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;
 294                 $diff = $this->getDiff( $otitle, $ntitle );
 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 diff table, including header
 318          * Note that the interface has changed, it's no longer static.
 319          * Returns false on error
 320          */
 321         function getDiff( $otitle, $ntitle ) {
 322                 $body = $this->getDiffBody();
 323                 if ( $body === false ) {
 324                         return false;
 325                 } else {
 326                         $multi = $this->getMultiNotice();
 327                         return $this->addHeader( $body, $otitle, $ntitle, $multi );
 328                 }
 329         }
 330
 331         /**
 332          * Get the diff table body, without header
 333          * Results are cached
 334          * Returns false on error
 335          */
 336         function getDiffBody() {
 337                 global $wgMemc;
 338                 $fname = 'DifferenceEngine::getDiffBody';
 339                 wfProfileIn( $fname );
 340
 341                 // Cacheable?
 342                 $key = false;
 343                 if ( $this->mOldid && $this->mNewid ) {
 344                         // Try cache
 345                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
 346                         $difftext = $wgMemc->get( $key );
 347                         if ( $difftext ) {
 348                                 wfIncrStats( 'diff_cache_hit' );
 349                                 $difftext = $this->localiseLineNumbers( $difftext );
 350                                 $difftext .= "\n<!-- diff cache key $key -->\n";
 351                                 wfProfileOut( $fname );
 352                                 return $difftext;
 353                         }
 354                 }
 355
 356                 #loadtext is permission safe, this just clears out the diff
 357                 if ( !$this->loadText() ) {
 358                         wfProfileOut( $fname );
 359                         return false;
 360                 } else if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
 361                   return '';
 362                 } else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 363                   return '';
 364                 }
 365
 366                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 367
 368                 // Save to cache for 7 days
 369                 if ( $key !== false && $difftext !== false ) {
 370                         wfIncrStats( 'diff_cache_miss' );
 371                         $wgMemc->set( $key, $difftext, 7*86400 );
 372                 } else {
 373                         wfIncrStats( 'diff_uncacheable' );
 374                 }
 375                 // Replace line numbers with the text in the user's language
 376                 if ( $difftext !== false ) {
 377                         $difftext = $this->localiseLineNumbers( $difftext );
 378                 }
 379                 wfProfileOut( $fname );
 380                 return $difftext;
 381         }
 382
 383         /**
 384          * Generate a diff, no caching
 385          * $otext and $ntext must be already segmented
 386          */
 387         function generateDiffBody( $otext, $ntext ) {
 388                 global $wgExternalDiffEngine, $wgContLang;
 389                 $fname = 'DifferenceEngine::generateDiffBody';
 390
 391                 $otext = str_replace( "\r\n", "\n", $otext );
 392                 $ntext = str_replace( "\r\n", "\n", $ntext );
 393
 394                 if ( $wgExternalDiffEngine == 'wikidiff' ) {
 395                         # For historical reasons, external diff engine expects
 396                         # input text to be HTML-escaped already
 397                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 398                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 399                         if( !function_exists( 'wikidiff_do_diff' ) ) {
 400                                 dl('php_wikidiff.so');
 401                         }
 402                         return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) );
 403                 }
 404
 405                 if ( $wgExternalDiffEngine == 'wikidiff2' ) {
 406                         # Better external diff engine, the 2 may some day be dropped
 407                         # This one does the escaping and segmenting itself
 408                         if ( !function_exists( 'wikidiff2_do_diff' ) ) {
 409                                 wfProfileIn( "$fname-dl" );
 410                                 @dl('php_wikidiff2.so');
 411                                 wfProfileOut( "$fname-dl" );
 412                         }
 413                         if ( function_exists( 'wikidiff2_do_diff' ) ) {
 414                                 wfProfileIn( 'wikidiff2_do_diff' );
 415                                 $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 416                                 wfProfileOut( 'wikidiff2_do_diff' );
 417                                 return $text;
 418                         }
 419                 }
 420                 if ( $wgExternalDiffEngine !== false ) {
 421                         # Diff via the shell
 422                         global $wgTmpDirectory;
 423                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 424                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 425
 426                         $tempFile1 = fopen( $tempName1, "w" );
 427                         if ( !$tempFile1 ) {
 428                                 wfProfileOut( $fname );
 429                                 return false;
 430                         }
 431                         $tempFile2 = fopen( $tempName2, "w" );
 432                         if ( !$tempFile2 ) {
 433                                 wfProfileOut( $fname );
 434                                 return false;
 435                         }
 436                         fwrite( $tempFile1, $otext );
 437                         fwrite( $tempFile2, $ntext );
 438                         fclose( $tempFile1 );
 439                         fclose( $tempFile2 );
 440                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 441                         wfProfileIn( "$fname-shellexec" );
 442                         $difftext = wfShellExec( $cmd );
 443                         wfProfileOut( "$fname-shellexec" );
 444                         unlink( $tempName1 );
 445                         unlink( $tempName2 );
 446                         return $difftext;
 447                 }
 448
 449                 # Native PHP diff
 450                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 451                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 452                 $diffs = new Diff( $ota, $nta );
 453                 $formatter = new TableDiffFormatter();
 454                 return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) );
 455         }
 456
 457
 458         /**
 459          * Replace line numbers with the text in the user's language
 460          */
 461         function localiseLineNumbers( $text ) {
 462                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 463                         array( &$this, 'localiseLineNumbersCb' ), $text );
 464         }
 465
 466         function localiseLineNumbersCb( $matches ) {
 467                 global $wgLang;
 468                 return wfMsgExt( 'lineno', array('parseinline'), $wgLang->formatNum( $matches[1] ) );
 469         }
 470
 471
 472         /**
 473          * If there are revisions between the ones being compared, return a note saying so.
 474          */
 475         function getMultiNotice() {
 476                 if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
 477                         return '';
 478
 479                 if( !$this->mOldPage->equals( $this->mNewPage ) ) {
 480                         // Comparing two different pages? Count would be meaningless.
 481                         return '';
 482                 }
 483
 484                 $oldid = $this->mOldRev->getId();
 485                 $newid = $this->mNewRev->getId();
 486                 if ( $oldid > $newid ) {
 487                         $tmp = $oldid; $oldid = $newid; $newid = $tmp;
 488                 }
 489
 490                 $n = $this->mTitle->countRevisionsBetween( $oldid, $newid );
 491                 if ( !$n )
 492                         return '';
 493
 494                 return wfMsgExt( 'diff-multi', array( 'parseinline' ), $n );
 495         }
 496
 497
 498         /**
 499          * Add the header to a diff body
 500          */
 501         function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
 502                 global $wgOut;
 503
 504                 if ( $this->mOldRev && $this->mOldRev->isDeleted(Revision::DELETED_TEXT) ) {
 505                    $otitle = '<span class="history-deleted">'.$otitle.'</span>';
 506                 }
 507                 if ( $this->mNewRev && $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 508                    $ntitle = '<span class="history-deleted">'.$ntitle.'</span>';
 509                 }
 510                 $header = "
 511                         <table class='diff'>
 512                         <col class='diff-marker' />
 513                         <col class='diff-content' />
 514                         <col class='diff-marker' />
 515                         <col class='diff-content' />
 516                         <tr>
 517                                 <td colspan='2' class='diff-otitle'>{$otitle}</td>
 518                                 <td colspan='2' class='diff-ntitle'>{$ntitle}</td>
 519                         </tr>
 520                 ";
 521
 522                 if ( $multi != '' )
 523                         $header .= "<tr><td colspan='4' align='center' class='diff-multi'>{$multi}</td></tr>";
 524
 525                 return $header . $diff . "</table>";
 526         }
 527
 528         /**
 529          * Use specified text instead of loading from the database
 530          */
 531         function setText( $oldText, $newText ) {
 532                 $this->mOldtext = $oldText;
 533                 $this->mNewtext = $newText;
 534                 $this->mTextLoaded = 2;
 535         }
 536
 537         /**
 538          * Load revision metadata for the specified articles. If newid is 0, then compare
 539          * the old article in oldid to the current article; if oldid is 0, then
 540          * compare the current article to the immediately previous one (ignoring the
 541          * value of newid).
 542          *
 543          * If oldid is false, leave the corresponding revision object set
 544          * to false. This is impossible via ordinary user input, and is provided for
 545          * API convenience.
 546          */
 547         function loadRevisionData() {
 548                 global $wgLang;
 549                 if ( $this->mRevisionsLoaded ) {
 550                         return true;
 551                 } else {
 552                         // Whether it succeeds or fails, we don't want to try again
 553                         $this->mRevisionsLoaded = true;
 554                 }
 555
 556                 // Load the new revision object
 557                 if( $this->mNewid ) {
 558                         $this->mNewRev = Revision::newFromId( $this->mNewid );
 559                 } else {
 560                         $this->mNewRev = Revision::newFromTitle( $this->mTitle );
 561                 }
 562
 563                 if( is_null( $this->mNewRev ) ) {
 564                         return false;
 565                 }
 566
 567                 // Set assorted variables
 568                 $timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 569                 $this->mNewPage = $this->mNewRev->getTitle();
 570                 if( $this->mNewRev->isCurrent() ) {
 571                         $newLink = $this->mNewPage->escapeLocalUrl();
 572                         $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
 573                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit' );
 574
 575                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a> ($timestamp)"
 576                                 . " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 577
 578                 } else {
 579                         $newLink = $this->mNewPage->escapeLocalUrl( 'oldid=' . $this->mNewid );
 580                         $newEdit = $this->mNewPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mNewid );
 581                         $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $timestamp ) );
 582
 583                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>"
 584                                 . " (<a href='$newEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 585                 }
 586
 587                 // Load the old revision object
 588                 $this->mOldRev = false;
 589                 if( $this->mOldid ) {
 590                         $this->mOldRev = Revision::newFromId( $this->mOldid );
 591                 } elseif ( $this->mOldid === 0 ) {
 592                         $rev = $this->mNewRev->getPrevious();
 593                         if( $rev ) {
 594                                 $this->mOldid = $rev->getId();
 595                                 $this->mOldRev = $rev;
 596                         } else {
 597                                 // No previous revision; mark to show as first-version only.
 598                                 $this->mOldid = false;
 599                                 $this->mOldRev = false;
 600                         }
 601                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
 602
 603                 if( is_null( $this->mOldRev ) ) {
 604                         return false;
 605                 }
 606
 607                 if ( $this->mOldRev ) {
 608                         $this->mOldPage = $this->mOldRev->getTitle();
 609
 610                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
 611                         $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
 612                         $oldEdit = $this->mOldPage->escapeLocalUrl( 'action=edit&oldid=' . $this->mOldid );
 613                         $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) )
 614                                 . "</a> (<a href='$oldEdit'>" . htmlspecialchars( wfMsg( 'editold' ) ) . "</a>)";
 615                         //now that we considered old rev, we can make undo link (bug 8133, multi-edit undo)
 616                         $newUndo = $this->mNewPage->escapeLocalUrl( 'action=edit&undoafter=' . $this->mOldid . '&undo=' . $this->mNewid);
 617                         $this->mNewtitle .= " (<a href='$newUndo'>" . htmlspecialchars( wfMsg( 'editundo' ) ) . "</a>)";
 618                 }
 619
 620                 return true;
 621         }
 622
 623         /**
 624          * Load the text of the revisions, as well as revision data.
 625          */
 626         function loadText() {
 627                 if ( $this->mTextLoaded == 2 ) {
 628                         return true;
 629                 } else {
 630                         // Whether it succeeds or fails, we don't want to try again
 631                         $this->mTextLoaded = 2;
 632                 }
 633
 634                 if ( !$this->loadRevisionData() ) {
 635                         return false;
 636                 }
 637                 if ( $this->mOldRev ) {
 638                         // FIXME: permission tests
 639                         $this->mOldtext = $this->mOldRev->revText();
 640                         if ( $this->mOldtext === false ) {
 641                                 return false;
 642                         }
 643                 }
 644                 if ( $this->mNewRev ) {
 645                         $this->mNewtext = $this->mNewRev->revText();
 646                         if ( $this->mNewtext === false ) {
 647                                 return false;
 648                         }
 649                 }
 650                 return true;
 651         }
 652
 653         /**
 654          * Load the text of the new revision, not the old one
 655          */
 656         function loadNewText() {
 657                 if ( $this->mTextLoaded >= 1 ) {
 658                         return true;
 659                 } else {
 660                         $this->mTextLoaded = 1;
 661                 }
 662                 if ( !$this->loadRevisionData() ) {
 663                         return false;
 664                 }
 665                 $this->mNewtext = $this->mNewRev->getText();
 666                 return true;
 667         }
 668
 669
 670 }
 671
 672 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 673 //
 674 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 675 // You may copy this code freely under the conditions of the GPL.
 676 //
 677
 678 define('USE_ASSERTS', function_exists('assert'));
 679
 680 /**
 681  * @todo document
 682  * @private
 683  * @addtogroup DifferenceEngine
 684  */
 685 class _DiffOp {
 686         var $type;
 687         var $orig;
 688         var $closing;
 689
 690         function reverse() {
 691                 trigger_error('pure virtual', E_USER_ERROR);
 692         }
 693
 694         function norig() {
 695                 return $this->orig ? sizeof($this->orig) : 0;
 696         }
 697
 698         function nclosing() {
 699                 return $this->closing ? sizeof($this->closing) : 0;
 700         }
 701 }
 702
 703 /**
 704  * @todo document
 705  * @private
 706  * @addtogroup DifferenceEngine
 707  */
 708 class _DiffOp_Copy extends _DiffOp {
 709         var $type = 'copy';
 710
 711         function _DiffOp_Copy ($orig, $closing = false) {
 712                 if (!is_array($closing))
 713                         $closing = $orig;
 714                 $this->orig = $orig;
 715                 $this->closing = $closing;
 716         }
 717
 718         function reverse() {
 719                 return new _DiffOp_Copy($this->closing, $this->orig);
 720         }
 721 }
 722
 723 /**
 724  * @todo document
 725  * @private
 726  * @addtogroup DifferenceEngine
 727  */
 728 class _DiffOp_Delete extends _DiffOp {
 729         var $type = 'delete';
 730
 731         function _DiffOp_Delete ($lines) {
 732                 $this->orig = $lines;
 733                 $this->closing = false;
 734         }
 735
 736         function reverse() {
 737                 return new _DiffOp_Add($this->orig);
 738         }
 739 }
 740
 741 /**
 742  * @todo document
 743  * @private
 744  * @addtogroup DifferenceEngine
 745  */
 746 class _DiffOp_Add extends _DiffOp {
 747         var $type = 'add';
 748
 749         function _DiffOp_Add ($lines) {
 750                 $this->closing = $lines;
 751                 $this->orig = false;
 752         }
 753
 754         function reverse() {
 755                 return new _DiffOp_Delete($this->closing);
 756         }
 757 }
 758
 759 /**
 760  * @todo document
 761  * @private
 762  * @addtogroup DifferenceEngine
 763  */
 764 class _DiffOp_Change extends _DiffOp {
 765         var $type = 'change';
 766
 767         function _DiffOp_Change ($orig, $closing) {
 768                 $this->orig = $orig;
 769                 $this->closing = $closing;
 770         }
 771
 772         function reverse() {
 773                 return new _DiffOp_Change($this->closing, $this->orig);
 774         }
 775 }
 776
 777
 778 /**
 779  * Class used internally by Diff to actually compute the diffs.
 780  *
 781  * The algorithm used here is mostly lifted from the perl module
 782  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 783  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 784  *
 785  * More ideas are taken from:
 786  *       http://www.ics.uci.edu/~eppstein/161/960229.html
 787  *
 788  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 789  * diffutils-2.7, which can be found at:
 790  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 791  *
 792  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 793  * are my own.
 794  *
 795  * Line length limits for robustness added by Tim Starling, 2005-08-31
 796  *
 797  * @author Geoffrey T. Dairiki, Tim Starling
 798  * @private
 799  * @addtogroup DifferenceEngine
 800  */
 801 class _DiffEngine
 802 {
 803         const MAX_XREF_LENGTH =  10000;
 804
 805         function diff ($from_lines, $to_lines) {
 806                 $fname = '_DiffEngine::diff';
 807                 wfProfileIn( $fname );
 808
 809                 $n_from = sizeof($from_lines);
 810                 $n_to = sizeof($to_lines);
 811
 812                 $this->xchanged = $this->ychanged = array();
 813                 $this->xv = $this->yv = array();
 814                 $this->xind = $this->yind = array();
 815                 unset($this->seq);
 816                 unset($this->in_seq);
 817                 unset($this->lcs);
 818
 819                 // Skip leading common lines.
 820                 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 821                         if ($from_lines[$skip] !== $to_lines[$skip])
 822                                 break;
 823                         $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 824                 }
 825                 // Skip trailing common lines.
 826                 $xi = $n_from; $yi = $n_to;
 827                 for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 828                         if ($from_lines[$xi] !== $to_lines[$yi])
 829                                 break;
 830                         $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 831                 }
 832
 833                 // Ignore lines which do not exist in both files.
 834                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 835                         $xhash[$this->_line_hash($from_lines[$xi])] = 1;
 836                 }
 837
 838                 for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 839                         $line = $to_lines[$yi];
 840                         if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
 841                                 continue;
 842                         $yhash[$this->_line_hash($line)] = 1;
 843                         $this->yv[] = $line;
 844                         $this->yind[] = $yi;
 845                 }
 846                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 847                         $line = $from_lines[$xi];
 848                         if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
 849                                 continue;
 850                         $this->xv[] = $line;
 851                         $this->xind[] = $xi;
 852                 }
 853
 854                 // Find the LCS.
 855                 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 856
 857                 // Merge edits when possible
 858                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 859                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 860
 861                 // Compute the edit operations.
 862                 $edits = array();
 863                 $xi = $yi = 0;
 864                 while ($xi < $n_from || $yi < $n_to) {
 865                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 866                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 867
 868                         // Skip matching "snake".
 869                         $copy = array();
 870                         while ( $xi < $n_from && $yi < $n_to
 871                                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 872                                 $copy[] = $from_lines[$xi++];
 873                                 ++$yi;
 874                         }
 875                         if ($copy)
 876                                 $edits[] = new _DiffOp_Copy($copy);
 877
 878                         // Find deletes & adds.
 879                         $delete = array();
 880                         while ($xi < $n_from && $this->xchanged[$xi])
 881                                 $delete[] = $from_lines[$xi++];
 882
 883                         $add = array();
 884                         while ($yi < $n_to && $this->ychanged[$yi])
 885                                 $add[] = $to_lines[$yi++];
 886
 887                         if ($delete && $add)
 888                                 $edits[] = new _DiffOp_Change($delete, $add);
 889                         elseif ($delete)
 890                                 $edits[] = new _DiffOp_Delete($delete);
 891                         elseif ($add)
 892                                 $edits[] = new _DiffOp_Add($add);
 893                 }
 894                 wfProfileOut( $fname );
 895                 return $edits;
 896         }
 897
 898         /**
 899          * Returns the whole line if it's small enough, or the MD5 hash otherwise
 900          */
 901         function _line_hash( $line ) {
 902                 if ( strlen( $line ) > self::MAX_XREF_LENGTH ) {
 903                         return md5( $line );
 904                 } else {
 905                         return $line;
 906                 }
 907         }
 908
 909
 910         /* Divide the Largest Common Subsequence (LCS) of the sequences
 911          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 912          * sized segments.
 913          *
 914          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
 915          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 916          * sub sequences.  The first sub-sequence is contained in [X0, X1),
 917          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 918          * that (X0, Y0) == (XOFF, YOFF) and
 919          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 920          *
 921          * This function assumes that the first lines of the specified portions
 922          * of the two files do not match, and likewise that the last lines do not
 923          * match.  The caller must trim matching lines from the beginning and end
 924          * of the portions it is going to specify.
 925          */
 926         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
 927                 $fname = '_DiffEngine::_diag';
 928                 wfProfileIn( $fname );
 929                 $flip = false;
 930
 931                 if ($xlim - $xoff > $ylim - $yoff) {
 932                         // Things seems faster (I'm not sure I understand why)
 933                                 // when the shortest sequence in X.
 934                                 $flip = true;
 935                         list ($xoff, $xlim, $yoff, $ylim)
 936                         = array( $yoff, $ylim, $xoff, $xlim);
 937                 }
 938
 939                 if ($flip)
 940                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 941                                 $ymatches[$this->xv[$i]][] = $i;
 942                 else
 943                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 944                                 $ymatches[$this->yv[$i]][] = $i;
 945
 946                 $this->lcs = 0;
 947                 $this->seq[0]= $yoff - 1;
 948                 $this->in_seq = array();
 949                 $ymids[0] = array();
 950
 951                 $numer = $xlim - $xoff + $nchunks - 1;
 952                 $x = $xoff;
 953                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
 954                         wfProfileIn( "$fname-chunk" );
 955                         if ($chunk > 0)
 956                                 for ($i = 0; $i <= $this->lcs; $i++)
 957                                         $ymids[$i][$chunk-1] = $this->seq[$i];
 958
 959                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
 960                         for ( ; $x < $x1; $x++) {
 961                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 962                                         if (empty($ymatches[$line]))
 963                                                 continue;
 964                                 $matches = $ymatches[$line];
 965                                 reset($matches);
 966                                 while (list ($junk, $y) = each($matches))
 967                                         if (empty($this->in_seq[$y])) {
 968                                                 $k = $this->_lcs_pos($y);
 969                                                 USE_ASSERTS && assert($k > 0);
 970                                                 $ymids[$k] = $ymids[$k-1];
 971                                                 break;
 972                                         }
 973                                 while (list ( /* $junk */, $y) = each($matches)) {
 974                                         if ($y > $this->seq[$k-1]) {
 975                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
 976                                                 // Optimization: this is a common case:
 977                                                 //      next match is just replacing previous match.
 978                                                 $this->in_seq[$this->seq[$k]] = false;
 979                                                 $this->seq[$k] = $y;
 980                                                 $this->in_seq[$y] = 1;
 981                                         } else if (empty($this->in_seq[$y])) {
 982                                                 $k = $this->_lcs_pos($y);
 983                                                 USE_ASSERTS && assert($k > 0);
 984                                                 $ymids[$k] = $ymids[$k-1];
 985                                         }
 986                                 }
 987                         }
 988                         wfProfileOut( "$fname-chunk" );
 989                 }
 990
 991                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
 992                 $ymid = $ymids[$this->lcs];
 993                 for ($n = 0; $n < $nchunks - 1; $n++) {
 994                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
 995                         $y1 = $ymid[$n] + 1;
 996                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
 997                 }
 998                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 999
1000                 wfProfileOut( $fname );
1001                 return array($this->lcs, $seps);
1002         }
1003
1004         function _lcs_pos ($ypos) {
1005                 $fname = '_DiffEngine::_lcs_pos';
1006                 wfProfileIn( $fname );
1007
1008                 $end = $this->lcs;
1009                 if ($end == 0 || $ypos > $this->seq[$end]) {
1010                         $this->seq[++$this->lcs] = $ypos;
1011                         $this->in_seq[$ypos] = 1;
1012                         wfProfileOut( $fname );
1013                         return $this->lcs;
1014                 }
1015
1016                 $beg = 1;
1017                 while ($beg < $end) {
1018                         $mid = (int)(($beg + $end) / 2);
1019                         if ( $ypos > $this->seq[$mid] )
1020                                 $beg = $mid + 1;
1021                         else
1022                                 $end = $mid;
1023                 }
1024
1025                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
1026
1027                 $this->in_seq[$this->seq[$end]] = false;
1028                 $this->seq[$end] = $ypos;
1029                 $this->in_seq[$ypos] = 1;
1030                 wfProfileOut( $fname );
1031                 return $end;
1032         }
1033
1034         /* Find LCS of two sequences.
1035          *
1036          * The results are recorded in the vectors $this->{x,y}changed[], by
1037          * storing a 1 in the element for each line that is an insertion
1038          * or deletion (ie. is not in the LCS).
1039          *
1040          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
1041          *
1042          * Note that XLIM, YLIM are exclusive bounds.
1043          * All line numbers are origin-0 and discarded lines are not counted.
1044          */
1045         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
1046                 $fname = '_DiffEngine::_compareseq';
1047                 wfProfileIn( $fname );
1048
1049                 // Slide down the bottom initial diagonal.
1050                 while ($xoff < $xlim && $yoff < $ylim
1051                            && $this->xv[$xoff] == $this->yv[$yoff]) {
1052                         ++$xoff;
1053                         ++$yoff;
1054                 }
1055
1056                 // Slide up the top initial diagonal.
1057                 while ($xlim > $xoff && $ylim > $yoff
1058                            && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
1059                         --$xlim;
1060                         --$ylim;
1061                 }
1062
1063                 if ($xoff == $xlim || $yoff == $ylim)
1064                         $lcs = 0;
1065                 else {
1066                         // This is ad hoc but seems to work well.
1067                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
1068                         //$nchunks = max(2,min(8,(int)$nchunks));
1069                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
1070                         list ($lcs, $seps)
1071                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
1072                 }
1073
1074                 if ($lcs == 0) {
1075                         // X and Y sequences have no common subsequence:
1076                         // mark all changed.
1077                         while ($yoff < $ylim)
1078                                 $this->ychanged[$this->yind[$yoff++]] = 1;
1079                         while ($xoff < $xlim)
1080                                 $this->xchanged[$this->xind[$xoff++]] = 1;
1081                 } else {
1082                         // Use the partitions to split this problem into subproblems.
1083                         reset($seps);
1084                         $pt1 = $seps[0];
1085                         while ($pt2 = next($seps)) {
1086                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
1087                                 $pt1 = $pt2;
1088                         }
1089                 }
1090                 wfProfileOut( $fname );
1091         }
1092
1093         /* Adjust inserts/deletes of identical lines to join changes
1094          * as much as possible.
1095          *
1096          * We do something when a run of changed lines include a
1097          * line at one end and has an excluded, identical line at the other.
1098          * We are free to choose which identical line is included.
1099          * `compareseq' usually chooses the one at the beginning,
1100          * but usually it is cleaner to consider the following identical line
1101          * to be the "change".
1102          *
1103          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
1104          */
1105         function _shift_boundaries ($lines, &$changed, $other_changed) {
1106                 $fname = '_DiffEngine::_shift_boundaries';
1107                 wfProfileIn( $fname );
1108                 $i = 0;
1109                 $j = 0;
1110
1111                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
1112                 $len = sizeof($lines);
1113                 $other_len = sizeof($other_changed);
1114
1115                 while (1) {
1116                         /*
1117                          * Scan forwards to find beginning of another run of changes.
1118                          * Also keep track of the corresponding point in the other file.
1119                          *
1120                          * Throughout this code, $i and $j are adjusted together so that
1121                          * the first $i elements of $changed and the first $j elements
1122                          * of $other_changed both contain the same number of zeros
1123                          * (unchanged lines).
1124                          * Furthermore, $j is always kept so that $j == $other_len or
1125                          * $other_changed[$j] == false.
1126                          */
1127                         while ($j < $other_len && $other_changed[$j])
1128                                 $j++;
1129
1130                         while ($i < $len && ! $changed[$i]) {
1131                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1132                                 $i++; $j++;
1133                                 while ($j < $other_len && $other_changed[$j])
1134                                         $j++;
1135                         }
1136
1137                         if ($i == $len)
1138                                 break;
1139
1140                         $start = $i;
1141
1142                         // Find the end of this run of changes.
1143                         while (++$i < $len && $changed[$i])
1144                                 continue;
1145
1146                         do {
1147                                 /*
1148                                  * Record the length of this run of changes, so that
1149                                  * we can later determine whether the run has grown.
1150                                  */
1151                                 $runlength = $i - $start;
1152
1153                                 /*
1154                                  * Move the changed region back, so long as the
1155                                  * previous unchanged line matches the last changed one.
1156                                  * This merges with previous changed regions.
1157                                  */
1158                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
1159                                         $changed[--$start] = 1;
1160                                         $changed[--$i] = false;
1161                                         while ($start > 0 && $changed[$start - 1])
1162                                                 $start--;
1163                                         USE_ASSERTS && assert('$j > 0');
1164                                         while ($other_changed[--$j])
1165                                                 continue;
1166                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1167                                 }
1168
1169                                 /*
1170                                  * Set CORRESPONDING to the end of the changed run, at the last
1171                                  * point where it corresponds to a changed run in the other file.
1172                                  * CORRESPONDING == LEN means no such point has been found.
1173                                  */
1174                                 $corresponding = $j < $other_len ? $i : $len;
1175
1176                                 /*
1177                                  * Move the changed region forward, so long as the
1178                                  * first changed line matches the following unchanged one.
1179                                  * This merges with following changed regions.
1180                                  * Do this second, so that if there are no merges,
1181                                  * the changed region is moved forward as far as possible.
1182                                  */
1183                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1184                                         $changed[$start++] = false;
1185                                         $changed[$i++] = 1;
1186                                         while ($i < $len && $changed[$i])
1187                                                 $i++;
1188
1189                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1190                                         $j++;
1191                                         if ($j < $other_len && $other_changed[$j]) {
1192                                                 $corresponding = $i;
1193                                                 while ($j < $other_len && $other_changed[$j])
1194                                                         $j++;
1195                                         }
1196                                 }
1197                         } while ($runlength != $i - $start);
1198
1199                         /*
1200                          * If possible, move the fully-merged run of changes
1201                          * back to a corresponding run in the other file.
1202                          */
1203                         while ($corresponding < $i) {
1204                                 $changed[--$start] = 1;
1205                                 $changed[--$i] = 0;
1206                                 USE_ASSERTS && assert('$j > 0');
1207                                 while ($other_changed[--$j])
1208                                         continue;
1209                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1210                         }
1211                 }
1212                 wfProfileOut( $fname );
1213         }
1214 }
1215
1216 /**
1217  * Class representing a 'diff' between two sequences of strings.
1218  * @todo document
1219  * @private
1220  * @addtogroup DifferenceEngine
1221  */
1222 class Diff
1223 {
1224         var $edits;
1225
1226         /**
1227          * Constructor.
1228          * Computes diff between sequences of strings.
1229          *
1230          * @param $from_lines array An array of strings.
1231          *                (Typically these are lines from a file.)
1232          * @param $to_lines array An array of strings.
1233          */
1234         function Diff($from_lines, $to_lines) {
1235                 $eng = new _DiffEngine;
1236                 $this->edits = $eng->diff($from_lines, $to_lines);
1237                 //$this->_check($from_lines, $to_lines);
1238         }
1239
1240         /**
1241          * Compute reversed Diff.
1242          *
1243          * SYNOPSIS:
1244          *
1245          *      $diff = new Diff($lines1, $lines2);
1246          *      $rev = $diff->reverse();
1247          * @return object A Diff object representing the inverse of the
1248          *                                original diff.
1249          */
1250         function reverse () {
1251                 $rev = $this;
1252                 $rev->edits = array();
1253                 foreach ($this->edits as $edit) {
1254                         $rev->edits[] = $edit->reverse();
1255                 }
1256                 return $rev;
1257         }
1258
1259         /**
1260          * Check for empty diff.
1261          *
1262          * @return bool True iff two sequences were identical.
1263          */
1264         function isEmpty () {
1265                 foreach ($this->edits as $edit) {
1266                         if ($edit->type != 'copy')
1267                                 return false;
1268                 }
1269                 return true;
1270         }
1271
1272         /**
1273          * Compute the length of the Longest Common Subsequence (LCS).
1274          *
1275          * This is mostly for diagnostic purposed.
1276          *
1277          * @return int The length of the LCS.
1278          */
1279         function lcs () {
1280                 $lcs = 0;
1281                 foreach ($this->edits as $edit) {
1282                         if ($edit->type == 'copy')
1283                                 $lcs += sizeof($edit->orig);
1284                 }
1285                 return $lcs;
1286         }
1287
1288         /**
1289          * Get the original set of lines.
1290          *
1291          * This reconstructs the $from_lines parameter passed to the
1292          * constructor.
1293          *
1294          * @return array The original sequence of strings.
1295          */
1296         function orig() {
1297                 $lines = array();
1298
1299                 foreach ($this->edits as $edit) {
1300                         if ($edit->orig)
1301                                 array_splice($lines, sizeof($lines), 0, $edit->orig);
1302                 }
1303                 return $lines;
1304         }
1305
1306         /**
1307          * Get the closing set of lines.
1308          *
1309          * This reconstructs the $to_lines parameter passed to the
1310          * constructor.
1311          *
1312          * @return array The sequence of strings.
1313          */
1314         function closing() {
1315                 $lines = array();
1316
1317                 foreach ($this->edits as $edit) {
1318                         if ($edit->closing)
1319                                 array_splice($lines, sizeof($lines), 0, $edit->closing);
1320                 }
1321                 return $lines;
1322         }
1323
1324         /**
1325          * Check a Diff for validity.
1326          *
1327          * This is here only for debugging purposes.
1328          */
1329         function _check ($from_lines, $to_lines) {
1330                 $fname = 'Diff::_check';
1331                 wfProfileIn( $fname );
1332                 if (serialize($from_lines) != serialize($this->orig()))
1333                         trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1334                 if (serialize($to_lines) != serialize($this->closing()))
1335                         trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1336
1337                 $rev = $this->reverse();
1338                 if (serialize($to_lines) != serialize($rev->orig()))
1339                         trigger_error("Reversed original doesn't match", E_USER_ERROR);
1340                 if (serialize($from_lines) != serialize($rev->closing()))
1341                         trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1342
1343
1344                 $prevtype = 'none';
1345                 foreach ($this->edits as $edit) {
1346                         if ( $prevtype == $edit->type )
1347                                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1348                         $prevtype = $edit->type;
1349                 }
1350
1351                 $lcs = $this->lcs();
1352                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1353                 wfProfileOut( $fname );
1354         }
1355 }
1356
1357 /**
1358  * @todo document, bad name.
1359  * @private
1360  * @addtogroup DifferenceEngine
1361  */
1362 class MappedDiff extends Diff
1363 {
1364         /**
1365          * Constructor.
1366          *
1367          * Computes diff between sequences of strings.
1368          *
1369          * This can be used to compute things like
1370          * case-insensitve diffs, or diffs which ignore
1371          * changes in white-space.
1372          *
1373          * @param $from_lines array An array of strings.
1374          *      (Typically these are lines from a file.)
1375          *
1376          * @param $to_lines array An array of strings.
1377          *
1378          * @param $mapped_from_lines array This array should
1379          *      have the same size number of elements as $from_lines.
1380          *      The elements in $mapped_from_lines and
1381          *      $mapped_to_lines are what is actually compared
1382          *      when computing the diff.
1383          *
1384          * @param $mapped_to_lines array This array should
1385          *      have the same number of elements as $to_lines.
1386          */
1387         function MappedDiff($from_lines, $to_lines,
1388                                                 $mapped_from_lines, $mapped_to_lines) {
1389                 $fname = 'MappedDiff::MappedDiff';
1390                 wfProfileIn( $fname );
1391
1392                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1393                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1394
1395                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1396
1397                 $xi = $yi = 0;
1398                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1399                         $orig = &$this->edits[$i]->orig;
1400                         if (is_array($orig)) {
1401                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1402                                 $xi += sizeof($orig);
1403                         }
1404
1405                         $closing = &$this->edits[$i]->closing;
1406                         if (is_array($closing)) {
1407                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1408                                 $yi += sizeof($closing);
1409                         }
1410                 }
1411                 wfProfileOut( $fname );
1412         }
1413 }
1414
1415 /**
1416  * A class to format Diffs
1417  *
1418  * This class formats the diff in classic diff format.
1419  * It is intended that this class be customized via inheritance,
1420  * to obtain fancier outputs.
1421  * @todo document
1422  * @private
1423  * @addtogroup DifferenceEngine
1424  */
1425 class DiffFormatter
1426 {
1427         /**
1428          * Number of leading context "lines" to preserve.
1429          *
1430          * This should be left at zero for this class, but subclasses
1431          * may want to set this to other values.
1432          */
1433         var $leading_context_lines = 0;
1434
1435         /**
1436          * Number of trailing context "lines" to preserve.
1437          *
1438          * This should be left at zero for this class, but subclasses
1439          * may want to set this to other values.
1440          */
1441         var $trailing_context_lines = 0;
1442
1443         /**
1444          * Format a diff.
1445          *
1446          * @param $diff object A Diff object.
1447          * @return string The formatted output.
1448          */
1449         function format($diff) {
1450                 $fname = 'DiffFormatter::format';
1451                 wfProfileIn( $fname );
1452
1453                 $xi = $yi = 1;
1454                 $block = false;
1455                 $context = array();
1456
1457                 $nlead = $this->leading_context_lines;
1458                 $ntrail = $this->trailing_context_lines;
1459
1460                 $this->_start_diff();
1461
1462                 foreach ($diff->edits as $edit) {
1463                         if ($edit->type == 'copy') {
1464                                 if (is_array($block)) {
1465                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1466                                                 $block[] = $edit;
1467                                         }
1468                                         else{
1469                                                 if ($ntrail) {
1470                                                         $context = array_slice($edit->orig, 0, $ntrail);
1471                                                         $block[] = new _DiffOp_Copy($context);
1472                                                 }
1473                                                 $this->_block($x0, $ntrail + $xi - $x0,
1474                                                                           $y0, $ntrail + $yi - $y0,
1475                                                                           $block);
1476                                                 $block = false;
1477                                         }
1478                                 }
1479                                 $context = $edit->orig;
1480                         }
1481                         else {
1482                                 if (! is_array($block)) {
1483                                         $context = array_slice($context, sizeof($context) - $nlead);
1484                                         $x0 = $xi - sizeof($context);
1485                                         $y0 = $yi - sizeof($context);
1486                                         $block = array();
1487                                         if ($context)
1488                                                 $block[] = new _DiffOp_Copy($context);
1489                                 }
1490                                 $block[] = $edit;
1491                         }
1492
1493                         if ($edit->orig)
1494                                 $xi += sizeof($edit->orig);
1495                         if ($edit->closing)
1496                                 $yi += sizeof($edit->closing);
1497                 }
1498
1499                 if (is_array($block))
1500                         $this->_block($x0, $xi - $x0,
1501                                                   $y0, $yi - $y0,
1502                                                   $block);
1503
1504                 $end = $this->_end_diff();
1505                 wfProfileOut( $fname );
1506                 return $end;
1507         }
1508
1509         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1510                 $fname = 'DiffFormatter::_block';
1511                 wfProfileIn( $fname );
1512                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1513                 foreach ($edits as $edit) {
1514                         if ($edit->type == 'copy')
1515                                 $this->_context($edit->orig);
1516                         elseif ($edit->type == 'add')
1517                                 $this->_added($edit->closing);
1518                         elseif ($edit->type == 'delete')
1519                                 $this->_deleted($edit->orig);
1520                         elseif ($edit->type == 'change')
1521                                 $this->_changed($edit->orig, $edit->closing);
1522                         else
1523                                 trigger_error('Unknown edit type', E_USER_ERROR);
1524                 }
1525                 $this->_end_block();
1526                 wfProfileOut( $fname );
1527         }
1528
1529         function _start_diff() {
1530                 ob_start();
1531         }
1532
1533         function _end_diff() {
1534                 $val = ob_get_contents();
1535                 ob_end_clean();
1536                 return $val;
1537         }
1538
1539         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1540                 if ($xlen > 1)
1541                         $xbeg .= "," . ($xbeg + $xlen - 1);
1542                 if ($ylen > 1)
1543                         $ybeg .= "," . ($ybeg + $ylen - 1);
1544
1545                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1546         }
1547
1548         function _start_block($header) {
1549                 echo $header;
1550         }
1551
1552         function _end_block() {
1553         }
1554
1555         function _lines($lines, $prefix = ' ') {
1556                 foreach ($lines as $line)
1557                         echo "$prefix $line\n";
1558         }
1559
1560         function _context($lines) {
1561                 $this->_lines($lines);
1562         }
1563
1564         function _added($lines) {
1565                 $this->_lines($lines, '>');
1566         }
1567         function _deleted($lines) {
1568                 $this->_lines($lines, '<');
1569         }
1570
1571         function _changed($orig, $closing) {
1572                 $this->_deleted($orig);
1573                 echo "---\n";
1574                 $this->_added($closing);
1575         }
1576 }
1577
1578
1579 /**
1580  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1581  *
1582  */
1583
1584 define('NBSP', '&#160;');                       // iso-8859-x non-breaking space.
1585
1586 /**
1587  * @todo document
1588  * @private
1589  * @addtogroup DifferenceEngine
1590  */
1591 class _HWLDF_WordAccumulator {
1592         function _HWLDF_WordAccumulator () {
1593                 $this->_lines = array();
1594                 $this->_line = '';
1595                 $this->_group = '';
1596                 $this->_tag = '';
1597         }
1598
1599         function _flushGroup ($new_tag) {
1600                 if ($this->_group !== '') {
1601                         if ($this->_tag == 'ins')
1602                                 $this->_line .= '<ins class="diffchange">' .
1603                                         htmlspecialchars ( $this->_group ) . '</ins>';
1604                         elseif ($this->_tag == 'del')
1605                                 $this->_line .= '<del class="diffchange">' .
1606                                         htmlspecialchars ( $this->_group ) . '</del>';
1607                         else
1608                                 $this->_line .= htmlspecialchars ( $this->_group );
1609                 }
1610                 $this->_group = '';
1611                 $this->_tag = $new_tag;
1612         }
1613
1614         function _flushLine ($new_tag) {
1615                 $this->_flushGroup($new_tag);
1616                 if ($this->_line != '')
1617                         array_push ( $this->_lines, $this->_line );
1618                 else
1619                         # make empty lines visible by inserting an NBSP
1620                         array_push ( $this->_lines, NBSP );
1621                 $this->_line = '';
1622         }
1623
1624         function addWords ($words, $tag = '') {
1625                 if ($tag != $this->_tag)
1626                         $this->_flushGroup($tag);
1627
1628                 foreach ($words as $word) {
1629                         // new-line should only come as first char of word.
1630                         if ($word == '')
1631                                 continue;
1632                         if ($word[0] == "\n") {
1633                                 $this->_flushLine($tag);
1634                                 $word = substr($word, 1);
1635                         }
1636                         assert(!strstr($word, "\n"));
1637                         $this->_group .= $word;
1638                 }
1639         }
1640
1641         function getLines() {
1642                 $this->_flushLine('~done');
1643                 return $this->_lines;
1644         }
1645 }
1646
1647 /**
1648  * @todo document
1649  * @private
1650  * @addtogroup DifferenceEngine
1651  */
1652 class WordLevelDiff extends MappedDiff
1653 {
1654         const MAX_LINE_LENGTH = 10000;
1655
1656         function WordLevelDiff ($orig_lines, $closing_lines) {
1657                 $fname = 'WordLevelDiff::WordLevelDiff';
1658                 wfProfileIn( $fname );
1659
1660                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1661                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1662
1663                 $this->MappedDiff($orig_words, $closing_words,
1664                                                   $orig_stripped, $closing_stripped);
1665                 wfProfileOut( $fname );
1666         }
1667
1668         function _split($lines) {
1669                 $fname = 'WordLevelDiff::_split';
1670                 wfProfileIn( $fname );
1671
1672                 $words = array();
1673                 $stripped = array();
1674                 $first = true;
1675                 foreach ( $lines as $line ) {
1676                         # If the line is too long, just pretend the entire line is one big word
1677                         # This prevents resource exhaustion problems
1678                         if ( $first ) {
1679                                 $first = false;
1680                         } else {
1681                                 $words[] = "\n";
1682                                 $stripped[] = "\n";
1683                         }
1684                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
1685                                 $words[] = $line;
1686                                 $stripped[] = $line;
1687                         } else {
1688                                 $m = array();
1689                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1690                                         $line, $m))
1691                                 {
1692                                         $words = array_merge( $words, $m[0] );
1693                                         $stripped = array_merge( $stripped, $m[1] );
1694                                 }
1695                         }
1696                 }
1697                 wfProfileOut( $fname );
1698                 return array($words, $stripped);
1699         }
1700
1701         function orig () {
1702                 $fname = 'WordLevelDiff::orig';
1703                 wfProfileIn( $fname );
1704                 $orig = new _HWLDF_WordAccumulator;
1705
1706                 foreach ($this->edits as $edit) {
1707                         if ($edit->type == 'copy')
1708                                 $orig->addWords($edit->orig);
1709                         elseif ($edit->orig)
1710                                 $orig->addWords($edit->orig, 'del');
1711                 }
1712                 $lines = $orig->getLines();
1713                 wfProfileOut( $fname );
1714                 return $lines;
1715         }
1716
1717         function closing () {
1718                 $fname = 'WordLevelDiff::closing';
1719                 wfProfileIn( $fname );
1720                 $closing = new _HWLDF_WordAccumulator;
1721
1722                 foreach ($this->edits as $edit) {
1723                         if ($edit->type == 'copy')
1724                                 $closing->addWords($edit->closing);
1725                         elseif ($edit->closing)
1726                                 $closing->addWords($edit->closing, 'ins');
1727                 }
1728                 $lines = $closing->getLines();
1729                 wfProfileOut( $fname );
1730                 return $lines;
1731         }
1732 }
1733
1734 /**
1735  *      Wikipedia Table style diff formatter.
1736  * @todo document
1737  * @private
1738  * @addtogroup DifferenceEngine
1739  */
1740 class TableDiffFormatter extends DiffFormatter
1741 {
1742         function TableDiffFormatter() {
1743                 $this->leading_context_lines = 2;
1744                 $this->trailing_context_lines = 2;
1745         }
1746
1747         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1748                 $r = '<tr><td colspan="2" class="diff-lineno"><!--LINE '.$xbeg."--></td>\n" .
1749                   '<td colspan="2" class="diff-lineno"><!--LINE '.$ybeg."--></td></tr>\n";
1750                 return $r;
1751         }
1752
1753         function _start_block( $header ) {
1754                 echo $header;
1755         }
1756
1757         function _end_block() {
1758         }
1759
1760         function _lines( $lines, $prefix=' ', $color='white' ) {
1761         }
1762
1763         # HTML-escape parameter before calling this
1764         function addedLine( $line ) {
1765                 return $this->wrapLine( '+', 'diff-addedline', $line );
1766         }
1767
1768         # HTML-escape parameter before calling this
1769         function deletedLine( $line ) {
1770                 return $this->wrapLine( '-', 'diff-deletedline', $line );
1771         }
1772
1773         # HTML-escape parameter before calling this
1774         function contextLine( $line ) {
1775                 return $this->wrapLine( ' ', 'diff-context', $line );
1776         }
1777
1778         private function wrapLine( $marker, $class, $line ) {
1779                 if( $line !== '' ) {
1780                         // The <div> wrapper is needed for 'overflow: auto' style to scroll properly
1781                         $line = "<div>$line</div>";
1782                 }
1783                 return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
1784         }
1785
1786         function emptyLine() {
1787                 return '<td colspan="2">&nbsp;</td>';
1788         }
1789
1790         function _added( $lines ) {
1791                 foreach ($lines as $line) {
1792                         echo '<tr>' . $this->emptyLine() .
1793                                 $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1794                 }
1795         }
1796
1797         function _deleted($lines) {
1798                 foreach ($lines as $line) {
1799                         echo '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
1800                           $this->emptyLine() . "</tr>\n";
1801                 }
1802         }
1803
1804         function _context( $lines ) {
1805                 foreach ($lines as $line) {
1806                         echo '<tr>' .
1807                                 $this->contextLine( htmlspecialchars ( $line ) ) .
1808                                 $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1809                 }
1810         }
1811
1812         function _changed( $orig, $closing ) {
1813                 $fname = 'TableDiffFormatter::_changed';
1814                 wfProfileIn( $fname );
1815
1816                 $diff = new WordLevelDiff( $orig, $closing );
1817                 $del = $diff->orig();
1818                 $add = $diff->closing();
1819
1820                 # Notice that WordLevelDiff returns HTML-escaped output.
1821                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
1822
1823                 while ( $line = array_shift( $del ) ) {
1824                         $aline = array_shift( $add );
1825                         echo '<tr>' . $this->deletedLine( $line ) .
1826                                 $this->addedLine( $aline ) . "</tr>\n";
1827                 }
1828                 foreach ($add as $line) {       # If any leftovers
1829                         echo '<tr>' . $this->emptyLine() .
1830                                 $this->addedLine( $line ) . "</tr>\n";
1831                 }
1832                 wfProfileOut( $fname );
1833         }
1834 }
1835
1836