includes/DifferenceEngine.php

   1 <?php
   2 # See diff.doc
   3
   4 class DifferenceEngine {
   5         /* private */ var $mOldid, $mNewid;
   6         /* private */ var $mOldtitle, $mNewtitle;
   7         /* private */ var $mOldtext, $mNewtext;
   8         /* private */ var $mOldUser, $mNewUser;
   9
  10         function DifferenceEngine( $old, $new )
  11         {
  12                 $this->mOldid = $old;
  13                 $this->mNewid = $new;
  14         }
  15
  16         function showDiffPage()
  17         {
  18                 global $wgUser, $wgTitle, $wgOut, $wgLang;
  19
  20                 $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
  21                   "{$this->mNewid})";
  22                 $mtext = wfMsg( "missingarticle", $t );
  23
  24                 $wgOut->setArticleFlag( false );
  25                 if ( ! $this->loadText() ) {
  26                         $wgOut->setPagetitle( wfMsg( "errorpagetitle" ) );
  27                         $wgOut->addHTML( $mtext );
  28                         return;
  29                 }
  30                 $wgOut->supressQuickbar();
  31                 $wgOut->setSubtitle( wfMsg( "difference" ) );
  32                 $wgOut->setRobotpolicy( "noindex,follow" );
  33
  34                 $sk = $wgUser->getSkin();
  35                 $talk = $wgLang->getNsText( NS_TALK );
  36                 $contribs = wfMsg( "contribslink" );
  37
  38                 $oldUserLink = $sk->makeLinkObj( Title::makeTitle( NS_USER, $this->mOldUser ), $this->mOldUser );
  39                 $newUserLink = $sk->makeLinkObj( Title::makeTitle( NS_USER, $this->mNewUser ), $this->mNewUser );
  40                 $oldUTLink = $sk->makeLinkObj( Title::makeTitle( NS_USER_TALK, $this->mOldUser ), $talk );
  41                 $newUTLink = $sk->makeLinkObj( Title::makeTitle( NS_USER_TALK, $this->mNewUser ), $talk );
  42                 $oldContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, "Contributions" ), $contribs,
  43                         "target=" . urlencode($this->mOldUser) );
  44                 $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, "Contributions" ), $contribs,
  45                         "target=" . urlencode($this->mNewUser) );
  46                 if ( !$this->mNewid && $wgUser->isSysop() ) {
  47                         $rollback = "&nbsp;&nbsp;&nbsp;<strong>[" . $sk->makeKnownLinkObj( $wgTitle, wfMsg( "rollbacklink" ),
  48                                 "action=rollback&from=" . urlencode($this->mNewUser) ) . "]</strong>";
  49                 } else {
  50                         $rollback = "";
  51                 }
  52
  53                 $oldHeader = "<strong>{$this->mOldtitle}</strong><br>$oldUserLink ($oldUTLink | $oldContribs)";
  54                 $newHeader = "<strong>{$this->mNewtitle}</strong><br>$newUserLink ($newUTLink | $newContribs) $rollback";
  55
  56                 DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
  57                   $oldHeader, $newHeader );
  58                 $wgOut->addHTML( "<hr><h2>{$this->mNewtitle}</h2>\n" );
  59                 $wgOut->addWikiText( $this->mNewtext );
  60         }
  61
  62         function showDiff( $otext, $ntext, $otitle, $ntitle )
  63         {
  64                 global $wgOut;
  65
  66                 $ota = explode( "\n", str_replace( "\r\n", "\n",
  67                   htmlspecialchars( $otext ) ) );
  68                 $nta = explode( "\n", str_replace( "\r\n", "\n",
  69                   htmlspecialchars( $ntext ) ) );
  70
  71                 $wgOut->addHTML( "<table width='98%' border=0
  72 cellpadding=0 cellspacing='4px'><tr>
  73 <td colspan=2 width='50%' align=center bgcolor='#cccccc'>
  74 {$otitle}</td>
  75 <td colspan=2 width='50%' align=center bgcolor='#cccccc'>
  76 {$ntitle}</td>
  77 </tr>\n" );
  78
  79                 $diffs = new Diff( $ota, $nta );
  80                 $formatter = new TableDiffFormatter();
  81                 $formatter->format( $diffs );
  82                 $wgOut->addHTML( "</table>\n" );
  83         }
  84
  85         # Load the text of the articles to compare.  If newid is 0, then compare
  86         # the old article in oldid to the current article; if oldid is 0, then
  87         # compare the current article to the immediately previous one (ignoring
  88         # the value of newid).
  89         #
  90         function loadText()
  91         {
  92                 global $wgTitle, $wgOut, $wgLang;
  93                 $fname = "DifferenceEngine::loadText";
  94
  95                 if ( 0 == $this->mNewid || 0 == $this->mOldid ) {
  96                         $wgOut->setArticleFlag( true );
  97                         $this->mNewtitle = wfMsg( "currentrev" );
  98                         $id = $wgTitle->getArticleID();
  99
 100                         $sql = "SELECT cur_text, cur_user_text FROM cur WHERE cur_id={$id}";
 101                         $res = wfQuery( $sql, DB_READ, $fname );
 102                         if ( 0 == wfNumRows( $res ) ) { return false; }
 103
 104                         $s = wfFetchObject( $res );
 105                         $this->mNewtext = $s->cur_text;
 106                         $this->mNewUser = $s->cur_user_text;
 107                 } else {
 108                         $sql = "SELECT old_timestamp,old_text,old_flags,old_user_text FROM old WHERE " .
 109                           "old_id={$this->mNewid}";
 110
 111                         $res = wfQuery( $sql, DB_READ, $fname );
 112                         if ( 0 == wfNumRows( $res ) ) { return false; }
 113
 114                         $s = wfFetchObject( $res );
 115                         $this->mNewtext = Article::getRevisionText( $s );
 116
 117                         $t = $wgLang->timeanddate( $s->old_timestamp, true );
 118                         $this->mNewtitle = wfMsg( "revisionasof", $t );
 119                         $this->mNewUser = $s->old_user_text;
 120                 }
 121                 if ( 0 == $this->mOldid ) {
 122                         $sql = "SELECT old_timestamp,old_text,old_flags,old_user_text " .
 123                           "FROM old USE INDEX (name_title_timestamp) WHERE " .
 124                           "old_namespace=" . $wgTitle->getNamespace() . " AND " .
 125                           "old_title='" . wfStrencode( $wgTitle->getDBkey() ) .
 126                           "' ORDER BY inverse_timestamp LIMIT 1";
 127                         $res = wfQuery( $sql, DB_READ, $fname );
 128                 } else {
 129                         $sql = "SELECT old_timestamp,old_text,old_flags,old_user_text FROM old WHERE " .
 130                           "old_id={$this->mOldid}";
 131                         $res = wfQuery( $sql, DB_READ, $fname );
 132                 }
 133                 if ( 0 == wfNumRows( $res ) ) { return false; }
 134
 135                 $s = wfFetchObject( $res );
 136                 $this->mOldtext = Article::getRevisionText( $s );
 137
 138                 $t = $wgLang->timeanddate( $s->old_timestamp, true );
 139                 $this->mOldtitle = wfMsg( "revisionasof", $t );
 140                 $this->mOldUser = $s->old_user_text;
 141
 142                 return true;
 143         }
 144 }
 145
 146 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 147 //
 148 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 149 // You may copy this code freely under the conditions of the GPL.
 150 //
 151
 152 define('USE_ASSERTS', function_exists('assert'));
 153
 154 class _DiffOp {
 155     var $type;
 156     var $orig;
 157     var $closing;
 158
 159     function reverse() {
 160         trigger_error("pure virtual", E_USER_ERROR);
 161     }
 162
 163     function norig() {
 164         return $this->orig ? sizeof($this->orig) : 0;
 165     }
 166
 167     function nclosing() {
 168         return $this->closing ? sizeof($this->closing) : 0;
 169     }
 170 }
 171
 172 class _DiffOp_Copy extends _DiffOp {
 173     var $type = 'copy';
 174
 175     function _DiffOp_Copy ($orig, $closing = false) {
 176         if (!is_array($closing))
 177             $closing = $orig;
 178         $this->orig = $orig;
 179         $this->closing = $closing;
 180     }
 181
 182     function reverse() {
 183         return new _DiffOp_Copy($this->closing, $this->orig);
 184     }
 185 }
 186
 187 class _DiffOp_Delete extends _DiffOp {
 188     var $type = 'delete';
 189
 190     function _DiffOp_Delete ($lines) {
 191         $this->orig = $lines;
 192         $this->closing = false;
 193     }
 194
 195     function reverse() {
 196         return new _DiffOp_Add($this->orig);
 197     }
 198 }
 199
 200 class _DiffOp_Add extends _DiffOp {
 201     var $type = 'add';
 202
 203     function _DiffOp_Add ($lines) {
 204         $this->closing = $lines;
 205         $this->orig = false;
 206     }
 207
 208     function reverse() {
 209         return new _DiffOp_Delete($this->closing);
 210     }
 211 }
 212
 213 class _DiffOp_Change extends _DiffOp {
 214     var $type = 'change';
 215
 216     function _DiffOp_Change ($orig, $closing) {
 217         $this->orig = $orig;
 218         $this->closing = $closing;
 219     }
 220
 221     function reverse() {
 222         return new _DiffOp_Change($this->closing, $this->orig);
 223     }
 224 }
 225
 226
 227 /**
 228  * Class used internally by Diff to actually compute the diffs.
 229  *
 230  * The algorithm used here is mostly lifted from the perl module
 231  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 232  *   http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 233  *
 234  * More ideas are taken from:
 235  *   http://www.ics.uci.edu/~eppstein/161/960229.html
 236  *
 237  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 238  * diffutils-2.7, which can be found at:
 239  *   ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 240  *
 241  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 242  * are my own.
 243  *
 244  * @author Geoffrey T. Dairiki
 245  * @access private
 246  */
 247 class _DiffEngine
 248 {
 249     function diff ($from_lines, $to_lines) {
 250         $n_from = sizeof($from_lines);
 251         $n_to = sizeof($to_lines);
 252
 253         $this->xchanged = $this->ychanged = array();
 254         $this->xv = $this->yv = array();
 255         $this->xind = $this->yind = array();
 256         unset($this->seq);
 257         unset($this->in_seq);
 258         unset($this->lcs);
 259
 260         // Skip leading common lines.
 261         for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 262             if ($from_lines[$skip] != $to_lines[$skip])
 263                 break;
 264             $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 265         }
 266         // Skip trailing common lines.
 267         $xi = $n_from; $yi = $n_to;
 268         for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 269             if ($from_lines[$xi] != $to_lines[$yi])
 270                 break;
 271             $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 272         }
 273
 274         // Ignore lines which do not exist in both files.
 275         for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
 276             $xhash[$from_lines[$xi]] = 1;
 277         for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 278             $line = $to_lines[$yi];
 279             if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
 280                 continue;
 281             $yhash[$line] = 1;
 282             $this->yv[] = $line;
 283             $this->yind[] = $yi;
 284         }
 285         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 286             $line = $from_lines[$xi];
 287             if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
 288                 continue;
 289             $this->xv[] = $line;
 290             $this->xind[] = $xi;
 291         }
 292
 293         // Find the LCS.
 294         $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 295
 296         // Merge edits when possible
 297         $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 298         $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 299
 300         // Compute the edit operations.
 301         $edits = array();
 302         $xi = $yi = 0;
 303         while ($xi < $n_from || $yi < $n_to) {
 304             USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 305             USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 306
 307             // Skip matching "snake".
 308             $copy = array();
 309             while ( $xi < $n_from && $yi < $n_to
 310                     && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 311                 $copy[] = $from_lines[$xi++];
 312                 ++$yi;
 313             }
 314             if ($copy)
 315                 $edits[] = new _DiffOp_Copy($copy);
 316
 317             // Find deletes & adds.
 318             $delete = array();
 319             while ($xi < $n_from && $this->xchanged[$xi])
 320                 $delete[] = $from_lines[$xi++];
 321
 322             $add = array();
 323             while ($yi < $n_to && $this->ychanged[$yi])
 324                 $add[] = $to_lines[$yi++];
 325
 326             if ($delete && $add)
 327                 $edits[] = new _DiffOp_Change($delete, $add);
 328             elseif ($delete)
 329                 $edits[] = new _DiffOp_Delete($delete);
 330             elseif ($add)
 331                 $edits[] = new _DiffOp_Add($add);
 332         }
 333         return $edits;
 334     }
 335
 336
 337     /* Divide the Largest Common Subsequence (LCS) of the sequences
 338      * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 339      * sized segments.
 340      *
 341      * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
 342      * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 343      * sub sequences.  The first sub-sequence is contained in [X0, X1),
 344      * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 345      * that (X0, Y0) == (XOFF, YOFF) and
 346      * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 347      *
 348      * This function assumes that the first lines of the specified portions
 349      * of the two files do not match, and likewise that the last lines do not
 350      * match.  The caller must trim matching lines from the beginning and end
 351      * of the portions it is going to specify.
 352      */
 353     function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
 354         $flip = false;
 355
 356         if ($xlim - $xoff > $ylim - $yoff) {
 357             // Things seems faster (I'm not sure I understand why)
 358             // when the shortest sequence in X.
 359             $flip = true;
 360             list ($xoff, $xlim, $yoff, $ylim)
 361                 = array( $yoff, $ylim, $xoff, $xlim);
 362         }
 363
 364         if ($flip)
 365             for ($i = $ylim - 1; $i >= $yoff; $i--)
 366                 $ymatches[$this->xv[$i]][] = $i;
 367         else
 368             for ($i = $ylim - 1; $i >= $yoff; $i--)
 369                 $ymatches[$this->yv[$i]][] = $i;
 370
 371         $this->lcs = 0;
 372         $this->seq[0]= $yoff - 1;
 373         $this->in_seq = array();
 374         $ymids[0] = array();
 375
 376         $numer = $xlim - $xoff + $nchunks - 1;
 377         $x = $xoff;
 378         for ($chunk = 0; $chunk < $nchunks; $chunk++) {
 379             if ($chunk > 0)
 380                 for ($i = 0; $i <= $this->lcs; $i++)
 381                     $ymids[$i][$chunk-1] = $this->seq[$i];
 382
 383             $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
 384             for ( ; $x < $x1; $x++) {
 385                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 386                 if (empty($ymatches[$line]))
 387                     continue;
 388                 $matches = $ymatches[$line];
 389                 reset($matches);
 390                 while (list ($junk, $y) = each($matches))
 391                     if (empty($this->in_seq[$y])) {
 392                         $k = $this->_lcs_pos($y);
 393                         USE_ASSERTS && assert($k > 0);
 394                         $ymids[$k] = $ymids[$k-1];
 395                         break;
 396                     }
 397                 while (list ($junk, $y) = each($matches)) {
 398                     if ($y > $this->seq[$k-1]) {
 399                         USE_ASSERTS && assert($y < $this->seq[$k]);
 400                         // Optimization: this is a common case:
 401                         //  next match is just replacing previous match.
 402                         $this->in_seq[$this->seq[$k]] = false;
 403                         $this->seq[$k] = $y;
 404                         $this->in_seq[$y] = 1;
 405                     }
 406                     else if (empty($this->in_seq[$y])) {
 407                         $k = $this->_lcs_pos($y);
 408                         USE_ASSERTS && assert($k > 0);
 409                         $ymids[$k] = $ymids[$k-1];
 410                     }
 411                 }
 412             }
 413         }
 414
 415         $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
 416         $ymid = $ymids[$this->lcs];
 417         for ($n = 0; $n < $nchunks - 1; $n++) {
 418             $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
 419             $y1 = $ymid[$n] + 1;
 420             $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
 421         }
 422         $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 423
 424         return array($this->lcs, $seps);
 425     }
 426
 427     function _lcs_pos ($ypos) {
 428         $end = $this->lcs;
 429         if ($end == 0 || $ypos > $this->seq[$end]) {
 430             $this->seq[++$this->lcs] = $ypos;
 431             $this->in_seq[$ypos] = 1;
 432             return $this->lcs;
 433         }
 434
 435         $beg = 1;
 436         while ($beg < $end) {
 437             $mid = (int)(($beg + $end) / 2);
 438             if ( $ypos > $this->seq[$mid] )
 439                 $beg = $mid + 1;
 440             else
 441                 $end = $mid;
 442         }
 443
 444         USE_ASSERTS && assert($ypos != $this->seq[$end]);
 445
 446         $this->in_seq[$this->seq[$end]] = false;
 447         $this->seq[$end] = $ypos;
 448         $this->in_seq[$ypos] = 1;
 449         return $end;
 450     }
 451
 452     /* Find LCS of two sequences.
 453      *
 454      * The results are recorded in the vectors $this->{x,y}changed[], by
 455      * storing a 1 in the element for each line that is an insertion
 456      * or deletion (ie. is not in the LCS).
 457      *
 458      * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
 459      *
 460      * Note that XLIM, YLIM are exclusive bounds.
 461      * All line numbers are origin-0 and discarded lines are not counted.
 462      */
 463     function _compareseq ($xoff, $xlim, $yoff, $ylim) {
 464         // Slide down the bottom initial diagonal.
 465         while ($xoff < $xlim && $yoff < $ylim
 466                && $this->xv[$xoff] == $this->yv[$yoff]) {
 467             ++$xoff;
 468             ++$yoff;
 469         }
 470
 471         // Slide up the top initial diagonal.
 472         while ($xlim > $xoff && $ylim > $yoff
 473                && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
 474             --$xlim;
 475             --$ylim;
 476         }
 477
 478         if ($xoff == $xlim || $yoff == $ylim)
 479             $lcs = 0;
 480         else {
 481             // This is ad hoc but seems to work well.
 482             //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
 483             //$nchunks = max(2,min(8,(int)$nchunks));
 484             $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
 485             list ($lcs, $seps)
 486                 = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
 487         }
 488
 489         if ($lcs == 0) {
 490             // X and Y sequences have no common subsequence:
 491             // mark all changed.
 492             while ($yoff < $ylim)
 493                 $this->ychanged[$this->yind[$yoff++]] = 1;
 494             while ($xoff < $xlim)
 495                 $this->xchanged[$this->xind[$xoff++]] = 1;
 496         }
 497         else {
 498             // Use the partitions to split this problem into subproblems.
 499             reset($seps);
 500             $pt1 = $seps[0];
 501             while ($pt2 = next($seps)) {
 502                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
 503                 $pt1 = $pt2;
 504             }
 505         }
 506     }
 507
 508     /* Adjust inserts/deletes of identical lines to join changes
 509      * as much as possible.
 510      *
 511      * We do something when a run of changed lines include a
 512      * line at one end and has an excluded, identical line at the other.
 513      * We are free to choose which identical line is included.
 514      * `compareseq' usually chooses the one at the beginning,
 515      * but usually it is cleaner to consider the following identical line
 516      * to be the "change".
 517      *
 518      * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
 519      */
 520     function _shift_boundaries ($lines, &$changed, $other_changed) {
 521         $i = 0;
 522         $j = 0;
 523
 524         USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
 525         $len = sizeof($lines);
 526         $other_len = sizeof($other_changed);
 527
 528         while (1) {
 529             /*
 530              * Scan forwards to find beginning of another run of changes.
 531              * Also keep track of the corresponding point in the other file.
 532              *
 533              * Throughout this code, $i and $j are adjusted together so that
 534              * the first $i elements of $changed and the first $j elements
 535              * of $other_changed both contain the same number of zeros
 536              * (unchanged lines).
 537              * Furthermore, $j is always kept so that $j == $other_len or
 538              * $other_changed[$j] == false.
 539              */
 540             while ($j < $other_len && $other_changed[$j])
 541                 $j++;
 542
 543             while ($i < $len && ! $changed[$i]) {
 544                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 545                 $i++; $j++;
 546                 while ($j < $other_len && $other_changed[$j])
 547                     $j++;
 548             }
 549
 550             if ($i == $len)
 551                 break;
 552
 553             $start = $i;
 554
 555             // Find the end of this run of changes.
 556             while (++$i < $len && $changed[$i])
 557                 continue;
 558
 559             do {
 560                 /*
 561                  * Record the length of this run of changes, so that
 562                  * we can later determine whether the run has grown.
 563                  */
 564                 $runlength = $i - $start;
 565
 566                 /*
 567                  * Move the changed region back, so long as the
 568                  * previous unchanged line matches the last changed one.
 569                  * This merges with previous changed regions.
 570                  */
 571                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
 572                     $changed[--$start] = 1;
 573                     $changed[--$i] = false;
 574                     while ($start > 0 && $changed[$start - 1])
 575                         $start--;
 576                     USE_ASSERTS && assert('$j > 0');
 577                     while ($other_changed[--$j])
 578                         continue;
 579                     USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
 580                 }
 581
 582                 /*
 583                  * Set CORRESPONDING to the end of the changed run, at the last
 584                  * point where it corresponds to a changed run in the other file.
 585                  * CORRESPONDING == LEN means no such point has been found.
 586                  */
 587                 $corresponding = $j < $other_len ? $i : $len;
 588
 589                 /*
 590                  * Move the changed region forward, so long as the
 591                  * first changed line matches the following unchanged one.
 592                  * This merges with following changed regions.
 593                  * Do this second, so that if there are no merges,
 594                  * the changed region is moved forward as far as possible.
 595                  */
 596                 while ($i < $len && $lines[$start] == $lines[$i]) {
 597                     $changed[$start++] = false;
 598                     $changed[$i++] = 1;
 599                     while ($i < $len && $changed[$i])
 600                         $i++;
 601
 602                     USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 603                     $j++;
 604                     if ($j < $other_len && $other_changed[$j]) {
 605                         $corresponding = $i;
 606                         while ($j < $other_len && $other_changed[$j])
 607                             $j++;
 608                     }
 609                 }
 610             } while ($runlength != $i - $start);
 611
 612             /*
 613              * If possible, move the fully-merged run of changes
 614              * back to a corresponding run in the other file.
 615              */
 616             while ($corresponding < $i) {
 617                 $changed[--$start] = 1;
 618                 $changed[--$i] = 0;
 619                 USE_ASSERTS && assert('$j > 0');
 620                 while ($other_changed[--$j])
 621                     continue;
 622                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
 623             }
 624         }
 625     }
 626 }
 627
 628 /**
 629  * Class representing a 'diff' between two sequences of strings.
 630  */
 631 class Diff
 632 {
 633     var $edits;
 634
 635     /**
 636      * Constructor.
 637      * Computes diff between sequences of strings.
 638      *
 639      * @param $from_lines array An array of strings.
 640      *        (Typically these are lines from a file.)
 641      * @param $to_lines array An array of strings.
 642      */
 643     function Diff($from_lines, $to_lines) {
 644         $eng = new _DiffEngine;
 645         $this->edits = $eng->diff($from_lines, $to_lines);
 646         //$this->_check($from_lines, $to_lines);
 647     }
 648
 649     /**
 650      * Compute reversed Diff.
 651      *
 652      * SYNOPSIS:
 653      *
 654      *  $diff = new Diff($lines1, $lines2);
 655      *  $rev = $diff->reverse();
 656      * @return object A Diff object representing the inverse of the
 657      *                original diff.
 658      */
 659     function reverse () {
 660         $rev = $this;
 661         $rev->edits = array();
 662         foreach ($this->edits as $edit) {
 663             $rev->edits[] = $edit->reverse();
 664         }
 665         return $rev;
 666     }
 667
 668     /**
 669      * Check for empty diff.
 670      *
 671      * @return bool True iff two sequences were identical.
 672      */
 673     function isEmpty () {
 674         foreach ($this->edits as $edit) {
 675             if ($edit->type != 'copy')
 676                 return false;
 677         }
 678         return true;
 679     }
 680
 681     /**
 682      * Compute the length of the Longest Common Subsequence (LCS).
 683      *
 684      * This is mostly for diagnostic purposed.
 685      *
 686      * @return int The length of the LCS.
 687      */
 688     function lcs () {
 689         $lcs = 0;
 690         foreach ($this->edits as $edit) {
 691             if ($edit->type == 'copy')
 692                 $lcs += sizeof($edit->orig);
 693         }
 694         return $lcs;
 695     }
 696
 697     /**
 698      * Get the original set of lines.
 699      *
 700      * This reconstructs the $from_lines parameter passed to the
 701      * constructor.
 702      *
 703      * @return array The original sequence of strings.
 704      */
 705     function orig() {
 706         $lines = array();
 707
 708         foreach ($this->edits as $edit) {
 709             if ($edit->orig)
 710                 array_splice($lines, sizeof($lines), 0, $edit->orig);
 711         }
 712         return $lines;
 713     }
 714
 715     /**
 716      * Get the closing set of lines.
 717      *
 718      * This reconstructs the $to_lines parameter passed to the
 719      * constructor.
 720      *
 721      * @return array The sequence of strings.
 722      */
 723     function closing() {
 724         $lines = array();
 725
 726         foreach ($this->edits as $edit) {
 727             if ($edit->closing)
 728                 array_splice($lines, sizeof($lines), 0, $edit->closing);
 729         }
 730         return $lines;
 731     }
 732
 733     /**
 734      * Check a Diff for validity.
 735      *
 736      * This is here only for debugging purposes.
 737      */
 738     function _check ($from_lines, $to_lines) {
 739         if (serialize($from_lines) != serialize($this->orig()))
 740             trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
 741         if (serialize($to_lines) != serialize($this->closing()))
 742             trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
 743
 744         $rev = $this->reverse();
 745         if (serialize($to_lines) != serialize($rev->orig()))
 746             trigger_error("Reversed original doesn't match", E_USER_ERROR);
 747         if (serialize($from_lines) != serialize($rev->closing()))
 748             trigger_error("Reversed closing doesn't match", E_USER_ERROR);
 749
 750
 751         $prevtype = 'none';
 752         foreach ($this->edits as $edit) {
 753             if ( $prevtype == $edit->type )
 754                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
 755             $prevtype = $edit->type;
 756         }
 757
 758         $lcs = $this->lcs();
 759         trigger_error("Diff okay: LCS = $lcs", E_USER_NOTICE);
 760     }
 761 }
 762
 763 /**
 764  * FIXME: bad name.
 765  */
 766 class MappedDiff
 767 extends Diff
 768 {
 769     /**
 770      * Constructor.
 771      *
 772      * Computes diff between sequences of strings.
 773      *
 774      * This can be used to compute things like
 775      * case-insensitve diffs, or diffs which ignore
 776      * changes in white-space.
 777      *
 778      * @param $from_lines array An array of strings.
 779      *  (Typically these are lines from a file.)
 780      *
 781      * @param $to_lines array An array of strings.
 782      *
 783      * @param $mapped_from_lines array This array should
 784      *  have the same size number of elements as $from_lines.
 785      *  The elements in $mapped_from_lines and
 786      *  $mapped_to_lines are what is actually compared
 787      *  when computing the diff.
 788      *
 789      * @param $mapped_to_lines array This array should
 790      *  have the same number of elements as $to_lines.
 791      */
 792     function MappedDiff($from_lines, $to_lines,
 793                         $mapped_from_lines, $mapped_to_lines) {
 794
 795         assert(sizeof($from_lines) == sizeof($mapped_from_lines));
 796         assert(sizeof($to_lines) == sizeof($mapped_to_lines));
 797
 798         $this->Diff($mapped_from_lines, $mapped_to_lines);
 799
 800         $xi = $yi = 0;
 801         for ($i = 0; $i < sizeof($this->edits); $i++) {
 802             $orig = &$this->edits[$i]->orig;
 803             if (is_array($orig)) {
 804                 $orig = array_slice($from_lines, $xi, sizeof($orig));
 805                 $xi += sizeof($orig);
 806             }
 807
 808             $closing = &$this->edits[$i]->closing;
 809             if (is_array($closing)) {
 810                 $closing = array_slice($to_lines, $yi, sizeof($closing));
 811                 $yi += sizeof($closing);
 812             }
 813         }
 814     }
 815 }
 816
 817 /**
 818  * A class to format Diffs
 819  *
 820  * This class formats the diff in classic diff format.
 821  * It is intended that this class be customized via inheritance,
 822  * to obtain fancier outputs.
 823  */
 824 class DiffFormatter
 825 {
 826     /**
 827      * Number of leading context "lines" to preserve.
 828      *
 829      * This should be left at zero for this class, but subclasses
 830      * may want to set this to other values.
 831      */
 832     var $leading_context_lines = 0;
 833
 834     /**
 835      * Number of trailing context "lines" to preserve.
 836      *
 837      * This should be left at zero for this class, but subclasses
 838      * may want to set this to other values.
 839      */
 840     var $trailing_context_lines = 0;
 841
 842     /**
 843      * Format a diff.
 844      *
 845      * @param $diff object A Diff object.
 846      * @return string The formatted output.
 847      */
 848     function format($diff) {
 849
 850         $xi = $yi = 1;
 851         $block = false;
 852         $context = array();
 853
 854         $nlead = $this->leading_context_lines;
 855         $ntrail = $this->trailing_context_lines;
 856
 857         $this->_start_diff();
 858
 859         foreach ($diff->edits as $edit) {
 860             if ($edit->type == 'copy') {
 861                 if (is_array($block)) {
 862                     if (sizeof($edit->orig) <= $nlead + $ntrail) {
 863                         $block[] = $edit;
 864                     }
 865                     else{
 866                         if ($ntrail) {
 867                             $context = array_slice($edit->orig, 0, $ntrail);
 868                             $block[] = new _DiffOp_Copy($context);
 869                         }
 870                         $this->_block($x0, $ntrail + $xi - $x0,
 871                                       $y0, $ntrail + $yi - $y0,
 872                                       $block);
 873                         $block = false;
 874                     }
 875                 }
 876                 $context = $edit->orig;
 877             }
 878             else {
 879                 if (! is_array($block)) {
 880                     $context = array_slice($context, sizeof($context) - $nlead);
 881                     $x0 = $xi - sizeof($context);
 882                     $y0 = $yi - sizeof($context);
 883                     $block = array();
 884                     if ($context)
 885                         $block[] = new _DiffOp_Copy($context);
 886                 }
 887                 $block[] = $edit;
 888             }
 889
 890             if ($edit->orig)
 891                 $xi += sizeof($edit->orig);
 892             if ($edit->closing)
 893                 $yi += sizeof($edit->closing);
 894         }
 895
 896         if (is_array($block))
 897             $this->_block($x0, $xi - $x0,
 898                           $y0, $yi - $y0,
 899                           $block);
 900
 901         return $this->_end_diff();
 902     }
 903
 904     function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
 905         $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
 906         foreach ($edits as $edit) {
 907             if ($edit->type == 'copy')
 908                 $this->_context($edit->orig);
 909             elseif ($edit->type == 'add')
 910                 $this->_added($edit->closing);
 911             elseif ($edit->type == 'delete')
 912                 $this->_deleted($edit->orig);
 913             elseif ($edit->type == 'change')
 914                 $this->_changed($edit->orig, $edit->closing);
 915             else
 916                 trigger_error("Unknown edit type", E_USER_ERROR);
 917         }
 918         $this->_end_block();
 919     }
 920
 921     function _start_diff() {
 922         ob_start();
 923     }
 924
 925     function _end_diff() {
 926         $val = ob_get_contents();
 927         ob_end_clean();
 928         return $val;
 929     }
 930
 931     function _block_header($xbeg, $xlen, $ybeg, $ylen) {
 932         if ($xlen > 1)
 933             $xbeg .= "," . ($xbeg + $xlen - 1);
 934         if ($ylen > 1)
 935             $ybeg .= "," . ($ybeg + $ylen - 1);
 936
 937         return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
 938     }
 939
 940     function _start_block($header) {
 941         echo $header;
 942     }
 943
 944     function _end_block() {
 945     }
 946
 947     function _lines($lines, $prefix = ' ') {
 948         foreach ($lines as $line)
 949             echo "$prefix $line\n";
 950     }
 951
 952     function _context($lines) {
 953         $this->_lines($lines);
 954     }
 955
 956     function _added($lines) {
 957         $this->_lines($lines, ">");
 958     }
 959     function _deleted($lines) {
 960         $this->_lines($lines, "<");
 961     }
 962
 963     function _changed($orig, $closing) {
 964         $this->_deleted($orig);
 965         echo "---\n";
 966         $this->_added($closing);
 967     }
 968 }
 969
 970
 971 /**
 972  *  Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
 973  *
 974  */
 975
 976 define('NBSP', "\xA0");         // iso-8859-x non-breaking space.
 977
 978 class _HWLDF_WordAccumulator {
 979     function _HWLDF_WordAccumulator () {
 980         $this->_lines = array();
 981         $this->_line = '';
 982         $this->_group = '';
 983         $this->_tag = '';
 984     }
 985
 986     function _flushGroup ($new_tag) {
 987         if ($this->_group !== '') {
 988           if ($this->_tag == 'mark')
 989             $this->_line .= "<font color=\"red\">$this->_group</font>";
 990           else
 991             $this->_line .= $this->_group;
 992         }
 993         $this->_group = '';
 994         $this->_tag = $new_tag;
 995     }
 996
 997     function _flushLine ($new_tag) {
 998         $this->_flushGroup($new_tag);
 999         if ($this->_line != '')
1000             $this->_lines[] = $this->_line;
1001         $this->_line = '';
1002     }
1003
1004     function addWords ($words, $tag = '') {
1005         if ($tag != $this->_tag)
1006             $this->_flushGroup($tag);
1007
1008         foreach ($words as $word) {
1009             // new-line should only come as first char of word.
1010             if ($word == '')
1011                 continue;
1012             if ($word[0] == "\n") {
1013                 $this->_group .= NBSP;
1014                 $this->_flushLine($tag);
1015                 $word = substr($word, 1);
1016             }
1017             assert(!strstr($word, "\n"));
1018             $this->_group .= $word;
1019         }
1020     }
1021
1022     function getLines() {
1023         $this->_flushLine('~done');
1024         return $this->_lines;
1025     }
1026 }
1027
1028 class WordLevelDiff extends MappedDiff
1029 {
1030     function WordLevelDiff ($orig_lines, $closing_lines) {
1031         list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1032         list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1033
1034
1035         $this->MappedDiff($orig_words, $closing_words,
1036                           $orig_stripped, $closing_stripped);
1037     }
1038
1039     function _split($lines) {
1040         // FIXME: fix POSIX char class.
1041 #        if (!preg_match_all('/ ( [^\S\n]+ | [[:alnum:]]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1042         if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1043                             implode("\n", $lines),
1044                             $m)) {
1045             return array(array(''), array(''));
1046         }
1047         return array($m[0], $m[1]);
1048     }
1049
1050     function orig () {
1051         $orig = new _HWLDF_WordAccumulator;
1052
1053         foreach ($this->edits as $edit) {
1054             if ($edit->type == 'copy')
1055                 $orig->addWords($edit->orig);
1056             elseif ($edit->orig)
1057                 $orig->addWords($edit->orig, 'mark');
1058         }
1059         return $orig->getLines();
1060     }
1061
1062     function closing () {
1063         $closing = new _HWLDF_WordAccumulator;
1064
1065         foreach ($this->edits as $edit) {
1066             if ($edit->type == 'copy')
1067                 $closing->addWords($edit->closing);
1068             elseif ($edit->closing)
1069                 $closing->addWords($edit->closing, 'mark');
1070         }
1071         return $closing->getLines();
1072     }
1073 }
1074
1075 /**
1076  *  Wikipedia Table style diff formatter.
1077  *
1078  */
1079 class TableDiffFormatter extends DiffFormatter
1080 {
1081         function TableDiffFormatter() {
1082                 $this->leading_context_lines = 2;
1083                 $this->trailing_context_lines = 2;
1084         }
1085
1086         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1087                 $l1 = wfMsg( "lineno", $xbeg );
1088                 $l2 = wfMsg( "lineno", $ybeg );
1089
1090                 $r = "<tr><td colspan=2 align=left><strong>{$l1}</strong></td>\n" .
1091                   "<td colspan=2 align=left><strong>{$l2}</strong></td></tr>\n";
1092                 return $r;
1093         }
1094
1095         function _start_block( $header ) {
1096                 global $wgOut;
1097                 $wgOut->addHTML( $header );
1098         }
1099
1100         function _end_block() {
1101         }
1102
1103         function _lines( $lines, $prefix=' ', $color="white" ) {
1104         }
1105
1106         function addedLine( $line ) {
1107                 return "<td>+</td><td bgcolor='#ccffcc'>" .
1108                   "<small>{$line}</small></td>";
1109         }
1110
1111         function deletedLine( $line ) {
1112                 return "<td>-</td><td bgcolor='#ffffaa'>" .
1113                   "<small>{$line}</small></td>";
1114         }
1115
1116         function emptyLine() {
1117                 return "<td colspan=2>&nbsp;</td>";
1118         }
1119
1120         function contextLine( $line ) {
1121                 return "<td> </td><td bgcolor='white'><small>{$line}</small></td>";
1122         }
1123
1124     function _added($lines) {
1125                 global $wgOut;
1126                 foreach ($lines as $line) {
1127                         $wgOut->addHTML( "<tr>" . $this->emptyLine() .
1128                           $this->addedLine( $line ) . "</tr>\n" );
1129                 }
1130         }
1131
1132         function _deleted($lines) {
1133                 global $wgOut;
1134                 foreach ($lines as $line) {
1135                         $wgOut->addHTML( "<tr>" . $this->deletedLine( $line ) .
1136                           $this->emptyLine() . "</tr>\n" );
1137                 }
1138         }
1139
1140         function _context( $lines ) {
1141                 global $wgOut;
1142                 foreach ($lines as $line) {
1143                         $wgOut->addHTML( "<tr>" . $this->contextLine( $line ) .
1144                           $this->contextLine( $line ) . "</tr>\n" );
1145                 }
1146         }
1147
1148         function _changed( $orig, $closing ) {
1149                 global $wgOut;
1150         $diff = new WordLevelDiff( $orig, $closing );
1151                 $del = $diff->orig();
1152                 $add = $diff->closing();
1153
1154                 while ( $line = array_shift( $del ) ) {
1155                         $aline = array_shift( $add );
1156                         $wgOut->addHTML( "<tr>" . $this->deletedLine( $line ) .
1157                           $this->addedLine( $aline ) . "</tr>\n" );
1158                 }
1159                 $this->_added( $add ); # If any leftovers
1160     }
1161 }
1162
1163 ?>