includes/DifferenceEngine.php

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