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