includes/DifferenceEngine.php

   1 <?php
   2 /**
   3  * See diff.doc
   4  * @package MediaWiki
   5  * @subpackage DifferenceEngine
   6  */
   7
   8 /** */
   9 require_once( 'Revision.php' );
  10
  11 define( 'MAX_DIFF_LINE', 10000 );
  12 define( 'MAX_DIFF_XREF_LENGTH', 10000 );
  13
  14 /**
  15  * @todo document
  16  * @access public
  17  * @package MediaWiki
  18  * @subpackage DifferenceEngine
  19  */
  20 class DifferenceEngine {
  21         /**#@+
  22          * @access private
  23          */
  24         var $mOldid, $mNewid, $mTitle;
  25         var $mOldtitle, $mNewtitle, $mPagetitle;
  26         var $mOldtext, $mNewtext;
  27         var $mOldUser, $mNewUser;
  28         var $mOldComment, $mNewComment;
  29         var $mOldPage, $mNewPage;
  30         var $mRcidMarkPatrolled;
  31         var $mOldRev, $mNewRev;
  32         var $mRevisionsLoaded = false; // Have the revisions been loaded
  33         var $mTextLoaded = 0; // How many text blobs have been loaded, 0, 1 or 2?
  34         /**#@-*/
  35
  36         /**
  37          * Constructor
  38          * @param Title $titleObj Title object that the diff is associated with
  39          * @param integer $old Old ID we want to show and diff with.
  40          * @param string $new Either 'prev' or 'next'.
  41          * @param integer $rcid ??? (default 0)
  42          */
  43         function DifferenceEngine( $titleObj = null, $old = 0, $new = 0, $rcid = 0 ) {
  44                 $this->mTitle = $titleObj;
  45
  46                 if ( 'prev' == $new ) {
  47                         # Show diff between revision $old and the previous one.
  48                         # Get previous one from DB.
  49                         #
  50                         $this->mNewid = intval($old);
  51
  52                         $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
  53
  54                 } elseif ( 'next' == $new ) {
  55                         # Show diff between revision $old and the previous one.
  56                         # Get previous one from DB.
  57                         #
  58                         $this->mOldid = intval($old);
  59                         $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
  60                         if ( false === $this->mNewid ) {
  61                                 # if no result, NewId points to the newest old revision. The only newer
  62                                 # revision is cur, which is "0".
  63                                 $this->mNewid = 0;
  64                         }
  65
  66                 } else {
  67                         $this->mOldid = intval($old);
  68                         $this->mNewid = intval($new);
  69                 }
  70                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  71         }
  72
  73         function showDiffPage() {
  74                 global $wgUser, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol,
  75                        $wgUseExternalEditor, $wgUseRCPatrol;
  76                 $fname = 'DifferenceEngine::showDiffPage';
  77                 wfProfileIn( $fname );
  78
  79                 # If external diffs are enabled both globally and for the user,
  80                 # we'll use the application/x-external-editor interface to call
  81                 # an external diff tool like kompare, kdiff3, etc.
  82                 if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
  83                         global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
  84                         $wgOut->disable();
  85                         header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
  86                         $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);
  87                         $url2=$this->mTitle->getFullURL("action=raw&oldid=".$this->mNewid);
  88                         $special=$wgLang->getNsText(NS_SPECIAL);
  89                         $control=<<<CONTROL
  90 [Process]
  91 Type=Diff text
  92 Engine=MediaWiki
  93 Script={$wgServer}{$wgScript}
  94 Special namespace={$special}
  95
  96 [File]
  97 Extension=wiki
  98 URL=$url1
  99
 100 [File 2]
 101 Extension=wiki
 102 URL=$url2
 103 CONTROL;
 104                         echo($control);
 105                         return;
 106                 }
 107
 108                 # mOldid is false if the difference engine is called with a "vague" query for
 109                 # a diff between a version V and its previous version V' AND the version V
 110                 # is the first version of that article. In that case, V' does not exist.
 111                 if ( $this->mOldid === false ) {
 112                         $this->showFirstRevision();
 113                         wfProfileOut( $fname );
 114                         return;
 115                 }
 116
 117                 $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 118                   "{$this->mNewid})";
 119                 $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 120
 121                 $wgOut->setArticleFlag( false );
 122                 if ( ! $this->loadRevisionData() ) {
 123                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 124                         $wgOut->addWikitext( $mtext );
 125                         wfProfileOut( $fname );
 126                         return;
 127                 }
 128                 if ( $this->mNewRev->isCurrent() ) {
 129                         $wgOut->setArticleFlag( true );
 130                 }
 131
 132                 $wgOut->suppressQuickbar();
 133
 134                 $oldTitle = $this->mOldPage->getPrefixedText();
 135                 $newTitle = $this->mNewPage->getPrefixedText();
 136                 if( $oldTitle == $newTitle ) {
 137                         $wgOut->setPageTitle( $newTitle );
 138                 } else {
 139                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 140                 }
 141                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 142                 $wgOut->setRobotpolicy( 'noindex,follow' );
 143
 144                 if ( !( $this->mOldPage->userCanRead() && $this->mNewPage->userCanRead() ) ) {
 145                         $wgOut->loginToUse();
 146                         $wgOut->output();
 147                         wfProfileOut( $fname );
 148                         exit;
 149                 }
 150
 151                 $sk = $wgUser->getSkin();
 152                 $talk = $wgContLang->getNsText( NS_TALK );
 153                 $contribs = wfMsg( 'contribslink' );
 154
 155                 $this->mOldComment = $sk->formatComment($this->mOldComment);
 156                 $this->mNewComment = $sk->formatComment($this->mNewComment);
 157
 158                 $oldUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 159                 $newUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mNewUser ), $this->mNewUser );
 160                 $oldUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ), $talk );
 161                 $newUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mNewUser ), $talk );
 162                 $oldContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 163                         'target=' . urlencode($this->mOldUser) );
 164                 $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 165                         'target=' . urlencode($this->mNewUser) );
 166                 if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
 167                         $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'rollbacklink' ),
 168                                 'action=rollback&from=' . urlencode($this->mNewUser) .
 169                                 '&token=' . urlencode( $wgUser->editToken( array( $this->mTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
 170                                 ']</strong>';
 171                 } else {
 172                         $rollback = '';
 173                 }
 174                 if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isLoggedIn() &&
 175                      ( $wgUser->isAllowed('rollback') || !$wgOnlySysopsCanPatrol ) )
 176                 {
 177                         $patrol = ' [' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'markaspatrolleddiff' ),
 178                                 "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
 179                 } else {
 180                         $patrol = '';
 181                 }
 182
 183                 $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
 184                         'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
 185                 if ( $this->mNewRev->isCurrent() ) {
 186                         $nextlink = '';
 187                 } else {
 188                         $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
 189                                 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 190                 }
 191
 192                 $oldHeader = "<strong>{$this->mOldtitle}</strong><br />$oldUserLink " .
 193                         "($oldUTLink | $oldContribs)<br />" . $this->mOldComment .
 194                         '<br />' . $prevlink;
 195                 $newHeader = "<strong>{$this->mNewtitle}</strong><br />$newUserLink " .
 196                         "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
 197                         '<br />' . $nextlink . $patrol;
 198
 199                 $this->showDiff( $oldHeader, $newHeader );
 200                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 201
 202                 if( !$this->mNewRev->isCurrent() ) {
 203                         $oldEditSectionSetting = $wgOut->mParserOptions->setEditSection( false );
 204                 }
 205
 206                 $this->loadNewText();
 207                 if( is_object( $this->mNewRev ) ) {
 208                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 209                 }
 210                 $wgOut->addWikiText( $this->mNewtext );
 211
 212                 if( !$this->mNewRev->isCurrent() ) {
 213                         $wgOut->mParserOptions->setEditSection( $oldEditSectionSetting );
 214                 }
 215
 216                 wfProfileOut( $fname );
 217         }
 218
 219         /**
 220          * Show the first revision of an article. Uses normal diff headers in
 221          * contrast to normal "old revision" display style.
 222          */
 223         function showFirstRevision() {
 224                 global $wgOut, $wgUser, $wgLang;
 225
 226                 $fname = 'DifferenceEngine::showFirstRevision';
 227                 wfProfileIn( $fname );
 228
 229                 # Get article text from the DB
 230                 #
 231                 if ( ! $this->loadNewText() ) {
 232                         $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 233                           "{$this->mNewid})";
 234                         $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 235                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 236                         $wgOut->addWikitext( $mtext );
 237                         wfProfileOut( $fname );
 238                         return;
 239                 }
 240                 if ( $this->mNewRev->isCurrent() ) {
 241                         $wgOut->setArticleFlag( true );
 242                 }
 243
 244                 # Check if user is allowed to look at this page. If not, bail out.
 245                 #
 246                 if ( !( $this->mTitle->userCanRead() ) ) {
 247                         $wgOut->loginToUse();
 248                         $wgOut->output();
 249                         wfProfileOut( $fname );
 250                         exit;
 251                 }
 252
 253                 # Prepare the header box
 254                 #
 255                 $sk = $wgUser->getSkin();
 256
 257                 $uTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ),  $wgLang->getNsText( NS_TALK ) );
 258                 $userLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 259                 $contribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), wfMsg( 'contribslink' ),
 260                         'target=' . urlencode($this->mOldUser) );
 261                 $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 262                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
 263                         "($uTLink | $contribs)<br />" . $this->mOldComment .
 264                         '<br />' . $nextlink. "</div>\n";
 265
 266                 $wgOut->addHTML( $header );
 267
 268                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 269                 $wgOut->setRobotpolicy( 'noindex,follow' );
 270
 271
 272                 # Show current revision
 273                 #
 274                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 275                 if( is_object( $this->mNewRev ) ) {
 276                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 277                 }
 278                 $wgOut->addWikiText( $this->mNewtext );
 279
 280                 wfProfileOut( $fname );
 281         }
 282
 283         /**
 284          * Get the diff text, send it to $wgOut
 285          * Returns false if the diff could not be generated, otherwise returns true
 286          */
 287         function showDiff( $otitle, $ntitle ) {
 288                 global $wgOut;
 289                 $diff = $this->getDiff( $otitle, $ntitle );
 290                 if ( $diff === false ) {
 291                         $wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" ) );
 292                         return false;
 293                 } else {
 294                         $wgOut->addHTML( $diff );
 295                         return true;
 296                 }
 297         }
 298
 299         /**
 300          * Get diff table, including header
 301          * Note that the interface has changed, it's no longer static.
 302          * Returns false on error
 303          */
 304         function getDiff( $otitle, $ntitle ) {
 305                 $body = $this->getDiffBody();
 306                 if ( $body === false ) {
 307                         return false;
 308                 } else {
 309                         return $this->addHeader( $body, $otitle, $ntitle );
 310                 }
 311         }
 312
 313         /**
 314          * Get the diff table body, without header
 315          * Returns false on error
 316          */
 317         function getDiffBody() {
 318                 global $wgUseExternalDiffEngine, $wgContLang, $wgMemc, $wgDBname;
 319
 320                 // Cacheable?
 321                 $key = false;
 322                 if ( $this->mOldid && $this->mNewid ) {
 323                         // Try cache
 324                         $key = "$wgDBname:diff:oldid:{$this->mOldid}:newid:{$this->mNewid}";
 325                         $difftext = $wgMemc->get( $key );
 326                         if ( $difftext ) {
 327                                 wfIncrStats( 'diff_cache_hit' );
 328                                 return $difftext;
 329                         }
 330                 }
 331
 332                 if ( !$this->loadText() ) {
 333                         return false;
 334                 }
 335
 336                 $otext = $wgContLang->segmentForDiff($this->mOldtext);
 337                 $ntext = $wgContLang->segmentForDiff($this->mNewtext);
 338                 if ( $wgUseExternalDiffEngine ) {
 339                         # For historical reasons, external diff engine expects
 340                         # input text to be HTML-escaped already
 341                         $otext = str_replace( "\r\n", "\n", htmlspecialchars ( $otext ) );
 342                         $ntext = str_replace( "\r\n", "\n", htmlspecialchars ( $ntext ) );
 343                         if( !function_exists( 'wikidiff_do_diff' ) ) {
 344                                 dl('php_wikidiff.so');
 345                         }
 346                         $difftext = wikidiff_do_diff( $otext, $ntext, 2 );
 347                 } else {
 348                         $ota = explode( "\n", str_replace( "\r\n", "\n", $otext ) );
 349                         $nta = explode( "\n", str_replace( "\r\n", "\n", $ntext ) );
 350                         $diffs =& new Diff( $ota, $nta );
 351                         $formatter =& new TableDiffFormatter();
 352                         $difftext = $formatter->format( $diffs );
 353                 }
 354                 $difftext = $wgContLang->unsegmentForDiff($difftext);
 355
 356                 // Save to cache for 7 days
 357                 if ( $key !== false ) {
 358                         wfIncrStats( 'diff_cache_miss' );
 359                         $wgMemc->set( $key, $difftext, 7*86400 );
 360                 } else {
 361                         wfIncrStats( 'diff_uncacheable' );
 362                 }
 363                 return $difftext;
 364         }
 365
 366         /**
 367          * Add the header to a diff body
 368          */
 369         function addHeader( $diff, $otitle, $ntitle ) {
 370                 $out = "
 371                         <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
 372                         <tr>
 373                                 <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
 374                                 <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
 375                         </tr>
 376                         $diff
 377                         </table>
 378                 ";
 379                 return $out;
 380         }
 381
 382         /**
 383          * Use specified text instead of loading from the database
 384          */
 385         function setText( $oldText, $newText ) {
 386                 $this->mOldtext = $oldText;
 387                 $this->mNewtext = $newText;
 388                 $this->mTextLoaded = 2;
 389         }
 390
 391         /**
 392          * Load revision metadata for the specified articles. If newid is 0, then compare
 393          * the old article in oldid to the current article; if oldid is 0, then
 394          * compare the current article to the immediately previous one (ignoring the
 395          * value of newid).
 396          *
 397          * If oldid is false, leave the corresponding revision object set
 398          * to false. This is impossible via ordinary user input, and is provided for
 399          * API convenience.
 400          */
 401         function loadRevisionData() {
 402                 global $wgLang;
 403                 if ( $this->mRevisionsLoaded ) {
 404                         return true;
 405                 } else {
 406                         // Whether it succeeds or fails, we don't want to try again
 407                         $this->mRevisionsLoaded = true;
 408                 }
 409
 410                 // Load the new revision object
 411                 if( $this->mNewid ) {
 412                         $this->mNewRev = Revision::newFromId( $this->mNewid );
 413                 } else {
 414                         $this->mNewRev = Revision::newFromTitle( $this->mTitle );
 415                 }
 416
 417                 if( is_null( $this->mNewRev ) ) {
 418                         return false;
 419                 }
 420
 421                 // Set assorted variables
 422                 if( $this->mNewRev->isCurrent() ) {
 423                         $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
 424                         $this->mNewPage = $this->mTitle;
 425                         $newLink = $this->mNewPage->escapeLocalUrl();
 426                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 427                 } else {
 428                         $this->mNewPage = $this->mNewRev->getTitle();
 429                         $newLink = $this->mNewPage->escapeLocalUrl ('oldid=' . $this->mNewid );
 430                         $t = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 431                         $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
 432                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 433                 }
 434
 435                 $this->mNewUser = $this->mNewRev->getUserText();
 436                 $this->mNewComment = $this->mNewRev->getComment();
 437
 438                 // Load the old revision object
 439                 $this->mOldRev = false;
 440                 if( $this->mOldid ) {
 441                         $this->mOldRev = Revision::newFromId( $this->mOldid );
 442                 } elseif ( $this->mOldid === 0 ) {
 443                         $this->mOldRev = $this->mNewRev->getPrevious();
 444                         $this->mOldid = $this->mOldRev->getId();
 445                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
 446
 447                 if( is_null( $this->mOldRev ) ) {
 448                         return false;
 449                 }
 450
 451                 if ( $this->mOldRev ) {
 452                         $this->mOldPage = $this->mOldRev->getTitle();
 453
 454                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
 455                         $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
 456                         $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
 457
 458
 459                         $this->mOldUser = $this->mOldRev->getUserText();
 460                         $this->mOldComment = $this->mOldRev->getComment();
 461                 }
 462
 463                 return true;
 464         }
 465
 466         /**
 467          * Load the text of the revisions, as well as revision data.
 468          */
 469         function loadText() {
 470                 if ( $this->mTextLoaded == 2 ) {
 471                         return true;
 472                 } else {
 473                         // Whether it succeeds or fails, we don't want to try again
 474                         $this->mTextLoaded = 2;
 475                 }
 476
 477                 if ( !$this->loadRevisionData() ) {
 478                         return false;
 479                 }
 480                 if ( $this->mOldRev ) {
 481                         $this->mOldtext = $this->mOldRev->getText();
 482                 }
 483                 if ( $this->mNewRev ) {
 484                         $this->mNewtext = $this->mNewRev->getText();
 485                 }
 486                 return true;
 487         }
 488
 489         /**
 490          * Load the text of the new revision, not the old one
 491          */
 492         function loadNewText() {
 493                 if ( $this->mTextLoaded >= 1 ) {
 494                         return true;
 495                 } else {
 496                         $this->mTextLoaded = 1;
 497                 }
 498                 if ( !$this->loadRevisionData() ) {
 499                         return false;
 500                 }
 501                 $this->mNewtext = $this->mNewRev->getText();
 502                 return true;
 503         }
 504
 505
 506 }
 507
 508 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 509 //
 510 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 511 // You may copy this code freely under the conditions of the GPL.
 512 //
 513
 514 define('USE_ASSERTS', function_exists('assert'));
 515
 516 /**
 517  * @todo document
 518  * @access private
 519  * @package MediaWiki
 520  * @subpackage DifferenceEngine
 521  */
 522 class _DiffOp {
 523         var $type;
 524         var $orig;
 525         var $closing;
 526
 527         function reverse() {
 528                 trigger_error('pure virtual', E_USER_ERROR);
 529         }
 530
 531         function norig() {
 532                 return $this->orig ? sizeof($this->orig) : 0;
 533         }
 534
 535         function nclosing() {
 536                 return $this->closing ? sizeof($this->closing) : 0;
 537         }
 538 }
 539
 540 /**
 541  * @todo document
 542  * @access private
 543  * @package MediaWiki
 544  * @subpackage DifferenceEngine
 545  */
 546 class _DiffOp_Copy extends _DiffOp {
 547         var $type = 'copy';
 548
 549         function _DiffOp_Copy ($orig, $closing = false) {
 550                 if (!is_array($closing))
 551                         $closing = $orig;
 552                 $this->orig = $orig;
 553                 $this->closing = $closing;
 554         }
 555
 556         function reverse() {
 557                 return new _DiffOp_Copy($this->closing, $this->orig);
 558         }
 559 }
 560
 561 /**
 562  * @todo document
 563  * @access private
 564  * @package MediaWiki
 565  * @subpackage DifferenceEngine
 566  */
 567 class _DiffOp_Delete extends _DiffOp {
 568         var $type = 'delete';
 569
 570         function _DiffOp_Delete ($lines) {
 571                 $this->orig = $lines;
 572                 $this->closing = false;
 573         }
 574
 575         function reverse() {
 576                 return new _DiffOp_Add($this->orig);
 577         }
 578 }
 579
 580 /**
 581  * @todo document
 582  * @access private
 583  * @package MediaWiki
 584  * @subpackage DifferenceEngine
 585  */
 586 class _DiffOp_Add extends _DiffOp {
 587         var $type = 'add';
 588
 589         function _DiffOp_Add ($lines) {
 590                 $this->closing = $lines;
 591                 $this->orig = false;
 592         }
 593
 594         function reverse() {
 595                 return new _DiffOp_Delete($this->closing);
 596         }
 597 }
 598
 599 /**
 600  * @todo document
 601  * @access private
 602  * @package MediaWiki
 603  * @subpackage DifferenceEngine
 604  */
 605 class _DiffOp_Change extends _DiffOp {
 606         var $type = 'change';
 607
 608         function _DiffOp_Change ($orig, $closing) {
 609                 $this->orig = $orig;
 610                 $this->closing = $closing;
 611         }
 612
 613         function reverse() {
 614                 return new _DiffOp_Change($this->closing, $this->orig);
 615         }
 616 }
 617
 618
 619 /**
 620  * Class used internally by Diff to actually compute the diffs.
 621  *
 622  * The algorithm used here is mostly lifted from the perl module
 623  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 624  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 625  *
 626  * More ideas are taken from:
 627  *       http://www.ics.uci.edu/~eppstein/161/960229.html
 628  *
 629  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 630  * diffutils-2.7, which can be found at:
 631  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 632  *
 633  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 634  * are my own.
 635  *
 636  * Line length limits for robustness added by Tim Starling, 2005-08-31
 637  *
 638  * @author Geoffrey T. Dairiki, Tim Starling
 639  * @access private
 640  * @package MediaWiki
 641  * @subpackage DifferenceEngine
 642  */
 643 class _DiffEngine
 644 {
 645         function diff ($from_lines, $to_lines) {
 646                 $fname = '_DiffEngine::diff';
 647                 wfProfileIn( $fname );
 648
 649                 $n_from = sizeof($from_lines);
 650                 $n_to = sizeof($to_lines);
 651
 652                 $this->xchanged = $this->ychanged = array();
 653                 $this->xv = $this->yv = array();
 654                 $this->xind = $this->yind = array();
 655                 unset($this->seq);
 656                 unset($this->in_seq);
 657                 unset($this->lcs);
 658
 659                 // Skip leading common lines.
 660                 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 661                         if ($from_lines[$skip] !== $to_lines[$skip])
 662                                 break;
 663                         $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 664                 }
 665                 // Skip trailing common lines.
 666                 $xi = $n_from; $yi = $n_to;
 667                 for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 668                         if ($from_lines[$xi] !== $to_lines[$yi])
 669                                 break;
 670                         $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 671                 }
 672
 673                 // Ignore lines which do not exist in both files.
 674                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 675                         $xhash[$this->_line_hash($from_lines[$xi])] = 1;
 676                 }
 677
 678                 for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 679                         $line = $to_lines[$yi];
 680                         if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
 681                                 continue;
 682                         $yhash[$this->_line_hash($line)] = 1;
 683                         $this->yv[] = $line;
 684                         $this->yind[] = $yi;
 685                 }
 686                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 687                         $line = $from_lines[$xi];
 688                         if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
 689                                 continue;
 690                         $this->xv[] = $line;
 691                         $this->xind[] = $xi;
 692                 }
 693
 694                 // Find the LCS.
 695                 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 696
 697                 // Merge edits when possible
 698                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 699                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 700
 701                 // Compute the edit operations.
 702                 $edits = array();
 703                 $xi = $yi = 0;
 704                 while ($xi < $n_from || $yi < $n_to) {
 705                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 706                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 707
 708                         // Skip matching "snake".
 709                         $copy = array();
 710                         while ( $xi < $n_from && $yi < $n_to
 711                                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 712                                 $copy[] = $from_lines[$xi++];
 713                                 ++$yi;
 714                         }
 715                         if ($copy)
 716                                 $edits[] = new _DiffOp_Copy($copy);
 717
 718                         // Find deletes & adds.
 719                         $delete = array();
 720                         while ($xi < $n_from && $this->xchanged[$xi])
 721                                 $delete[] = $from_lines[$xi++];
 722
 723                         $add = array();
 724                         while ($yi < $n_to && $this->ychanged[$yi])
 725                                 $add[] = $to_lines[$yi++];
 726
 727                         if ($delete && $add)
 728                                 $edits[] = new _DiffOp_Change($delete, $add);
 729                         elseif ($delete)
 730                                 $edits[] = new _DiffOp_Delete($delete);
 731                         elseif ($add)
 732                                 $edits[] = new _DiffOp_Add($add);
 733                 }
 734                 wfProfileOut( $fname );
 735                 return $edits;
 736         }
 737
 738         /**
 739          * Returns the whole line if it's small enough, or the MD5 hash otherwise
 740          */
 741         function _line_hash( $line ) {
 742                 if ( strlen( $line ) > MAX_DIFF_XREF_LENGTH ) {
 743                         return md5( $line );
 744                 } else {
 745                         return $line;
 746                 }
 747         }
 748
 749
 750         /* Divide the Largest Common Subsequence (LCS) of the sequences
 751          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 752          * sized segments.
 753          *
 754          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
 755          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 756          * sub sequences.  The first sub-sequence is contained in [X0, X1),
 757          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 758          * that (X0, Y0) == (XOFF, YOFF) and
 759          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 760          *
 761          * This function assumes that the first lines of the specified portions
 762          * of the two files do not match, and likewise that the last lines do not
 763          * match.  The caller must trim matching lines from the beginning and end
 764          * of the portions it is going to specify.
 765          */
 766         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
 767                 $fname = '_DiffEngine::_diag';
 768                 wfProfileIn( $fname );
 769                 $flip = false;
 770
 771                 if ($xlim - $xoff > $ylim - $yoff) {
 772                         // Things seems faster (I'm not sure I understand why)
 773                                 // when the shortest sequence in X.
 774                                 $flip = true;
 775                         list ($xoff, $xlim, $yoff, $ylim)
 776                         = array( $yoff, $ylim, $xoff, $xlim);
 777                 }
 778
 779                 if ($flip)
 780                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 781                                 $ymatches[$this->xv[$i]][] = $i;
 782                 else
 783                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 784                                 $ymatches[$this->yv[$i]][] = $i;
 785
 786                 $this->lcs = 0;
 787                 $this->seq[0]= $yoff - 1;
 788                 $this->in_seq = array();
 789                 $ymids[0] = array();
 790
 791                 $numer = $xlim - $xoff + $nchunks - 1;
 792                 $x = $xoff;
 793                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
 794                         wfProfileIn( "$fname-chunk" );
 795                         if ($chunk > 0)
 796                                 for ($i = 0; $i <= $this->lcs; $i++)
 797                                         $ymids[$i][$chunk-1] = $this->seq[$i];
 798
 799                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
 800                         for ( ; $x < $x1; $x++) {
 801                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 802                                         if (empty($ymatches[$line]))
 803                                                 continue;
 804                                 $matches = $ymatches[$line];
 805                                 reset($matches);
 806                                 while (list ($junk, $y) = each($matches))
 807                                         if (empty($this->in_seq[$y])) {
 808                                                 $k = $this->_lcs_pos($y);
 809                                                 USE_ASSERTS && assert($k > 0);
 810                                                 $ymids[$k] = $ymids[$k-1];
 811                                                 break;
 812                                         }
 813                                 while (list ($junk, $y) = each($matches)) {
 814                                         if ($y > $this->seq[$k-1]) {
 815                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
 816                                                 // Optimization: this is a common case:
 817                                                 //      next match is just replacing previous match.
 818                                                 $this->in_seq[$this->seq[$k]] = false;
 819                                                 $this->seq[$k] = $y;
 820                                                 $this->in_seq[$y] = 1;
 821                                         } else if (empty($this->in_seq[$y])) {
 822                                                 $k = $this->_lcs_pos($y);
 823                                                 USE_ASSERTS && assert($k > 0);
 824                                                 $ymids[$k] = $ymids[$k-1];
 825                                         }
 826                                 }
 827                         }
 828                         wfProfileOut( "$fname-chunk" );
 829                 }
 830
 831                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
 832                 $ymid = $ymids[$this->lcs];
 833                 for ($n = 0; $n < $nchunks - 1; $n++) {
 834                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
 835                         $y1 = $ymid[$n] + 1;
 836                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
 837                 }
 838                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 839
 840                 wfProfileOut( $fname );
 841                 return array($this->lcs, $seps);
 842         }
 843
 844         function _lcs_pos ($ypos) {
 845                 $fname = '_DiffEngine::_lcs_pos';
 846                 wfProfileIn( $fname );
 847
 848                 $end = $this->lcs;
 849                 if ($end == 0 || $ypos > $this->seq[$end]) {
 850                         $this->seq[++$this->lcs] = $ypos;
 851                         $this->in_seq[$ypos] = 1;
 852                         wfProfileOut( $fname );
 853                         return $this->lcs;
 854                 }
 855
 856                 $beg = 1;
 857                 while ($beg < $end) {
 858                         $mid = (int)(($beg + $end) / 2);
 859                         if ( $ypos > $this->seq[$mid] )
 860                                 $beg = $mid + 1;
 861                         else
 862                                 $end = $mid;
 863                 }
 864
 865                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
 866
 867                 $this->in_seq[$this->seq[$end]] = false;
 868                 $this->seq[$end] = $ypos;
 869                 $this->in_seq[$ypos] = 1;
 870                 wfProfileOut( $fname );
 871                 return $end;
 872         }
 873
 874         /* Find LCS of two sequences.
 875          *
 876          * The results are recorded in the vectors $this->{x,y}changed[], by
 877          * storing a 1 in the element for each line that is an insertion
 878          * or deletion (ie. is not in the LCS).
 879          *
 880          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
 881          *
 882          * Note that XLIM, YLIM are exclusive bounds.
 883          * All line numbers are origin-0 and discarded lines are not counted.
 884          */
 885         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
 886                 $fname = '_DiffEngine::_compareseq';
 887                 wfProfileIn( $fname );
 888
 889                 // Slide down the bottom initial diagonal.
 890                 while ($xoff < $xlim && $yoff < $ylim
 891                            && $this->xv[$xoff] == $this->yv[$yoff]) {
 892                         ++$xoff;
 893                         ++$yoff;
 894                 }
 895
 896                 // Slide up the top initial diagonal.
 897                 while ($xlim > $xoff && $ylim > $yoff
 898                            && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
 899                         --$xlim;
 900                         --$ylim;
 901                 }
 902
 903                 if ($xoff == $xlim || $yoff == $ylim)
 904                         $lcs = 0;
 905                 else {
 906                         // This is ad hoc but seems to work well.
 907                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
 908                         //$nchunks = max(2,min(8,(int)$nchunks));
 909                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
 910                         list ($lcs, $seps)
 911                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
 912                 }
 913
 914                 if ($lcs == 0) {
 915                         // X and Y sequences have no common subsequence:
 916                         // mark all changed.
 917                         while ($yoff < $ylim)
 918                                 $this->ychanged[$this->yind[$yoff++]] = 1;
 919                         while ($xoff < $xlim)
 920                                 $this->xchanged[$this->xind[$xoff++]] = 1;
 921                 } else {
 922                         // Use the partitions to split this problem into subproblems.
 923                         reset($seps);
 924                         $pt1 = $seps[0];
 925                         while ($pt2 = next($seps)) {
 926                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
 927                                 $pt1 = $pt2;
 928                         }
 929                 }
 930                 wfProfileOut( $fname );
 931         }
 932
 933         /* Adjust inserts/deletes of identical lines to join changes
 934          * as much as possible.
 935          *
 936          * We do something when a run of changed lines include a
 937          * line at one end and has an excluded, identical line at the other.
 938          * We are free to choose which identical line is included.
 939          * `compareseq' usually chooses the one at the beginning,
 940          * but usually it is cleaner to consider the following identical line
 941          * to be the "change".
 942          *
 943          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
 944          */
 945         function _shift_boundaries ($lines, &$changed, $other_changed) {
 946                 $fname = '_DiffEngine::_shift_boundaries';
 947                 wfProfileIn( $fname );
 948                 $i = 0;
 949                 $j = 0;
 950
 951                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
 952                 $len = sizeof($lines);
 953                 $other_len = sizeof($other_changed);
 954
 955                 while (1) {
 956                         /*
 957                          * Scan forwards to find beginning of another run of changes.
 958                          * Also keep track of the corresponding point in the other file.
 959                          *
 960                          * Throughout this code, $i and $j are adjusted together so that
 961                          * the first $i elements of $changed and the first $j elements
 962                          * of $other_changed both contain the same number of zeros
 963                          * (unchanged lines).
 964                          * Furthermore, $j is always kept so that $j == $other_len or
 965                          * $other_changed[$j] == false.
 966                          */
 967                         while ($j < $other_len && $other_changed[$j])
 968                                 $j++;
 969
 970                         while ($i < $len && ! $changed[$i]) {
 971                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 972                                 $i++; $j++;
 973                                 while ($j < $other_len && $other_changed[$j])
 974                                         $j++;
 975                         }
 976
 977                         if ($i == $len)
 978                                 break;
 979
 980                         $start = $i;
 981
 982                         // Find the end of this run of changes.
 983                         while (++$i < $len && $changed[$i])
 984                                 continue;
 985
 986                         do {
 987                                 /*
 988                                  * Record the length of this run of changes, so that
 989                                  * we can later determine whether the run has grown.
 990                                  */
 991                                 $runlength = $i - $start;
 992
 993                                 /*
 994                                  * Move the changed region back, so long as the
 995                                  * previous unchanged line matches the last changed one.
 996                                  * This merges with previous changed regions.
 997                                  */
 998                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
 999                                         $changed[--$start] = 1;
1000                                         $changed[--$i] = false;
1001                                         while ($start > 0 && $changed[$start - 1])
1002                                                 $start--;
1003                                         USE_ASSERTS && assert('$j > 0');
1004                                         while ($other_changed[--$j])
1005                                                 continue;
1006                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1007                                 }
1008
1009                                 /*
1010                                  * Set CORRESPONDING to the end of the changed run, at the last
1011                                  * point where it corresponds to a changed run in the other file.
1012                                  * CORRESPONDING == LEN means no such point has been found.
1013                                  */
1014                                 $corresponding = $j < $other_len ? $i : $len;
1015
1016                                 /*
1017                                  * Move the changed region forward, so long as the
1018                                  * first changed line matches the following unchanged one.
1019                                  * This merges with following changed regions.
1020                                  * Do this second, so that if there are no merges,
1021                                  * the changed region is moved forward as far as possible.
1022                                  */
1023                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1024                                         $changed[$start++] = false;
1025                                         $changed[$i++] = 1;
1026                                         while ($i < $len && $changed[$i])
1027                                                 $i++;
1028
1029                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1030                                         $j++;
1031                                         if ($j < $other_len && $other_changed[$j]) {
1032                                                 $corresponding = $i;
1033                                                 while ($j < $other_len && $other_changed[$j])
1034                                                         $j++;
1035                                         }
1036                                 }
1037                         } while ($runlength != $i - $start);
1038
1039                         /*
1040                          * If possible, move the fully-merged run of changes
1041                          * back to a corresponding run in the other file.
1042                          */
1043                         while ($corresponding < $i) {
1044                                 $changed[--$start] = 1;
1045                                 $changed[--$i] = 0;
1046                                 USE_ASSERTS && assert('$j > 0');
1047                                 while ($other_changed[--$j])
1048                                         continue;
1049                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1050                         }
1051                 }
1052                 wfProfileOut( $fname );
1053         }
1054 }
1055
1056 /**
1057  * Class representing a 'diff' between two sequences of strings.
1058  * @todo document
1059  * @access private
1060  * @package MediaWiki
1061  * @subpackage DifferenceEngine
1062  */
1063 class Diff
1064 {
1065         var $edits;
1066
1067         /**
1068          * Constructor.
1069          * Computes diff between sequences of strings.
1070          *
1071          * @param $from_lines array An array of strings.
1072          *                (Typically these are lines from a file.)
1073          * @param $to_lines array An array of strings.
1074          */
1075         function Diff($from_lines, $to_lines) {
1076                 $eng = new _DiffEngine;
1077                 $this->edits = $eng->diff($from_lines, $to_lines);
1078                 //$this->_check($from_lines, $to_lines);
1079         }
1080
1081         /**
1082          * Compute reversed Diff.
1083          *
1084          * SYNOPSIS:
1085          *
1086          *      $diff = new Diff($lines1, $lines2);
1087          *      $rev = $diff->reverse();
1088          * @return object A Diff object representing the inverse of the
1089          *                                original diff.
1090          */
1091         function reverse () {
1092                 $rev = $this;
1093                 $rev->edits = array();
1094                 foreach ($this->edits as $edit) {
1095                         $rev->edits[] = $edit->reverse();
1096                 }
1097                 return $rev;
1098         }
1099
1100         /**
1101          * Check for empty diff.
1102          *
1103          * @return bool True iff two sequences were identical.
1104          */
1105         function isEmpty () {
1106                 foreach ($this->edits as $edit) {
1107                         if ($edit->type != 'copy')
1108                                 return false;
1109                 }
1110                 return true;
1111         }
1112
1113         /**
1114          * Compute the length of the Longest Common Subsequence (LCS).
1115          *
1116          * This is mostly for diagnostic purposed.
1117          *
1118          * @return int The length of the LCS.
1119          */
1120         function lcs () {
1121                 $lcs = 0;
1122                 foreach ($this->edits as $edit) {
1123                         if ($edit->type == 'copy')
1124                                 $lcs += sizeof($edit->orig);
1125                 }
1126                 return $lcs;
1127         }
1128
1129         /**
1130          * Get the original set of lines.
1131          *
1132          * This reconstructs the $from_lines parameter passed to the
1133          * constructor.
1134          *
1135          * @return array The original sequence of strings.
1136          */
1137         function orig() {
1138                 $lines = array();
1139
1140                 foreach ($this->edits as $edit) {
1141                         if ($edit->orig)
1142                                 array_splice($lines, sizeof($lines), 0, $edit->orig);
1143                 }
1144                 return $lines;
1145         }
1146
1147         /**
1148          * Get the closing set of lines.
1149          *
1150          * This reconstructs the $to_lines parameter passed to the
1151          * constructor.
1152          *
1153          * @return array The sequence of strings.
1154          */
1155         function closing() {
1156                 $lines = array();
1157
1158                 foreach ($this->edits as $edit) {
1159                         if ($edit->closing)
1160                                 array_splice($lines, sizeof($lines), 0, $edit->closing);
1161                 }
1162                 return $lines;
1163         }
1164
1165         /**
1166          * Check a Diff for validity.
1167          *
1168          * This is here only for debugging purposes.
1169          */
1170         function _check ($from_lines, $to_lines) {
1171                 $fname = 'Diff::_check';
1172                 wfProfileIn( $fname );
1173                 if (serialize($from_lines) != serialize($this->orig()))
1174                         trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1175                 if (serialize($to_lines) != serialize($this->closing()))
1176                         trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1177
1178                 $rev = $this->reverse();
1179                 if (serialize($to_lines) != serialize($rev->orig()))
1180                         trigger_error("Reversed original doesn't match", E_USER_ERROR);
1181                 if (serialize($from_lines) != serialize($rev->closing()))
1182                         trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1183
1184
1185                 $prevtype = 'none';
1186                 foreach ($this->edits as $edit) {
1187                         if ( $prevtype == $edit->type )
1188                                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1189                         $prevtype = $edit->type;
1190                 }
1191
1192                 $lcs = $this->lcs();
1193                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1194                 wfProfileOut( $fname );
1195         }
1196 }
1197
1198 /**
1199  * FIXME: bad name.
1200  * @todo document
1201  * @access private
1202  * @package MediaWiki
1203  * @subpackage DifferenceEngine
1204  */
1205 class MappedDiff extends Diff
1206 {
1207         /**
1208          * Constructor.
1209          *
1210          * Computes diff between sequences of strings.
1211          *
1212          * This can be used to compute things like
1213          * case-insensitve diffs, or diffs which ignore
1214          * changes in white-space.
1215          *
1216          * @param $from_lines array An array of strings.
1217          *      (Typically these are lines from a file.)
1218          *
1219          * @param $to_lines array An array of strings.
1220          *
1221          * @param $mapped_from_lines array This array should
1222          *      have the same size number of elements as $from_lines.
1223          *      The elements in $mapped_from_lines and
1224          *      $mapped_to_lines are what is actually compared
1225          *      when computing the diff.
1226          *
1227          * @param $mapped_to_lines array This array should
1228          *      have the same number of elements as $to_lines.
1229          */
1230         function MappedDiff($from_lines, $to_lines,
1231                                                 $mapped_from_lines, $mapped_to_lines) {
1232                 $fname = 'MappedDiff::MappedDiff';
1233                 wfProfileIn( $fname );
1234
1235                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1236                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1237
1238                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1239
1240                 $xi = $yi = 0;
1241                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1242                         $orig = &$this->edits[$i]->orig;
1243                         if (is_array($orig)) {
1244                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1245                                 $xi += sizeof($orig);
1246                         }
1247
1248                         $closing = &$this->edits[$i]->closing;
1249                         if (is_array($closing)) {
1250                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1251                                 $yi += sizeof($closing);
1252                         }
1253                 }
1254                 wfProfileOut( $fname );
1255         }
1256 }
1257
1258 /**
1259  * A class to format Diffs
1260  *
1261  * This class formats the diff in classic diff format.
1262  * It is intended that this class be customized via inheritance,
1263  * to obtain fancier outputs.
1264  * @todo document
1265  * @access private
1266  * @package MediaWiki
1267  * @subpackage DifferenceEngine
1268  */
1269 class DiffFormatter
1270 {
1271         /**
1272          * Number of leading context "lines" to preserve.
1273          *
1274          * This should be left at zero for this class, but subclasses
1275          * may want to set this to other values.
1276          */
1277         var $leading_context_lines = 0;
1278
1279         /**
1280          * Number of trailing context "lines" to preserve.
1281          *
1282          * This should be left at zero for this class, but subclasses
1283          * may want to set this to other values.
1284          */
1285         var $trailing_context_lines = 0;
1286
1287         /**
1288          * Format a diff.
1289          *
1290          * @param $diff object A Diff object.
1291          * @return string The formatted output.
1292          */
1293         function format($diff) {
1294                 $fname = 'DiffFormatter::format';
1295                 wfProfileIn( $fname );
1296
1297                 $xi = $yi = 1;
1298                 $block = false;
1299                 $context = array();
1300
1301                 $nlead = $this->leading_context_lines;
1302                 $ntrail = $this->trailing_context_lines;
1303
1304                 $this->_start_diff();
1305
1306                 foreach ($diff->edits as $edit) {
1307                         if ($edit->type == 'copy') {
1308                                 if (is_array($block)) {
1309                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1310                                                 $block[] = $edit;
1311                                         }
1312                                         else{
1313                                                 if ($ntrail) {
1314                                                         $context = array_slice($edit->orig, 0, $ntrail);
1315                                                         $block[] = new _DiffOp_Copy($context);
1316                                                 }
1317                                                 $this->_block($x0, $ntrail + $xi - $x0,
1318                                                                           $y0, $ntrail + $yi - $y0,
1319                                                                           $block);
1320                                                 $block = false;
1321                                         }
1322                                 }
1323                                 $context = $edit->orig;
1324                         }
1325                         else {
1326                                 if (! is_array($block)) {
1327                                         $context = array_slice($context, sizeof($context) - $nlead);
1328                                         $x0 = $xi - sizeof($context);
1329                                         $y0 = $yi - sizeof($context);
1330                                         $block = array();
1331                                         if ($context)
1332                                                 $block[] = new _DiffOp_Copy($context);
1333                                 }
1334                                 $block[] = $edit;
1335                         }
1336
1337                         if ($edit->orig)
1338                                 $xi += sizeof($edit->orig);
1339                         if ($edit->closing)
1340                                 $yi += sizeof($edit->closing);
1341                 }
1342
1343                 if (is_array($block))
1344                         $this->_block($x0, $xi - $x0,
1345                                                   $y0, $yi - $y0,
1346                                                   $block);
1347
1348                 $end = $this->_end_diff();
1349                 wfProfileOut( $fname );
1350                 return $end;
1351         }
1352
1353         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1354                 $fname = 'DiffFormatter::_block';
1355                 wfProfileIn( $fname );
1356                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1357                 foreach ($edits as $edit) {
1358                         if ($edit->type == 'copy')
1359                                 $this->_context($edit->orig);
1360                         elseif ($edit->type == 'add')
1361                                 $this->_added($edit->closing);
1362                         elseif ($edit->type == 'delete')
1363                                 $this->_deleted($edit->orig);
1364                         elseif ($edit->type == 'change')
1365                                 $this->_changed($edit->orig, $edit->closing);
1366                         else
1367                                 trigger_error('Unknown edit type', E_USER_ERROR);
1368                 }
1369                 $this->_end_block();
1370                 wfProfileOut( $fname );
1371         }
1372
1373         function _start_diff() {
1374                 ob_start();
1375         }
1376
1377         function _end_diff() {
1378                 $val = ob_get_contents();
1379                 ob_end_clean();
1380                 return $val;
1381         }
1382
1383         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1384                 if ($xlen > 1)
1385                         $xbeg .= "," . ($xbeg + $xlen - 1);
1386                 if ($ylen > 1)
1387                         $ybeg .= "," . ($ybeg + $ylen - 1);
1388
1389                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1390         }
1391
1392         function _start_block($header) {
1393                 echo $header;
1394         }
1395
1396         function _end_block() {
1397         }
1398
1399         function _lines($lines, $prefix = ' ') {
1400                 foreach ($lines as $line)
1401                         echo "$prefix $line\n";
1402         }
1403
1404         function _context($lines) {
1405                 $this->_lines($lines);
1406         }
1407
1408         function _added($lines) {
1409                 $this->_lines($lines, '>');
1410         }
1411         function _deleted($lines) {
1412                 $this->_lines($lines, '<');
1413         }
1414
1415         function _changed($orig, $closing) {
1416                 $this->_deleted($orig);
1417                 echo "---\n";
1418                 $this->_added($closing);
1419         }
1420 }
1421
1422
1423 /**
1424  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1425  *
1426  */
1427
1428 define('NBSP', '&#160;');                       // iso-8859-x non-breaking space.
1429
1430 /**
1431  * @todo document
1432  * @access private
1433  * @package MediaWiki
1434  * @subpackage DifferenceEngine
1435  */
1436 class _HWLDF_WordAccumulator {
1437         function _HWLDF_WordAccumulator () {
1438                 $this->_lines = array();
1439                 $this->_line = '';
1440                 $this->_group = '';
1441                 $this->_tag = '';
1442         }
1443
1444         function _flushGroup ($new_tag) {
1445                 if ($this->_group !== '') {
1446                         if ($this->_tag == 'mark')
1447                                 $this->_line .= '<span class="diffchange">' .
1448                                         htmlspecialchars ( $this->_group ) . '</span>';
1449                         else
1450                                 $this->_line .= htmlspecialchars ( $this->_group );
1451                 }
1452                 $this->_group = '';
1453                 $this->_tag = $new_tag;
1454         }
1455
1456         function _flushLine ($new_tag) {
1457                 $this->_flushGroup($new_tag);
1458                 if ($this->_line != '')
1459                         array_push ( $this->_lines, $this->_line );
1460                 else
1461                         # make empty lines visible by inserting an NBSP
1462                         array_push ( $this->_lines, NBSP );
1463                 $this->_line = '';
1464         }
1465
1466         function addWords ($words, $tag = '') {
1467                 if ($tag != $this->_tag)
1468                         $this->_flushGroup($tag);
1469
1470                 foreach ($words as $word) {
1471                         // new-line should only come as first char of word.
1472                         if ($word == '')
1473                                 continue;
1474                         if ($word[0] == "\n") {
1475                                 $this->_flushLine($tag);
1476                                 $word = substr($word, 1);
1477                         }
1478                         assert(!strstr($word, "\n"));
1479                         $this->_group .= $word;
1480                 }
1481         }
1482
1483         function getLines() {
1484                 $this->_flushLine('~done');
1485                 return $this->_lines;
1486         }
1487 }
1488
1489 /**
1490  * @todo document
1491  * @access private
1492  * @package MediaWiki
1493  * @subpackage DifferenceEngine
1494  */
1495 class WordLevelDiff extends MappedDiff
1496 {
1497         function WordLevelDiff ($orig_lines, $closing_lines) {
1498                 $fname = 'WordLevelDiff::WordLevelDiff';
1499                 wfProfileIn( $fname );
1500
1501                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1502                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1503
1504                 $this->MappedDiff($orig_words, $closing_words,
1505                                                   $orig_stripped, $closing_stripped);
1506                 wfProfileOut( $fname );
1507         }
1508
1509         function _split($lines) {
1510                 $fname = 'WordLevelDiff::_split';
1511                 wfProfileIn( $fname );
1512
1513                 $words = array();
1514                 $stripped = array();
1515                 $first = true;
1516                 foreach ( $lines as $line ) {
1517                         # If the line is too long, just pretend the entire line is one big word
1518                         # This prevents resource exhaustion problems
1519                         if ( $first ) {
1520                                 $first = false;
1521                         } else {
1522                                 $words[] = "\n";
1523                                 $stripped[] = "\n";
1524                         }
1525                         if ( strlen( $line ) > MAX_DIFF_LINE ) {
1526                                 $words[] = $line;
1527                                 $stripped[] = $line;
1528                         } else {
1529                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1530                                         $line, $m))
1531                                 {
1532                                         $words = array_merge( $words, $m[0] );
1533                                         $stripped = array_merge( $stripped, $m[1] );
1534                                 }
1535                         }
1536                 }
1537                 wfProfileOut( $fname );
1538                 return array($words, $stripped);
1539         }
1540
1541         function orig () {
1542                 $fname = 'WordLevelDiff::orig';
1543                 wfProfileIn( $fname );
1544                 $orig = new _HWLDF_WordAccumulator;
1545
1546                 foreach ($this->edits as $edit) {
1547                         if ($edit->type == 'copy')
1548                                 $orig->addWords($edit->orig);
1549                         elseif ($edit->orig)
1550                                 $orig->addWords($edit->orig, 'mark');
1551                 }
1552                 $lines = $orig->getLines();
1553                 wfProfileOut( $fname );
1554                 return $lines;
1555         }
1556
1557         function closing () {
1558                 $fname = 'WordLevelDiff::closing';
1559                 wfProfileIn( $fname );
1560                 $closing = new _HWLDF_WordAccumulator;
1561
1562                 foreach ($this->edits as $edit) {
1563                         if ($edit->type == 'copy')
1564                                 $closing->addWords($edit->closing);
1565                         elseif ($edit->closing)
1566                                 $closing->addWords($edit->closing, 'mark');
1567                 }
1568                 $lines = $closing->getLines();
1569                 wfProfileOut( $fname );
1570                 return $lines;
1571         }
1572 }
1573
1574 /**
1575  *      Wikipedia Table style diff formatter.
1576  * @todo document
1577  * @access private
1578  * @package MediaWiki
1579  * @subpackage DifferenceEngine
1580  */
1581 class TableDiffFormatter extends DiffFormatter
1582 {
1583         function TableDiffFormatter() {
1584                 $this->leading_context_lines = 2;
1585                 $this->trailing_context_lines = 2;
1586         }
1587
1588         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1589                 $l1 = wfMsg( 'lineno', $xbeg );
1590                 $l2 = wfMsg( 'lineno', $ybeg );
1591
1592                 $r = '<tr><td colspan="2" align="left"><strong>'.$l1."</strong></td>\n" .
1593                   '<td colspan="2" align="left"><strong>'.$l2."</strong></td></tr>\n";
1594                 return $r;
1595         }
1596
1597         function _start_block( $header ) {
1598                 global $wgOut;
1599                 echo $header;
1600         }
1601
1602         function _end_block() {
1603         }
1604
1605         function _lines( $lines, $prefix=' ', $color='white' ) {
1606         }
1607
1608         # HTML-escape parameter before calling this
1609         function addedLine( $line ) {
1610                 return "<td>+</td><td class='diff-addedline'>{$line}</td>";
1611         }
1612
1613         # HTML-escape parameter before calling this
1614         function deletedLine( $line ) {
1615                 return "<td>-</td><td class='diff-deletedline'>{$line}</td>";
1616         }
1617
1618         # HTML-escape parameter before calling this
1619         function contextLine( $line ) {
1620                 return "<td> </td><td class='diff-context'>{$line}</td>";
1621         }
1622
1623         function emptyLine() {
1624                 return '<td colspan="2">&nbsp;</td>';
1625         }
1626
1627         function _added( $lines ) {
1628                 foreach ($lines as $line) {
1629                         echo '<tr>' . $this->emptyLine() .
1630                                 $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1631                 }
1632         }
1633
1634         function _deleted($lines) {
1635                 foreach ($lines as $line) {
1636                         echo '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
1637                           $this->emptyLine() . "</tr>\n";
1638                 }
1639         }
1640
1641         function _context( $lines ) {
1642                 foreach ($lines as $line) {
1643                         echo '<tr>' .
1644                                 $this->contextLine( htmlspecialchars ( $line ) ) .
1645                                 $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1646                 }
1647         }
1648
1649         function _changed( $orig, $closing ) {
1650                 $fname = 'TableDiffFormatter::_changed';
1651                 wfProfileIn( $fname );
1652
1653                 $diff = new WordLevelDiff( $orig, $closing );
1654                 $del = $diff->orig();
1655                 $add = $diff->closing();
1656
1657                 # Notice that WordLevelDiff returns HTML-escaped output.
1658                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
1659
1660                 while ( $line = array_shift( $del ) ) {
1661                         $aline = array_shift( $add );
1662                         echo '<tr>' . $this->deletedLine( $line ) .
1663                                 $this->addedLine( $aline ) . "</tr>\n";
1664                 }
1665                 foreach ($add as $line) {       # If any leftovers
1666                         echo '<tr>' . $this->emptyLine() .
1667                                 $this->addedLine( $line ) . "</tr>\n";
1668                 }
1669                 wfProfileOut( $fname );
1670         }
1671 }
1672
1673 ?>