includes/DifferenceEngine.php

   1 <?php
   2 /**
   3  * See diff.doc
   4  * @todo indicate where diff.doc can be found.
   5  * @addtogroup DifferenceEngine
   6  */
   7
   8 /**
   9  * Constant to indicate diff cache compatibility.
  10  * Bump this when changing the diff formatting in a way that
  11  * fixes important bugs or such to force cached diff views to
  12  * clear.
  13  */
  14 define( 'MW_DIFF_VERSION', '1.11a' );
  15
  16 /**
  17  * @todo document
  18  * @public
  19  * @addtogroup DifferenceEngine
  20  */
  21 class DifferenceEngine {
  22         /**#@+
  23          * @private
  24          */
  25         var $mOldid, $mNewid, $mTitle;
  26         var $mOldtitle, $mNewtitle, $mPagetitle;
  27         var $mOldtext, $mNewtext;
  28         var $mOldPage, $mNewPage;
  29         var $mRcidMarkPatrolled;
  30         var $mOldRev, $mNewRev;
  31         var $mRevisionsLoaded = false; // Have the revisions been loaded
  32         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  33         /**#@-*/
  34
  35         /**
  36          * Constructor
  37          * @param $titleObj Title object that the diff is associated with
  38          * @param $old Integer: old ID we want to show and diff with.
  39          * @param $new String: either 'prev' or 'next'.
  40          * @param $rcid Integer: ??? FIXME (default 0)
  41          * @param $refreshCache boolean If set, refreshes the diff cache
  42          */
  43         function DifferenceEngine( $titleObj = null, $old = 0, $new = 0, $rcid = 0, $refreshCache = false ) {
  44                 $this->mTitle = $titleObj;
  45                 wfDebug("DifferenceEngine old '$old' new '$new' rcid '$rcid'\n");
  46
  47                 if ( 'prev' === $new ) {
  48                         # Show diff between revision $old and the previous one.
  49                         # Get previous one from DB.
  50                         #
  51                         $this->mNewid = intval($old);
  52
  53                         $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
  54
  55                 } elseif ( 'next' === $new ) {
  56                         # Show diff between revision $old and the previous one.
  57                         # Get previous one from DB.
  58                         #
  59                         $this->mOldid = intval($old);
  60                         $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
  61                         if ( false === $this->mNewid ) {
  62                                 # if no result, NewId points to the newest old revision. The only newer
  63                                 # revision is cur, which is "0".
  64                                 $this->mNewid = 0;
  65                         }
  66
  67                 } else if( 'cur' === $new ) {
  68                         # Show diff between revision $old and the current one.
  69                         # Get previous one from DB.
  70                         #
  71                         $this->mNewid = $this->mTitle->getLatestRevID();
  72
  73                         $this->mOldid = intval($old);
  74                 } else {
  75                         $this->mOldid = intval($old);
  76                         $this->mNewid = intval($new);
  77                 }
  78                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  79                 $this->mRefreshCache = $refreshCache;
  80         }
  81
  82         function showDiffPage( $diffOnly = false ) {
  83                 global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol;
  84                 $fname = 'DifferenceEngine::showDiffPage';
  85                 wfProfileIn( $fname );
  86
  87                 # If external diffs are enabled both globally and for the user,
  88                 # we'll use the application/x-external-editor interface to call
  89                 # an external diff tool like kompare, kdiff3, etc.
  90                 if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
  91                         global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
  92                         $wgOut->disable();
  93                         header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
  94                         $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);
  95                         $url2=$this->mTitle->getFullURL("action=raw&oldid=".$this->mNewid);
  96                         $special=$wgLang->getNsText(NS_SPECIAL);
  97                         $control=<<<CONTROL
  98 [Process]
  99 Type=Diff text
 100 Engine=MediaWiki
 101 Script={$wgServer}{$wgScript}
 102 Special namespace={$special}
 103
 104 [File]
 105 Extension=wiki
 106 URL=$url1
 107
 108 [File 2]
 109 Extension=wiki
 110 URL=$url2
 111 CONTROL;
 112                         echo($control);
 113                         return;
 114                 }
 115
 116                 $wgOut->setArticleFlag( false );
 117                 if ( ! $this->loadRevisionData() ) {
 118                         $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, {$this->mNewid})";
 119                         $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 120                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 121                         $wgOut->addWikitext( $mtext );
 122                         wfProfileOut( $fname );
 123                         return;
 124                 }
 125
 126                 wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 127
 128                 if ( $this->mNewRev->isCurrent() ) {
 129                         $wgOut->setArticleFlag( true );
 130                 }
 131
 132                 # mOldid is false if the difference engine is called with a "vague" query for
 133                 # a diff between a version V and its previous version V' AND the version V
 134                 # is the first version of that article. In that case, V' does not exist.
 135                 if ( $this->mOldid === false ) {
 136                         $this->showFirstRevision();
 137                         $this->renderNewRevision();  // should we respect $diffOnly here or not?
 138                         wfProfileOut( $fname );
 139                         return;
 140                 }
 141
 142                 $wgOut->suppressQuickbar();
 143
 144                 $oldTitle = $this->mOldPage->getPrefixedText();
 145                 $newTitle = $this->mNewPage->getPrefixedText();
 146                 if( $oldTitle == $newTitle ) {
 147                         $wgOut->setPageTitle( $newTitle );
 148                 } else {
 149                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 150                 }
 151                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 152                 $wgOut->setRobotpolicy( 'noindex,nofollow' );
 153
 154                 if ( !( $this->mOldPage->userCanRead() && $this->mNewPage->userCanRead() ) ) {
 155                         $wgOut->loginToUse();
 156                         $wgOut->output();
 157                         wfProfileOut( $fname );
 158                         exit;
 159                 }
 160
 161                 $sk = $wgUser->getSkin();
 162
 163                 if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
 164                         $rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
 165                 } else {
 166                         $rollback = '';
 167                 }
 168
 169                 // Prepare a change patrol link, if applicable
 170                 if( $wgUseRCPatrol && $wgUser->isAllowed( 'patrol' ) ) {
 171                         // If we've been given an explicit change identifier, use it; saves time
 172                         if( $this->mRcidMarkPatrolled ) {
 173                                 $rcid = $this->mRcidMarkPatrolled;
 174                         } else {
 175                                 // Look for an unpatrolled change corresponding to this diff
 176                                 $db = wfGetDB( DB_SLAVE );
 177                                 $change = RecentChange::newFromConds(
 178                                         array(
 179                                                 // Add redundant timestamp condition so we can use the
 180                                                 // existing index
 181                                                 'rc_timestamp' => $db->timestamp( $this->mNewRev->getTimestamp() ),
 182                                                 'rc_this_oldid' => $this->mNewid,
 183                                                 'rc_last_oldid' => $this->mOldid,
 184                                                 'rc_patrolled' => 0,
 185                                         ),
 186                                         __METHOD__
 187                                 );
 188                                 if( $change instanceof RecentChange ) {
 189                                         $rcid = $change->mAttribs['rc_id'];
 190                                 } else {
 191                                         // None found
 192                                         $rcid = 0;
 193                                 }
 194                         }
 195                         // Build the link
 196                         if( $rcid ) {
 197                                 $patrol = ' [' . $sk->makeKnownLinkObj(
 198                                         $this->mTitle,
 199                                         wfMsgHtml( 'markaspatrolleddiff' ),
 200                                         "action=markpatrolled&rcid={$rcid}"
 201                                 ) . ']';
 202                         } else {
 203                                 $patrol = '';
 204                         }
 205                 } else {
 206                         $patrol = '';
 207                 }
 208
 209                 $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
 210                         'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
 211                 if ( $this->mNewRev->isCurrent() ) {
 212                         $nextlink = '&nbsp;';
 213                 } else {
 214                         $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
 215                                 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 216                 }
 217
 218                 $oldminor = '';
 219                 $newminor = '';
 220
 221                 if ($this->mOldRev->mMinorEdit == 1) {
 222                         $oldminor = wfElement( 'span', array( 'class' => 'minor' ),
 223                                 wfMsg( 'minoreditletter') ) . ' ';
 224                 }
 225
 226                 if ($this->mNewRev->mMinorEdit == 1) {
 227                         $newminor = wfElement( 'span', array( 'class' => 'minor' ),
 228                         wfMsg( 'minoreditletter') ) . ' ';
 229                 }
 230
 231                 $rdel = ''; $ldel = '';
 232                 if( $wgUser->isAllowed( 'deleterevision' ) ) {
 233                         $revdel = SpecialPage::getTitleFor( 'Revisiondelete' );
 234                         if( !$this->mOldRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 235                         // If revision was hidden from sysops
 236                                 $ldel = wfMsgHtml('rev-delundel');
 237                         } else {
 238                                 $ldel = $sk->makeKnownLinkObj( $revdel,
 239                                         wfMsgHtml('rev-delundel'),
 240                                         'target=' . urlencode( $this->mOldRev->mTitle->getPrefixedDbkey() ) .
 241                                         '&oldid=' . urlencode( $this->mOldRev->getId() ) );
 242                                 // Bolden oversighted content
 243                                 if( $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 244                                         $ldel = "<strong>$ldel</strong>";
 245                         }
 246                         $ldel = "&nbsp;&nbsp;&nbsp;<tt>(<small>$ldel</small>)</tt> ";
 247                         // We don't currently handle well changing the top revision's settings
 248                         if( $this->mNewRev->isCurrent() ) {
 249                         // If revision was hidden from sysops
 250                                 $rdel = wfMsgHtml('rev-delundel');
 251                         } else if( !$this->mNewRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 252                         // If revision was hidden from sysops
 253                                 $rdel = wfMsgHtml('rev-delundel');
 254                         } else {
 255                                 $rdel = $sk->makeKnownLinkObj( $revdel,
 256                                         wfMsgHtml('rev-delundel'),
 257                                         'target=' . urlencode( $this->mNewRev->mTitle->getPrefixedDbkey() ) .
 258                                         '&oldid=' . urlencode( $this->mNewRev->getId() ) );
 259                                 // Bolden oversighted content
 260                                 if( $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) )
 261                                         $rdel = "<strong>$rdel</strong>";
 262                         }
 263                         $rdel = "&nbsp;&nbsp;&nbsp;<tt>(<small>$rdel</small>)</tt> ";
 264                 }
 265
 266                 $oldHeader = '<div id="mw-diff-otitle1"><strong>'.$this->mOldtitle.'</strong></div>' .
 267                         '<div id="mw-diff-otitle2">' . $sk->revUserTools( $this->mOldRev, true ) . "</div>" .
 268                         '<div id="mw-diff-otitle3">' . $oldminor . $sk->revComment( $this->mOldRev, !$diffOnly, true ) . $ldel . "</div>" .
 269                         '<div id="mw-diff-otitle4">' . $prevlink .'</div>';
 270                 $newHeader = '<div id="mw-diff-ntitle1"><strong>'.$this->mNewtitle.'</strong></div>' .
 271                         '<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, true ) . " $rollback</div>" .
 272                         '<div id="mw-diff-ntitle3">' . $newminor . $sk->revComment( $this->mNewRev, !$diffOnly, true ) . $rdel . "</div>" .
 273                         '<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
 274
 275                 $this->showDiff( $oldHeader, $newHeader );
 276
 277                 if ( !$diffOnly )
 278                         $this->renderNewRevision();
 279
 280                 wfProfileOut( $fname );
 281         }
 282
 283         /**
 284          * Show the new revision of the page.
 285          */
 286         function renderNewRevision() {
 287                 global $wgOut;
 288                 $fname = 'DifferenceEngine::renderNewRevision';
 289                 wfProfileIn( $fname );
 290
 291                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 292                 #add deleted rev tag if needed
 293                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 294                         $wgOut->addWikiText( wfMsg( 'rev-deleted-text-permission' ) );
 295                 } else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 296                         $wgOut->addWikiText( wfMsg( 'rev-deleted-text-view' ) );
 297                 }
 298
 299                 if( !$this->mNewRev->isCurrent() ) {
 300                         $oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
 301                 }
 302
 303                 $this->loadNewText();
 304                 if( is_object( $this->mNewRev ) ) {
 305                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 306                 }
 307
 308                 $wgOut->addWikiTextTidy( $this->mNewtext );
 309
 310                 if( !$this->mNewRev->isCurrent() ) {
 311                         $wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
 312                 }
 313
 314                 wfProfileOut( $fname );
 315         }
 316
 317         /**
 318          * Show the first revision of an article. Uses normal diff headers in
 319          * contrast to normal "old revision" display style.
 320          */
 321         function showFirstRevision() {
 322                 global $wgOut, $wgUser;
 323
 324                 $fname = 'DifferenceEngine::showFirstRevision';
 325                 wfProfileIn( $fname );
 326
 327                 # Get article text from the DB
 328                 #
 329                 if ( ! $this->loadNewText() ) {
 330                         $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 331                           "{$this->mNewid})";
 332                         $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 333                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 334                         $wgOut->addWikitext( $mtext );
 335                         wfProfileOut( $fname );
 336                         return;
 337                 }
 338                 if ( $this->mNewRev->isCurrent() ) {
 339                         $wgOut->setArticleFlag( true );
 340                 }
 341
 342                 # Check if user is allowed to look at this page. If not, bail out.
 343                 #
 344                 if ( !( $this->mTitle->userCanRead() ) ) {
 345                         $wgOut->loginToUse();
 346                         $wgOut->output();
 347                         wfProfileOut( $fname );
 348                         exit;
 349                 }
 350
 351                 # Prepare the header box
 352                 #
 353                 $sk = $wgUser->getSkin();
 354
 355                 $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 356                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />" .
 357                         $sk->revUserTools( $this->mNewRev ) . "<br />" .
 358                         $sk->revComment( $this->mNewRev ) . "<br />" .
 359                         $nextlink . "</div>\n";
 360
 361                 $wgOut->addHTML( $header );
 362
 363                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 364                 $wgOut->setRobotpolicy( 'noindex,nofollow' );
 365
 366                 wfProfileOut( $fname );
 367         }
 368
 369         /**
 370          * Get the diff text, send it to $wgOut
 371          * Returns false if the diff could not be generated, otherwise returns true
 372          */
 373         function showDiff( $otitle, $ntitle ) {
 374                 global $wgOut;
 375                 $diff = $this->getDiff( $otitle, $ntitle );
 376                 if ( $diff === false ) {
 377                         $wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>(fixme, bug)</nowiki>" ) );
 378                         return false;
 379                 } else {
 380                         $this->showDiffStyle();
 381                         $wgOut->addHTML( $diff );
 382                         return true;
 383                 }
 384         }
 385
 386         /**
 387          * Add style sheets and supporting JS for diff display.
 388          */
 389         function showDiffStyle() {
 390                 global $wgStylePath, $wgStyleVersion, $wgOut;
 391                 $wgOut->addStyle( 'common/diff.css' );
 392
 393                 // JS is needed to detect old versions of Mozilla to work around an annoyance bug.
 394                 $wgOut->addScript( "<script type=\"text/javascript\" src=\"$wgStylePath/common/diff.js?$wgStyleVersion\"></script>" );
 395         }
 396
 397         /**
 398          * Get complete diff table, including header
 399          *
 400          * @param Title $otitle Old title
 401          * @param Title $ntitle New title
 402          * @return mixed
 403          */
 404         function getDiff( $otitle, $ntitle ) {
 405                 $body = $this->getDiffBody();
 406                 if ( $body === false ) {
 407                         return false;
 408                 } else {
 409                         $multi = $this->getMultiNotice();
 410                         return $this->addHeader( $body, $otitle, $ntitle, $multi );
 411                 }
 412         }
 413
 414         /**
 415          * Get the diff table body, without header
 416          *
 417          * @return mixed
 418          */
 419         function getDiffBody() {
 420                 global $wgMemc;
 421                 $fname = 'DifferenceEngine::getDiffBody';
 422                 wfProfileIn( $fname );
 423
 424                 // Cacheable?
 425                 $key = false;
 426                 if ( $this->mOldid && $this->mNewid ) {
 427                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
 428                         // Try cache
 429                         if ( !$this->mRefreshCache ) {
 430                                 $difftext = $wgMemc->get( $key );
 431                                 if ( $difftext ) {
 432                                         wfIncrStats( 'diff_cache_hit' );
 433                                         $difftext = $this->localiseLineNumbers( $difftext );
 434                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 435                                         wfProfileOut( $fname );
 436                                         return $difftext;
 437                                 }
 438                         } // don't try to load but save the result
 439                 }
 440
 441                 // Loadtext is permission safe, this just clears out the diff
 442                 if ( !$this->loadText() ) {
 443                         wfProfileOut( $fname );
 444                         return false;
 445                 } else if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
 446                         return '';
 447                 } else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 448                         return '';
 449                 }
 450
 451                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 452
 453                 // Save to cache for 7 days
 454                 // Only do this for public revs, otherwise an admin can view the diff and a non-admin can nab it!
 455                 if ( $this->mOldRev && $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
 456                         wfIncrStats( 'diff_uncacheable' );
 457                 } else if ( $this->mNewRev && $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 458                         wfIncrStats( 'diff_uncacheable' );
 459                 } else if ( $key !== false && $difftext !== false ) {
 460                         wfIncrStats( 'diff_cache_miss' );
 461                         $wgMemc->set( $key, $difftext, 7*86400 );
 462                 } else {
 463                         wfIncrStats( 'diff_uncacheable' );
 464                 }
 465                 // Replace line numbers with the text in the user's language
 466                 if ( $difftext !== false ) {
 467                         $difftext = $this->localiseLineNumbers( $difftext );
 468                 }
 469                 wfProfileOut( $fname );
 470                 return $difftext;
 471         }
 472
 473         /**
 474          * Generate a diff, no caching
 475          * $otext and $ntext must be already segmented
 476          */
 477         function generateDiffBody( $otext, $ntext ) {
 478                 global $wgExternalDiffEngine, $wgContLang;
 479                 $fname = 'DifferenceEngine::generateDiffBody';
 480
 481                 $otext = str_replace( "\r\n", "\n", $otext );
 482                 $ntext = str_replace( "\r\n", "\n", $ntext );
 483
 484                 if ( $wgExternalDiffEngine == 'wikidiff' ) {
 485                         # For historical reasons, external diff engine expects
 486                         # input text to be HTML-escaped already
 487                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 488                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 489                         if( !function_exists( 'wikidiff_do_diff' ) ) {
 490                                 dl('php_wikidiff.so');
 491                         }
 492                         return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) );
 493                 }
 494
 495                 if ( $wgExternalDiffEngine == 'wikidiff2' ) {
 496                         # Better external diff engine, the 2 may some day be dropped
 497                         # This one does the escaping and segmenting itself
 498                         if ( !function_exists( 'wikidiff2_do_diff' ) ) {
 499                                 wfProfileIn( "$fname-dl" );
 500                                 @dl('php_wikidiff2.so');
 501                                 wfProfileOut( "$fname-dl" );
 502                         }
 503                         if ( function_exists( 'wikidiff2_do_diff' ) ) {
 504                                 wfProfileIn( 'wikidiff2_do_diff' );
 505                                 $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 506                                 wfProfileOut( 'wikidiff2_do_diff' );
 507                                 return $text;
 508                         }
 509                 }
 510                 if ( $wgExternalDiffEngine !== false ) {
 511                         # Diff via the shell
 512                         global $wgTmpDirectory;
 513                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 514                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 515
 516                         $tempFile1 = fopen( $tempName1, "w" );
 517                         if ( !$tempFile1 ) {
 518                                 wfProfileOut( $fname );
 519                                 return false;
 520                         }
 521                         $tempFile2 = fopen( $tempName2, "w" );
 522                         if ( !$tempFile2 ) {
 523                                 wfProfileOut( $fname );
 524                                 return false;
 525                         }
 526                         fwrite( $tempFile1, $otext );
 527                         fwrite( $tempFile2, $ntext );
 528                         fclose( $tempFile1 );
 529                         fclose( $tempFile2 );
 530                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 531                         wfProfileIn( "$fname-shellexec" );
 532                         $difftext = wfShellExec( $cmd );
 533                         wfProfileOut( "$fname-shellexec" );
 534                         unlink( $tempName1 );
 535                         unlink( $tempName2 );
 536                         return $difftext;
 537                 }
 538
 539                 # Native PHP diff
 540                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 541                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 542                 $diffs = new Diff( $ota, $nta );
 543                 $formatter = new TableDiffFormatter();
 544                 return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 545         }
 546
 547
 548         /**
 549          * Replace line numbers with the text in the user's language
 550          */
 551         function localiseLineNumbers( $text ) {
 552                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 553                         array( &$this, 'localiseLineNumbersCb' ), $text );
 554         }
 555
 556         function localiseLineNumbersCb( $matches ) {
 557                 global $wgLang;
 558                 return wfMsgExt( 'lineno', array('parseinline'), $wgLang->formatNum( $matches[1] ) );
 559         }
 560
 561
 562         /**
 563          * If there are revisions between the ones being compared, return a note saying so.
 564          */
 565         function getMultiNotice() {
 566                 if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
 567                         return '';
 568
 569                 if( !$this->mOldPage->equals( $this->mNewPage ) ) {
 570                         // Comparing two different pages? Count would be meaningless.
 571                         return '';
 572                 }
 573
 574                 $oldid = $this->mOldRev->getId();
 575                 $newid = $this->mNewRev->getId();
 576                 if ( $oldid > $newid ) {
 577                         $tmp = $oldid; $oldid = $newid; $newid = $tmp;
 578                 }
 579
 580                 $n = $this->mTitle->countRevisionsBetween( $oldid, $newid );
 581                 if ( !$n )
 582                         return '';
 583
 584                 return wfMsgExt( 'diff-multi', array( 'parseinline' ), $n );
 585         }
 586
 587
 588         /**
 589          * Add the header to a diff body
 590          */
 591         static function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
 592                 global $wgOut;
 593
 594                 $header = "
 595                         <table class='diff'>
 596                         <col class='diff-marker' />
 597                         <col class='diff-content' />
 598                         <col class='diff-marker' />
 599                         <col class='diff-content' />
 600                         <tr>
 601                                 <td colspan='2' class='diff-otitle'>{$otitle}</td>
 602                                 <td colspan='2' class='diff-ntitle'>{$ntitle}</td>
 603                         </tr>
 604                 ";
 605
 606                 if ( $multi != '' )
 607                         $header .= "<tr><td colspan='4' align='center' class='diff-multi'>{$multi}</td></tr>";
 608
 609                 return $header . $diff . "</table>";
 610         }
 611
 612         /**
 613          * Use specified text instead of loading from the database
 614          */
 615         function setText( $oldText, $newText ) {
 616                 $this->mOldtext = $oldText;
 617                 $this->mNewtext = $newText;
 618                 $this->mTextLoaded = 2;
 619         }
 620
 621         /**
 622          * Load revision metadata for the specified articles. If newid is 0, then compare
 623          * the old article in oldid to the current article; if oldid is 0, then
 624          * compare the current article to the immediately previous one (ignoring the
 625          * value of newid).
 626          *
 627          * If oldid is false, leave the corresponding revision object set
 628          * to false. This is impossible via ordinary user input, and is provided for
 629          * API convenience.
 630          */
 631         function loadRevisionData() {
 632                 global $wgLang;
 633                 if ( $this->mRevisionsLoaded ) {
 634                         return true;
 635                 } else {
 636                         // Whether it succeeds or fails, we don't want to try again
 637                         $this->mRevisionsLoaded = true;
 638                 }
 639
 640                 // Load the new revision object
 641                 $this->mNewRev = $this->mNewid
 642                         ? Revision::newFromId( $this->mNewid )
 643                         : Revision::newFromTitle( $this->mTitle );
 644                 if( !$this->mNewRev instanceof Revision )
 645                         return false;
 646
 647                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
 648                 $this->mNewid = $this->mNewRev->getId();
 649
 650                 // Set assorted variables
 651                 $timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 652                 $this->mNewPage = $this->mNewRev->getTitle();
 653                 if( $this->mNewRev->isCurrent() ) {
 654                         $newLink = $this->mNewPage->escapeLocalUrl();
 655                         $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
 656                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit' );
 657
 658                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a> ($timestamp)"
 659                                 . " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 660
 661                 } else {
 662                         $newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
 663                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mNewid );
 664                         $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $timestamp ) );
 665
 666                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>"
 667                                 . " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 668                 }
 669                 if ( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 670                         $this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
 671                 } else if ( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 672                         $this->mNewtitle = '<span class="history-deleted">'.$this->mNewtitle.'</span>';
 673                 }
 674
 675                 // Load the old revision object
 676                 $this->mOldRev = false;
 677                 if( $this->mOldid ) {
 678                         $this->mOldRev = Revision::newFromId( $this->mOldid );
 679                 } elseif ( $this->mOldid === 0 ) {
 680                         $rev = $this->mNewRev->getPrevious();
 681                         if( $rev ) {
 682                                 $this->mOldid = $rev->getId();
 683                                 $this->mOldRev = $rev;
 684                         } else {
 685                                 // No previous revision; mark to show as first-version only.
 686                                 $this->mOldid = false;
 687                                 $this->mOldRev = false;
 688                         }
 689                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
 690
 691                 if( is_null( $this->mOldRev ) ) {
 692                         return false;
 693                 }
 694
 695                 if ( $this->mOldRev ) {
 696                         $this->mOldPage = $this->mOldRev->getTitle();
 697
 698                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
 699                         $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
 700                         $oldEdit = $this->mOldPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mOldid );
 701                         $this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
 702
 703                         $this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
 704                                 . "(<a href='$oldEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 705                         // Add an "undo" link
 706                         $newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undoafter=' . $this->mOldid . '&undo=' . $this->mNewid);
 707                         if ( $this->mNewRev->userCan(Revision::DELETED_TEXT) )
 708                                 $this->mNewtitle .= " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
 709
 710                         if ( !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
 711                                 $this->mOldtitle = "<span class='history-deleted'>{$this->mOldPagetitle}</span>";
 712                         } else if ( $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
 713                                 $this->mOldtitle = '<span class="history-deleted">'.$this->mOldtitle.'</span>';
 714                         }
 715                 }
 716
 717                 return true;
 718         }
 719
 720         /**
 721          * Load the text of the revisions, as well as revision data.
 722          */
 723         function loadText() {
 724                 if ( $this->mTextLoaded == 2 ) {
 725                         return true;
 726                 } else {
 727                         // Whether it succeeds or fails, we don't want to try again
 728                         $this->mTextLoaded = 2;
 729                 }
 730
 731                 if ( !$this->loadRevisionData() ) {
 732                         return false;
 733                 }
 734                 if ( $this->mOldRev ) {
 735                         $this->mOldtext = $this->mOldRev->revText();
 736                         if ( $this->mOldtext === false ) {
 737                                 return false;
 738                         }
 739                 }
 740                 if ( $this->mNewRev ) {
 741                         $this->mNewtext = $this->mNewRev->revText();
 742                         if ( $this->mNewtext === false ) {
 743                                 return false;
 744                         }
 745                 }
 746                 return true;
 747         }
 748
 749         /**
 750          * Load the text of the new revision, not the old one
 751          */
 752         function loadNewText() {
 753                 if ( $this->mTextLoaded >= 1 ) {
 754                         return true;
 755                 } else {
 756                         $this->mTextLoaded = 1;
 757                 }
 758                 if ( !$this->loadRevisionData() ) {
 759                         return false;
 760                 }
 761                 $this->mNewtext = $this->mNewRev->getText();
 762                 return true;
 763         }
 764
 765
 766 }
 767
 768 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 769 //
 770 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 771 // You may copy this code freely under the conditions of the GPL.
 772 //
 773
 774 define('USE_ASSERTS', function_exists('assert'));
 775
 776 /**
 777  * @todo document
 778  * @private
 779  * @addtogroup DifferenceEngine
 780  */
 781 class _DiffOp {
 782         var $type;
 783         var $orig;
 784         var $closing;
 785
 786         function reverse() {
 787                 trigger_error('pure virtual', E_USER_ERROR);
 788         }
 789
 790         function norig() {
 791                 return $this->orig ? sizeof($this->orig) : 0;
 792         }
 793
 794         function nclosing() {
 795                 return $this->closing ? sizeof($this->closing) : 0;
 796         }
 797 }
 798
 799 /**
 800  * @todo document
 801  * @private
 802  * @addtogroup DifferenceEngine
 803  */
 804 class _DiffOp_Copy extends _DiffOp {
 805         var $type = 'copy';
 806
 807         function _DiffOp_Copy ($orig, $closing = false) {
 808                 if (!is_array($closing))
 809                         $closing = $orig;
 810                 $this->orig = $orig;
 811                 $this->closing = $closing;
 812         }
 813
 814         function reverse() {
 815                 return new _DiffOp_Copy($this->closing, $this->orig);
 816         }
 817 }
 818
 819 /**
 820  * @todo document
 821  * @private
 822  * @addtogroup DifferenceEngine
 823  */
 824 class _DiffOp_Delete extends _DiffOp {
 825         var $type = 'delete';
 826
 827         function _DiffOp_Delete ($lines) {
 828                 $this->orig = $lines;
 829                 $this->closing = false;
 830         }
 831
 832         function reverse() {
 833                 return new _DiffOp_Add($this->orig);
 834         }
 835 }
 836
 837 /**
 838  * @todo document
 839  * @private
 840  * @addtogroup DifferenceEngine
 841  */
 842 class _DiffOp_Add extends _DiffOp {
 843         var $type = 'add';
 844
 845         function _DiffOp_Add ($lines) {
 846                 $this->closing = $lines;
 847                 $this->orig = false;
 848         }
 849
 850         function reverse() {
 851                 return new _DiffOp_Delete($this->closing);
 852         }
 853 }
 854
 855 /**
 856  * @todo document
 857  * @private
 858  * @addtogroup DifferenceEngine
 859  */
 860 class _DiffOp_Change extends _DiffOp {
 861         var $type = 'change';
 862
 863         function _DiffOp_Change ($orig, $closing) {
 864                 $this->orig = $orig;
 865                 $this->closing = $closing;
 866         }
 867
 868         function reverse() {
 869                 return new _DiffOp_Change($this->closing, $this->orig);
 870         }
 871 }
 872
 873
 874 /**
 875  * Class used internally by Diff to actually compute the diffs.
 876  *
 877  * The algorithm used here is mostly lifted from the perl module
 878  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 879  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 880  *
 881  * More ideas are taken from:
 882  *       http://www.ics.uci.edu/~eppstein/161/960229.html
 883  *
 884  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 885  * diffutils-2.7, which can be found at:
 886  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 887  *
 888  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 889  * are my own.
 890  *
 891  * Line length limits for robustness added by Tim Starling, 2005-08-31
 892  *
 893  * @author Geoffrey T. Dairiki, Tim Starling
 894  * @private
 895  * @addtogroup DifferenceEngine
 896  */
 897 class _DiffEngine
 898 {
 899         const MAX_XREF_LENGTH =  10000;
 900
 901         function diff ($from_lines, $to_lines) {
 902                 $fname = '_DiffEngine::diff';
 903                 wfProfileIn( $fname );
 904
 905                 $n_from = sizeof($from_lines);
 906                 $n_to = sizeof($to_lines);
 907
 908                 $this->xchanged = $this->ychanged = array();
 909                 $this->xv = $this->yv = array();
 910                 $this->xind = $this->yind = array();
 911                 unset($this->seq);
 912                 unset($this->in_seq);
 913                 unset($this->lcs);
 914
 915                 // Skip leading common lines.
 916                 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 917                         if ($from_lines[$skip] !== $to_lines[$skip])
 918                                 break;
 919                         $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 920                 }
 921                 // Skip trailing common lines.
 922                 $xi = $n_from; $yi = $n_to;
 923                 for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 924                         if ($from_lines[$xi] !== $to_lines[$yi])
 925                                 break;
 926                         $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 927                 }
 928
 929                 // Ignore lines which do not exist in both files.
 930                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 931                         $xhash[$this->_line_hash($from_lines[$xi])] = 1;
 932                 }
 933
 934                 for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 935                         $line = $to_lines[$yi];
 936                         if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
 937                                 continue;
 938                         $yhash[$this->_line_hash($line)] = 1;
 939                         $this->yv[] = $line;
 940                         $this->yind[] = $yi;
 941                 }
 942                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 943                         $line = $from_lines[$xi];
 944                         if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
 945                                 continue;
 946                         $this->xv[] = $line;
 947                         $this->xind[] = $xi;
 948                 }
 949
 950                 // Find the LCS.
 951                 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 952
 953                 // Merge edits when possible
 954                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 955                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 956
 957                 // Compute the edit operations.
 958                 $edits = array();
 959                 $xi = $yi = 0;
 960                 while ($xi < $n_from || $yi < $n_to) {
 961                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 962                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 963
 964                         // Skip matching "snake".
 965                         $copy = array();
 966                         while ( $xi < $n_from && $yi < $n_to
 967                                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 968                                 $copy[] = $from_lines[$xi++];
 969                                 ++$yi;
 970                         }
 971                         if ($copy)
 972                                 $edits[] = new _DiffOp_Copy($copy);
 973
 974                         // Find deletes & adds.
 975                         $delete = array();
 976                         while ($xi < $n_from && $this->xchanged[$xi])
 977                                 $delete[] = $from_lines[$xi++];
 978
 979                         $add = array();
 980                         while ($yi < $n_to && $this->ychanged[$yi])
 981                                 $add[] = $to_lines[$yi++];
 982
 983                         if ($delete && $add)
 984                                 $edits[] = new _DiffOp_Change($delete, $add);
 985                         elseif ($delete)
 986                                 $edits[] = new _DiffOp_Delete($delete);
 987                         elseif ($add)
 988                                 $edits[] = new _DiffOp_Add($add);
 989                 }
 990                 wfProfileOut( $fname );
 991                 return $edits;
 992         }
 993
 994         /**
 995          * Returns the whole line if it's small enough, or the MD5 hash otherwise
 996          */
 997         function _line_hash( $line ) {
 998                 if ( strlen( $line ) > self::MAX_XREF_LENGTH ) {
 999                         return md5( $line );
1000                 } else {
1001                         return $line;
1002                 }
1003         }
1004
1005
1006         /* Divide the Largest Common Subsequence (LCS) of the sequences
1007          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
1008          * sized segments.
1009          *
1010          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
1011          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
1012          * sub sequences.  The first sub-sequence is contained in [X0, X1),
1013          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
1014          * that (X0, Y0) == (XOFF, YOFF) and
1015          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
1016          *
1017          * This function assumes that the first lines of the specified portions
1018          * of the two files do not match, and likewise that the last lines do not
1019          * match.  The caller must trim matching lines from the beginning and end
1020          * of the portions it is going to specify.
1021          */
1022         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
1023                 $fname = '_DiffEngine::_diag';
1024                 wfProfileIn( $fname );
1025                 $flip = false;
1026
1027                 if ($xlim - $xoff > $ylim - $yoff) {
1028                         // Things seems faster (I'm not sure I understand why)
1029                                 // when the shortest sequence in X.
1030                                 $flip = true;
1031                         list ($xoff, $xlim, $yoff, $ylim)
1032                         = array( $yoff, $ylim, $xoff, $xlim);
1033                 }
1034
1035                 if ($flip)
1036                         for ($i = $ylim - 1; $i >= $yoff; $i--)
1037                                 $ymatches[$this->xv[$i]][] = $i;
1038                 else
1039                         for ($i = $ylim - 1; $i >= $yoff; $i--)
1040                                 $ymatches[$this->yv[$i]][] = $i;
1041
1042                 $this->lcs = 0;
1043                 $this->seq[0]= $yoff - 1;
1044                 $this->in_seq = array();
1045                 $ymids[0] = array();
1046
1047                 $numer = $xlim - $xoff + $nchunks - 1;
1048                 $x = $xoff;
1049                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
1050                         wfProfileIn( "$fname-chunk" );
1051                         if ($chunk > 0)
1052                                 for ($i = 0; $i <= $this->lcs; $i++)
1053                                         $ymids[$i][$chunk-1] = $this->seq[$i];
1054
1055                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
1056                         for ( ; $x < $x1; $x++) {
1057                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
1058                                         if (empty($ymatches[$line]))
1059                                                 continue;
1060                                 $matches = $ymatches[$line];
1061                                 reset($matches);
1062                                 while (list ($junk, $y) = each($matches))
1063                                         if (empty($this->in_seq[$y])) {
1064                                                 $k = $this->_lcs_pos($y);
1065                                                 USE_ASSERTS && assert($k > 0);
1066                                                 $ymids[$k] = $ymids[$k-1];
1067                                                 break;
1068                                         }
1069                                 while (list ( /* $junk */, $y) = each($matches)) {
1070                                         if ($y > $this->seq[$k-1]) {
1071                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
1072                                                 // Optimization: this is a common case:
1073                                                 //      next match is just replacing previous match.
1074                                                 $this->in_seq[$this->seq[$k]] = false;
1075                                                 $this->seq[$k] = $y;
1076                                                 $this->in_seq[$y] = 1;
1077                                         } else if (empty($this->in_seq[$y])) {
1078                                                 $k = $this->_lcs_pos($y);
1079                                                 USE_ASSERTS && assert($k > 0);
1080                                                 $ymids[$k] = $ymids[$k-1];
1081                                         }
1082                                 }
1083                         }
1084                         wfProfileOut( "$fname-chunk" );
1085                 }
1086
1087                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
1088                 $ymid = $ymids[$this->lcs];
1089                 for ($n = 0; $n < $nchunks - 1; $n++) {
1090                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
1091                         $y1 = $ymid[$n] + 1;
1092                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
1093                 }
1094                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
1095
1096                 wfProfileOut( $fname );
1097                 return array($this->lcs, $seps);
1098         }
1099
1100         function _lcs_pos ($ypos) {
1101                 $fname = '_DiffEngine::_lcs_pos';
1102                 wfProfileIn( $fname );
1103
1104                 $end = $this->lcs;
1105                 if ($end == 0 || $ypos > $this->seq[$end]) {
1106                         $this->seq[++$this->lcs] = $ypos;
1107                         $this->in_seq[$ypos] = 1;
1108                         wfProfileOut( $fname );
1109                         return $this->lcs;
1110                 }
1111
1112                 $beg = 1;
1113                 while ($beg < $end) {
1114                         $mid = (int)(($beg + $end) / 2);
1115                         if ( $ypos > $this->seq[$mid] )
1116                                 $beg = $mid + 1;
1117                         else
1118                                 $end = $mid;
1119                 }
1120
1121                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
1122
1123                 $this->in_seq[$this->seq[$end]] = false;
1124                 $this->seq[$end] = $ypos;
1125                 $this->in_seq[$ypos] = 1;
1126                 wfProfileOut( $fname );
1127                 return $end;
1128         }
1129
1130         /* Find LCS of two sequences.
1131          *
1132          * The results are recorded in the vectors $this->{x,y}changed[], by
1133          * storing a 1 in the element for each line that is an insertion
1134          * or deletion (ie. is not in the LCS).
1135          *
1136          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
1137          *
1138          * Note that XLIM, YLIM are exclusive bounds.
1139          * All line numbers are origin-0 and discarded lines are not counted.
1140          */
1141         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
1142                 $fname = '_DiffEngine::_compareseq';
1143                 wfProfileIn( $fname );
1144
1145                 // Slide down the bottom initial diagonal.
1146                 while ($xoff < $xlim && $yoff < $ylim
1147                            && $this->xv[$xoff] == $this->yv[$yoff]) {
1148                         ++$xoff;
1149                         ++$yoff;
1150                 }
1151
1152                 // Slide up the top initial diagonal.
1153                 while ($xlim > $xoff && $ylim > $yoff
1154                            && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
1155                         --$xlim;
1156                         --$ylim;
1157                 }
1158
1159                 if ($xoff == $xlim || $yoff == $ylim)
1160                         $lcs = 0;
1161                 else {
1162                         // This is ad hoc but seems to work well.
1163                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
1164                         //$nchunks = max(2,min(8,(int)$nchunks));
1165                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
1166                         list ($lcs, $seps)
1167                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
1168                 }
1169
1170                 if ($lcs == 0) {
1171                         // X and Y sequences have no common subsequence:
1172                         // mark all changed.
1173                         while ($yoff < $ylim)
1174                                 $this->ychanged[$this->yind[$yoff++]] = 1;
1175                         while ($xoff < $xlim)
1176                                 $this->xchanged[$this->xind[$xoff++]] = 1;
1177                 } else {
1178                         // Use the partitions to split this problem into subproblems.
1179                         reset($seps);
1180                         $pt1 = $seps[0];
1181                         while ($pt2 = next($seps)) {
1182                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
1183                                 $pt1 = $pt2;
1184                         }
1185                 }
1186                 wfProfileOut( $fname );
1187         }
1188
1189         /* Adjust inserts/deletes of identical lines to join changes
1190          * as much as possible.
1191          *
1192          * We do something when a run of changed lines include a
1193          * line at one end and has an excluded, identical line at the other.
1194          * We are free to choose which identical line is included.
1195          * `compareseq' usually chooses the one at the beginning,
1196          * but usually it is cleaner to consider the following identical line
1197          * to be the "change".
1198          *
1199          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
1200          */
1201         function _shift_boundaries ($lines, &$changed, $other_changed) {
1202                 $fname = '_DiffEngine::_shift_boundaries';
1203                 wfProfileIn( $fname );
1204                 $i = 0;
1205                 $j = 0;
1206
1207                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
1208                 $len = sizeof($lines);
1209                 $other_len = sizeof($other_changed);
1210
1211                 while (1) {
1212                         /*
1213                          * Scan forwards to find beginning of another run of changes.
1214                          * Also keep track of the corresponding point in the other file.
1215                          *
1216                          * Throughout this code, $i and $j are adjusted together so that
1217                          * the first $i elements of $changed and the first $j elements
1218                          * of $other_changed both contain the same number of zeros
1219                          * (unchanged lines).
1220                          * Furthermore, $j is always kept so that $j == $other_len or
1221                          * $other_changed[$j] == false.
1222                          */
1223                         while ($j < $other_len && $other_changed[$j])
1224                                 $j++;
1225
1226                         while ($i < $len && ! $changed[$i]) {
1227                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1228                                 $i++; $j++;
1229                                 while ($j < $other_len && $other_changed[$j])
1230                                         $j++;
1231                         }
1232
1233                         if ($i == $len)
1234                                 break;
1235
1236                         $start = $i;
1237
1238                         // Find the end of this run of changes.
1239                         while (++$i < $len && $changed[$i])
1240                                 continue;
1241
1242                         do {
1243                                 /*
1244                                  * Record the length of this run of changes, so that
1245                                  * we can later determine whether the run has grown.
1246                                  */
1247                                 $runlength = $i - $start;
1248
1249                                 /*
1250                                  * Move the changed region back, so long as the
1251                                  * previous unchanged line matches the last changed one.
1252                                  * This merges with previous changed regions.
1253                                  */
1254                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
1255                                         $changed[--$start] = 1;
1256                                         $changed[--$i] = false;
1257                                         while ($start > 0 && $changed[$start - 1])
1258                                                 $start--;
1259                                         USE_ASSERTS && assert('$j > 0');
1260                                         while ($other_changed[--$j])
1261                                                 continue;
1262                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1263                                 }
1264
1265                                 /*
1266                                  * Set CORRESPONDING to the end of the changed run, at the last
1267                                  * point where it corresponds to a changed run in the other file.
1268                                  * CORRESPONDING == LEN means no such point has been found.
1269                                  */
1270                                 $corresponding = $j < $other_len ? $i : $len;
1271
1272                                 /*
1273                                  * Move the changed region forward, so long as the
1274                                  * first changed line matches the following unchanged one.
1275                                  * This merges with following changed regions.
1276                                  * Do this second, so that if there are no merges,
1277                                  * the changed region is moved forward as far as possible.
1278                                  */
1279                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1280                                         $changed[$start++] = false;
1281                                         $changed[$i++] = 1;
1282                                         while ($i < $len && $changed[$i])
1283                                                 $i++;
1284
1285                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1286                                         $j++;
1287                                         if ($j < $other_len && $other_changed[$j]) {
1288                                                 $corresponding = $i;
1289                                                 while ($j < $other_len && $other_changed[$j])
1290                                                         $j++;
1291                                         }
1292                                 }
1293                         } while ($runlength != $i - $start);
1294
1295                         /*
1296                          * If possible, move the fully-merged run of changes
1297                          * back to a corresponding run in the other file.
1298                          */
1299                         while ($corresponding < $i) {
1300                                 $changed[--$start] = 1;
1301                                 $changed[--$i] = 0;
1302                                 USE_ASSERTS && assert('$j > 0');
1303                                 while ($other_changed[--$j])
1304                                         continue;
1305                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1306                         }
1307                 }
1308                 wfProfileOut( $fname );
1309         }
1310 }
1311
1312 /**
1313  * Class representing a 'diff' between two sequences of strings.
1314  * @todo document
1315  * @private
1316  * @addtogroup DifferenceEngine
1317  */
1318 class Diff
1319 {
1320         var $edits;
1321
1322         /**
1323          * Constructor.
1324          * Computes diff between sequences of strings.
1325          *
1326          * @param $from_lines array An array of strings.
1327          *                (Typically these are lines from a file.)
1328          * @param $to_lines array An array of strings.
1329          */
1330         function Diff($from_lines, $to_lines) {
1331                 $eng = new _DiffEngine;
1332                 $this->edits = $eng->diff($from_lines, $to_lines);
1333                 //$this->_check($from_lines, $to_lines);
1334         }
1335
1336         /**
1337          * Compute reversed Diff.
1338          *
1339          * SYNOPSIS:
1340          *
1341          *      $diff = new Diff($lines1, $lines2);
1342          *      $rev = $diff->reverse();
1343          * @return object A Diff object representing the inverse of the
1344          *                                original diff.
1345          */
1346         function reverse () {
1347                 $rev = $this;
1348                 $rev->edits = array();
1349                 foreach ($this->edits as $edit) {
1350                         $rev->edits[] = $edit->reverse();
1351                 }
1352                 return $rev;
1353         }
1354
1355         /**
1356          * Check for empty diff.
1357          *
1358          * @return bool True iff two sequences were identical.
1359          */
1360         function isEmpty () {
1361                 foreach ($this->edits as $edit) {
1362                         if ($edit->type != 'copy')
1363                                 return false;
1364                 }
1365                 return true;
1366         }
1367
1368         /**
1369          * Compute the length of the Longest Common Subsequence (LCS).
1370          *
1371          * This is mostly for diagnostic purposed.
1372          *
1373          * @return int The length of the LCS.
1374          */
1375         function lcs () {
1376                 $lcs = 0;
1377                 foreach ($this->edits as $edit) {
1378                         if ($edit->type == 'copy')
1379                                 $lcs += sizeof($edit->orig);
1380                 }
1381                 return $lcs;
1382         }
1383
1384         /**
1385          * Get the original set of lines.
1386          *
1387          * This reconstructs the $from_lines parameter passed to the
1388          * constructor.
1389          *
1390          * @return array The original sequence of strings.
1391          */
1392         function orig() {
1393                 $lines = array();
1394
1395                 foreach ($this->edits as $edit) {
1396                         if ($edit->orig)
1397                                 array_splice($lines, sizeof($lines), 0, $edit->orig);
1398                 }
1399                 return $lines;
1400         }
1401
1402         /**
1403          * Get the closing set of lines.
1404          *
1405          * This reconstructs the $to_lines parameter passed to the
1406          * constructor.
1407          *
1408          * @return array The sequence of strings.
1409          */
1410         function closing() {
1411                 $lines = array();
1412
1413                 foreach ($this->edits as $edit) {
1414                         if ($edit->closing)
1415                                 array_splice($lines, sizeof($lines), 0, $edit->closing);
1416                 }
1417                 return $lines;
1418         }
1419
1420         /**
1421          * Check a Diff for validity.
1422          *
1423          * This is here only for debugging purposes.
1424          */
1425         function _check ($from_lines, $to_lines) {
1426                 $fname = 'Diff::_check';
1427                 wfProfileIn( $fname );
1428                 if (serialize($from_lines) != serialize($this->orig()))
1429                         trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1430                 if (serialize($to_lines) != serialize($this->closing()))
1431                         trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1432
1433                 $rev = $this->reverse();
1434                 if (serialize($to_lines) != serialize($rev->orig()))
1435                         trigger_error("Reversed original doesn't match", E_USER_ERROR);
1436                 if (serialize($from_lines) != serialize($rev->closing()))
1437                         trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1438
1439
1440                 $prevtype = 'none';
1441                 foreach ($this->edits as $edit) {
1442                         if ( $prevtype == $edit->type )
1443                                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1444                         $prevtype = $edit->type;
1445                 }
1446
1447                 $lcs = $this->lcs();
1448                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1449                 wfProfileOut( $fname );
1450         }
1451 }
1452
1453 /**
1454  * @todo document, bad name.
1455  * @private
1456  * @addtogroup DifferenceEngine
1457  */
1458 class MappedDiff extends Diff
1459 {
1460         /**
1461          * Constructor.
1462          *
1463          * Computes diff between sequences of strings.
1464          *
1465          * This can be used to compute things like
1466          * case-insensitve diffs, or diffs which ignore
1467          * changes in white-space.
1468          *
1469          * @param $from_lines array An array of strings.
1470          *      (Typically these are lines from a file.)
1471          *
1472          * @param $to_lines array An array of strings.
1473          *
1474          * @param $mapped_from_lines array This array should
1475          *      have the same size number of elements as $from_lines.
1476          *      The elements in $mapped_from_lines and
1477          *      $mapped_to_lines are what is actually compared
1478          *      when computing the diff.
1479          *
1480          * @param $mapped_to_lines array This array should
1481          *      have the same number of elements as $to_lines.
1482          */
1483         function MappedDiff($from_lines, $to_lines,
1484                                                 $mapped_from_lines, $mapped_to_lines) {
1485                 $fname = 'MappedDiff::MappedDiff';
1486                 wfProfileIn( $fname );
1487
1488                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1489                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1490
1491                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1492
1493                 $xi = $yi = 0;
1494                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1495                         $orig = &$this->edits[$i]->orig;
1496                         if (is_array($orig)) {
1497                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1498                                 $xi += sizeof($orig);
1499                         }
1500
1501                         $closing = &$this->edits[$i]->closing;
1502                         if (is_array($closing)) {
1503                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1504                                 $yi += sizeof($closing);
1505                         }
1506                 }
1507                 wfProfileOut( $fname );
1508         }
1509 }
1510
1511 /**
1512  * A class to format Diffs
1513  *
1514  * This class formats the diff in classic diff format.
1515  * It is intended that this class be customized via inheritance,
1516  * to obtain fancier outputs.
1517  * @todo document
1518  * @private
1519  * @addtogroup DifferenceEngine
1520  */
1521 class DiffFormatter
1522 {
1523         /**
1524          * Number of leading context "lines" to preserve.
1525          *
1526          * This should be left at zero for this class, but subclasses
1527          * may want to set this to other values.
1528          */
1529         var $leading_context_lines = 0;
1530
1531         /**
1532          * Number of trailing context "lines" to preserve.
1533          *
1534          * This should be left at zero for this class, but subclasses
1535          * may want to set this to other values.
1536          */
1537         var $trailing_context_lines = 0;
1538
1539         /**
1540          * Format a diff.
1541          *
1542          * @param $diff object A Diff object.
1543          * @return string The formatted output.
1544          */
1545         function format($diff) {
1546                 $fname = 'DiffFormatter::format';
1547                 wfProfileIn( $fname );
1548
1549                 $xi = $yi = 1;
1550                 $block = false;
1551                 $context = array();
1552
1553                 $nlead = $this->leading_context_lines;
1554                 $ntrail = $this->trailing_context_lines;
1555
1556                 $this->_start_diff();
1557
1558                 foreach ($diff->edits as $edit) {
1559                         if ($edit->type == 'copy') {
1560                                 if (is_array($block)) {
1561                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1562                                                 $block[] = $edit;
1563                                         }
1564                                         else{
1565                                                 if ($ntrail) {
1566                                                         $context = array_slice($edit->orig, 0, $ntrail);
1567                                                         $block[] = new _DiffOp_Copy($context);
1568                                                 }
1569                                                 $this->_block($x0, $ntrail + $xi - $x0,
1570                                                                           $y0, $ntrail + $yi - $y0,
1571                                                                           $block);
1572                                                 $block = false;
1573                                         }
1574                                 }
1575                                 $context = $edit->orig;
1576                         }
1577                         else {
1578                                 if (! is_array($block)) {
1579                                         $context = array_slice($context, sizeof($context) - $nlead);
1580                                         $x0 = $xi - sizeof($context);
1581                                         $y0 = $yi - sizeof($context);
1582                                         $block = array();
1583                                         if ($context)
1584                                                 $block[] = new _DiffOp_Copy($context);
1585                                 }
1586                                 $block[] = $edit;
1587                         }
1588
1589                         if ($edit->orig)
1590                                 $xi += sizeof($edit->orig);
1591                         if ($edit->closing)
1592                                 $yi += sizeof($edit->closing);
1593                 }
1594
1595                 if (is_array($block))
1596                         $this->_block($x0, $xi - $x0,
1597                                                   $y0, $yi - $y0,
1598                                                   $block);
1599
1600                 $end = $this->_end_diff();
1601                 wfProfileOut( $fname );
1602                 return $end;
1603         }
1604
1605         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1606                 $fname = 'DiffFormatter::_block';
1607                 wfProfileIn( $fname );
1608                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1609                 foreach ($edits as $edit) {
1610                         if ($edit->type == 'copy')
1611                                 $this->_context($edit->orig);
1612                         elseif ($edit->type == 'add')
1613                                 $this->_added($edit->closing);
1614                         elseif ($edit->type == 'delete')
1615                                 $this->_deleted($edit->orig);
1616                         elseif ($edit->type == 'change')
1617                                 $this->_changed($edit->orig, $edit->closing);
1618                         else
1619                                 trigger_error('Unknown edit type', E_USER_ERROR);
1620                 }
1621                 $this->_end_block();
1622                 wfProfileOut( $fname );
1623         }
1624
1625         function _start_diff() {
1626                 ob_start();
1627         }
1628
1629         function _end_diff() {
1630                 $val = ob_get_contents();
1631                 ob_end_clean();
1632                 return $val;
1633         }
1634
1635         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1636                 if ($xlen > 1)
1637                         $xbeg .= "," . ($xbeg + $xlen - 1);
1638                 if ($ylen > 1)
1639                         $ybeg .= "," . ($ybeg + $ylen - 1);
1640
1641                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1642         }
1643
1644         function _start_block($header) {
1645                 echo $header;
1646         }
1647
1648         function _end_block() {
1649         }
1650
1651         function _lines($lines, $prefix = ' ') {
1652                 foreach ($lines as $line)
1653                         echo "$prefix $line\n";
1654         }
1655
1656         function _context($lines) {
1657                 $this->_lines($lines);
1658         }
1659
1660         function _added($lines) {
1661                 $this->_lines($lines, '>');
1662         }
1663         function _deleted($lines) {
1664                 $this->_lines($lines, '<');
1665         }
1666
1667         function _changed($orig, $closing) {
1668                 $this->_deleted($orig);
1669                 echo "---\n";
1670                 $this->_added($closing);
1671         }
1672 }
1673
1674
1675 /**
1676  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1677  *
1678  */
1679
1680 define('NBSP', '&#160;');                       // iso-8859-x non-breaking space.
1681
1682 /**
1683  * @todo document
1684  * @private
1685  * @addtogroup DifferenceEngine
1686  */
1687 class _HWLDF_WordAccumulator {
1688         function _HWLDF_WordAccumulator () {
1689                 $this->_lines = array();
1690                 $this->_line = '';
1691                 $this->_group = '';
1692                 $this->_tag = '';
1693         }
1694
1695         function _flushGroup ($new_tag) {
1696                 if ($this->_group !== '') {
1697                         if ($this->_tag == 'ins')
1698                                 $this->_line .= '<ins class="diffchange">' .
1699                                         htmlspecialchars ( $this->_group ) . '</ins>';
1700                         elseif ($this->_tag == 'del')
1701                                 $this->_line .= '<del class="diffchange">' .
1702                                         htmlspecialchars ( $this->_group ) . '</del>';
1703                         else
1704                                 $this->_line .= htmlspecialchars ( $this->_group );
1705                 }
1706                 $this->_group = '';
1707                 $this->_tag = $new_tag;
1708         }
1709
1710         function _flushLine ($new_tag) {
1711                 $this->_flushGroup($new_tag);
1712                 if ($this->_line != '')
1713                         array_push ( $this->_lines, $this->_line );
1714                 else
1715                         # make empty lines visible by inserting an NBSP
1716                         array_push ( $this->_lines, NBSP );
1717                 $this->_line = '';
1718         }
1719
1720         function addWords ($words, $tag = '') {
1721                 if ($tag != $this->_tag)
1722                         $this->_flushGroup($tag);
1723
1724                 foreach ($words as $word) {
1725                         // new-line should only come as first char of word.
1726                         if ($word == '')
1727                                 continue;
1728                         if ($word[0] == "\n") {
1729                                 $this->_flushLine($tag);
1730                                 $word = substr($word, 1);
1731                         }
1732                         assert(!strstr($word, "\n"));
1733                         $this->_group .= $word;
1734                 }
1735         }
1736
1737         function getLines() {
1738                 $this->_flushLine('~done');
1739                 return $this->_lines;
1740         }
1741 }
1742
1743 /**
1744  * @todo document
1745  * @private
1746  * @addtogroup DifferenceEngine
1747  */
1748 class WordLevelDiff extends MappedDiff
1749 {
1750         const MAX_LINE_LENGTH = 10000;
1751
1752         function WordLevelDiff ($orig_lines, $closing_lines) {
1753                 $fname = 'WordLevelDiff::WordLevelDiff';
1754                 wfProfileIn( $fname );
1755
1756                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1757                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1758
1759                 $this->MappedDiff($orig_words, $closing_words,
1760                                                   $orig_stripped, $closing_stripped);
1761                 wfProfileOut( $fname );
1762         }
1763
1764         function _split($lines) {
1765                 $fname = 'WordLevelDiff::_split';
1766                 wfProfileIn( $fname );
1767
1768                 $words = array();
1769                 $stripped = array();
1770                 $first = true;
1771                 foreach ( $lines as $line ) {
1772                         # If the line is too long, just pretend the entire line is one big word
1773                         # This prevents resource exhaustion problems
1774                         if ( $first ) {
1775                                 $first = false;
1776                         } else {
1777                                 $words[] = "\n";
1778                                 $stripped[] = "\n";
1779                         }
1780                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
1781                                 $words[] = $line;
1782                                 $stripped[] = $line;
1783                         } else {
1784                                 $m = array();
1785                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1786                                         $line, $m))
1787                                 {
1788                                         $words = array_merge( $words, $m[0] );
1789                                         $stripped = array_merge( $stripped, $m[1] );
1790                                 }
1791                         }
1792                 }
1793                 wfProfileOut( $fname );
1794                 return array($words, $stripped);
1795         }
1796
1797         function orig () {
1798                 $fname = 'WordLevelDiff::orig';
1799                 wfProfileIn( $fname );
1800                 $orig = new _HWLDF_WordAccumulator;
1801
1802                 foreach ($this->edits as $edit) {
1803                         if ($edit->type == 'copy')
1804                                 $orig->addWords($edit->orig);
1805                         elseif ($edit->orig)
1806                                 $orig->addWords($edit->orig, 'del');
1807                 }
1808                 $lines = $orig->getLines();
1809                 wfProfileOut( $fname );
1810                 return $lines;
1811         }
1812
1813         function closing () {
1814                 $fname = 'WordLevelDiff::closing';
1815                 wfProfileIn( $fname );
1816                 $closing = new _HWLDF_WordAccumulator;
1817
1818                 foreach ($this->edits as $edit) {
1819                         if ($edit->type == 'copy')
1820                                 $closing->addWords($edit->closing);
1821                         elseif ($edit->closing)
1822                                 $closing->addWords($edit->closing, 'ins');
1823                 }
1824                 $lines = $closing->getLines();
1825                 wfProfileOut( $fname );
1826                 return $lines;
1827         }
1828 }
1829
1830 /**
1831  *      Wikipedia Table style diff formatter.
1832  * @todo document
1833  * @private
1834  * @addtogroup DifferenceEngine
1835  */
1836 class TableDiffFormatter extends DiffFormatter
1837 {
1838         function TableDiffFormatter() {
1839                 $this->leading_context_lines = 2;
1840                 $this->trailing_context_lines = 2;
1841         }
1842
1843         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1844                 $r = '<tr><td colspan="2" class="diff-lineno"><!--LINE '.$xbeg."--></td>\n" .
1845                   '<td colspan="2" class="diff-lineno"><!--LINE '.$ybeg."--></td></tr>\n";
1846                 return $r;
1847         }
1848
1849         function _start_block( $header ) {
1850                 echo $header;
1851         }
1852
1853         function _end_block() {
1854         }
1855
1856         function _lines( $lines, $prefix=' ', $color='white' ) {
1857         }
1858
1859         # HTML-escape parameter before calling this
1860         function addedLine( $line ) {
1861                 return $this->wrapLine( '+', 'diff-addedline', $line );
1862         }
1863
1864         # HTML-escape parameter before calling this
1865         function deletedLine( $line ) {
1866                 return $this->wrapLine( '-', 'diff-deletedline', $line );
1867         }
1868
1869         # HTML-escape parameter before calling this
1870         function contextLine( $line ) {
1871                 return $this->wrapLine( ' ', 'diff-context', $line );
1872         }
1873
1874         private function wrapLine( $marker, $class, $line ) {
1875                 if( $line !== '' ) {
1876                         // The <div> wrapper is needed for 'overflow: auto' style to scroll properly
1877                         $line = "<div>$line</div>";
1878                 }
1879                 return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
1880         }
1881
1882         function emptyLine() {
1883                 return '<td colspan="2">&nbsp;</td>';
1884         }
1885
1886         function _added( $lines ) {
1887                 foreach ($lines as $line) {
1888                         echo '<tr>' . $this->emptyLine() .
1889                                 $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1890                 }
1891         }
1892
1893         function _deleted($lines) {
1894                 foreach ($lines as $line) {
1895                         echo '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
1896                           $this->emptyLine() . "</tr>\n";
1897                 }
1898         }
1899
1900         function _context( $lines ) {
1901                 foreach ($lines as $line) {
1902                         echo '<tr>' .
1903                                 $this->contextLine( htmlspecialchars ( $line ) ) .
1904                                 $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1905                 }
1906         }
1907
1908         function _changed( $orig, $closing ) {
1909                 $fname = 'TableDiffFormatter::_changed';
1910                 wfProfileIn( $fname );
1911
1912                 $diff = new WordLevelDiff( $orig, $closing );
1913                 $del = $diff->orig();
1914                 $add = $diff->closing();
1915
1916                 # Notice that WordLevelDiff returns HTML-escaped output.
1917                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
1918
1919                 while ( $line = array_shift( $del ) ) {
1920                         $aline = array_shift( $add );
1921                         echo '<tr>' . $this->deletedLine( $line ) .
1922                                 $this->addedLine( $aline ) . "</tr>\n";
1923                 }
1924                 foreach ($add as $line) {       # If any leftovers
1925                         echo '<tr>' . $this->emptyLine() .
1926                                 $this->addedLine( $line ) . "</tr>\n";
1927                 }
1928                 wfProfileOut( $fname );
1929         }
1930 }
1931
1932
1933