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