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