includes/diff/DifferenceEngine.php

   1 <?php
   2 /**
   3  * @defgroup DifferenceEngine DifferenceEngine
   4  */
   5
   6 /**
   7  * Constant to indicate diff cache compatibility.
   8  * Bump this when changing the diff formatting in a way that
   9  * fixes important bugs or such to force cached diff views to
  10  * clear.
  11  */
  12 define( 'MW_DIFF_VERSION', '1.11a' );
  13
  14 /**
  15  * @todo document
  16  * @ingroup DifferenceEngine
  17  */
  18 class DifferenceEngine {
  19         /**#@+
  20          * @private
  21          */
  22         var $mOldid, $mNewid, $mTitle;
  23         var $mOldtitle, $mNewtitle, $mPagetitle;
  24         var $mOldtext, $mNewtext;
  25         var $mOldPage, $mNewPage;
  26         var $mRcidMarkPatrolled;
  27         var $mOldRev, $mNewRev;
  28         var $mRevisionsLoaded = false; // Have the revisions been loaded
  29         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  30         var $mCacheHit = false; // Was the diff fetched from cache?
  31         var $htmldiff;
  32
  33         /**
  34          * Set this to true to add debug info to the HTML output.
  35          * Warning: this may cause RSS readers to spuriously mark articles as "new"
  36          * (bug 20601)
  37          */
  38         var $enableDebugComment = false;
  39
  40         // If true, line X is not displayed when X is 1, for example to increase
  41         // readability and conserve space with many small diffs.
  42         protected $mReducedLineNumbers = false;
  43
  44         protected $unhide = false;
  45         /**#@-*/
  46
  47         /**
  48          * Constructor
  49          * @param $titleObj Title object that the diff is associated with
  50          * @param $old Integer: old ID we want to show and diff with.
  51          * @param $new String: either 'prev' or 'next'.
  52          * @param $rcid Integer: ??? FIXME (default 0)
  53          * @param $refreshCache boolean If set, refreshes the diff cache
  54          * @param $htmldiff boolean If set, output using HTMLDiff instead of raw wikicode diff
  55          * @param $unhide boolean If set, allow viewing deleted revs
  56          */
  57         function __construct( $titleObj = null, $old = 0, $new = 0, $rcid = 0,
  58                 $refreshCache = false, $htmldiff = false, $unhide = false )
  59         {
  60                 if ( $titleObj ) {
  61                         $this->mTitle = $titleObj;
  62                 } else {
  63                         global $wgTitle;
  64                         $this->mTitle = $wgTitle;
  65                 }
  66                 wfDebug("DifferenceEngine old '$old' new '$new' rcid '$rcid'\n");
  67
  68                 if ( 'prev' === $new ) {
  69                         # Show diff between revision $old and the previous one.
  70                         # Get previous one from DB.
  71                         $this->mNewid = intval($old);
  72                         $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
  73                 } elseif ( 'next' === $new ) {
  74                         # Show diff between revision $old and the next one.
  75                         # Get next one from DB.
  76                         $this->mOldid = intval($old);
  77                         $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
  78                         if ( false === $this->mNewid ) {
  79                                 # if no result, NewId points to the newest old revision. The only newer
  80                                 # revision is cur, which is "0".
  81                                 $this->mNewid = 0;
  82                         }
  83                 } else {
  84                         $this->mOldid = intval($old);
  85                         $this->mNewid = intval($new);
  86                         wfRunHooks( 'NewDifferenceEngine', array(&$titleObj, &$this->mOldid, &$this->mNewid, $old, $new) );
  87                 }
  88                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  89                 $this->mRefreshCache = $refreshCache;
  90                 $this->htmldiff = $htmldiff;
  91                 $this->unhide = $unhide;
  92         }
  93
  94         function setReducedLineNumbers( $value = true ) {
  95                 $this->mReducedLineNumbers = $value;
  96         }
  97
  98         function getTitle() {
  99                 return $this->mTitle;
 100         }
 101
 102         function wasCacheHit() {
 103                 return $this->mCacheHit;
 104         }
 105
 106         function getOldid() {
 107                 return $this->mOldid;
 108         }
 109
 110         function getNewid() {
 111                 return $this->mNewid;
 112         }
 113
 114         function showDiffPage( $diffOnly = false ) {
 115                 global $wgUser, $wgOut, $wgUseExternalEditor, $wgUseRCPatrol, $wgEnableHtmlDiff;
 116                 wfProfileIn( __METHOD__ );
 117
 118
 119                 # If external diffs are enabled both globally and for the user,
 120                 # we'll use the application/x-external-editor interface to call
 121                 # an external diff tool like kompare, kdiff3, etc.
 122                 if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
 123                         global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
 124                         $wgOut->disable();
 125                         header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
 126                         $url1=$this->mTitle->getFullURL( array(
 127                                 'action' => 'raw',
 128                                 'oldid' => $this->mOldid
 129                         ) );
 130                         $url2=$this->mTitle->getFullURL( array(
 131                                 'action' => 'raw',
 132                                 'oldid' => $this->mNewid
 133                         ) );
 134                         $special=$wgLang->getNsText(NS_SPECIAL);
 135                         $control=<<<CONTROL
 136                         [Process]
 137                         Type=Diff text
 138                         Engine=MediaWiki
 139                         Script={$wgServer}{$wgScript}
 140                         Special namespace={$special}
 141
 142                         [File]
 143                         Extension=wiki
 144                         URL=$url1
 145
 146                         [File 2]
 147                         Extension=wiki
 148                         URL=$url2
 149 CONTROL;
 150                         echo($control);
 151                         return;
 152                 }
 153
 154                 $wgOut->setArticleFlag( false );
 155                 if ( !$this->loadRevisionData() ) {
 156                         $t = $this->mTitle->getPrefixedText();
 157                         $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
 158                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 159                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
 160                         wfProfileOut( __METHOD__ );
 161                         return;
 162                 }
 163
 164                 wfRunHooks( 'DiffViewHeader', array( $this, $this->mOldRev, $this->mNewRev ) );
 165
 166                 if ( $this->mNewRev->isCurrent() ) {
 167                         $wgOut->setArticleFlag( true );
 168                 }
 169
 170                 # mOldid is false if the difference engine is called with a "vague" query for
 171                 # a diff between a version V and its previous version V' AND the version V
 172                 # is the first version of that article. In that case, V' does not exist.
 173                 if ( $this->mOldid === false ) {
 174                         $this->showFirstRevision();
 175                         $this->renderNewRevision();  // should we respect $diffOnly here or not?
 176                         wfProfileOut( __METHOD__ );
 177                         return;
 178                 }
 179
 180                 $wgOut->suppressQuickbar();
 181
 182                 $oldTitle = $this->mOldPage->getPrefixedText();
 183                 $newTitle = $this->mNewPage->getPrefixedText();
 184                 if( $oldTitle == $newTitle ) {
 185                         $wgOut->setPageTitle( $newTitle );
 186                 } else {
 187                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 188                 }
 189                 $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
 190                 $wgOut->setRobotPolicy( 'noindex,nofollow' );
 191
 192                 if ( !$this->mOldPage->userCanRead() || !$this->mNewPage->userCanRead() ) {
 193                         $wgOut->loginToUse();
 194                         $wgOut->output();
 195                         $wgOut->disable();
 196                         wfProfileOut( __METHOD__ );
 197                         return;
 198                 }
 199
 200                 $sk = $wgUser->getSkin();
 201
 202                 // Check if page is editable
 203                 $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
 204                 if ( $editable && $this->mNewRev->isCurrent() && $wgUser->isAllowed( 'rollback' ) ) {
 205                         $rollback = '&nbsp;&nbsp;&nbsp;' . $sk->generateRollback( $this->mNewRev );
 206                 } else {
 207                         $rollback = '';
 208                 }
 209
 210                 // Prepare a change patrol link, if applicable
 211                 if( $wgUseRCPatrol && $this->mTitle->userCan('patrol') ) {
 212                         // If we've been given an explicit change identifier, use it; saves time
 213                         if( $this->mRcidMarkPatrolled ) {
 214                                 $rcid = $this->mRcidMarkPatrolled;
 215                                 $rc = RecentChange::newFromId( $rcid );
 216                                 // Already patrolled?
 217                                 $rcid = is_object($rc) && !$rc->getAttribute('rc_patrolled') ? $rcid : 0;
 218                         } else {
 219                                 // Look for an unpatrolled change corresponding to this diff
 220                                 $db = wfGetDB( DB_SLAVE );
 221                                 $change = RecentChange::newFromConds(
 222                                         array(
 223                                         // Redundant user,timestamp condition so we can use the existing index
 224                                                 'rc_user_text'  => $this->mNewRev->getRawUserText(),
 225                                                 'rc_timestamp'  => $db->timestamp( $this->mNewRev->getTimestamp() ),
 226                                                 'rc_this_oldid' => $this->mNewid,
 227                                                 'rc_last_oldid' => $this->mOldid,
 228                                                 'rc_patrolled'  => 0
 229                                         ),
 230                                         __METHOD__
 231                                 );
 232                                 if( $change instanceof RecentChange ) {
 233                                         $rcid = $change->mAttribs['rc_id'];
 234                                         $this->mRcidMarkPatrolled = $rcid;
 235                                 } else {
 236                                         // None found
 237                                         $rcid = 0;
 238                                 }
 239                         }
 240                         // Build the link
 241                         if( $rcid ) {
 242                                 $patrol = ' <span class="patrollink">[' . $sk->link(
 243                                         $this->mTitle,
 244                                         wfMsgHtml( 'markaspatrolleddiff' ),
 245                                         array(),
 246                                         array(
 247                                                 'action' => 'markpatrolled',
 248                                                 'rcid' => $rcid
 249                                         ),
 250                                         array(
 251                                                 'known',
 252                                                 'noclasses'
 253                                         )
 254                                 ) . ']</span>';
 255                         } else {
 256                                 $patrol = '';
 257                         }
 258                 } else {
 259                         $patrol = '';
 260                 }
 261
 262                 # Carry over 'diffonly' param via navigation links
 263                 if( $diffOnly != $wgUser->getBoolOption('diffonly') ) {
 264                         $query['diffonly'] = $diffOnly;
 265                 }
 266
 267                 $htmldiffarg = $this->htmlDiffArgument();
 268
 269                 if( $htmldiffarg ) {
 270                         $query['htmldiff'] = $htmldiffarg['htmldiff'];
 271                 }
 272
 273                 # Make "previous revision link"
 274                 $query['diff'] = 'prev';
 275                 $query['oldid'] = $this->mOldid;
 276
 277                 $prevlink = $sk->link(
 278                         $this->mTitle,
 279                         wfMsgHtml( 'previousdiff' ),
 280                         array(
 281                                 'id' => 'differences-prevlink'
 282                         ),
 283                         $query,
 284                         array(
 285                                 'known',
 286                                 'noclasses'
 287                         )
 288                 );
 289                 # Make "next revision link"
 290                 $query['diff'] = 'next';
 291                 $query['oldid'] = $this->mNewid;
 292
 293                 if( $this->mNewRev->isCurrent() ) {
 294                         $nextlink = '&nbsp;';
 295                 } else {
 296                         $nextlink = $sk->link(
 297                                 $this->mTitle,
 298                                 wfMsgHtml( 'nextdiff' ),
 299                                 array(
 300                                         'id' => 'differences-nextlink'
 301                                 ),
 302                                 $query,
 303                                 array(
 304                                         'known',
 305                                         'noclasses'
 306                                 )
 307                         );
 308                 }
 309
 310                 $oldminor = '';
 311                 $newminor = '';
 312
 313                 if( $this->mOldRev->isMinor() ) {
 314                         $oldminor = ChangesList::flag( 'minor' );
 315                 }
 316                 if( $this->mNewRev->isMinor() ) {
 317                         $newminor = ChangesList::flag( 'minor' );
 318                 }
 319
 320                 $rdel = ''; $ldel = '';
 321                 if( $wgUser->isAllowed( 'deleterevision' ) ) {
 322                         if( !$this->mOldRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 323                                 // If revision was hidden from sysops
 324                                 $ldel = Xml::tags( 'span', array( 'class' => 'mw-revdelundel-link' ), '(' . wfMsgHtml( 'rev-delundel' ) . ')' );
 325                         } else {
 326                                 $query = array(
 327                                         'type' => 'revision',
 328                                         'target' => $this->mOldRev->mTitle->getPrefixedDbkey(),
 329                                         'ids' => $this->mOldRev->getId()
 330                                 );
 331                                 $ldel = $sk->revDeleteLink( $query, $this->mOldRev->isDeleted( Revision::DELETED_RESTRICTED ) );
 332                         }
 333                         $ldel = "&nbsp;&nbsp;&nbsp;$ldel ";
 334                         if( !$this->mNewRev->userCan( Revision::DELETED_RESTRICTED ) ) {
 335                                 // If revision was hidden from sysops
 336                                 $rdel = Xml::tags( 'span', array( 'class'=>'mw-revdelundel-link' ), '('.wfMsgHtml( 'rev-delundel' ).')' );
 337                         } else {
 338                                 $query = array(
 339                                         'type' => 'revision',
 340                                         'target' =>  $this->mNewRev->mTitle->getPrefixedDbkey(),
 341                                         'ids' => $this->mNewRev->getId()
 342                                 );
 343                                 $rdel = $sk->revDeleteLink( $query, $this->mNewRev->isDeleted( Revision::DELETED_RESTRICTED ) );
 344                         }
 345                         $rdel = "&nbsp;&nbsp;&nbsp;$rdel ";
 346                 }
 347
 348                 $oldHeader = '<div id="mw-diff-otitle1"><strong>'.$this->mOldtitle.'</strong></div>' .
 349                         '<div id="mw-diff-otitle2">' . $sk->revUserTools( $this->mOldRev, !$this->unhide ) . "</div>" .
 350                         '<div id="mw-diff-otitle3">' . $oldminor . $sk->revComment( $this->mOldRev, !$diffOnly, !$this->unhide ).$ldel."</div>" .
 351                         '<div id="mw-diff-otitle4">' . $prevlink .'</div>';
 352                 $newHeader = '<div id="mw-diff-ntitle1"><strong>'.$this->mNewtitle.'</strong></div>' .
 353                         '<div id="mw-diff-ntitle2">' . $sk->revUserTools( $this->mNewRev, !$this->unhide ) . " $rollback</div>" .
 354                         '<div id="mw-diff-ntitle3">' . $newminor . $sk->revComment( $this->mNewRev, !$diffOnly, !$this->unhide ).$rdel."</div>" .
 355                         '<div id="mw-diff-ntitle4">' . $nextlink . $patrol . '</div>';
 356
 357                 # Check if this user can see the revisions
 358                 $allowed = $this->mOldRev->userCan(Revision::DELETED_TEXT)
 359                         && $this->mNewRev->userCan(Revision::DELETED_TEXT);
 360                 $deleted = $this->mOldRev->isDeleted(Revision::DELETED_TEXT)
 361                         || $this->mNewRev->isDeleted(Revision::DELETED_TEXT);
 362                 # Output the diff if allowed...
 363                 if( $deleted && (!$this->unhide || !$allowed) ) {
 364                         $this->showDiffStyle();
 365                         $multi = $this->getMultiNotice();
 366                         $wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 367                         if( !$allowed ) {
 368                                 # Give explanation for why revision is not visible
 369                                 $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
 370                                         array( 'rev-deleted-no-diff' ) );
 371                         } else {
 372                                 # Give explanation and add a link to view the diff...
 373                                 $link = $this->mTitle->getFullUrl( array(
 374                                         'diff' => $this->mNewid,
 375                                         'oldid' => $this->mOldid,
 376                                         'unhide' => 1
 377                                 ) );
 378                                 $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n",
 379                                         array( 'rev-deleted-unhide-diff', $link ) );
 380                         }
 381                 } else if( $wgEnableHtmlDiff && $this->htmldiff ) {
 382                         $multi = $this->getMultiNotice();
 383                         $wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
 384                                 $this->mTitle,
 385                                 wfMsgHtml( 'wikicodecomparison' ),
 386                                 array(
 387                                         'id' => 'differences-switchtype'
 388                                 ),
 389                                 array(
 390                                         'diff' => $this->mNewid,
 391                                         'oldid' => $this->mOldid,
 392                                         'htmldiff' => 0
 393                                 ),
 394                                 array(
 395                                         'known',
 396                                         'noclasses'
 397                                 )
 398                         ) . '</div>');
 399                         $wgOut->addHTML( $this->addHeader( '', $oldHeader, $newHeader, $multi ) );
 400                         $this->renderHtmlDiff();
 401                 } else {
 402                         if( $wgEnableHtmlDiff ) {
 403                                 $wgOut->addHTML( '<div class="diff-switchtype">' . $sk->link(
 404                                         $this->mTitle,
 405                                         wfMsgHtml( 'visualcomparison' ),
 406                                         array(
 407                                                 'id' => 'differences-switchtype'
 408                                         ),
 409                                         array(
 410                                                 'diff' => $this->mNewid,
 411                                                 'oldid' => $this->mOldid,
 412                                                 'htmldiff' => 1
 413                                         ),
 414                                         array(
 415                                                 'known',
 416                                                 'noclasses'
 417                                         )
 418                                 ) . '</div>');
 419                         }
 420                         $this->showDiff( $oldHeader, $newHeader );
 421                         if( !$diffOnly ) {
 422                                 $this->renderNewRevision();
 423                         }
 424                 }
 425                 wfProfileOut( __METHOD__ );
 426         }
 427
 428         /**
 429          * Show the new revision of the page.
 430          */
 431         function renderNewRevision() {
 432                 global $wgOut, $wgUser;
 433                 wfProfileIn( __METHOD__ );
 434
 435                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 436                 # Add deleted rev tag if needed
 437                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 438                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
 439                 } else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 440                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
 441                 }
 442
 443                 if( !$this->mNewRev->isCurrent() ) {
 444                         $oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
 445                 }
 446
 447                 $this->loadNewText();
 448                 if( is_object( $this->mNewRev ) ) {
 449                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 450                 }
 451
 452                 if( $this->mTitle->isCssJsSubpage() || $this->mTitle->isCssOrJsPage() ) {
 453                         // Stolen from Article::view --AG 2007-10-11
 454                         // Give hooks a chance to customise the output
 455                         if( wfRunHooks( 'ShowRawCssJs', array( $this->mNewtext, $this->mTitle, $wgOut ) ) ) {
 456                                 // Wrap the whole lot in a <pre> and don't parse
 457                                 $m = array();
 458                                 preg_match( '!\.(css|js)$!u', $this->mTitle->getText(), $m );
 459                                 $wgOut->addHTML( "<pre class=\"mw-code mw-{$m[1]}\" dir=\"ltr\">\n" );
 460                                 $wgOut->addHTML( htmlspecialchars( $this->mNewtext ) );
 461                                 $wgOut->addHTML( "\n</pre>\n" );
 462                         }
 463                 } else {
 464                         $wgOut->addWikiTextTidy( $this->mNewtext );
 465                 }
 466
 467                 if( is_object( $this->mNewRev ) && !$this->mNewRev->isCurrent() ) {
 468                         $wgOut->parserOptions()->setEditSection( $oldEditSectionSetting );
 469                 }
 470                 # Add redundant patrol link on bottom...
 471                 if( $this->mRcidMarkPatrolled && $this->mTitle->quickUserCan('patrol') ) {
 472                         $sk = $wgUser->getSkin();
 473                         $wgOut->addHTML(
 474                                 "<div class='patrollink'>[" . $sk->link(
 475                                         $this->mTitle,
 476                                         wfMsgHtml( 'markaspatrolleddiff' ),
 477                                         array(),
 478                                         array(
 479                                                 'action' => 'markpatrolled',
 480                                                 'rcid' => $this->mRcidMarkPatrolled
 481                                         )
 482                                 ) . ']</div>'
 483                          );
 484                 }
 485
 486                 wfProfileOut( __METHOD__ );
 487         }
 488
 489
 490         function renderHtmlDiff() {
 491                 global $wgOut, $wgParser, $wgDebugComments;
 492                 wfProfileIn( __METHOD__ );
 493
 494                 $this->showDiffStyle();
 495
 496                 $wgOut->addHTML( '<h2>'.wfMsgHtml( 'visual-comparison' )."</h2>\n" );
 497                 #add deleted rev tag if needed
 498                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 499                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-permission' );
 500                 } else if( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
 501                         $wgOut->wrapWikiMsg( "<div class='mw-warning plainlinks'>\n$1</div>\n", 'rev-deleted-text-view' );
 502                 }
 503
 504                 if( !$this->mNewRev->isCurrent() ) {
 505                         $oldEditSectionSetting = $wgOut->parserOptions()->setEditSection( false );
 506                 }
 507
 508                 $this->loadText();
 509
 510                 // Old revision
 511                 if( is_object( $this->mOldRev ) ) {
 512                         $wgOut->setRevisionId( $this->mOldRev->getId() );
 513                 }
 514
 515                 $popts = $wgOut->parserOptions();
 516                 $oldTidy = $popts->setTidy( true );
 517                 $popts->setEditSection( false );
 518
 519                 $parserOutput = $wgParser->parse( $this->mOldtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
 520                 $popts->setTidy( $oldTidy );
 521
 522                 //only for new?
 523                 //$wgOut->addParserOutputNoText( $parserOutput );
 524                 $oldHtml = $parserOutput->getText();
 525                 wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$oldHtml ) );
 526
 527                 // New revision
 528                 if( is_object( $this->mNewRev ) ) {
 529                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 530                 }
 531
 532                 $popts = $wgOut->parserOptions();
 533                 $oldTidy = $popts->setTidy( true );
 534
 535                 $parserOutput = $wgParser->parse( $this->mNewtext, $this->getTitle(), $popts, true, true, $wgOut->getRevisionId() );
 536                 $popts->setTidy( $oldTidy );
 537
 538                 $wgOut->addParserOutputNoText( $parserOutput );
 539                 $newHtml = $parserOutput->getText();
 540                 wfRunHooks( 'OutputPageBeforeHTML', array( &$wgOut, &$newHtml ) );
 541
 542                 unset($parserOutput, $popts);
 543
 544                 $differ = new HTMLDiffer(new DelegatingContentHandler($wgOut));
 545                 $differ->htmlDiff($oldHtml, $newHtml);
 546                 if ( $wgDebugComments ) {
 547                         $wgOut->addHTML( "\n<!-- HtmlDiff Debug Output:\n" . HTMLDiffer::getDebugOutput() . " End Debug -->" );
 548                 }
 549
 550                 wfProfileOut( __METHOD__ );
 551         }
 552
 553         /**
 554          * Show the first revision of an article. Uses normal diff headers in
 555          * contrast to normal "old revision" display style.
 556          */
 557         function showFirstRevision() {
 558                 global $wgOut, $wgUser;
 559                 wfProfileIn( __METHOD__ );
 560
 561                 # Get article text from the DB
 562                 #
 563                 if ( ! $this->loadNewText() ) {
 564                         $t = $this->mTitle->getPrefixedText();
 565                         $d = wfMsgExt( 'missingarticle-diff', array( 'escape' ), $this->mOldid, $this->mNewid );
 566                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 567                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>$t</nowiki>", $d );
 568                         wfProfileOut( __METHOD__ );
 569                         return;
 570                 }
 571                 if ( $this->mNewRev->isCurrent() ) {
 572                         $wgOut->setArticleFlag( true );
 573                 }
 574
 575                 # Check if user is allowed to look at this page. If not, bail out.
 576                 #
 577                 if ( !$this->mTitle->userCanRead() ) {
 578                         $wgOut->loginToUse();
 579                         $wgOut->output();
 580                         wfProfileOut( __METHOD__ );
 581                         throw new MWException("Permission Error: you do not have access to view this page");
 582                 }
 583
 584                 # Prepare the header box
 585                 #
 586                 $sk = $wgUser->getSkin();
 587
 588                 $next = $this->mTitle->getNextRevisionID( $this->mNewid );
 589                 if( !$next ) {
 590                         $nextlink = '';
 591                 } else {
 592                         $nextlink = '<br/>' . $sk->link(
 593                                 $this->mTitle,
 594                                 wfMsgHtml( 'nextdiff' ),
 595                                 array(
 596                                         'id' => 'differences-nextlink'
 597                                 ),
 598                                 array(
 599                                         'diff' => 'next',
 600                                         'oldid' => $this->mNewid,
 601                                         $this->htmlDiffArgument()
 602                                 ),
 603                                 array(
 604                                         'known',
 605                                         'noclasses'
 606                                 )
 607                         );
 608                 }
 609                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\">" .
 610                         $sk->revUserTools( $this->mNewRev ) . "<br/>" . $sk->revComment( $this->mNewRev ) . $nextlink . "</div>\n";
 611
 612                 $wgOut->addHTML( $header );
 613
 614                 $wgOut->setSubtitle( wfMsgExt( 'difference', array( 'parseinline' ) ) );
 615                 $wgOut->setRobotPolicy( 'noindex,nofollow' );
 616
 617                 wfProfileOut( __METHOD__ );
 618         }
 619
 620         function htmlDiffArgument(){
 621                 global $wgEnableHtmlDiff;
 622                 if($wgEnableHtmlDiff){
 623                         if($this->htmldiff){
 624                                 return array( 'htmldiff' => 1 );
 625                         }else{
 626                                 return array( 'htmldiff' => 0 );
 627                         }
 628                 }else{
 629                         return array();
 630                 }
 631         }
 632
 633         /**
 634          * Get the diff text, send it to $wgOut
 635          * Returns false if the diff could not be generated, otherwise returns true
 636          */
 637         function showDiff( $otitle, $ntitle ) {
 638                 global $wgOut;
 639                 $diff = $this->getDiff( $otitle, $ntitle );
 640                 if ( $diff === false ) {
 641                         $wgOut->addWikiMsg( 'missing-article', "<nowiki>(fixme, bug)</nowiki>", '' );
 642                         return false;
 643                 } else {
 644                         $this->showDiffStyle();
 645                         $wgOut->addHTML( $diff );
 646                         return true;
 647                 }
 648         }
 649
 650         /**
 651          * Add style sheets and supporting JS for diff display.
 652          */
 653         function showDiffStyle() {
 654                 global $wgStylePath, $wgStyleVersion, $wgOut;
 655                 $wgOut->addStyle( 'common/diff.css' );
 656
 657                 // JS is needed to detect old versions of Mozilla to work around an annoyance bug.
 658                 $wgOut->addScript( "<script type=\"text/javascript\" src=\"$wgStylePath/common/diff.js?$wgStyleVersion\"></script>" );
 659         }
 660
 661         /**
 662          * Get complete diff table, including header
 663          *
 664          * @param Title $otitle Old title
 665          * @param Title $ntitle New title
 666          * @return mixed
 667          */
 668         function getDiff( $otitle, $ntitle ) {
 669                 $body = $this->getDiffBody();
 670                 if ( $body === false ) {
 671                         return false;
 672                 } else {
 673                         $multi = $this->getMultiNotice();
 674                         return $this->addHeader( $body, $otitle, $ntitle, $multi );
 675                 }
 676         }
 677
 678         /**
 679          * Get the diff table body, without header
 680          *
 681          * @return mixed
 682          */
 683         function getDiffBody() {
 684                 global $wgMemc;
 685                 wfProfileIn( __METHOD__ );
 686                 $this->mCacheHit = true;
 687                 // Check if the diff should be hidden from this user
 688                 if ( !$this->loadRevisionData() )
 689                         return '';
 690                 if ( $this->mOldRev && !$this->mOldRev->userCan(Revision::DELETED_TEXT) ) {
 691                         return '';
 692                 } else if ( $this->mNewRev && !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
 693                         return '';
 694                 } else if ( $this->mOldRev && $this->mNewRev && $this->mOldRev->getID() == $this->mNewRev->getID() ) {
 695                         return '';
 696                 }
 697                 // Cacheable?
 698                 $key = false;
 699                 if ( $this->mOldid && $this->mNewid ) {
 700                         $key = wfMemcKey( 'diff', 'version', MW_DIFF_VERSION, 'oldid', $this->mOldid, 'newid', $this->mNewid );
 701                         // Try cache
 702                         if ( !$this->mRefreshCache ) {
 703                                 $difftext = $wgMemc->get( $key );
 704                                 if ( $difftext ) {
 705                                         wfIncrStats( 'diff_cache_hit' );
 706                                         $difftext = $this->localiseLineNumbers( $difftext );
 707                                         $difftext .= "\n<!-- diff cache key $key -->\n";
 708                                         wfProfileOut( __METHOD__ );
 709                                         return $difftext;
 710                                 }
 711                         } // don't try to load but save the result
 712                 }
 713                 $this->mCacheHit = false;
 714
 715                 // Loadtext is permission safe, this just clears out the diff
 716                 if ( !$this->loadText() ) {
 717                         wfProfileOut( __METHOD__ );
 718                         return false;
 719                 }
 720
 721                 $difftext = $this->generateDiffBody( $this->mOldtext, $this->mNewtext );
 722
 723                 // Save to cache for 7 days
 724                 if ( !wfRunHooks( 'AbortDiffCache', array( &$this ) ) ) {
 725                         wfIncrStats( 'diff_uncacheable' );
 726                 } else if ( $key !== false && $difftext !== false ) {
 727                         wfIncrStats( 'diff_cache_miss' );
 728                         $wgMemc->set( $key, $difftext, 7*86400 );
 729                 } else {
 730                         wfIncrStats( 'diff_uncacheable' );
 731                 }
 732                 // Replace line numbers with the text in the user's language
 733                 if ( $difftext !== false ) {
 734                         $difftext = $this->localiseLineNumbers( $difftext );
 735                 }
 736                 wfProfileOut( __METHOD__ );
 737                 return $difftext;
 738         }
 739
 740         /**
 741          * Make sure the proper modules are loaded before we try to
 742          * make the diff
 743          */
 744         private function initDiffEngines() {
 745                 global $wgExternalDiffEngine;
 746                 if ( $wgExternalDiffEngine == 'wikidiff' && !function_exists( 'wikidiff_do_diff' ) ) {
 747                         wfProfileIn( __METHOD__ . '-php_wikidiff.so' );
 748                         wfSuppressWarnings();
 749                         dl( 'php_wikidiff.so' );
 750                         wfRestoreWarnings();
 751                         wfProfileOut( __METHOD__ . '-php_wikidiff.so' );
 752                 }
 753                 else if ( $wgExternalDiffEngine == 'wikidiff2' && !function_exists( 'wikidiff2_do_diff' ) ) {
 754                         wfProfileIn( __METHOD__ . '-php_wikidiff2.so' );
 755                         wfSuppressWarnings();
 756                         dl( 'php_wikidiff2.so' );
 757                         wfRestoreWarnings();
 758                         wfProfileOut( __METHOD__ . '-php_wikidiff2.so' );
 759                 }
 760         }
 761
 762         /**
 763          * Generate a diff, no caching
 764          * $otext and $ntext must be already segmented
 765          */
 766         function generateDiffBody( $otext, $ntext ) {
 767                 global $wgExternalDiffEngine, $wgContLang;
 768
 769                 $otext = str_replace( "\r\n", "\n", $otext );
 770                 $ntext = str_replace( "\r\n", "\n", $ntext );
 771
 772                 $this->initDiffEngines();
 773
 774                 if ( $wgExternalDiffEngine == 'wikidiff' && function_exists( 'wikidiff_do_diff' ) ) {
 775                         # For historical reasons, external diff engine expects
 776                         # input text to be HTML-escaped already
 777                         $otext = htmlspecialchars ( $wgContLang->segmentForDiff( $otext ) );
 778                         $ntext = htmlspecialchars ( $wgContLang->segmentForDiff( $ntext ) );
 779                         return $wgContLang->unsegementForDiff( wikidiff_do_diff( $otext, $ntext, 2 ) ) .
 780                         $this->debug( 'wikidiff1' );
 781                 }
 782
 783                 if ( $wgExternalDiffEngine == 'wikidiff2' && function_exists( 'wikidiff2_do_diff' ) ) {
 784                         # Better external diff engine, the 2 may some day be dropped
 785                         # This one does the escaping and segmenting itself
 786                         wfProfileIn( 'wikidiff2_do_diff' );
 787                         $text = wikidiff2_do_diff( $otext, $ntext, 2 );
 788                         $text .= $this->debug( 'wikidiff2' );
 789                         wfProfileOut( 'wikidiff2_do_diff' );
 790                         return $text;
 791                 }
 792                 if ( $wgExternalDiffEngine != 'wikidiff3' && $wgExternalDiffEngine !== false ) {
 793                         # Diff via the shell
 794                         global $wgTmpDirectory;
 795                         $tempName1 = tempnam( $wgTmpDirectory, 'diff_' );
 796                         $tempName2 = tempnam( $wgTmpDirectory, 'diff_' );
 797
 798                         $tempFile1 = fopen( $tempName1, "w" );
 799                         if ( !$tempFile1 ) {
 800                                 wfProfileOut( __METHOD__ );
 801                                 return false;
 802                         }
 803                         $tempFile2 = fopen( $tempName2, "w" );
 804                         if ( !$tempFile2 ) {
 805                                 wfProfileOut( __METHOD__ );
 806                                 return false;
 807                         }
 808                         fwrite( $tempFile1, $otext );
 809                         fwrite( $tempFile2, $ntext );
 810                         fclose( $tempFile1 );
 811                         fclose( $tempFile2 );
 812                         $cmd = wfEscapeShellArg( $wgExternalDiffEngine, $tempName1, $tempName2 );
 813                         wfProfileIn( __METHOD__ . "-shellexec" );
 814                         $difftext = wfShellExec( $cmd );
 815                         $difftext .= $this->debug( "external $wgExternalDiffEngine" );
 816                         wfProfileOut( __METHOD__ . "-shellexec" );
 817                         unlink( $tempName1 );
 818                         unlink( $tempName2 );
 819                         return $difftext;
 820                 }
 821
 822                 # Native PHP diff
 823                 $ota = explode( "\n", $wgContLang->segmentForDiff( $otext ) );
 824                 $nta = explode( "\n", $wgContLang->segmentForDiff( $ntext ) );
 825                 $diffs = new Diff( $ota, $nta );
 826                 $formatter = new TableDiffFormatter();
 827                 return $wgContLang->unsegmentForDiff( $formatter->format( $diffs ) ) .
 828                 $this->debug();
 829         }
 830
 831         /**
 832          * Generate a debug comment indicating diff generating time,
 833          * server node, and generator backend.
 834          */
 835         protected function debug( $generator="internal" ) {
 836                 global $wgShowHostnames;
 837                 if ( !$this->enableDebugComment ) {
 838                         return '';
 839                 }
 840                 $data = array( $generator );
 841                 if( $wgShowHostnames ) {
 842                         $data[] = wfHostname();
 843                 }
 844                 $data[] = wfTimestamp( TS_DB );
 845                 return "<!-- diff generator: " .
 846                 implode( " ",
 847                 array_map(
 848                                         "htmlspecialchars",
 849                 $data ) ) .
 850                         " -->\n";
 851         }
 852
 853         /**
 854          * Replace line numbers with the text in the user's language
 855          */
 856         function localiseLineNumbers( $text ) {
 857                 return preg_replace_callback( '/<!--LINE (\d+)-->/',
 858                 array( &$this, 'localiseLineNumbersCb' ), $text );
 859         }
 860
 861         function localiseLineNumbersCb( $matches ) {
 862                 global $wgLang;
 863                 if ( $matches[1] === '1' && $this->mReducedLineNumbers ) return '';
 864                 return wfMsgExt( 'lineno', 'escape', $wgLang->formatNum( $matches[1] ) );
 865         }
 866
 867
 868         /**
 869          * If there are revisions between the ones being compared, return a note saying so.
 870          */
 871         function getMultiNotice() {
 872                 if ( !is_object($this->mOldRev) || !is_object($this->mNewRev) )
 873                 return '';
 874
 875                 if( !$this->mOldPage->equals( $this->mNewPage ) ) {
 876                         // Comparing two different pages? Count would be meaningless.
 877                         return '';
 878                 }
 879
 880                 $oldid = $this->mOldRev->getId();
 881                 $newid = $this->mNewRev->getId();
 882                 if ( $oldid > $newid ) {
 883                         $tmp = $oldid; $oldid = $newid; $newid = $tmp;
 884                 }
 885
 886                 $n = $this->mTitle->countRevisionsBetween( $oldid, $newid );
 887                 if ( !$n )
 888                 return '';
 889
 890                 return wfMsgExt( 'diff-multi', array( 'parseinline' ), $n );
 891         }
 892
 893
 894         /**
 895          * Add the header to a diff body
 896          */
 897         static function addHeader( $diff, $otitle, $ntitle, $multi = '' ) {
 898                 $colspan = 1;
 899                 $header = "<table class='diff'>";
 900                 if( $diff ) { // Safari/Chrome show broken output if cols not used
 901                         $header .= "
 902                         <col class='diff-marker' />
 903                         <col class='diff-content' />
 904                         <col class='diff-marker' />
 905                         <col class='diff-content' />";
 906                         $colspan = 2;
 907                 }
 908                 $header .= "
 909                 <tr valign='top'>
 910                 <td colspan='$colspan' class='diff-otitle'>{$otitle}</td>
 911                 <td colspan='$colspan' class='diff-ntitle'>{$ntitle}</td>
 912                 </tr>";
 913
 914                 if ( $multi != '' )
 915                 $header .= "<tr><td colspan='4' align='center' class='diff-multi'>{$multi}</td></tr>";
 916
 917                 return $header . $diff . "</table>";
 918         }
 919
 920         /**
 921          * Use specified text instead of loading from the database
 922          */
 923         function setText( $oldText, $newText ) {
 924                 $this->mOldtext = $oldText;
 925                 $this->mNewtext = $newText;
 926                 $this->mTextLoaded = 2;
 927                 $this->mRevisionsLoaded = true;
 928         }
 929
 930         /**
 931          * Load revision metadata for the specified articles. If newid is 0, then compare
 932          * the old article in oldid to the current article; if oldid is 0, then
 933          * compare the current article to the immediately previous one (ignoring the
 934          * value of newid).
 935          *
 936          * If oldid is false, leave the corresponding revision object set
 937          * to false. This is impossible via ordinary user input, and is provided for
 938          * API convenience.
 939          */
 940         function loadRevisionData() {
 941                 global $wgLang, $wgUser;
 942                 if ( $this->mRevisionsLoaded ) {
 943                         return true;
 944                 } else {
 945                         // Whether it succeeds or fails, we don't want to try again
 946                         $this->mRevisionsLoaded = true;
 947                 }
 948
 949                 // Load the new revision object
 950                 $this->mNewRev = $this->mNewid
 951                         ? Revision::newFromId( $this->mNewid )
 952                         : Revision::newFromTitle( $this->mTitle );
 953                 if( !$this->mNewRev instanceof Revision )
 954                         return false;
 955
 956                 // Update the new revision ID in case it was 0 (makes life easier doing UI stuff)
 957                 $this->mNewid = $this->mNewRev->getId();
 958
 959                 // Check if page is editable
 960                 $editable = $this->mNewRev->getTitle()->userCan( 'edit' );
 961
 962                 // Set assorted variables
 963                 $timestamp = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 964                 $dateofrev = $wgLang->date( $this->mNewRev->getTimestamp(), true );
 965                 $timeofrev = $wgLang->time( $this->mNewRev->getTimestamp(), true );
 966                 $this->mNewPage = $this->mNewRev->getTitle();
 967                 if( $this->mNewRev->isCurrent() ) {
 968                         $newLink = $this->mNewPage->escapeLocalUrl( array(
 969                                 'oldid' => $this->mNewid
 970                         ) );
 971                         $this->mPagetitle = htmlspecialchars( wfMsg(
 972                                 'currentrev-asof',
 973                                 $timestamp,
 974                                 $dateofrev,
 975                                 $timeofrev
 976                         ) );
 977                         $newEdit = $this->mNewPage->escapeLocalUrl( array(
 978                                 'action' => 'edit'
 979                         ) );
 980
 981                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 982                         $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
 983                 } else {
 984                         $newLink = $this->mNewPage->escapeLocalUrl( array(
 985                                 'oldid' => $this->mNewid
 986                         ) );
 987                         $newEdit = $this->mNewPage->escapeLocalUrl( array(
 988                                 'action' => 'edit',
 989                                 'oldid' => $this->mNewid
 990                         ) );
 991                         $this->mPagetitle = htmlspecialchars( wfMsg(
 992                                 'revisionasof',
 993                                 $timestamp,
 994                                 $dateofrev,
 995                                 $timeofrev
 996                         ) );
 997
 998                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 999                         $this->mNewtitle .= " (<a href='$newEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
1000                 }
1001                 if( !$this->mNewRev->userCan(Revision::DELETED_TEXT) ) {
1002                         $this->mNewtitle = "<span class='history-deleted'>{$this->mPagetitle}</span>";
1003                 } else if ( $this->mNewRev->isDeleted(Revision::DELETED_TEXT) ) {
1004                         $this->mNewtitle = "<span class='history-deleted'>{$this->mNewtitle}</span>";
1005                 }
1006
1007                 // Load the old revision object
1008                 $this->mOldRev = false;
1009                 if( $this->mOldid ) {
1010                         $this->mOldRev = Revision::newFromId( $this->mOldid );
1011                 } elseif ( $this->mOldid === 0 ) {
1012                         $rev = $this->mNewRev->getPrevious();
1013                         if( $rev ) {
1014                                 $this->mOldid = $rev->getId();
1015                                 $this->mOldRev = $rev;
1016                         } else {
1017                                 // No previous revision; mark to show as first-version only.
1018                                 $this->mOldid = false;
1019                                 $this->mOldRev = false;
1020                         }
1021                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
1022
1023                 if( is_null( $this->mOldRev ) ) {
1024                         return false;
1025                 }
1026
1027                 if ( $this->mOldRev ) {
1028                         $this->mOldPage = $this->mOldRev->getTitle();
1029
1030                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
1031                         $dateofrev = $wgLang->date( $this->mOldRev->getTimestamp(), true );
1032                         $timeofrev = $wgLang->time( $this->mOldRev->getTimestamp(), true );
1033                         $oldLink = $this->mOldPage->escapeLocalUrl( array(
1034                                 'oldid' => $this->mOldid
1035                         ) );
1036                         $oldEdit = $this->mOldPage->escapeLocalUrl( array(
1037                                 'action' => 'edit',
1038                                 'oldid' => $this->mOldid
1039                         ) );
1040                         $this->mOldPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t, $dateofrev, $timeofrev ) );
1041
1042                         $this->mOldtitle = "<a href='$oldLink'>{$this->mOldPagetitle}</a>"
1043                         . " (<a href='$oldEdit'>" . wfMsgHtml( $editable ? 'editold' : 'viewsourceold' ) . "</a>)";
1044                         // Add an "undo" link
1045                         $newUndo = $this->mNewPage->escapeLocalUrl( array(
1046                                 'action' => 'edit',
1047                                 'undoafter' => $this->mOldid,
1048                                 'undo' => $this->mNewid
1049                         ) );
1050                         $htmlLink = htmlspecialchars( wfMsg( 'editundo' ) );
1051                         $htmlTitle = $wgUser->getSkin()->tooltip( 'undo' );
1052                         if( $editable && !$this->mOldRev->isDeleted( Revision::DELETED_TEXT ) && !$this->mNewRev->isDeleted( Revision::DELETED_TEXT ) ) {
1053                                 $this->mNewtitle .= " (<a href='$newUndo' $htmlTitle>" . $htmlLink . "</a>)";
1054                         }
1055
1056                         if( !$this->mOldRev->userCan( Revision::DELETED_TEXT ) ) {
1057                                 $this->mOldtitle = '<span class="history-deleted">' . $this->mOldPagetitle . '</span>';
1058                         } else if( $this->mOldRev->isDeleted( Revision::DELETED_TEXT ) ) {
1059                                 $this->mOldtitle = '<span class="history-deleted">' . $this->mOldtitle . '</span>';
1060                         }
1061                 }
1062
1063                 return true;
1064         }
1065
1066         /**
1067          * Load the text of the revisions, as well as revision data.
1068          */
1069         function loadText() {
1070                 if ( $this->mTextLoaded == 2 ) {
1071                         return true;
1072                 } else {
1073                         // Whether it succeeds or fails, we don't want to try again
1074                         $this->mTextLoaded = 2;
1075                 }
1076
1077                 if ( !$this->loadRevisionData() ) {
1078                         return false;
1079                 }
1080                 if ( $this->mOldRev ) {
1081                         $this->mOldtext = $this->mOldRev->getText( Revision::FOR_THIS_USER );
1082                         if ( $this->mOldtext === false ) {
1083                                 return false;
1084                         }
1085                 }
1086                 if ( $this->mNewRev ) {
1087                         $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1088                         if ( $this->mNewtext === false ) {
1089                                 return false;
1090                         }
1091                 }
1092                 return true;
1093         }
1094
1095         /**
1096          * Load the text of the new revision, not the old one
1097          */
1098         function loadNewText() {
1099                 if ( $this->mTextLoaded >= 1 ) {
1100                         return true;
1101                 } else {
1102                         $this->mTextLoaded = 1;
1103                 }
1104                 if ( !$this->loadRevisionData() ) {
1105                         return false;
1106                 }
1107                 $this->mNewtext = $this->mNewRev->getText( Revision::FOR_THIS_USER );
1108                 return true;
1109         }
1110 }
1111
1112 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
1113 //
1114 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
1115 // You may copy this code freely under the conditions of the GPL.
1116 //
1117
1118 define('USE_ASSERTS', function_exists('assert'));
1119
1120 /**
1121  * @todo document
1122  * @private
1123  * @ingroup DifferenceEngine
1124  */
1125 class _DiffOp {
1126         var $type;
1127         var $orig;
1128         var $closing;
1129
1130         function reverse() {
1131                 trigger_error('pure virtual', E_USER_ERROR);
1132         }
1133
1134         function norig() {
1135                 return $this->orig ? sizeof($this->orig) : 0;
1136         }
1137
1138         function nclosing() {
1139                 return $this->closing ? sizeof($this->closing) : 0;
1140         }
1141 }
1142
1143 /**
1144  * @todo document
1145  * @private
1146  * @ingroup DifferenceEngine
1147  */
1148 class _DiffOp_Copy extends _DiffOp {
1149         var $type = 'copy';
1150
1151         function _DiffOp_Copy ($orig, $closing = false) {
1152                 if (!is_array($closing))
1153                 $closing = $orig;
1154                 $this->orig = $orig;
1155                 $this->closing = $closing;
1156         }
1157
1158         function reverse() {
1159                 return new _DiffOp_Copy($this->closing, $this->orig);
1160         }
1161 }
1162
1163 /**
1164  * @todo document
1165  * @private
1166  * @ingroup DifferenceEngine
1167  */
1168 class _DiffOp_Delete extends _DiffOp {
1169         var $type = 'delete';
1170
1171         function _DiffOp_Delete ($lines) {
1172                 $this->orig = $lines;
1173                 $this->closing = false;
1174         }
1175
1176         function reverse() {
1177                 return new _DiffOp_Add($this->orig);
1178         }
1179 }
1180
1181 /**
1182  * @todo document
1183  * @private
1184  * @ingroup DifferenceEngine
1185  */
1186 class _DiffOp_Add extends _DiffOp {
1187         var $type = 'add';
1188
1189         function _DiffOp_Add ($lines) {
1190                 $this->closing = $lines;
1191                 $this->orig = false;
1192         }
1193
1194         function reverse() {
1195                 return new _DiffOp_Delete($this->closing);
1196         }
1197 }
1198
1199 /**
1200  * @todo document
1201  * @private
1202  * @ingroup DifferenceEngine
1203  */
1204 class _DiffOp_Change extends _DiffOp {
1205         var $type = 'change';
1206
1207         function _DiffOp_Change ($orig, $closing) {
1208                 $this->orig = $orig;
1209                 $this->closing = $closing;
1210         }
1211
1212         function reverse() {
1213                 return new _DiffOp_Change($this->closing, $this->orig);
1214         }
1215 }
1216
1217 /**
1218  * Class used internally by Diff to actually compute the diffs.
1219  *
1220  * The algorithm used here is mostly lifted from the perl module
1221  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
1222  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
1223  *
1224  * More ideas are taken from:
1225  *       http://www.ics.uci.edu/~eppstein/161/960229.html
1226  *
1227  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
1228  * diffutils-2.7, which can be found at:
1229  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
1230  *
1231  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
1232  * are my own.
1233  *
1234  * Line length limits for robustness added by Tim Starling, 2005-08-31
1235  * Alternative implementation added by Guy Van den Broeck, 2008-07-30
1236  *
1237  * @author Geoffrey T. Dairiki, Tim Starling, Guy Van den Broeck
1238  * @private
1239  * @ingroup DifferenceEngine
1240  */
1241 class _DiffEngine {
1242
1243         const MAX_XREF_LENGTH =  10000;
1244
1245         function diff ($from_lines, $to_lines){
1246                 wfProfileIn( __METHOD__ );
1247
1248                 // Diff and store locally
1249                 $this->diff_local($from_lines, $to_lines);
1250
1251                 // Merge edits when possible
1252                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
1253                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
1254
1255                 // Compute the edit operations.
1256                 $n_from = sizeof($from_lines);
1257                 $n_to = sizeof($to_lines);
1258
1259                 $edits = array();
1260                 $xi = $yi = 0;
1261                 while ($xi < $n_from || $yi < $n_to) {
1262                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
1263                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
1264
1265                         // Skip matching "snake".
1266                         $copy = array();
1267                         while ( $xi < $n_from && $yi < $n_to
1268                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
1269                                 $copy[] = $from_lines[$xi++];
1270                                 ++$yi;
1271                         }
1272                         if ($copy)
1273                         $edits[] = new _DiffOp_Copy($copy);
1274
1275                         // Find deletes & adds.
1276                         $delete = array();
1277                         while ($xi < $n_from && $this->xchanged[$xi])
1278                         $delete[] = $from_lines[$xi++];
1279
1280                         $add = array();
1281                         while ($yi < $n_to && $this->ychanged[$yi])
1282                         $add[] = $to_lines[$yi++];
1283
1284                         if ($delete && $add)
1285                         $edits[] = new _DiffOp_Change($delete, $add);
1286                         elseif ($delete)
1287                         $edits[] = new _DiffOp_Delete($delete);
1288                         elseif ($add)
1289                         $edits[] = new _DiffOp_Add($add);
1290                 }
1291                 wfProfileOut( __METHOD__ );
1292                 return $edits;
1293         }
1294
1295         function diff_local ($from_lines, $to_lines) {
1296                 global $wgExternalDiffEngine;
1297                 wfProfileIn( __METHOD__);
1298
1299                 if($wgExternalDiffEngine == 'wikidiff3'){
1300                         // wikidiff3
1301                         $wikidiff3 = new WikiDiff3();
1302                         $wikidiff3->diff($from_lines, $to_lines);
1303                         $this->xchanged = $wikidiff3->removed;
1304                         $this->ychanged = $wikidiff3->added;
1305                         unset($wikidiff3);
1306                 }else{
1307                         // old diff
1308                         $n_from = sizeof($from_lines);
1309                         $n_to = sizeof($to_lines);
1310                         $this->xchanged = $this->ychanged = array();
1311                         $this->xv = $this->yv = array();
1312                         $this->xind = $this->yind = array();
1313                         unset($this->seq);
1314                         unset($this->in_seq);
1315                         unset($this->lcs);
1316
1317                         // Skip leading common lines.
1318                         for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
1319                                 if ($from_lines[$skip] !== $to_lines[$skip])
1320                                 break;
1321                                 $this->xchanged[$skip] = $this->ychanged[$skip] = false;
1322                         }
1323                         // Skip trailing common lines.
1324                         $xi = $n_from; $yi = $n_to;
1325                         for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
1326                                 if ($from_lines[$xi] !== $to_lines[$yi])
1327                                 break;
1328                                 $this->xchanged[$xi] = $this->ychanged[$yi] = false;
1329                         }
1330
1331                         // Ignore lines which do not exist in both files.
1332                         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
1333                                 $xhash[$this->_line_hash($from_lines[$xi])] = 1;
1334                         }
1335
1336                         for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
1337                                 $line = $to_lines[$yi];
1338                                 if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
1339                                 continue;
1340                                 $yhash[$this->_line_hash($line)] = 1;
1341                                 $this->yv[] = $line;
1342                                 $this->yind[] = $yi;
1343                         }
1344                         for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
1345                                 $line = $from_lines[$xi];
1346                                 if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
1347                                 continue;
1348                                 $this->xv[] = $line;
1349                                 $this->xind[] = $xi;
1350                         }
1351
1352                         // Find the LCS.
1353                         $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
1354                 }
1355                 wfProfileOut( __METHOD__ );
1356         }
1357
1358         /**
1359          * Returns the whole line if it's small enough, or the MD5 hash otherwise
1360          */
1361         function _line_hash( $line ) {
1362                 if ( strlen( $line ) > self::MAX_XREF_LENGTH ) {
1363                         return md5( $line );
1364                 } else {
1365                         return $line;
1366                 }
1367         }
1368
1369         /* Divide the Largest Common Subsequence (LCS) of the sequences
1370          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
1371          * sized segments.
1372          *
1373          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
1374          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
1375          * sub sequences.  The first sub-sequence is contained in [X0, X1),
1376          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
1377          * that (X0, Y0) == (XOFF, YOFF) and
1378          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
1379          *
1380          * This function assumes that the first lines of the specified portions
1381          * of the two files do not match, and likewise that the last lines do not
1382          * match.  The caller must trim matching lines from the beginning and end
1383          * of the portions it is going to specify.
1384          */
1385         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
1386                 $flip = false;
1387
1388                 if ($xlim - $xoff > $ylim - $yoff) {
1389                         // Things seems faster (I'm not sure I understand why)
1390                         // when the shortest sequence in X.
1391                         $flip = true;
1392                         list ($xoff, $xlim, $yoff, $ylim)
1393                         = array( $yoff, $ylim, $xoff, $xlim);
1394                 }
1395
1396                 if ($flip)
1397                 for ($i = $ylim - 1; $i >= $yoff; $i--)
1398                 $ymatches[$this->xv[$i]][] = $i;
1399                 else
1400                 for ($i = $ylim - 1; $i >= $yoff; $i--)
1401                 $ymatches[$this->yv[$i]][] = $i;
1402
1403                 $this->lcs = 0;
1404                 $this->seq[0]= $yoff - 1;
1405                 $this->in_seq = array();
1406                 $ymids[0] = array();
1407
1408                 $numer = $xlim - $xoff + $nchunks - 1;
1409                 $x = $xoff;
1410                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
1411                         if ($chunk > 0)
1412                         for ($i = 0; $i <= $this->lcs; $i++)
1413                         $ymids[$i][$chunk-1] = $this->seq[$i];
1414
1415                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
1416                         for ( ; $x < $x1; $x++) {
1417                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
1418                                 if (empty($ymatches[$line]))
1419                                 continue;
1420                                 $matches = $ymatches[$line];
1421                                 reset($matches);
1422                                 while (list ($junk, $y) = each($matches))
1423                                 if (empty($this->in_seq[$y])) {
1424                                         $k = $this->_lcs_pos($y);
1425                                         USE_ASSERTS && assert($k > 0);
1426                                         $ymids[$k] = $ymids[$k-1];
1427                                         break;
1428                                 }
1429                                 while (list ( /* $junk */, $y) = each($matches)) {
1430                                         if ($y > $this->seq[$k-1]) {
1431                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
1432                                                 // Optimization: this is a common case:
1433                                                 //      next match is just replacing previous match.
1434                                                 $this->in_seq[$this->seq[$k]] = false;
1435                                                 $this->seq[$k] = $y;
1436                                                 $this->in_seq[$y] = 1;
1437                                         } else if (empty($this->in_seq[$y])) {
1438                                                 $k = $this->_lcs_pos($y);
1439                                                 USE_ASSERTS && assert($k > 0);
1440                                                 $ymids[$k] = $ymids[$k-1];
1441                                         }
1442                                 }
1443                         }
1444                 }
1445
1446                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
1447                 $ymid = $ymids[$this->lcs];
1448                 for ($n = 0; $n < $nchunks - 1; $n++) {
1449                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
1450                         $y1 = $ymid[$n] + 1;
1451                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
1452                 }
1453                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
1454
1455                 return array($this->lcs, $seps);
1456         }
1457
1458         function _lcs_pos ($ypos) {
1459                 $end = $this->lcs;
1460                 if ($end == 0 || $ypos > $this->seq[$end]) {
1461                         $this->seq[++$this->lcs] = $ypos;
1462                         $this->in_seq[$ypos] = 1;
1463                         return $this->lcs;
1464                 }
1465
1466                 $beg = 1;
1467                 while ($beg < $end) {
1468                         $mid = (int)(($beg + $end) / 2);
1469                         if ( $ypos > $this->seq[$mid] )
1470                         $beg = $mid + 1;
1471                         else
1472                         $end = $mid;
1473                 }
1474
1475                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
1476
1477                 $this->in_seq[$this->seq[$end]] = false;
1478                 $this->seq[$end] = $ypos;
1479                 $this->in_seq[$ypos] = 1;
1480                 return $end;
1481         }
1482
1483         /* Find LCS of two sequences.
1484          *
1485          * The results are recorded in the vectors $this->{x,y}changed[], by
1486          * storing a 1 in the element for each line that is an insertion
1487          * or deletion (ie. is not in the LCS).
1488          *
1489          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
1490          *
1491          * Note that XLIM, YLIM are exclusive bounds.
1492          * All line numbers are origin-0 and discarded lines are not counted.
1493          */
1494         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
1495                 // Slide down the bottom initial diagonal.
1496                 while ($xoff < $xlim && $yoff < $ylim
1497                 && $this->xv[$xoff] == $this->yv[$yoff]) {
1498                         ++$xoff;
1499                         ++$yoff;
1500                 }
1501
1502                 // Slide up the top initial diagonal.
1503                 while ($xlim > $xoff && $ylim > $yoff
1504                 && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
1505                         --$xlim;
1506                         --$ylim;
1507                 }
1508
1509                 if ($xoff == $xlim || $yoff == $ylim)
1510                 $lcs = 0;
1511                 else {
1512                         // This is ad hoc but seems to work well.
1513                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
1514                         //$nchunks = max(2,min(8,(int)$nchunks));
1515                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
1516                         list ($lcs, $seps)
1517                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
1518                 }
1519
1520                 if ($lcs == 0) {
1521                         // X and Y sequences have no common subsequence:
1522                         // mark all changed.
1523                         while ($yoff < $ylim)
1524                         $this->ychanged[$this->yind[$yoff++]] = 1;
1525                         while ($xoff < $xlim)
1526                         $this->xchanged[$this->xind[$xoff++]] = 1;
1527                 } else {
1528                         // Use the partitions to split this problem into subproblems.
1529                         reset($seps);
1530                         $pt1 = $seps[0];
1531                         while ($pt2 = next($seps)) {
1532                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
1533                                 $pt1 = $pt2;
1534                         }
1535                 }
1536         }
1537
1538         /* Adjust inserts/deletes of identical lines to join changes
1539          * as much as possible.
1540          *
1541          * We do something when a run of changed lines include a
1542          * line at one end and has an excluded, identical line at the other.
1543          * We are free to choose which identical line is included.
1544          * `compareseq' usually chooses the one at the beginning,
1545          * but usually it is cleaner to consider the following identical line
1546          * to be the "change".
1547          *
1548          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
1549          */
1550         function _shift_boundaries ($lines, &$changed, $other_changed) {
1551                 wfProfileIn( __METHOD__ );
1552                 $i = 0;
1553                 $j = 0;
1554
1555                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
1556                 $len = sizeof($lines);
1557                 $other_len = sizeof($other_changed);
1558
1559                 while (1) {
1560                         /*
1561                          * Scan forwards to find beginning of another run of changes.
1562                          * Also keep track of the corresponding point in the other file.
1563                          *
1564                          * Throughout this code, $i and $j are adjusted together so that
1565                          * the first $i elements of $changed and the first $j elements
1566                          * of $other_changed both contain the same number of zeros
1567                          * (unchanged lines).
1568                          * Furthermore, $j is always kept so that $j == $other_len or
1569                          * $other_changed[$j] == false.
1570                          */
1571                         while ($j < $other_len && $other_changed[$j])
1572                         $j++;
1573
1574                         while ($i < $len && ! $changed[$i]) {
1575                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1576                                 $i++; $j++;
1577                                 while ($j < $other_len && $other_changed[$j])
1578                                 $j++;
1579                         }
1580
1581                         if ($i == $len)
1582                         break;
1583
1584                         $start = $i;
1585
1586                         // Find the end of this run of changes.
1587                         while (++$i < $len && $changed[$i])
1588                         continue;
1589
1590                         do {
1591                                 /*
1592                                  * Record the length of this run of changes, so that
1593                                  * we can later determine whether the run has grown.
1594                                  */
1595                                 $runlength = $i - $start;
1596
1597                                 /*
1598                                  * Move the changed region back, so long as the
1599                                  * previous unchanged line matches the last changed one.
1600                                  * This merges with previous changed regions.
1601                                  */
1602                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
1603                                         $changed[--$start] = 1;
1604                                         $changed[--$i] = false;
1605                                         while ($start > 0 && $changed[$start - 1])
1606                                         $start--;
1607                                         USE_ASSERTS && assert('$j > 0');
1608                                         while ($other_changed[--$j])
1609                                         continue;
1610                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1611                                 }
1612
1613                                 /*
1614                                  * Set CORRESPONDING to the end of the changed run, at the last
1615                                  * point where it corresponds to a changed run in the other file.
1616                                  * CORRESPONDING == LEN means no such point has been found.
1617                                  */
1618                                 $corresponding = $j < $other_len ? $i : $len;
1619
1620                                 /*
1621                                  * Move the changed region forward, so long as the
1622                                  * first changed line matches the following unchanged one.
1623                                  * This merges with following changed regions.
1624                                  * Do this second, so that if there are no merges,
1625                                  * the changed region is moved forward as far as possible.
1626                                  */
1627                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1628                                         $changed[$start++] = false;
1629                                         $changed[$i++] = 1;
1630                                         while ($i < $len && $changed[$i])
1631                                         $i++;
1632
1633                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1634                                         $j++;
1635                                         if ($j < $other_len && $other_changed[$j]) {
1636                                                 $corresponding = $i;
1637                                                 while ($j < $other_len && $other_changed[$j])
1638                                                 $j++;
1639                                         }
1640                                 }
1641                         } while ($runlength != $i - $start);
1642
1643                         /*
1644                          * If possible, move the fully-merged run of changes
1645                          * back to a corresponding run in the other file.
1646                          */
1647                         while ($corresponding < $i) {
1648                                 $changed[--$start] = 1;
1649                                 $changed[--$i] = 0;
1650                                 USE_ASSERTS && assert('$j > 0');
1651                                 while ($other_changed[--$j])
1652                                 continue;
1653                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1654                         }
1655                 }
1656                 wfProfileOut( __METHOD__ );
1657         }
1658 }
1659
1660 /**
1661  * Class representing a 'diff' between two sequences of strings.
1662  * @todo document
1663  * @private
1664  * @ingroup DifferenceEngine
1665  */
1666 class Diff
1667 {
1668         var $edits;
1669
1670         /**
1671          * Constructor.
1672          * Computes diff between sequences of strings.
1673          *
1674          * @param $from_lines array An array of strings.
1675          *                (Typically these are lines from a file.)
1676          * @param $to_lines array An array of strings.
1677          */
1678         function Diff($from_lines, $to_lines) {
1679                 $eng = new _DiffEngine;
1680                 $this->edits = $eng->diff($from_lines, $to_lines);
1681                 //$this->_check($from_lines, $to_lines);
1682         }
1683
1684         /**
1685          * Compute reversed Diff.
1686          *
1687          * SYNOPSIS:
1688          *
1689          *      $diff = new Diff($lines1, $lines2);
1690          *      $rev = $diff->reverse();
1691          * @return object A Diff object representing the inverse of the
1692          *                                original diff.
1693          */
1694         function reverse () {
1695                 $rev = $this;
1696                 $rev->edits = array();
1697                 foreach ($this->edits as $edit) {
1698                         $rev->edits[] = $edit->reverse();
1699                 }
1700                 return $rev;
1701         }
1702
1703         /**
1704          * Check for empty diff.
1705          *
1706          * @return bool True iff two sequences were identical.
1707          */
1708         function isEmpty () {
1709                 foreach ($this->edits as $edit) {
1710                         if ($edit->type != 'copy')
1711                         return false;
1712                 }
1713                 return true;
1714         }
1715
1716         /**
1717          * Compute the length of the Longest Common Subsequence (LCS).
1718          *
1719          * This is mostly for diagnostic purposed.
1720          *
1721          * @return int The length of the LCS.
1722          */
1723         function lcs () {
1724                 $lcs = 0;
1725                 foreach ($this->edits as $edit) {
1726                         if ($edit->type == 'copy')
1727                         $lcs += sizeof($edit->orig);
1728                 }
1729                 return $lcs;
1730         }
1731
1732         /**
1733          * Get the original set of lines.
1734          *
1735          * This reconstructs the $from_lines parameter passed to the
1736          * constructor.
1737          *
1738          * @return array The original sequence of strings.
1739          */
1740         function orig() {
1741                 $lines = array();
1742
1743                 foreach ($this->edits as $edit) {
1744                         if ($edit->orig)
1745                         array_splice($lines, sizeof($lines), 0, $edit->orig);
1746                 }
1747                 return $lines;
1748         }
1749
1750         /**
1751          * Get the closing set of lines.
1752          *
1753          * This reconstructs the $to_lines parameter passed to the
1754          * constructor.
1755          *
1756          * @return array The sequence of strings.
1757          */
1758         function closing() {
1759                 $lines = array();
1760
1761                 foreach ($this->edits as $edit) {
1762                         if ($edit->closing)
1763                         array_splice($lines, sizeof($lines), 0, $edit->closing);
1764                 }
1765                 return $lines;
1766         }
1767
1768         /**
1769          * Check a Diff for validity.
1770          *
1771          * This is here only for debugging purposes.
1772          */
1773         function _check ($from_lines, $to_lines) {
1774                 wfProfileIn( __METHOD__ );
1775                 if (serialize($from_lines) != serialize($this->orig()))
1776                 trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1777                 if (serialize($to_lines) != serialize($this->closing()))
1778                 trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1779
1780                 $rev = $this->reverse();
1781                 if (serialize($to_lines) != serialize($rev->orig()))
1782                 trigger_error("Reversed original doesn't match", E_USER_ERROR);
1783                 if (serialize($from_lines) != serialize($rev->closing()))
1784                 trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1785
1786
1787                 $prevtype = 'none';
1788                 foreach ($this->edits as $edit) {
1789                         if ( $prevtype == $edit->type )
1790                         trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1791                         $prevtype = $edit->type;
1792                 }
1793
1794                 $lcs = $this->lcs();
1795                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1796                 wfProfileOut( __METHOD__ );
1797         }
1798 }
1799
1800 /**
1801  * @todo document, bad name.
1802  * @private
1803  * @ingroup DifferenceEngine
1804  */
1805 class MappedDiff extends Diff
1806 {
1807         /**
1808          * Constructor.
1809          *
1810          * Computes diff between sequences of strings.
1811          *
1812          * This can be used to compute things like
1813          * case-insensitve diffs, or diffs which ignore
1814          * changes in white-space.
1815          *
1816          * @param $from_lines array An array of strings.
1817          *      (Typically these are lines from a file.)
1818          *
1819          * @param $to_lines array An array of strings.
1820          *
1821          * @param $mapped_from_lines array This array should
1822          *      have the same size number of elements as $from_lines.
1823          *      The elements in $mapped_from_lines and
1824          *      $mapped_to_lines are what is actually compared
1825          *      when computing the diff.
1826          *
1827          * @param $mapped_to_lines array This array should
1828          *      have the same number of elements as $to_lines.
1829          */
1830         function MappedDiff($from_lines, $to_lines,
1831         $mapped_from_lines, $mapped_to_lines) {
1832                 wfProfileIn( __METHOD__ );
1833
1834                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1835                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1836
1837                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1838
1839                 $xi = $yi = 0;
1840                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1841                         $orig = &$this->edits[$i]->orig;
1842                         if (is_array($orig)) {
1843                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1844                                 $xi += sizeof($orig);
1845                         }
1846
1847                         $closing = &$this->edits[$i]->closing;
1848                         if (is_array($closing)) {
1849                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1850                                 $yi += sizeof($closing);
1851                         }
1852                 }
1853                 wfProfileOut( __METHOD__ );
1854         }
1855 }
1856
1857 /**
1858  * A class to format Diffs
1859  *
1860  * This class formats the diff in classic diff format.
1861  * It is intended that this class be customized via inheritance,
1862  * to obtain fancier outputs.
1863  * @todo document
1864  * @private
1865  * @ingroup DifferenceEngine
1866  */
1867 class DiffFormatter {
1868         /**
1869          * Number of leading context "lines" to preserve.
1870          *
1871          * This should be left at zero for this class, but subclasses
1872          * may want to set this to other values.
1873          */
1874         var $leading_context_lines = 0;
1875
1876         /**
1877          * Number of trailing context "lines" to preserve.
1878          *
1879          * This should be left at zero for this class, but subclasses
1880          * may want to set this to other values.
1881          */
1882         var $trailing_context_lines = 0;
1883
1884         /**
1885          * Format a diff.
1886          *
1887          * @param $diff object A Diff object.
1888          * @return string The formatted output.
1889          */
1890         function format($diff) {
1891                 wfProfileIn( __METHOD__ );
1892
1893                 $xi = $yi = 1;
1894                 $block = false;
1895                 $context = array();
1896
1897                 $nlead = $this->leading_context_lines;
1898                 $ntrail = $this->trailing_context_lines;
1899
1900                 $this->_start_diff();
1901
1902                 foreach ($diff->edits as $edit) {
1903                         if ($edit->type == 'copy') {
1904                                 if (is_array($block)) {
1905                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1906                                                 $block[] = $edit;
1907                                         }
1908                                         else{
1909                                                 if ($ntrail) {
1910                                                         $context = array_slice($edit->orig, 0, $ntrail);
1911                                                         $block[] = new _DiffOp_Copy($context);
1912                                                 }
1913                                                 $this->_block($x0, $ntrail + $xi - $x0,
1914                                                 $y0, $ntrail + $yi - $y0,
1915                                                 $block);
1916                                                 $block = false;
1917                                         }
1918                                 }
1919                                 $context = $edit->orig;
1920                         }
1921                         else {
1922                                 if (! is_array($block)) {
1923                                         $context = array_slice($context, sizeof($context) - $nlead);
1924                                         $x0 = $xi - sizeof($context);
1925                                         $y0 = $yi - sizeof($context);
1926                                         $block = array();
1927                                         if ($context)
1928                                         $block[] = new _DiffOp_Copy($context);
1929                                 }
1930                                 $block[] = $edit;
1931                         }
1932
1933                         if ($edit->orig)
1934                         $xi += sizeof($edit->orig);
1935                         if ($edit->closing)
1936                         $yi += sizeof($edit->closing);
1937                 }
1938
1939                 if (is_array($block))
1940                 $this->_block($x0, $xi - $x0,
1941                 $y0, $yi - $y0,
1942                 $block);
1943
1944                 $end = $this->_end_diff();
1945                 wfProfileOut( __METHOD__ );
1946                 return $end;
1947         }
1948
1949         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1950                 wfProfileIn( __METHOD__ );
1951                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1952                 foreach ($edits as $edit) {
1953                         if ($edit->type == 'copy')
1954                         $this->_context($edit->orig);
1955                         elseif ($edit->type == 'add')
1956                         $this->_added($edit->closing);
1957                         elseif ($edit->type == 'delete')
1958                         $this->_deleted($edit->orig);
1959                         elseif ($edit->type == 'change')
1960                         $this->_changed($edit->orig, $edit->closing);
1961                         else
1962                         trigger_error('Unknown edit type', E_USER_ERROR);
1963                 }
1964                 $this->_end_block();
1965                 wfProfileOut( __METHOD__ );
1966         }
1967
1968         function _start_diff() {
1969                 ob_start();
1970         }
1971
1972         function _end_diff() {
1973                 $val = ob_get_contents();
1974                 ob_end_clean();
1975                 return $val;
1976         }
1977
1978         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1979                 if ($xlen > 1)
1980                 $xbeg .= "," . ($xbeg + $xlen - 1);
1981                 if ($ylen > 1)
1982                 $ybeg .= "," . ($ybeg + $ylen - 1);
1983
1984                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1985         }
1986
1987         function _start_block($header) {
1988                 echo $header . "\n";
1989         }
1990
1991         function _end_block() {
1992         }
1993
1994         function _lines($lines, $prefix = ' ') {
1995                 foreach ($lines as $line)
1996                 echo "$prefix $line\n";
1997         }
1998
1999         function _context($lines) {
2000                 $this->_lines($lines);
2001         }
2002
2003         function _added($lines) {
2004                 $this->_lines($lines, '>');
2005         }
2006         function _deleted($lines) {
2007                 $this->_lines($lines, '<');
2008         }
2009
2010         function _changed($orig, $closing) {
2011                 $this->_deleted($orig);
2012                 echo "---\n";
2013                 $this->_added($closing);
2014         }
2015 }
2016
2017 /**
2018  * A formatter that outputs unified diffs
2019  * @ingroup DifferenceEngine
2020  */
2021
2022 class UnifiedDiffFormatter extends DiffFormatter {
2023         var $leading_context_lines = 2;
2024         var $trailing_context_lines = 2;
2025
2026         function _added($lines) {
2027                 $this->_lines($lines, '+');
2028         }
2029         function _deleted($lines) {
2030                 $this->_lines($lines, '-');
2031         }
2032         function _changed($orig, $closing) {
2033                 $this->_deleted($orig);
2034                 $this->_added($closing);
2035         }
2036         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
2037                 return "@@ -$xbeg,$xlen +$ybeg,$ylen @@";
2038         }
2039 }
2040
2041 /**
2042  * A pseudo-formatter that just passes along the Diff::$edits array
2043  * @ingroup DifferenceEngine
2044  */
2045 class ArrayDiffFormatter extends DiffFormatter {
2046         function format($diff) {
2047                 $oldline = 1;
2048                 $newline = 1;
2049                 $retval = array();
2050                 foreach($diff->edits as $edit)
2051                 switch($edit->type) {
2052                         case 'add':
2053                                 foreach($edit->closing as $l) {
2054                                         $retval[] = array(
2055                                                         'action' => 'add',
2056                                                         'new'=> $l,
2057                                                         'newline' => $newline++
2058                                         );
2059                                 }
2060                                 break;
2061                         case 'delete':
2062                                 foreach($edit->orig as $l) {
2063                                         $retval[] = array(
2064                                                         'action' => 'delete',
2065                                                         'old' => $l,
2066                                                         'oldline' => $oldline++,
2067                                         );
2068                                 }
2069                                 break;
2070                         case 'change':
2071                                 foreach($edit->orig as $i => $l) {
2072                                         $retval[] = array(
2073                                                         'action' => 'change',
2074                                                         'old' => $l,
2075                                                         'new' => @$edit->closing[$i],
2076                                                         'oldline' => $oldline++,
2077                                                         'newline' => $newline++,
2078                                         );
2079                                 }
2080                                 break;
2081                         case 'copy':
2082                                 $oldline += count($edit->orig);
2083                                 $newline += count($edit->orig);
2084                 }
2085                 return $retval;
2086         }
2087 }
2088
2089 /**
2090  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
2091  *
2092  */
2093
2094 define('NBSP', '&#160;'); // iso-8859-x non-breaking space.
2095
2096 /**
2097  * @todo document
2098  * @private
2099  * @ingroup DifferenceEngine
2100  */
2101 class _HWLDF_WordAccumulator {
2102         function _HWLDF_WordAccumulator () {
2103                 $this->_lines = array();
2104                 $this->_line = '';
2105                 $this->_group = '';
2106                 $this->_tag = '';
2107         }
2108
2109         function _flushGroup ($new_tag) {
2110                 if ($this->_group !== '') {
2111                         if ($this->_tag == 'ins')
2112                         $this->_line .= '<ins class="diffchange diffchange-inline">' .
2113                         htmlspecialchars ( $this->_group ) . '</ins>';
2114                         elseif ($this->_tag == 'del')
2115                         $this->_line .= '<del class="diffchange diffchange-inline">' .
2116                         htmlspecialchars ( $this->_group ) . '</del>';
2117                         else
2118                         $this->_line .= htmlspecialchars ( $this->_group );
2119                 }
2120                 $this->_group = '';
2121                 $this->_tag = $new_tag;
2122         }
2123
2124         function _flushLine ($new_tag) {
2125                 $this->_flushGroup($new_tag);
2126                 if ($this->_line != '')
2127                 array_push ( $this->_lines, $this->_line );
2128                 else
2129                 # make empty lines visible by inserting an NBSP
2130                 array_push ( $this->_lines, NBSP );
2131                 $this->_line = '';
2132         }
2133
2134         function addWords ($words, $tag = '') {
2135                 if ($tag != $this->_tag)
2136                 $this->_flushGroup($tag);
2137
2138                 foreach ($words as $word) {
2139                         // new-line should only come as first char of word.
2140                         if ($word == '')
2141                         continue;
2142                         if ($word[0] == "\n") {
2143                                 $this->_flushLine($tag);
2144                                 $word = substr($word, 1);
2145                         }
2146                         assert(!strstr($word, "\n"));
2147                         $this->_group .= $word;
2148                 }
2149         }
2150
2151         function getLines() {
2152                 $this->_flushLine('~done');
2153                 return $this->_lines;
2154         }
2155 }
2156
2157 /**
2158  * @todo document
2159  * @private
2160  * @ingroup DifferenceEngine
2161  */
2162 class WordLevelDiff extends MappedDiff {
2163         const MAX_LINE_LENGTH = 10000;
2164
2165         function WordLevelDiff ($orig_lines, $closing_lines) {
2166                 wfProfileIn( __METHOD__ );
2167
2168                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
2169                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
2170
2171                 $this->MappedDiff($orig_words, $closing_words,
2172                 $orig_stripped, $closing_stripped);
2173                 wfProfileOut( __METHOD__ );
2174         }
2175
2176         function _split($lines) {
2177                 wfProfileIn( __METHOD__ );
2178
2179                 $words = array();
2180                 $stripped = array();
2181                 $first = true;
2182                 foreach ( $lines as $line ) {
2183                         # If the line is too long, just pretend the entire line is one big word
2184                         # This prevents resource exhaustion problems
2185                         if ( $first ) {
2186                                 $first = false;
2187                         } else {
2188                                 $words[] = "\n";
2189                                 $stripped[] = "\n";
2190                         }
2191                         if ( strlen( $line ) > self::MAX_LINE_LENGTH ) {
2192                                 $words[] = $line;
2193                                 $stripped[] = $line;
2194                         } else {
2195                                 $m = array();
2196                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
2197                                 $line, $m))
2198                                 {
2199                                         $words = array_merge( $words, $m[0] );
2200                                         $stripped = array_merge( $stripped, $m[1] );
2201                                 }
2202                         }
2203                 }
2204                 wfProfileOut( __METHOD__ );
2205                 return array($words, $stripped);
2206         }
2207
2208         function orig () {
2209                 wfProfileIn( __METHOD__ );
2210                 $orig = new _HWLDF_WordAccumulator;
2211
2212                 foreach ($this->edits as $edit) {
2213                         if ($edit->type == 'copy')
2214                         $orig->addWords($edit->orig);
2215                         elseif ($edit->orig)
2216                         $orig->addWords($edit->orig, 'del');
2217                 }
2218                 $lines = $orig->getLines();
2219                 wfProfileOut( __METHOD__ );
2220                 return $lines;
2221         }
2222
2223         function closing () {
2224                 wfProfileIn( __METHOD__ );
2225                 $closing = new _HWLDF_WordAccumulator;
2226
2227                 foreach ($this->edits as $edit) {
2228                         if ($edit->type == 'copy')
2229                         $closing->addWords($edit->closing);
2230                         elseif ($edit->closing)
2231                         $closing->addWords($edit->closing, 'ins');
2232                 }
2233                 $lines = $closing->getLines();
2234                 wfProfileOut( __METHOD__ );
2235                 return $lines;
2236         }
2237 }
2238
2239 /**
2240  * Wikipedia Table style diff formatter.
2241  * @todo document
2242  * @private
2243  * @ingroup DifferenceEngine
2244  */
2245 class TableDiffFormatter extends DiffFormatter {
2246         function TableDiffFormatter() {
2247                 $this->leading_context_lines = 2;
2248                 $this->trailing_context_lines = 2;
2249         }
2250
2251         public static function escapeWhiteSpace( $msg ) {
2252                 $msg = preg_replace( '/^ /m', '&nbsp; ', $msg );
2253                 $msg = preg_replace( '/ $/m', ' &nbsp;', $msg );
2254                 $msg = preg_replace( '/  /', '&nbsp; ', $msg );
2255                 return $msg;
2256         }
2257
2258         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
2259                 $r = '<tr><td colspan="2" class="diff-lineno"><!--LINE '.$xbeg."--></td>\n" .
2260                   '<td colspan="2" class="diff-lineno"><!--LINE '.$ybeg."--></td></tr>\n";
2261                 return $r;
2262         }
2263
2264         function _start_block( $header ) {
2265                 echo $header;
2266         }
2267
2268         function _end_block() {
2269         }
2270
2271         function _lines( $lines, $prefix=' ', $color='white' ) {
2272         }
2273
2274         # HTML-escape parameter before calling this
2275         function addedLine( $line ) {
2276                 return $this->wrapLine( '+', 'diff-addedline', $line );
2277         }
2278
2279         # HTML-escape parameter before calling this
2280         function deletedLine( $line ) {
2281                 return $this->wrapLine( '-', 'diff-deletedline', $line );
2282         }
2283
2284         # HTML-escape parameter before calling this
2285         function contextLine( $line ) {
2286                 return $this->wrapLine( ' ', 'diff-context', $line );
2287         }
2288
2289         private function wrapLine( $marker, $class, $line ) {
2290                 if( $line !== '' ) {
2291                         // The <div> wrapper is needed for 'overflow: auto' style to scroll properly
2292                         $line = Xml::tags( 'div', null, $this->escapeWhiteSpace( $line ) );
2293                 }
2294                 return "<td class='diff-marker'>$marker</td><td class='$class'>$line</td>";
2295         }
2296
2297         function emptyLine() {
2298                 return '<td colspan="2">&nbsp;</td>';
2299         }
2300
2301         function _added( $lines ) {
2302                 foreach ($lines as $line) {
2303                         echo '<tr>' . $this->emptyLine() .
2304                         $this->addedLine( '<ins class="diffchange">' .
2305                         htmlspecialchars ( $line ) . '</ins>' ) . "</tr>\n";
2306                 }
2307         }
2308
2309         function _deleted($lines) {
2310                 foreach ($lines as $line) {
2311                         echo '<tr>' . $this->deletedLine( '<del class="diffchange">' .
2312                         htmlspecialchars ( $line ) . '</del>' ) .
2313                         $this->emptyLine() . "</tr>\n";
2314                 }
2315         }
2316
2317         function _context( $lines ) {
2318                 foreach ($lines as $line) {
2319                         echo '<tr>' .
2320                         $this->contextLine( htmlspecialchars ( $line ) ) .
2321                         $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
2322                 }
2323         }
2324
2325         function _changed( $orig, $closing ) {
2326                 wfProfileIn( __METHOD__ );
2327
2328                 $diff = new WordLevelDiff( $orig, $closing );
2329                 $del = $diff->orig();
2330                 $add = $diff->closing();
2331
2332                 # Notice that WordLevelDiff returns HTML-escaped output.
2333                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
2334
2335                 while ( $line = array_shift( $del ) ) {
2336                         $aline = array_shift( $add );
2337                         echo '<tr>' . $this->deletedLine( $line ) .
2338                         $this->addedLine( $aline ) . "</tr>\n";
2339                 }
2340                 foreach ($add as $line) {       # If any leftovers
2341                         echo '<tr>' . $this->emptyLine() .
2342                         $this->addedLine( $line ) . "</tr>\n";
2343                 }
2344                 wfProfileOut( __METHOD__ );
2345         }
2346 }