lines
 923          * @param $closing_lines
 924          */
 925         function __construct( $orig_lines, $closing_lines ) {
 926                 wfProfileIn( __METHOD__ );
 927
 928                 list( $orig_words, $orig_stripped ) = $this->split( $orig_lines );
 929                 list( $closing_words, $closing_stripped ) = $this->split( $closing_lines );
 930
 931                 parent::__construct( $orig_words, $closing_words,
 932                         $orig_stripped, $closing_stripped );
 933                 wfProfileOut( __METHOD__ );
 934         }
 935
 936         /**
 937          * @param $lines
 938          * @return array
 939          */
 940         private function split( $lines ) {
 941                 wfProfileIn( __METHOD__ );
 942
 943                 $words = array();
 944                 $stripped = array();
 945                 $first = true;
 946                 foreach ( $lines as $line ) {
 947                         # If the line is too long, just pretend the entire line is one big word
 948                         # This prevents resource exhaustion problems
 949                         if ( $first ) {
 950                                 $first = false;
 951                         } else {
 952                                 $words[] = "\n";
 953                                 $stripped[] = "\n";
 954                         }
 955                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
 956                                 $words[] = $line;
 957                                 $stripped[] = $line;
 958                         } else {
 959                                 $m = array();
 960                                 if ( preg_match_all( '/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
 961                                         $line, $m )
 962                                 ) {
 963                                         foreach ( $m[0] as $word ) {
 964                                                 $words[] = $word;
 965                                         }
 966                                         foreach ( $m[1] as $stripped_word ) {
 967                                                 $stripped[] = $stripped_word;
 968                                         }
 969                                 }
 970                         }
 971                 }
 972                 wfProfileOut( __METHOD__ );
 973
 974                 return array( $words, $stripped );
 975         }
 976
 977         /**
 978          * @return array
 979          */
 980         public function orig() {
 981                 wfProfileIn( __METHOD__ );
 982                 $orig = new HWLDFWordAccumulator;
 983
 984                 foreach ( $this->edits as $edit ) {
 985                         if ( $edit->type == 'copy' ) {
 986                                 $orig->addWords( $edit->orig );
 987                         } elseif ( $edit->orig ) {
 988                                 $orig->addWords( $edit->orig, 'del' );
 989                         }
 990                 }
 991                 $lines = $orig->getLines();
 992                 wfProfileOut( __METHOD__ );
 993
 994                 return $lines;
 995         }
 996
 997         /**
 998          * @return array
 999          */
1000         public function closing() {
1001                 wfProfileIn( __METHOD__ );
1002                 $closing = new HWLDFWordAccumulator;
1003
1004                 foreach ( $this->edits as $edit ) {
1005                         if ( $edit->type == 'copy' ) {
1006                                 $closing->addWords( $edit->closing );
1007                         } elseif ( $edit->closing ) {
1008                                 $closing->addWords( $edit->closing, 'ins' );
1009                         }
1010                 }
1011                 $lines = $closing->getLines();
1012                 wfProfileOut( __METHOD__ );
1013
1014                 return $lines;
1015         }
1016 }