includes/DifferenceEngine.php

   1 <?php
   2 # See diff.doc
   3
   4 class DifferenceEngine {
   5         /* private */ var $mOldid, $mNewid;
   6         /* private */ var $mOldtitle, $mNewtitle, $mPagetitle;
   7         /* private */ var $mOldtext, $mNewtext;
   8         /* private */ var $mOldUser, $mNewUser;
   9         /* private */ var $mOldComment, $mNewComment;
  10         /* private */ var $mOldPage, $mNewPage;
  11         /* private */ var $mRcidMarkPatrolled;
  12
  13         function DifferenceEngine( $old, $new, $rcid = 0 )
  14         {
  15                 global $wgTitle;
  16                 if ( 'prev' == $new ) {
  17                         # Show diff between revision $old and the previous one.
  18                         # Get previous one from DB.
  19                         #
  20                         $this->mNewid = intval($old);
  21                         $dbr =& wfGetDB( DB_SLAVE );
  22                         $this->mOldid = $dbr->selectField( 'old', 'old_id',
  23                                 "old_title='" . $wgTitle->getDBkey() . "'" .
  24                                 ' AND old_namespace=' . $wgTitle->getNamespace() .
  25                                 " AND old_id<{$this->mNewid} ORDER BY old_id DESC" );
  26
  27                 } elseif ( 'next' == $new ) {
  28
  29                         # Show diff between revision $old and the previous one.
  30                         # Get previous one from DB.
  31                         #
  32                         $this->mOldid = intval($old);
  33                         $dbr =& wfGetDB( DB_SLAVE );
  34                         $this->mNewid = $dbr->selectField( 'old', 'old_id',
  35                                 "old_title='" . $wgTitle->getDBkey() . "'" .
  36                                 ' AND old_namespace=' . $wgTitle->getNamespace() .
  37                                 " AND old_id>{$this->mOldid} ORDER BY old_id " );
  38                         if ( false === $this->mNewid ) {
  39                                 # if no result, NewId points to the newest old revision. The only newer
  40                                 # revision is cur, which is "0".
  41                                 $this->mNewid = 0;
  42                         }
  43
  44                 } else {
  45
  46                         $this->mOldid = intval($old);
  47                         $this->mNewid = intval($new);
  48                 }
  49                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  50         }
  51
  52         function showDiffPage()
  53         {
  54                 global $wgUser, $wgTitle, $wgOut, $wgLang, $wgOnlySysopsCanPatrol, $wgUseRCPatrol;
  55                 $fname = 'DifferenceEngine::showDiffPage';
  56                 wfProfileIn( $fname );
  57
  58                 # mOldid is false if the difference engine is called with a "vague" query for
  59                 # a diff between a version V and its previous version V' AND the version V
  60                 # is the first version of that article. In that case, V' does not exist.
  61                 if ( $this->mOldid === false ) {
  62                         $this->showFirstRevision();
  63                         wfProfileOut( $fname );
  64                         return;
  65                 }
  66
  67                 $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
  68                   "{$this->mNewid})";
  69                 $mtext = wfMsg( 'missingarticle', $t );
  70
  71                 $wgOut->setArticleFlag( false );
  72                 if ( ! $this->loadText() ) {
  73                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
  74                         $wgOut->addHTML( $mtext );
  75                         wfProfileOut( $fname );
  76                         return;
  77                 }
  78                 $wgOut->suppressQuickbar();
  79
  80                 $oldTitle = $this->mOldPage->getPrefixedText();
  81                 $newTitle = $this->mNewPage->getPrefixedText();
  82                 if( $oldTitle == $newTitle ) {
  83                         $wgOut->setPageTitle( $newTitle );
  84                 } else {
  85                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
  86                 }
  87                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
  88                 $wgOut->setRobotpolicy( 'noindex,follow' );
  89
  90                 if ( !( $this->mOldPage->userCanRead() && $this->mNewPage->userCanRead() ) ) {
  91                         $wgOut->loginToUse();
  92                         $wgOut->output();
  93                         wfProfileOut( $fname );
  94                         exit;
  95                 }
  96
  97                 $sk = $wgUser->getSkin();
  98                 $talk = $wgLang->getNsText( NS_TALK );
  99                 $contribs = wfMsg( 'contribslink' );
 100
 101                 $this->mOldComment = $sk->formatComment($this->mOldComment);
 102                 $this->mNewComment = $sk->formatComment($this->mNewComment);
 103
 104                 $oldUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 105                 $newUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mNewUser ), $this->mNewUser );
 106                 $oldUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ), $talk );
 107                 $newUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mNewUser ), $talk );
 108                 $oldContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 109                         'target=' . urlencode($this->mOldUser) );
 110                 $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 111                         'target=' . urlencode($this->mNewUser) );
 112                 if ( !$this->mNewid && $wgUser->isSysop() ) {
 113                         $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'rollbacklink' ),
 114                                 'action=rollback&from=' . urlencode($this->mNewUser) ) . ']</strong>';
 115                 } else {
 116                         $rollback = '';
 117                 }
 118                 if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->getID() != 0 &&
 119                      ( $wgUser->isSysop() || !$wgOnlySysopsCanPatrol ) )
 120                 {
 121                         $patrol = ' [' . $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'markaspatrolleddiff' ),
 122                                 "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
 123                 } else {
 124                         $patrol = '';
 125                 }
 126
 127                 $prevlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'previousdiff' ), 'diff=prev&oldid='.$this->mOldid );
 128                 if ( $this->mNewid == 0 ) {
 129                         $nextlink = '';
 130                 } else {
 131                         $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid );
 132                 }
 133
 134                 $oldHeader = "<strong>{$this->mOldtitle}</strong><br />$oldUserLink " .
 135                         "($oldUTLink | $oldContribs)<br />" . $this->mOldComment .
 136                         '<br />' . $prevlink;
 137                 $newHeader = "<strong>{$this->mNewtitle}</strong><br />$newUserLink " .
 138                         "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
 139                         '<br />' . $nextlink . $patrol;
 140
 141                 DifferenceEngine::showDiff( $this->mOldtext, $this->mNewtext,
 142                   $oldHeader, $newHeader );
 143                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 144                 $wgOut->addWikiText( $this->mNewtext );
 145
 146                 wfProfileOut( $fname );
 147         }
 148
 149         # Show the first revision of an article. Uses normal diff headers in contrast to normal
 150         # "old revision" display style.
 151         #
 152         function showFirstRevision()
 153         {
 154                 global $wgOut, $wgTitle, $wgUser, $wgLang;
 155
 156                 $fname = 'DifferenceEngine::showFirstRevision';
 157                 wfProfileIn( $fname );
 158
 159
 160                 $this->mOldid = $this->mNewid; # hack to make loadText() work.
 161
 162                 # Get article text from the DB
 163                 #
 164                 if ( ! $this->loadText() ) {
 165                         $t = $wgTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 166                           "{$this->mNewid})";
 167                         $mtext = wfMsg( 'missingarticle', $t );
 168                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 169                         $wgOut->addHTML( $mtext );
 170                         wfProfileOut( $fname );
 171                         return;
 172                 }
 173
 174                 # Check if user is allowed to look at this page. If not, bail out.
 175                 #
 176                 if ( !( $this->mOldPage->userCanRead() ) ) {
 177                         $wgOut->loginToUse();
 178                         $wgOut->output();
 179                         wfProfileOut( $fname );
 180                         exit;
 181                 }
 182
 183                 # Prepare the header box
 184                 #
 185                 $sk = $wgUser->getSkin();
 186
 187                 $uTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ),  $wgLang->getNsText( NS_TALK ) );
 188                 $userLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 189                 $contribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), wfMsg( 'contribslink' ),
 190                         'target=' . urlencode($this->mOldUser) );
 191                 $nextlink = $sk->makeKnownLinkObj( $wgTitle, wfMsg( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid );
 192                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
 193                         "($uTLink | $contribs)<br />" . $this->mOldComment .
 194                         '<br />' . $nextlink. "</div>\n";
 195
 196                 $wgOut->addHTML( $header );
 197
 198                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 199                 $wgOut->setRobotpolicy( 'noindex,follow' );
 200
 201
 202                 # Show current revision
 203                 #
 204                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 205                 $wgOut->addWikiText( $this->mNewtext );
 206
 207                 wfProfileOut( $fname );
 208         }
 209
 210         function showDiff( $otext, $ntext, $otitle, $ntitle )
 211         {
 212                 global $wgOut, $wgUseExternalDiffEngine;
 213
 214                 $wgOut->addHTML( "
 215                         <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
 216                         <tr>
 217                                 <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
 218                                 <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
 219                         </tr>
 220                 " );
 221
 222                 if ( $wgUseExternalDiffEngine ) {
 223                         # For historical reasons, external diff engine expects
 224                         # input text to be HTML-escaped already
 225                         $otext = str_replace( "\r\n", "\n", htmlspecialchars ( $otext ) );
 226                         $ntext = str_replace( "\r\n", "\n", htmlspecialchars ( $ntext ) );
 227                         dl('php_wikidiff.so');
 228                         $wgOut->addHTML( wikidiff_do_diff( $otext, $ntext, 2) );
 229                 } else {
 230                         $ota = explode( "\n", str_replace( "\r\n", "\n", $otext ) );
 231                         $nta = explode( "\n", str_replace( "\r\n", "\n", $ntext ) );
 232                         $diffs = new Diff( $ota, $nta );
 233                         $formatter = new TableDiffFormatter();
 234                         $formatter->format( $diffs );
 235                 }
 236                 $wgOut->addHTML( "</table>\n" );
 237         }
 238
 239         # Load the text of the articles to compare.  If newid is 0, then compare
 240         # the old article in oldid to the current article; if oldid is 0, then
 241         # compare the current article to the immediately previous one (ignoring
 242         # the value of newid).
 243         #
 244         function loadText()
 245         {
 246                 global $wgTitle, $wgOut, $wgLang;
 247                 $fname = 'DifferenceEngine::loadText';
 248
 249                 $dbr =& wfGetDB( DB_SLAVE );
 250                 if ( 0 == $this->mNewid || 0 == $this->mOldid ) {
 251                         $wgOut->setArticleFlag( true );
 252                         $newLink = $wgTitle->getLocalUrl();
 253                         $this->mPagetitle = wfMsg( 'currentrev' );
 254                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 255                         $id = $wgTitle->getArticleID();
 256
 257                         $s = $dbr->getArray( 'cur', array( 'cur_text', 'cur_user_text', 'cur_comment' ),
 258                                 array( 'cur_id' => $id ), $fname );
 259                         if ( $s === false ) {
 260                                 return false;
 261                         }
 262
 263                         $this->mNewPage = &$wgTitle;
 264                         $this->mNewtext = $s->cur_text;
 265                         $this->mNewUser = $s->cur_user_text;
 266                         $this->mNewComment = $s->cur_comment;
 267                 } else {
 268                         $s = $dbr->getArray( 'old', array( 'old_namespace','old_title','old_timestamp', 'old_text',
 269                                 'old_flags','old_user_text','old_comment' ), array( 'old_id' => $this->mNewid ), $fname );
 270
 271                         if ( $s === false ) {
 272                                 return false;
 273                         }
 274
 275                         $this->mNewtext = Article::getRevisionText( $s );
 276
 277                         $t = $wgLang->timeanddate( $s->old_timestamp, true );
 278                         $this->mNewPage = Title::MakeTitle( $s->old_namespace, $s->old_title );
 279                         $newLink = $wgTitle->getLocalUrl ('oldid=' . $this->mNewid);
 280                         $this->mPagetitle = wfMsg( 'revisionasof', $t );
 281                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 282                         $this->mNewUser = $s->old_user_text;
 283                         $this->mNewComment = $s->old_comment;
 284                 }
 285                 if ( 0 == $this->mOldid ) {
 286                         $s = $dbr->getArray( 'old',
 287                                 array( 'old_namespace','old_title','old_timestamp','old_text', 'old_flags','old_user_text','old_comment' ),
 288                                 array( /* WHERE */
 289                                         'old_namespace' => $this->mNewPage->getNamespace(),
 290                                         'old_title' => $this->mNewPage->getDBkey()
 291                                 ), $fname, array( 'ORDER BY' => 'inverse_timestamp', 'USE INDEX' => 'name_title_timestamp' )
 292                         );
 293                 } else {
 294                         $s = $dbr->getArray( 'old',
 295                                 array( 'old_namespace','old_title','old_timestamp','old_text','old_flags','old_user_text','old_comment'),
 296                                 array( 'old_id' => $this->mOldid ),
 297                                 $fname
 298                         );
 299                 }
 300                 if ( $s === false ) {
 301                         return false;
 302                 }
 303                 $this->mOldPage = Title::MakeTitle( $s->old_namespace, $s->old_title );
 304                 $this->mOldtext = Article::getRevisionText( $s );
 305
 306                 $t = $wgLang->timeanddate( $s->old_timestamp, true );
 307                 $oldLink = $this->mOldPage->getLocalUrl ('oldid=' . $this->mOldid);
 308                 $this->mOldtitle = "<a href='$oldLink'>" . wfMsg( 'revisionasof', $t ) . '</a>';
 309                 $this->mOldUser = $s->old_user_text;
 310                 $this->mOldComment = $s->old_comment;
 311
 312                 return true;
 313         }
 314 }
 315
 316 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 317 //
 318 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 319 // You may copy this code freely under the conditions of the GPL.
 320 //
 321
 322 define('USE_ASSERTS', function_exists('assert'));
 323
 324 class _DiffOp {
 325         var $type;
 326         var $orig;
 327         var $closing;
 328
 329         function reverse() {
 330                 trigger_error('pure virtual', E_USER_ERROR);
 331         }
 332
 333         function norig() {
 334                 return $this->orig ? sizeof($this->orig) : 0;
 335         }
 336
 337         function nclosing() {
 338                 return $this->closing ? sizeof($this->closing) : 0;
 339         }
 340 }
 341
 342 class _DiffOp_Copy extends _DiffOp {
 343         var $type = 'copy';
 344
 345         function _DiffOp_Copy ($orig, $closing = false) {
 346                 if (!is_array($closing))
 347                         $closing = $orig;
 348                 $this->orig = $orig;
 349                 $this->closing = $closing;
 350         }
 351
 352         function reverse() {
 353                 return new _DiffOp_Copy($this->closing, $this->orig);
 354         }
 355 }
 356
 357 class _DiffOp_Delete extends _DiffOp {
 358         var $type = 'delete';
 359
 360         function _DiffOp_Delete ($lines) {
 361                 $this->orig = $lines;
 362                 $this->closing = false;
 363         }
 364
 365         function reverse() {
 366                 return new _DiffOp_Add($this->orig);
 367         }
 368 }
 369
 370 class _DiffOp_Add extends _DiffOp {
 371         var $type = 'add';
 372
 373         function _DiffOp_Add ($lines) {
 374                 $this->closing = $lines;
 375                 $this->orig = false;
 376         }
 377
 378         function reverse() {
 379                 return new _DiffOp_Delete($this->closing);
 380         }
 381 }
 382
 383 class _DiffOp_Change extends _DiffOp {
 384         var $type = 'change';
 385
 386         function _DiffOp_Change ($orig, $closing) {
 387                 $this->orig = $orig;
 388                 $this->closing = $closing;
 389         }
 390
 391         function reverse() {
 392                 return new _DiffOp_Change($this->closing, $this->orig);
 393         }
 394 }
 395
 396
 397 /**
 398  * Class used internally by Diff to actually compute the diffs.
 399  *
 400  * The algorithm used here is mostly lifted from the perl module
 401  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 402  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 403  *
 404  * More ideas are taken from:
 405  *       http://www.ics.uci.edu/~eppstein/161/960229.html
 406  *
 407  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 408  * diffutils-2.7, which can be found at:
 409  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 410  *
 411  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 412  * are my own.
 413  *
 414  * @author Geoffrey T. Dairiki
 415  * @access private
 416  */
 417 class _DiffEngine
 418 {
 419         function diff ($from_lines, $to_lines) {
 420                 $n_from = sizeof($from_lines);
 421                 $n_to = sizeof($to_lines);
 422
 423                 $this->xchanged = $this->ychanged = array();
 424                 $this->xv = $this->yv = array();
 425                 $this->xind = $this->yind = array();
 426                 unset($this->seq);
 427                 unset($this->in_seq);
 428                 unset($this->lcs);
 429
 430                 // Skip leading common lines.
 431                 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 432                         if ($from_lines[$skip] != $to_lines[$skip])
 433                                 break;
 434                         $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 435                 }
 436                 // Skip trailing common lines.
 437                 $xi = $n_from; $yi = $n_to;
 438                 for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 439                         if ($from_lines[$xi] != $to_lines[$yi])
 440                                 break;
 441                         $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 442                 }
 443
 444                 // Ignore lines which do not exist in both files.
 445                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++)
 446                         $xhash[$from_lines[$xi]] = 1;
 447                 for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 448                         $line = $to_lines[$yi];
 449                         if ( ($this->ychanged[$yi] = empty($xhash[$line])) )
 450                                 continue;
 451                         $yhash[$line] = 1;
 452                         $this->yv[] = $line;
 453                         $this->yind[] = $yi;
 454                 }
 455                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 456                         $line = $from_lines[$xi];
 457                         if ( ($this->xchanged[$xi] = empty($yhash[$line])) )
 458                                 continue;
 459                         $this->xv[] = $line;
 460                         $this->xind[] = $xi;
 461                 }
 462
 463                 // Find the LCS.
 464                 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 465
 466                 // Merge edits when possible
 467                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 468                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 469
 470                 // Compute the edit operations.
 471                 $edits = array();
 472                 $xi = $yi = 0;
 473                 while ($xi < $n_from || $yi < $n_to) {
 474                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 475                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 476
 477                         // Skip matching "snake".
 478                         $copy = array();
 479                         while ( $xi < $n_from && $yi < $n_to
 480                                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 481                                 $copy[] = $from_lines[$xi++];
 482                                 ++$yi;
 483                         }
 484                         if ($copy)
 485                                 $edits[] = new _DiffOp_Copy($copy);
 486
 487                         // Find deletes & adds.
 488                         $delete = array();
 489                         while ($xi < $n_from && $this->xchanged[$xi])
 490                                 $delete[] = $from_lines[$xi++];
 491
 492                         $add = array();
 493                         while ($yi < $n_to && $this->ychanged[$yi])
 494                                 $add[] = $to_lines[$yi++];
 495
 496                         if ($delete && $add)
 497                                 $edits[] = new _DiffOp_Change($delete, $add);
 498                         elseif ($delete)
 499                                 $edits[] = new _DiffOp_Delete($delete);
 500                         elseif ($add)
 501                                 $edits[] = new _DiffOp_Add($add);
 502                 }
 503                 return $edits;
 504         }
 505
 506
 507         /* Divide the Largest Common Subsequence (LCS) of the sequences
 508          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 509          * sized segments.
 510          *
 511          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
 512          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 513          * sub sequences.  The first sub-sequence is contained in [X0, X1),
 514          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 515          * that (X0, Y0) == (XOFF, YOFF) and
 516          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 517          *
 518          * This function assumes that the first lines of the specified portions
 519          * of the two files do not match, and likewise that the last lines do not
 520          * match.  The caller must trim matching lines from the beginning and end
 521          * of the portions it is going to specify.
 522          */
 523         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
 524         $flip = false;
 525
 526         if ($xlim - $xoff > $ylim - $yoff) {
 527                 // Things seems faster (I'm not sure I understand why)
 528                         // when the shortest sequence in X.
 529                         $flip = true;
 530                 list ($xoff, $xlim, $yoff, $ylim)
 531                 = array( $yoff, $ylim, $xoff, $xlim);
 532                 }
 533
 534         if ($flip)
 535                 for ($i = $ylim - 1; $i >= $yoff; $i--)
 536                 $ymatches[$this->xv[$i]][] = $i;
 537         else
 538                 for ($i = $ylim - 1; $i >= $yoff; $i--)
 539                 $ymatches[$this->yv[$i]][] = $i;
 540
 541         $this->lcs = 0;
 542         $this->seq[0]= $yoff - 1;
 543         $this->in_seq = array();
 544         $ymids[0] = array();
 545
 546         $numer = $xlim - $xoff + $nchunks - 1;
 547         $x = $xoff;
 548         for ($chunk = 0; $chunk < $nchunks; $chunk++) {
 549                 if ($chunk > 0)
 550                 for ($i = 0; $i <= $this->lcs; $i++)
 551                         $ymids[$i][$chunk-1] = $this->seq[$i];
 552
 553                 $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
 554                 for ( ; $x < $x1; $x++) {
 555                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 556                                 if (empty($ymatches[$line]))
 557                         continue;
 558                 $matches = $ymatches[$line];
 559                                 reset($matches);
 560                 while (list ($junk, $y) = each($matches))
 561                         if (empty($this->in_seq[$y])) {
 562                         $k = $this->_lcs_pos($y);
 563                         USE_ASSERTS && assert($k > 0);
 564                         $ymids[$k] = $ymids[$k-1];
 565                         break;
 566                                         }
 567                 while (list ($junk, $y) = each($matches)) {
 568                         if ($y > $this->seq[$k-1]) {
 569                         USE_ASSERTS && assert($y < $this->seq[$k]);
 570                         // Optimization: this is a common case:
 571                         //      next match is just replacing previous match.
 572                         $this->in_seq[$this->seq[$k]] = false;
 573                         $this->seq[$k] = $y;
 574                         $this->in_seq[$y] = 1;
 575                                         }
 576                         else if (empty($this->in_seq[$y])) {
 577                         $k = $this->_lcs_pos($y);
 578                         USE_ASSERTS && assert($k > 0);
 579                         $ymids[$k] = $ymids[$k-1];
 580                                         }
 581                                 }
 582                         }
 583                 }
 584
 585         $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
 586         $ymid = $ymids[$this->lcs];
 587         for ($n = 0; $n < $nchunks - 1; $n++) {
 588                 $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
 589                 $y1 = $ymid[$n] + 1;
 590                 $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
 591                 }
 592         $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 593
 594         return array($this->lcs, $seps);
 595         }
 596
 597         function _lcs_pos ($ypos) {
 598         $end = $this->lcs;
 599         if ($end == 0 || $ypos > $this->seq[$end]) {
 600                 $this->seq[++$this->lcs] = $ypos;
 601                 $this->in_seq[$ypos] = 1;
 602                 return $this->lcs;
 603                 }
 604
 605         $beg = 1;
 606         while ($beg < $end) {
 607                 $mid = (int)(($beg + $end) / 2);
 608                 if ( $ypos > $this->seq[$mid] )
 609                 $beg = $mid + 1;
 610                 else
 611                 $end = $mid;
 612                 }
 613
 614         USE_ASSERTS && assert($ypos != $this->seq[$end]);
 615
 616         $this->in_seq[$this->seq[$end]] = false;
 617         $this->seq[$end] = $ypos;
 618         $this->in_seq[$ypos] = 1;
 619         return $end;
 620         }
 621
 622         /* Find LCS of two sequences.
 623          *
 624          * The results are recorded in the vectors $this->{x,y}changed[], by
 625          * storing a 1 in the element for each line that is an insertion
 626          * or deletion (ie. is not in the LCS).
 627          *
 628          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
 629          *
 630          * Note that XLIM, YLIM are exclusive bounds.
 631          * All line numbers are origin-0 and discarded lines are not counted.
 632          */
 633         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
 634         // Slide down the bottom initial diagonal.
 635         while ($xoff < $xlim && $yoff < $ylim
 636                            && $this->xv[$xoff] == $this->yv[$yoff]) {
 637                 ++$xoff;
 638                 ++$yoff;
 639                 }
 640
 641         // Slide up the top initial diagonal.
 642         while ($xlim > $xoff && $ylim > $yoff
 643                            && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
 644                 --$xlim;
 645                 --$ylim;
 646                 }
 647
 648         if ($xoff == $xlim || $yoff == $ylim)
 649                 $lcs = 0;
 650         else {
 651                 // This is ad hoc but seems to work well.
 652                 //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
 653                 //$nchunks = max(2,min(8,(int)$nchunks));
 654                 $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
 655                 list ($lcs, $seps)
 656                 = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
 657                 }
 658
 659         if ($lcs == 0) {
 660                 // X and Y sequences have no common subsequence:
 661                 // mark all changed.
 662                 while ($yoff < $ylim)
 663                 $this->ychanged[$this->yind[$yoff++]] = 1;
 664                 while ($xoff < $xlim)
 665                 $this->xchanged[$this->xind[$xoff++]] = 1;
 666                 }
 667         else {
 668                 // Use the partitions to split this problem into subproblems.
 669                 reset($seps);
 670                 $pt1 = $seps[0];
 671                 while ($pt2 = next($seps)) {
 672                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
 673                 $pt1 = $pt2;
 674                         }
 675                 }
 676         }
 677
 678         /* Adjust inserts/deletes of identical lines to join changes
 679          * as much as possible.
 680          *
 681          * We do something when a run of changed lines include a
 682          * line at one end and has an excluded, identical line at the other.
 683          * We are free to choose which identical line is included.
 684          * `compareseq' usually chooses the one at the beginning,
 685          * but usually it is cleaner to consider the following identical line
 686          * to be the "change".
 687          *
 688          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
 689          */
 690         function _shift_boundaries ($lines, &$changed, $other_changed) {
 691         $i = 0;
 692         $j = 0;
 693
 694         USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
 695         $len = sizeof($lines);
 696         $other_len = sizeof($other_changed);
 697
 698         while (1) {
 699                 /*
 700                  * Scan forwards to find beginning of another run of changes.
 701                  * Also keep track of the corresponding point in the other file.
 702                  *
 703                  * Throughout this code, $i and $j are adjusted together so that
 704                  * the first $i elements of $changed and the first $j elements
 705                  * of $other_changed both contain the same number of zeros
 706                  * (unchanged lines).
 707                  * Furthermore, $j is always kept so that $j == $other_len or
 708                  * $other_changed[$j] == false.
 709                  */
 710                 while ($j < $other_len && $other_changed[$j])
 711                 $j++;
 712
 713                 while ($i < $len && ! $changed[$i]) {
 714                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 715                 $i++; $j++;
 716                 while ($j < $other_len && $other_changed[$j])
 717                         $j++;
 718                         }
 719
 720                 if ($i == $len)
 721                 break;
 722
 723                 $start = $i;
 724
 725                 // Find the end of this run of changes.
 726                 while (++$i < $len && $changed[$i])
 727                 continue;
 728
 729                 do {
 730                 /*
 731                  * Record the length of this run of changes, so that
 732                  * we can later determine whether the run has grown.
 733                  */
 734                 $runlength = $i - $start;
 735
 736                 /*
 737                  * Move the changed region back, so long as the
 738                  * previous unchanged line matches the last changed one.
 739                  * This merges with previous changed regions.
 740                  */
 741                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
 742                         $changed[--$start] = 1;
 743                         $changed[--$i] = false;
 744                         while ($start > 0 && $changed[$start - 1])
 745                         $start--;
 746                         USE_ASSERTS && assert('$j > 0');
 747                         while ($other_changed[--$j])
 748                         continue;
 749                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
 750                                 }
 751
 752                 /*
 753                  * Set CORRESPONDING to the end of the changed run, at the last
 754                  * point where it corresponds to a changed run in the other file.
 755                  * CORRESPONDING == LEN means no such point has been found.
 756                  */
 757                 $corresponding = $j < $other_len ? $i : $len;
 758
 759                 /*
 760                  * Move the changed region forward, so long as the
 761                  * first changed line matches the following unchanged one.
 762                  * This merges with following changed regions.
 763                  * Do this second, so that if there are no merges,
 764                  * the changed region is moved forward as far as possible.
 765                  */
 766                 while ($i < $len && $lines[$start] == $lines[$i]) {
 767                         $changed[$start++] = false;
 768                         $changed[$i++] = 1;
 769                         while ($i < $len && $changed[$i])
 770                         $i++;
 771
 772                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 773                         $j++;
 774                         if ($j < $other_len && $other_changed[$j]) {
 775                         $corresponding = $i;
 776                         while ($j < $other_len && $other_changed[$j])
 777                                 $j++;
 778                                         }
 779                                 }
 780                         } while ($runlength != $i - $start);
 781
 782                 /*
 783                  * If possible, move the fully-merged run of changes
 784                  * back to a corresponding run in the other file.
 785                  */
 786                 while ($corresponding < $i) {
 787                 $changed[--$start] = 1;
 788                 $changed[--$i] = 0;
 789                 USE_ASSERTS && assert('$j > 0');
 790                 while ($other_changed[--$j])
 791                         continue;
 792                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
 793                         }
 794                 }
 795         }
 796 }
 797
 798 /**
 799  * Class representing a 'diff' between two sequences of strings.
 800  */
 801 class Diff
 802 {
 803         var $edits;
 804
 805         /**
 806          * Constructor.
 807          * Computes diff between sequences of strings.
 808          *
 809          * @param $from_lines array An array of strings.
 810          *                (Typically these are lines from a file.)
 811          * @param $to_lines array An array of strings.
 812          */
 813         function Diff($from_lines, $to_lines) {
 814                 $eng = new _DiffEngine;
 815                 $this->edits = $eng->diff($from_lines, $to_lines);
 816                 //$this->_check($from_lines, $to_lines);
 817         }
 818
 819         /**
 820          * Compute reversed Diff.
 821          *
 822          * SYNOPSIS:
 823          *
 824          *      $diff = new Diff($lines1, $lines2);
 825          *      $rev = $diff->reverse();
 826          * @return object A Diff object representing the inverse of the
 827          *                                original diff.
 828          */
 829         function reverse () {
 830         $rev = $this;
 831                 $rev->edits = array();
 832                 foreach ($this->edits as $edit) {
 833                         $rev->edits[] = $edit->reverse();
 834                 }
 835         return $rev;
 836         }
 837
 838         /**
 839          * Check for empty diff.
 840          *
 841          * @return bool True iff two sequences were identical.
 842          */
 843         function isEmpty () {
 844                 foreach ($this->edits as $edit) {
 845                         if ($edit->type != 'copy')
 846                                 return false;
 847                 }
 848                 return true;
 849         }
 850
 851         /**
 852          * Compute the length of the Longest Common Subsequence (LCS).
 853          *
 854          * This is mostly for diagnostic purposed.
 855          *
 856          * @return int The length of the LCS.
 857          */
 858         function lcs () {
 859         $lcs = 0;
 860                 foreach ($this->edits as $edit) {
 861                         if ($edit->type == 'copy')
 862                                 $lcs += sizeof($edit->orig);
 863                 }
 864         return $lcs;
 865         }
 866
 867         /**
 868          * Get the original set of lines.
 869          *
 870          * This reconstructs the $from_lines parameter passed to the
 871          * constructor.
 872          *
 873          * @return array The original sequence of strings.
 874          */
 875         function orig() {
 876                 $lines = array();
 877
 878                 foreach ($this->edits as $edit) {
 879                         if ($edit->orig)
 880                                 array_splice($lines, sizeof($lines), 0, $edit->orig);
 881                 }
 882                 return $lines;
 883         }
 884
 885         /**
 886          * Get the closing set of lines.
 887          *
 888          * This reconstructs the $to_lines parameter passed to the
 889          * constructor.
 890          *
 891          * @return array The sequence of strings.
 892          */
 893         function closing() {
 894                 $lines = array();
 895
 896                 foreach ($this->edits as $edit) {
 897                         if ($edit->closing)
 898                                 array_splice($lines, sizeof($lines), 0, $edit->closing);
 899                 }
 900                 return $lines;
 901         }
 902
 903         /**
 904          * Check a Diff for validity.
 905          *
 906          * This is here only for debugging purposes.
 907          */
 908         function _check ($from_lines, $to_lines) {
 909                 if (serialize($from_lines) != serialize($this->orig()))
 910                         trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
 911                 if (serialize($to_lines) != serialize($this->closing()))
 912                         trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
 913
 914                 $rev = $this->reverse();
 915                 if (serialize($to_lines) != serialize($rev->orig()))
 916                         trigger_error("Reversed original doesn't match", E_USER_ERROR);
 917                 if (serialize($from_lines) != serialize($rev->closing()))
 918                         trigger_error("Reversed closing doesn't match", E_USER_ERROR);
 919
 920
 921                 $prevtype = 'none';
 922                 foreach ($this->edits as $edit) {
 923                         if ( $prevtype == $edit->type )
 924                                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
 925                         $prevtype = $edit->type;
 926                 }
 927
 928                 $lcs = $this->lcs();
 929                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
 930         }
 931 }
 932
 933 /**
 934  * FIXME: bad name.
 935  */
 936 class MappedDiff
 937 extends Diff
 938 {
 939         /**
 940          * Constructor.
 941          *
 942          * Computes diff between sequences of strings.
 943          *
 944          * This can be used to compute things like
 945          * case-insensitve diffs, or diffs which ignore
 946          * changes in white-space.
 947          *
 948          * @param $from_lines array An array of strings.
 949          *      (Typically these are lines from a file.)
 950          *
 951          * @param $to_lines array An array of strings.
 952          *
 953          * @param $mapped_from_lines array This array should
 954          *      have the same size number of elements as $from_lines.
 955          *      The elements in $mapped_from_lines and
 956          *      $mapped_to_lines are what is actually compared
 957          *      when computing the diff.
 958          *
 959          * @param $mapped_to_lines array This array should
 960          *      have the same number of elements as $to_lines.
 961          */
 962         function MappedDiff($from_lines, $to_lines,
 963                                                 $mapped_from_lines, $mapped_to_lines) {
 964
 965                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
 966                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
 967
 968                 $this->Diff($mapped_from_lines, $mapped_to_lines);
 969
 970                 $xi = $yi = 0;
 971                 for ($i = 0; $i < sizeof($this->edits); $i++) {
 972                         $orig = &$this->edits[$i]->orig;
 973                         if (is_array($orig)) {
 974                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
 975                                 $xi += sizeof($orig);
 976                         }
 977
 978                         $closing = &$this->edits[$i]->closing;
 979                         if (is_array($closing)) {
 980                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
 981                                 $yi += sizeof($closing);
 982                         }
 983                 }
 984         }
 985 }
 986
 987 /**
 988  * A class to format Diffs
 989  *
 990  * This class formats the diff in classic diff format.
 991  * It is intended that this class be customized via inheritance,
 992  * to obtain fancier outputs.
 993  */
 994 class DiffFormatter
 995 {
 996         /**
 997          * Number of leading context "lines" to preserve.
 998          *
 999          * This should be left at zero for this class, but subclasses
1000          * may want to set this to other values.
1001          */
1002         var $leading_context_lines = 0;
1003
1004         /**
1005          * Number of trailing context "lines" to preserve.
1006          *
1007          * This should be left at zero for this class, but subclasses
1008          * may want to set this to other values.
1009          */
1010         var $trailing_context_lines = 0;
1011
1012         /**
1013          * Format a diff.
1014          *
1015          * @param $diff object A Diff object.
1016          * @return string The formatted output.
1017          */
1018         function format($diff) {
1019
1020                 $xi = $yi = 1;
1021                 $block = false;
1022                 $context = array();
1023
1024                 $nlead = $this->leading_context_lines;
1025                 $ntrail = $this->trailing_context_lines;
1026
1027                 $this->_start_diff();
1028
1029                 foreach ($diff->edits as $edit) {
1030                         if ($edit->type == 'copy') {
1031                                 if (is_array($block)) {
1032                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1033                                                 $block[] = $edit;
1034                                         }
1035                                         else{
1036                                                 if ($ntrail) {
1037                                                         $context = array_slice($edit->orig, 0, $ntrail);
1038                                                         $block[] = new _DiffOp_Copy($context);
1039                                                 }
1040                                                 $this->_block($x0, $ntrail + $xi - $x0,
1041                                                                           $y0, $ntrail + $yi - $y0,
1042                                                                           $block);
1043                                                 $block = false;
1044                                         }
1045                                 }
1046                                 $context = $edit->orig;
1047                         }
1048                         else {
1049                                 if (! is_array($block)) {
1050                                         $context = array_slice($context, sizeof($context) - $nlead);
1051                                         $x0 = $xi - sizeof($context);
1052                                         $y0 = $yi - sizeof($context);
1053                                         $block = array();
1054                                         if ($context)
1055                                                 $block[] = new _DiffOp_Copy($context);
1056                                 }
1057                                 $block[] = $edit;
1058                         }
1059
1060                         if ($edit->orig)
1061                                 $xi += sizeof($edit->orig);
1062                         if ($edit->closing)
1063                                 $yi += sizeof($edit->closing);
1064                 }
1065
1066                 if (is_array($block))
1067                         $this->_block($x0, $xi - $x0,
1068                                                   $y0, $yi - $y0,
1069                                                   $block);
1070
1071                 return $this->_end_diff();
1072         }
1073
1074         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1075                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1076                 foreach ($edits as $edit) {
1077                         if ($edit->type == 'copy')
1078                                 $this->_context($edit->orig);
1079                         elseif ($edit->type == 'add')
1080                                 $this->_added($edit->closing);
1081                         elseif ($edit->type == 'delete')
1082                                 $this->_deleted($edit->orig);
1083                         elseif ($edit->type == 'change')
1084                                 $this->_changed($edit->orig, $edit->closing);
1085                         else
1086                                 trigger_error('Unknown edit type', E_USER_ERROR);
1087                 }
1088                 $this->_end_block();
1089         }
1090
1091         function _start_diff() {
1092                 ob_start();
1093         }
1094
1095         function _end_diff() {
1096                 $val = ob_get_contents();
1097                 ob_end_clean();
1098                 return $val;
1099         }
1100
1101         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1102                 if ($xlen > 1)
1103                         $xbeg .= "," . ($xbeg + $xlen - 1);
1104                 if ($ylen > 1)
1105                         $ybeg .= "," . ($ybeg + $ylen - 1);
1106
1107                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1108         }
1109
1110         function _start_block($header) {
1111                 echo $header;
1112         }
1113
1114         function _end_block() {
1115         }
1116
1117         function _lines($lines, $prefix = ' ') {
1118                 foreach ($lines as $line)
1119                         echo "$prefix $line\n";
1120         }
1121
1122         function _context($lines) {
1123                 $this->_lines($lines);
1124         }
1125
1126         function _added($lines) {
1127                 $this->_lines($lines, '>');
1128         }
1129         function _deleted($lines) {
1130                 $this->_lines($lines, '<');
1131         }
1132
1133         function _changed($orig, $closing) {
1134                 $this->_deleted($orig);
1135                 echo "---\n";
1136                 $this->_added($closing);
1137         }
1138 }
1139
1140
1141 /**
1142  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1143  *
1144  */
1145
1146 define('NBSP', '&#160;');                       // iso-8859-x non-breaking space.
1147
1148 class _HWLDF_WordAccumulator {
1149         function _HWLDF_WordAccumulator () {
1150                 $this->_lines = array();
1151                 $this->_line = '';
1152                 $this->_group = '';
1153                 $this->_tag = '';
1154         }
1155
1156         function _flushGroup ($new_tag) {
1157                 if ($this->_group !== '') {
1158                         if ($this->_tag == 'mark')
1159                                 $this->_line .= '<span class="diffchange">' .
1160                                         htmlspecialchars ( $this->_group ) . '</span>';
1161                         else
1162                                 $this->_line .= htmlspecialchars ( $this->_group );
1163                 }
1164                 $this->_group = '';
1165                 $this->_tag = $new_tag;
1166         }
1167
1168         function _flushLine ($new_tag) {
1169                 $this->_flushGroup($new_tag);
1170                 if ($this->_line != '')
1171                         array_push ( $this->_lines, $this->_line );
1172                 else
1173                         # make empty lines visible by inserting an NBSP
1174                         array_push ( $this->_lines, NBSP );
1175                 $this->_line = '';
1176         }
1177
1178         function addWords ($words, $tag = '') {
1179                 if ($tag != $this->_tag)
1180                         $this->_flushGroup($tag);
1181
1182                 foreach ($words as $word) {
1183                         // new-line should only come as first char of word.
1184                         if ($word == '')
1185                                 continue;
1186                         if ($word[0] == "\n") {
1187                                 $this->_flushLine($tag);
1188                                 $word = substr($word, 1);
1189                         }
1190                         assert(!strstr($word, "\n"));
1191                         $this->_group .= $word;
1192                 }
1193         }
1194
1195         function getLines() {
1196                 $this->_flushLine('~done');
1197                 return $this->_lines;
1198         }
1199 }
1200
1201 class WordLevelDiff extends MappedDiff
1202 {
1203         function WordLevelDiff ($orig_lines, $closing_lines) {
1204                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1205                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1206
1207
1208                 $this->MappedDiff($orig_words, $closing_words,
1209                                                   $orig_stripped, $closing_stripped);
1210         }
1211
1212         function _split($lines) {
1213                 if (!preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1214                                                         implode("\n", $lines),
1215                                                         $m)) {
1216                         return array(array(''), array(''));
1217                 }
1218                 return array($m[0], $m[1]);
1219         }
1220
1221         function orig () {
1222                 $orig = new _HWLDF_WordAccumulator;
1223
1224                 foreach ($this->edits as $edit) {
1225                         if ($edit->type == 'copy')
1226                                 $orig->addWords($edit->orig);
1227                         elseif ($edit->orig)
1228                                 $orig->addWords($edit->orig, 'mark');
1229                 }
1230                 return $orig->getLines();
1231         }
1232
1233         function closing () {
1234                 $closing = new _HWLDF_WordAccumulator;
1235
1236                 foreach ($this->edits as $edit) {
1237                         if ($edit->type == 'copy')
1238                                 $closing->addWords($edit->closing);
1239                         elseif ($edit->closing)
1240                                 $closing->addWords($edit->closing, 'mark');
1241                 }
1242                 return $closing->getLines();
1243         }
1244 }
1245
1246 /**
1247  *      Wikipedia Table style diff formatter.
1248  *
1249  */
1250 class TableDiffFormatter extends DiffFormatter
1251 {
1252         function TableDiffFormatter() {
1253                 $this->leading_context_lines = 2;
1254                 $this->trailing_context_lines = 2;
1255         }
1256
1257         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1258                 $l1 = wfMsg( 'lineno', $xbeg );
1259                 $l2 = wfMsg( 'lineno', $ybeg );
1260
1261                 $r = '<tr><td colspan="2" align="left"><strong>'.$l1."</strong></td>\n" .
1262                   '<td colspan="2" align="left"><strong>'.$l2."</strong></td></tr>\n";
1263                 return $r;
1264         }
1265
1266         function _start_block( $header ) {
1267                 global $wgOut;
1268                 $wgOut->addHTML( $header );
1269         }
1270
1271         function _end_block() {
1272         }
1273
1274         function _lines( $lines, $prefix=' ', $color='white' ) {
1275         }
1276
1277         # HTML-escape parameter before calling this
1278         function addedLine( $line ) {
1279                 return "<td>+</td><td class='diff-addedline'>{$line}</td>";
1280         }
1281
1282         # HTML-escape parameter before calling this
1283         function deletedLine( $line ) {
1284                 return "<td>-</td><td class='diff-deletedline'>{$line}</td>";
1285         }
1286
1287         # HTML-escape parameter before calling this
1288         function contextLine( $line ) {
1289                 return "<td> </td><td class='diff-context'>{$line}</td>";
1290         }
1291
1292         function emptyLine() {
1293                 return '<td colspan="2">&nbsp;</td>';
1294         }
1295
1296         function _added( $lines ) {
1297                 global $wgOut;
1298                 foreach ($lines as $line) {
1299                         $wgOut->addHTML( '<tr>' . $this->emptyLine() .
1300                                 $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n" );
1301                 }
1302         }
1303
1304         function _deleted($lines) {
1305                 global $wgOut;
1306                 foreach ($lines as $line) {
1307                         $wgOut->addHTML( '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
1308                           $this->emptyLine() . "</tr>\n" );
1309                 }
1310         }
1311
1312         function _context( $lines ) {
1313                 global $wgOut;
1314                 foreach ($lines as $line) {
1315                         $wgOut->addHTML( '<tr>' .
1316                                 $this->contextLine( htmlspecialchars ( $line ) ) .
1317                                 $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n" );
1318                 }
1319         }
1320
1321         function _changed( $orig, $closing ) {
1322                 global $wgOut;
1323                 $diff = new WordLevelDiff( $orig, $closing );
1324                 $del = $diff->orig();
1325                 $add = $diff->closing();
1326
1327                 # Notice that WordLevelDiff returns HTML-escaped output.
1328                 # Hence, we will be calling addedLine without HTML-escaping.
1329
1330                 while ( $line = array_shift( $del ) ) {
1331                         $aline = array_shift( $add );
1332                         $wgOut->addHTML( '<tr>' . $this->deletedLine( $line ) .
1333                                 $this->addedLine( $aline ) . "</tr>\n" );
1334                 }
1335                 $this->_added( $add ); # If any leftovers
1336         }
1337 }
1338
1339 ?>