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 = $titleObj;
  45                 wfDebug("DifferenceEngine old '$old' new '$new' rcid '$rcid'\n");
  46
  47                 if ( 'prev' == $new ) {
  48                         # Show diff between revision $old and the previous one.
  49                         # Get previous one from DB.
  50                         #
  51                         $this->mNewid = intval($old);
  52
  53                         $this->mOldid = $this->mTitle->getPreviousRevisionID( $this->mNewid );
  54
  55                 } elseif ( 'next' == $new ) {
  56                         # Show diff between revision $old and the previous one.
  57                         # Get previous one from DB.
  58                         #
  59                         $this->mOldid = intval($old);
  60                         $this->mNewid = $this->mTitle->getNextRevisionID( $this->mOldid );
  61                         if ( false === $this->mNewid ) {
  62                                 # if no result, NewId points to the newest old revision. The only newer
  63                                 # revision is cur, which is "0".
  64                                 $this->mNewid = 0;
  65                         }
  66
  67                 } else {
  68                         $this->mOldid = intval($old);
  69                         $this->mNewid = intval($new);
  70                 }
  71                 $this->mRcidMarkPatrolled = intval($rcid);  # force it to be an integer
  72         }
  73
  74         function showDiffPage() {
  75                 global $wgUser, $wgOut, $wgContLang, $wgOnlySysopsCanPatrol,
  76                        $wgUseExternalEditor, $wgUseRCPatrol;
  77                 $fname = 'DifferenceEngine::showDiffPage';
  78                 wfProfileIn( $fname );
  79
  80                 # If external diffs are enabled both globally and for the user,
  81                 # we'll use the application/x-external-editor interface to call
  82                 # an external diff tool like kompare, kdiff3, etc.
  83                 if($wgUseExternalEditor && $wgUser->getOption('externaldiff')) {
  84                         global $wgInputEncoding,$wgServer,$wgScript,$wgLang;
  85                         $wgOut->disable();
  86                         header ( "Content-type: application/x-external-editor; charset=".$wgInputEncoding );
  87                         $url1=$this->mTitle->getFullURL("action=raw&oldid=".$this->mOldid);
  88                         $url2=$this->mTitle->getFullURL("action=raw&oldid=".$this->mNewid);
  89                         $special=$wgLang->getNsText(NS_SPECIAL);
  90                         $control=<<<CONTROL
  91 [Process]
  92 Type=Diff text
  93 Engine=MediaWiki
  94 Script={$wgServer}{$wgScript}
  95 Special namespace={$special}
  96
  97 [File]
  98 Extension=wiki
  99 URL=$url1
 100
 101 [File 2]
 102 Extension=wiki
 103 URL=$url2
 104 CONTROL;
 105                         echo($control);
 106                         return;
 107                 }
 108
 109                 $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 110                   "{$this->mNewid})";
 111                 $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 112
 113                 $wgOut->setArticleFlag( false );
 114                 if ( ! $this->loadRevisionData() ) {
 115                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 116                         $wgOut->addWikitext( $mtext );
 117                         wfProfileOut( $fname );
 118                         return;
 119                 }
 120                 if ( $this->mNewRev->isCurrent() ) {
 121                         $wgOut->setArticleFlag( true );
 122                 }
 123
 124                 # mOldid is false if the difference engine is called with a "vague" query for
 125                 # a diff between a version V and its previous version V' AND the version V
 126                 # is the first version of that article. In that case, V' does not exist.
 127                 if ( $this->mOldid === false ) {
 128                         $this->showFirstRevision();
 129                         wfProfileOut( $fname );
 130                         return;
 131                 }
 132
 133                 $wgOut->suppressQuickbar();
 134
 135                 $oldTitle = $this->mOldPage->getPrefixedText();
 136                 $newTitle = $this->mNewPage->getPrefixedText();
 137                 if( $oldTitle == $newTitle ) {
 138                         $wgOut->setPageTitle( $newTitle );
 139                 } else {
 140                         $wgOut->setPageTitle( $oldTitle . ', ' . $newTitle );
 141                 }
 142                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 143                 $wgOut->setRobotpolicy( 'noindex,follow' );
 144
 145                 if ( !( $this->mOldPage->userCanRead() && $this->mNewPage->userCanRead() ) ) {
 146                         $wgOut->loginToUse();
 147                         $wgOut->output();
 148                         wfProfileOut( $fname );
 149                         exit;
 150                 }
 151
 152                 $sk = $wgUser->getSkin();
 153                 $talk = $wgContLang->getNsText( NS_TALK );
 154                 $contribs = wfMsg( 'contribslink' );
 155
 156                 $this->mOldComment = $sk->formatComment($this->mOldComment);
 157                 $this->mNewComment = $sk->formatComment($this->mNewComment);
 158
 159                 $oldUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 160                 $newUserLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mNewUser ), $this->mNewUser );
 161                 $oldUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ), $talk );
 162                 $newUTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mNewUser ), $talk );
 163                 $oldContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 164                         'target=' . urlencode($this->mOldUser) );
 165                 $newContribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), $contribs,
 166                         'target=' . urlencode($this->mNewUser) );
 167                 if ( $this->mNewRev->isCurrent() && $wgUser->isAllowed('rollback') ) {
 168                         $rollback = '&nbsp;&nbsp;&nbsp;<strong>[' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'rollbacklink' ),
 169                                 'action=rollback&from=' . urlencode($this->mNewUser) .
 170                                 '&token=' . urlencode( $wgUser->editToken( array( $this->mTitle->getPrefixedText(), $this->mNewUser ) ) ) ) .
 171                                 ']</strong>';
 172                 } else {
 173                         $rollback = '';
 174                 }
 175                 if ( $wgUseRCPatrol && $this->mRcidMarkPatrolled != 0 && $wgUser->isLoggedIn() &&
 176                      ( $wgUser->isAllowed('rollback') || !$wgOnlySysopsCanPatrol ) )
 177                 {
 178                         $patrol = ' [' . $sk->makeKnownLinkObj( $this->mTitle, wfMsg( 'markaspatrolleddiff' ),
 179                                 "action=markpatrolled&rcid={$this->mRcidMarkPatrolled}" ) . ']';
 180                 } else {
 181                         $patrol = '';
 182                 }
 183
 184                 $prevlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'previousdiff' ),
 185                         'diff=prev&oldid='.$this->mOldid, '', '', 'id="differences-prevlink"' );
 186                 if ( $this->mNewRev->isCurrent() ) {
 187                         $nextlink = '';
 188                 } else {
 189                         $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ),
 190                                 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 191                 }
 192
 193                 $oldHeader = "<strong>{$this->mOldtitle}</strong><br />$oldUserLink " .
 194                         "($oldUTLink | $oldContribs)<br />" . $this->mOldComment .
 195                         '<br />' . $prevlink;
 196                 $newHeader = "<strong>{$this->mNewtitle}</strong><br />$newUserLink " .
 197                         "($newUTLink | $newContribs) $rollback<br />" . $this->mNewComment .
 198                         '<br />' . $nextlink . $patrol;
 199
 200                 $this->showDiff( $oldHeader, $newHeader );
 201                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 202
 203                 if( !$this->mNewRev->isCurrent() ) {
 204                         $oldEditSectionSetting = $wgOut->mParserOptions->setEditSection( false );
 205                 }
 206
 207                 $this->loadNewText();
 208                 if( is_object( $this->mNewRev ) ) {
 209                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 210                 }
 211                 $wgOut->addSecondaryWikiText( $this->mNewtext );
 212
 213                 if( !$this->mNewRev->isCurrent() ) {
 214                         $wgOut->mParserOptions->setEditSection( $oldEditSectionSetting );
 215                 }
 216
 217                 wfProfileOut( $fname );
 218         }
 219
 220         /**
 221          * Show the first revision of an article. Uses normal diff headers in
 222          * contrast to normal "old revision" display style.
 223          */
 224         function showFirstRevision() {
 225                 global $wgOut, $wgUser, $wgLang;
 226
 227                 $fname = 'DifferenceEngine::showFirstRevision';
 228                 wfProfileIn( $fname );
 229
 230                 # Get article text from the DB
 231                 #
 232                 if ( ! $this->loadNewText() ) {
 233                         $t = $this->mTitle->getPrefixedText() . " (Diff: {$this->mOldid}, " .
 234                           "{$this->mNewid})";
 235                         $mtext = wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" );
 236                         $wgOut->setPagetitle( wfMsg( 'errorpagetitle' ) );
 237                         $wgOut->addWikitext( $mtext );
 238                         wfProfileOut( $fname );
 239                         return;
 240                 }
 241                 if ( $this->mNewRev->isCurrent() ) {
 242                         $wgOut->setArticleFlag( true );
 243                 }
 244
 245                 # Check if user is allowed to look at this page. If not, bail out.
 246                 #
 247                 if ( !( $this->mTitle->userCanRead() ) ) {
 248                         $wgOut->loginToUse();
 249                         $wgOut->output();
 250                         wfProfileOut( $fname );
 251                         exit;
 252                 }
 253
 254                 # Prepare the header box
 255                 #
 256                 $sk = $wgUser->getSkin();
 257
 258                 $uTLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER_TALK, $this->mOldUser ),  $wgLang->getNsText( NS_TALK ) );
 259                 $userLink = $sk->makeLinkObj( Title::makeTitleSafe( NS_USER, $this->mOldUser ), $this->mOldUser );
 260                 $contribs = $sk->makeKnownLinkObj( Title::makeTitle( NS_SPECIAL, 'Contributions' ), wfMsg( 'contribslink' ),
 261                         'target=' . urlencode($this->mOldUser) );
 262                 $nextlink = $sk->makeKnownLinkObj( $this->mTitle, wfMsgHtml( 'nextdiff' ), 'diff=next&oldid='.$this->mNewid, '', '', 'id="differences-nextlink"' );
 263                 $header = "<div class=\"firstrevisionheader\" style=\"text-align: center\"><strong>{$this->mOldtitle}</strong><br />$userLink " .
 264                         "($uTLink | $contribs)<br />" . $this->mOldComment .
 265                         '<br />' . $nextlink. "</div>\n";
 266
 267                 $wgOut->addHTML( $header );
 268
 269                 $wgOut->setSubtitle( wfMsg( 'difference' ) );
 270                 $wgOut->setRobotpolicy( 'noindex,follow' );
 271
 272
 273                 # Show current revision
 274                 #
 275                 $wgOut->addHTML( "<hr /><h2>{$this->mPagetitle}</h2>\n" );
 276                 if( is_object( $this->mNewRev ) ) {
 277                         $wgOut->setRevisionId( $this->mNewRev->getId() );
 278                 }
 279                 $wgOut->addSecondaryWikiText( $this->mNewtext );
 280
 281                 wfProfileOut( $fname );
 282         }
 283
 284         /**
 285          * Get the diff text, send it to $wgOut
 286          * Returns false if the diff could not be generated, otherwise returns true
 287          */
 288         function showDiff( $otitle, $ntitle ) {
 289                 global $wgOut;
 290                 $diff = $this->getDiff( $otitle, $ntitle );
 291                 if ( $diff === false ) {
 292                         $wgOut->addWikitext( wfMsg( 'missingarticle', "<nowiki>$t</nowiki>" ) );
 293                         return false;
 294                 } else {
 295                         $wgOut->addHTML( $diff );
 296                         return true;
 297                 }
 298         }
 299
 300         /**
 301          * Get diff table, including header
 302          * Note that the interface has changed, it's no longer static.
 303          * Returns false on error
 304          */
 305         function getDiff( $otitle, $ntitle ) {
 306                 $body = $this->getDiffBody();
 307                 if ( $body === false ) {
 308                         return false;
 309                 } else {
 310                         return $this->addHeader( $body, $otitle, $ntitle );
 311                 }
 312         }
 313
 314         /**
 315          * Get the diff table body, without header
 316          * Returns false on error
 317          */
 318         function getDiffBody() {
 319                 global $wgUseExternalDiffEngine, $wgContLang, $wgMemc, $wgDBname;
 320
 321                 // Cacheable?
 322                 $key = false;
 323                 if ( $this->mOldid && $this->mNewid ) {
 324                         // Try cache
 325                         $key = "$wgDBname:diff:oldid:{$this->mOldid}:newid:{$this->mNewid}";
 326                         $difftext = $wgMemc->get( $key );
 327                         if ( $difftext ) {
 328                                 wfIncrStats( 'diff_cache_hit' );
 329                                 $difftext .= "\n<!-- diff cache key $key -->\n";
 330                                 return $difftext;
 331                         }
 332                 }
 333
 334                 if ( !$this->loadText() ) {
 335                         return false;
 336                 }
 337
 338                 $otext = $wgContLang->segmentForDiff($this->mOldtext);
 339                 $ntext = $wgContLang->segmentForDiff($this->mNewtext);
 340                 if ( $wgUseExternalDiffEngine ) {
 341                         # For historical reasons, external diff engine expects
 342                         # input text to be HTML-escaped already
 343                         $otext = str_replace( "\r\n", "\n", htmlspecialchars ( $otext ) );
 344                         $ntext = str_replace( "\r\n", "\n", htmlspecialchars ( $ntext ) );
 345                         if( !function_exists( 'wikidiff_do_diff' ) ) {
 346                                 dl('php_wikidiff.so');
 347                         }
 348                         $difftext = wikidiff_do_diff( $otext, $ntext, 2 );
 349                 } else {
 350                         $ota = explode( "\n", str_replace( "\r\n", "\n", $otext ) );
 351                         $nta = explode( "\n", str_replace( "\r\n", "\n", $ntext ) );
 352                         $diffs =& new Diff( $ota, $nta );
 353                         $formatter =& new TableDiffFormatter();
 354                         $difftext = $formatter->format( $diffs );
 355                 }
 356                 $difftext = $wgContLang->unsegmentForDiff($difftext);
 357
 358                 // Save to cache for 7 days
 359                 if ( $key !== false ) {
 360                         wfIncrStats( 'diff_cache_miss' );
 361                         $wgMemc->set( $key, $difftext, 7*86400 );
 362                 } else {
 363                         wfIncrStats( 'diff_uncacheable' );
 364                 }
 365                 return $difftext;
 366         }
 367
 368         /**
 369          * Add the header to a diff body
 370          */
 371         function addHeader( $diff, $otitle, $ntitle ) {
 372                 $out = "
 373                         <table border='0' width='98%' cellpadding='0' cellspacing='4' class='diff'>
 374                         <tr>
 375                                 <td colspan='2' width='50%' align='center' class='diff-otitle'>{$otitle}</td>
 376                                 <td colspan='2' width='50%' align='center' class='diff-ntitle'>{$ntitle}</td>
 377                         </tr>
 378                         $diff
 379                         </table>
 380                 ";
 381                 return $out;
 382         }
 383
 384         /**
 385          * Use specified text instead of loading from the database
 386          */
 387         function setText( $oldText, $newText ) {
 388                 $this->mOldtext = $oldText;
 389                 $this->mNewtext = $newText;
 390                 $this->mTextLoaded = 2;
 391         }
 392
 393         /**
 394          * Load revision metadata for the specified articles. If newid is 0, then compare
 395          * the old article in oldid to the current article; if oldid is 0, then
 396          * compare the current article to the immediately previous one (ignoring the
 397          * value of newid).
 398          *
 399          * If oldid is false, leave the corresponding revision object set
 400          * to false. This is impossible via ordinary user input, and is provided for
 401          * API convenience.
 402          */
 403         function loadRevisionData() {
 404                 global $wgLang;
 405                 if ( $this->mRevisionsLoaded ) {
 406                         return true;
 407                 } else {
 408                         // Whether it succeeds or fails, we don't want to try again
 409                         $this->mRevisionsLoaded = true;
 410                 }
 411
 412                 // Load the new revision object
 413                 if( $this->mNewid ) {
 414                         $this->mNewRev = Revision::newFromId( $this->mNewid );
 415                 } else {
 416                         $this->mNewRev = Revision::newFromTitle( $this->mTitle );
 417                 }
 418
 419                 if( is_null( $this->mNewRev ) ) {
 420                         return false;
 421                 }
 422
 423                 // Set assorted variables
 424                 if( $this->mNewRev->isCurrent() ) {
 425                         $this->mPagetitle = htmlspecialchars( wfMsg( 'currentrev' ) );
 426                         $this->mNewPage = $this->mTitle;
 427                         $newLink = $this->mNewPage->escapeLocalUrl();
 428                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 429                 } else {
 430                         $this->mNewPage = $this->mNewRev->getTitle();
 431                         $newLink = $this->mNewPage->escapeLocalUrl ('oldid=' . $this->mNewid );
 432                         $t = $wgLang->timeanddate( $this->mNewRev->getTimestamp(), true );
 433                         $this->mPagetitle = htmlspecialchars( wfMsg( 'revisionasof', $t ) );
 434                         $this->mNewtitle = "<a href='$newLink'>{$this->mPagetitle}</a>";
 435                 }
 436
 437                 $this->mNewUser = $this->mNewRev->getUserText();
 438                 $this->mNewComment = $this->mNewRev->getComment();
 439
 440                 // Load the old revision object
 441                 $this->mOldRev = false;
 442                 if( $this->mOldid ) {
 443                         $this->mOldRev = Revision::newFromId( $this->mOldid );
 444                 } elseif ( $this->mOldid === 0 ) {
 445                         $rev = $this->mNewRev->getPrevious();
 446                         if( $rev ) {
 447                                 $this->mOldid = $rev->getId();
 448                                 $this->mOldRev = $rev;
 449                         } else {
 450                                 // No previous revision; mark to show as first-version only.
 451                                 $this->mOldid = false;
 452                                 $this->mOldRev = false;
 453                         }
 454                 }/* elseif ( $this->mOldid === false ) leave mOldRev false; */
 455
 456                 if( is_null( $this->mOldRev ) ) {
 457                         return false;
 458                 }
 459
 460                 if ( $this->mOldRev ) {
 461                         $this->mOldPage = $this->mOldRev->getTitle();
 462
 463                         $t = $wgLang->timeanddate( $this->mOldRev->getTimestamp(), true );
 464                         $oldLink = $this->mOldPage->escapeLocalUrl( 'oldid=' . $this->mOldid );
 465                         $this->mOldtitle = "<a href='$oldLink'>" . htmlspecialchars( wfMsg( 'revisionasof', $t ) ) . '</a>';
 466
 467
 468                         $this->mOldUser = $this->mOldRev->getUserText();
 469                         $this->mOldComment = $this->mOldRev->getComment();
 470                 }
 471
 472                 return true;
 473         }
 474
 475         /**
 476          * Load the text of the revisions, as well as revision data.
 477          */
 478         function loadText() {
 479                 if ( $this->mTextLoaded == 2 ) {
 480                         return true;
 481                 } else {
 482                         // Whether it succeeds or fails, we don't want to try again
 483                         $this->mTextLoaded = 2;
 484                 }
 485
 486                 if ( !$this->loadRevisionData() ) {
 487                         return false;
 488                 }
 489                 if ( $this->mOldRev ) {
 490                         $this->mOldtext = $this->mOldRev->getText();
 491                         if ( $this->mOldtext === false ) {
 492                                 return false;
 493                         }
 494                 }
 495                 if ( $this->mNewRev ) {
 496                         $this->mNewtext = $this->mNewRev->getText();
 497                         if ( $this->mNewtext === false ) {
 498                                 return false;
 499                         }
 500                 }
 501                 return true;
 502         }
 503
 504         /**
 505          * Load the text of the new revision, not the old one
 506          */
 507         function loadNewText() {
 508                 if ( $this->mTextLoaded >= 1 ) {
 509                         return true;
 510                 } else {
 511                         $this->mTextLoaded = 1;
 512                 }
 513                 if ( !$this->loadRevisionData() ) {
 514                         return false;
 515                 }
 516                 $this->mNewtext = $this->mNewRev->getText();
 517                 return true;
 518         }
 519
 520
 521 }
 522
 523 // A PHP diff engine for phpwiki. (Taken from phpwiki-1.3.3)
 524 //
 525 // Copyright (C) 2000, 2001 Geoffrey T. Dairiki <dairiki@dairiki.org>
 526 // You may copy this code freely under the conditions of the GPL.
 527 //
 528
 529 define('USE_ASSERTS', function_exists('assert'));
 530
 531 /**
 532  * @todo document
 533  * @access private
 534  * @package MediaWiki
 535  * @subpackage DifferenceEngine
 536  */
 537 class _DiffOp {
 538         var $type;
 539         var $orig;
 540         var $closing;
 541
 542         function reverse() {
 543                 trigger_error('pure virtual', E_USER_ERROR);
 544         }
 545
 546         function norig() {
 547                 return $this->orig ? sizeof($this->orig) : 0;
 548         }
 549
 550         function nclosing() {
 551                 return $this->closing ? sizeof($this->closing) : 0;
 552         }
 553 }
 554
 555 /**
 556  * @todo document
 557  * @access private
 558  * @package MediaWiki
 559  * @subpackage DifferenceEngine
 560  */
 561 class _DiffOp_Copy extends _DiffOp {
 562         var $type = 'copy';
 563
 564         function _DiffOp_Copy ($orig, $closing = false) {
 565                 if (!is_array($closing))
 566                         $closing = $orig;
 567                 $this->orig = $orig;
 568                 $this->closing = $closing;
 569         }
 570
 571         function reverse() {
 572                 return new _DiffOp_Copy($this->closing, $this->orig);
 573         }
 574 }
 575
 576 /**
 577  * @todo document
 578  * @access private
 579  * @package MediaWiki
 580  * @subpackage DifferenceEngine
 581  */
 582 class _DiffOp_Delete extends _DiffOp {
 583         var $type = 'delete';
 584
 585         function _DiffOp_Delete ($lines) {
 586                 $this->orig = $lines;
 587                 $this->closing = false;
 588         }
 589
 590         function reverse() {
 591                 return new _DiffOp_Add($this->orig);
 592         }
 593 }
 594
 595 /**
 596  * @todo document
 597  * @access private
 598  * @package MediaWiki
 599  * @subpackage DifferenceEngine
 600  */
 601 class _DiffOp_Add extends _DiffOp {
 602         var $type = 'add';
 603
 604         function _DiffOp_Add ($lines) {
 605                 $this->closing = $lines;
 606                 $this->orig = false;
 607         }
 608
 609         function reverse() {
 610                 return new _DiffOp_Delete($this->closing);
 611         }
 612 }
 613
 614 /**
 615  * @todo document
 616  * @access private
 617  * @package MediaWiki
 618  * @subpackage DifferenceEngine
 619  */
 620 class _DiffOp_Change extends _DiffOp {
 621         var $type = 'change';
 622
 623         function _DiffOp_Change ($orig, $closing) {
 624                 $this->orig = $orig;
 625                 $this->closing = $closing;
 626         }
 627
 628         function reverse() {
 629                 return new _DiffOp_Change($this->closing, $this->orig);
 630         }
 631 }
 632
 633
 634 /**
 635  * Class used internally by Diff to actually compute the diffs.
 636  *
 637  * The algorithm used here is mostly lifted from the perl module
 638  * Algorithm::Diff (version 1.06) by Ned Konz, which is available at:
 639  *       http://www.perl.com/CPAN/authors/id/N/NE/NEDKONZ/Algorithm-Diff-1.06.zip
 640  *
 641  * More ideas are taken from:
 642  *       http://www.ics.uci.edu/~eppstein/161/960229.html
 643  *
 644  * Some ideas are (and a bit of code) are from from analyze.c, from GNU
 645  * diffutils-2.7, which can be found at:
 646  *       ftp://gnudist.gnu.org/pub/gnu/diffutils/diffutils-2.7.tar.gz
 647  *
 648  * closingly, some ideas (subdivision by NCHUNKS > 2, and some optimizations)
 649  * are my own.
 650  *
 651  * Line length limits for robustness added by Tim Starling, 2005-08-31
 652  *
 653  * @author Geoffrey T. Dairiki, Tim Starling
 654  * @access private
 655  * @package MediaWiki
 656  * @subpackage DifferenceEngine
 657  */
 658 class _DiffEngine
 659 {
 660         function diff ($from_lines, $to_lines) {
 661                 $fname = '_DiffEngine::diff';
 662                 wfProfileIn( $fname );
 663
 664                 $n_from = sizeof($from_lines);
 665                 $n_to = sizeof($to_lines);
 666
 667                 $this->xchanged = $this->ychanged = array();
 668                 $this->xv = $this->yv = array();
 669                 $this->xind = $this->yind = array();
 670                 unset($this->seq);
 671                 unset($this->in_seq);
 672                 unset($this->lcs);
 673
 674                 // Skip leading common lines.
 675                 for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) {
 676                         if ($from_lines[$skip] !== $to_lines[$skip])
 677                                 break;
 678                         $this->xchanged[$skip] = $this->ychanged[$skip] = false;
 679                 }
 680                 // Skip trailing common lines.
 681                 $xi = $n_from; $yi = $n_to;
 682                 for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) {
 683                         if ($from_lines[$xi] !== $to_lines[$yi])
 684                                 break;
 685                         $this->xchanged[$xi] = $this->ychanged[$yi] = false;
 686                 }
 687
 688                 // Ignore lines which do not exist in both files.
 689                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 690                         $xhash[$this->_line_hash($from_lines[$xi])] = 1;
 691                 }
 692
 693                 for ($yi = $skip; $yi < $n_to - $endskip; $yi++) {
 694                         $line = $to_lines[$yi];
 695                         if ( ($this->ychanged[$yi] = empty($xhash[$this->_line_hash($line)])) )
 696                                 continue;
 697                         $yhash[$this->_line_hash($line)] = 1;
 698                         $this->yv[] = $line;
 699                         $this->yind[] = $yi;
 700                 }
 701                 for ($xi = $skip; $xi < $n_from - $endskip; $xi++) {
 702                         $line = $from_lines[$xi];
 703                         if ( ($this->xchanged[$xi] = empty($yhash[$this->_line_hash($line)])) )
 704                                 continue;
 705                         $this->xv[] = $line;
 706                         $this->xind[] = $xi;
 707                 }
 708
 709                 // Find the LCS.
 710                 $this->_compareseq(0, sizeof($this->xv), 0, sizeof($this->yv));
 711
 712                 // Merge edits when possible
 713                 $this->_shift_boundaries($from_lines, $this->xchanged, $this->ychanged);
 714                 $this->_shift_boundaries($to_lines, $this->ychanged, $this->xchanged);
 715
 716                 // Compute the edit operations.
 717                 $edits = array();
 718                 $xi = $yi = 0;
 719                 while ($xi < $n_from || $yi < $n_to) {
 720                         USE_ASSERTS && assert($yi < $n_to || $this->xchanged[$xi]);
 721                         USE_ASSERTS && assert($xi < $n_from || $this->ychanged[$yi]);
 722
 723                         // Skip matching "snake".
 724                         $copy = array();
 725                         while ( $xi < $n_from && $yi < $n_to
 726                                         && !$this->xchanged[$xi] && !$this->ychanged[$yi]) {
 727                                 $copy[] = $from_lines[$xi++];
 728                                 ++$yi;
 729                         }
 730                         if ($copy)
 731                                 $edits[] = new _DiffOp_Copy($copy);
 732
 733                         // Find deletes & adds.
 734                         $delete = array();
 735                         while ($xi < $n_from && $this->xchanged[$xi])
 736                                 $delete[] = $from_lines[$xi++];
 737
 738                         $add = array();
 739                         while ($yi < $n_to && $this->ychanged[$yi])
 740                                 $add[] = $to_lines[$yi++];
 741
 742                         if ($delete && $add)
 743                                 $edits[] = new _DiffOp_Change($delete, $add);
 744                         elseif ($delete)
 745                                 $edits[] = new _DiffOp_Delete($delete);
 746                         elseif ($add)
 747                                 $edits[] = new _DiffOp_Add($add);
 748                 }
 749                 wfProfileOut( $fname );
 750                 return $edits;
 751         }
 752
 753         /**
 754          * Returns the whole line if it's small enough, or the MD5 hash otherwise
 755          */
 756         function _line_hash( $line ) {
 757                 if ( strlen( $line ) > MAX_DIFF_XREF_LENGTH ) {
 758                         return md5( $line );
 759                 } else {
 760                         return $line;
 761                 }
 762         }
 763
 764
 765         /* Divide the Largest Common Subsequence (LCS) of the sequences
 766          * [XOFF, XLIM) and [YOFF, YLIM) into NCHUNKS approximately equally
 767          * sized segments.
 768          *
 769          * Returns (LCS, PTS).  LCS is the length of the LCS. PTS is an
 770          * array of NCHUNKS+1 (X, Y) indexes giving the diving points between
 771          * sub sequences.  The first sub-sequence is contained in [X0, X1),
 772          * [Y0, Y1), the second in [X1, X2), [Y1, Y2) and so on.  Note
 773          * that (X0, Y0) == (XOFF, YOFF) and
 774          * (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM).
 775          *
 776          * This function assumes that the first lines of the specified portions
 777          * of the two files do not match, and likewise that the last lines do not
 778          * match.  The caller must trim matching lines from the beginning and end
 779          * of the portions it is going to specify.
 780          */
 781         function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) {
 782                 $fname = '_DiffEngine::_diag';
 783                 wfProfileIn( $fname );
 784                 $flip = false;
 785
 786                 if ($xlim - $xoff > $ylim - $yoff) {
 787                         // Things seems faster (I'm not sure I understand why)
 788                                 // when the shortest sequence in X.
 789                                 $flip = true;
 790                         list ($xoff, $xlim, $yoff, $ylim)
 791                         = array( $yoff, $ylim, $xoff, $xlim);
 792                 }
 793
 794                 if ($flip)
 795                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 796                                 $ymatches[$this->xv[$i]][] = $i;
 797                 else
 798                         for ($i = $ylim - 1; $i >= $yoff; $i--)
 799                                 $ymatches[$this->yv[$i]][] = $i;
 800
 801                 $this->lcs = 0;
 802                 $this->seq[0]= $yoff - 1;
 803                 $this->in_seq = array();
 804                 $ymids[0] = array();
 805
 806                 $numer = $xlim - $xoff + $nchunks - 1;
 807                 $x = $xoff;
 808                 for ($chunk = 0; $chunk < $nchunks; $chunk++) {
 809                         wfProfileIn( "$fname-chunk" );
 810                         if ($chunk > 0)
 811                                 for ($i = 0; $i <= $this->lcs; $i++)
 812                                         $ymids[$i][$chunk-1] = $this->seq[$i];
 813
 814                         $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks);
 815                         for ( ; $x < $x1; $x++) {
 816                                 $line = $flip ? $this->yv[$x] : $this->xv[$x];
 817                                         if (empty($ymatches[$line]))
 818                                                 continue;
 819                                 $matches = $ymatches[$line];
 820                                 reset($matches);
 821                                 while (list ($junk, $y) = each($matches))
 822                                         if (empty($this->in_seq[$y])) {
 823                                                 $k = $this->_lcs_pos($y);
 824                                                 USE_ASSERTS && assert($k > 0);
 825                                                 $ymids[$k] = $ymids[$k-1];
 826                                                 break;
 827                                         }
 828                                 while (list ($junk, $y) = each($matches)) {
 829                                         if ($y > $this->seq[$k-1]) {
 830                                                 USE_ASSERTS && assert($y < $this->seq[$k]);
 831                                                 // Optimization: this is a common case:
 832                                                 //      next match is just replacing previous match.
 833                                                 $this->in_seq[$this->seq[$k]] = false;
 834                                                 $this->seq[$k] = $y;
 835                                                 $this->in_seq[$y] = 1;
 836                                         } else if (empty($this->in_seq[$y])) {
 837                                                 $k = $this->_lcs_pos($y);
 838                                                 USE_ASSERTS && assert($k > 0);
 839                                                 $ymids[$k] = $ymids[$k-1];
 840                                         }
 841                                 }
 842                         }
 843                         wfProfileOut( "$fname-chunk" );
 844                 }
 845
 846                 $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff);
 847                 $ymid = $ymids[$this->lcs];
 848                 for ($n = 0; $n < $nchunks - 1; $n++) {
 849                         $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks);
 850                         $y1 = $ymid[$n] + 1;
 851                         $seps[] = $flip ? array($y1, $x1) : array($x1, $y1);
 852                 }
 853                 $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim);
 854
 855                 wfProfileOut( $fname );
 856                 return array($this->lcs, $seps);
 857         }
 858
 859         function _lcs_pos ($ypos) {
 860                 $fname = '_DiffEngine::_lcs_pos';
 861                 wfProfileIn( $fname );
 862
 863                 $end = $this->lcs;
 864                 if ($end == 0 || $ypos > $this->seq[$end]) {
 865                         $this->seq[++$this->lcs] = $ypos;
 866                         $this->in_seq[$ypos] = 1;
 867                         wfProfileOut( $fname );
 868                         return $this->lcs;
 869                 }
 870
 871                 $beg = 1;
 872                 while ($beg < $end) {
 873                         $mid = (int)(($beg + $end) / 2);
 874                         if ( $ypos > $this->seq[$mid] )
 875                                 $beg = $mid + 1;
 876                         else
 877                                 $end = $mid;
 878                 }
 879
 880                 USE_ASSERTS && assert($ypos != $this->seq[$end]);
 881
 882                 $this->in_seq[$this->seq[$end]] = false;
 883                 $this->seq[$end] = $ypos;
 884                 $this->in_seq[$ypos] = 1;
 885                 wfProfileOut( $fname );
 886                 return $end;
 887         }
 888
 889         /* Find LCS of two sequences.
 890          *
 891          * The results are recorded in the vectors $this->{x,y}changed[], by
 892          * storing a 1 in the element for each line that is an insertion
 893          * or deletion (ie. is not in the LCS).
 894          *
 895          * The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
 896          *
 897          * Note that XLIM, YLIM are exclusive bounds.
 898          * All line numbers are origin-0 and discarded lines are not counted.
 899          */
 900         function _compareseq ($xoff, $xlim, $yoff, $ylim) {
 901                 $fname = '_DiffEngine::_compareseq';
 902                 wfProfileIn( $fname );
 903
 904                 // Slide down the bottom initial diagonal.
 905                 while ($xoff < $xlim && $yoff < $ylim
 906                            && $this->xv[$xoff] == $this->yv[$yoff]) {
 907                         ++$xoff;
 908                         ++$yoff;
 909                 }
 910
 911                 // Slide up the top initial diagonal.
 912                 while ($xlim > $xoff && $ylim > $yoff
 913                            && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) {
 914                         --$xlim;
 915                         --$ylim;
 916                 }
 917
 918                 if ($xoff == $xlim || $yoff == $ylim)
 919                         $lcs = 0;
 920                 else {
 921                         // This is ad hoc but seems to work well.
 922                         //$nchunks = sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5);
 923                         //$nchunks = max(2,min(8,(int)$nchunks));
 924                         $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1;
 925                         list ($lcs, $seps)
 926                         = $this->_diag($xoff,$xlim,$yoff, $ylim,$nchunks);
 927                 }
 928
 929                 if ($lcs == 0) {
 930                         // X and Y sequences have no common subsequence:
 931                         // mark all changed.
 932                         while ($yoff < $ylim)
 933                                 $this->ychanged[$this->yind[$yoff++]] = 1;
 934                         while ($xoff < $xlim)
 935                                 $this->xchanged[$this->xind[$xoff++]] = 1;
 936                 } else {
 937                         // Use the partitions to split this problem into subproblems.
 938                         reset($seps);
 939                         $pt1 = $seps[0];
 940                         while ($pt2 = next($seps)) {
 941                                 $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]);
 942                                 $pt1 = $pt2;
 943                         }
 944                 }
 945                 wfProfileOut( $fname );
 946         }
 947
 948         /* Adjust inserts/deletes of identical lines to join changes
 949          * as much as possible.
 950          *
 951          * We do something when a run of changed lines include a
 952          * line at one end and has an excluded, identical line at the other.
 953          * We are free to choose which identical line is included.
 954          * `compareseq' usually chooses the one at the beginning,
 955          * but usually it is cleaner to consider the following identical line
 956          * to be the "change".
 957          *
 958          * This is extracted verbatim from analyze.c (GNU diffutils-2.7).
 959          */
 960         function _shift_boundaries ($lines, &$changed, $other_changed) {
 961                 $fname = '_DiffEngine::_shift_boundaries';
 962                 wfProfileIn( $fname );
 963                 $i = 0;
 964                 $j = 0;
 965
 966                 USE_ASSERTS && assert('sizeof($lines) == sizeof($changed)');
 967                 $len = sizeof($lines);
 968                 $other_len = sizeof($other_changed);
 969
 970                 while (1) {
 971                         /*
 972                          * Scan forwards to find beginning of another run of changes.
 973                          * Also keep track of the corresponding point in the other file.
 974                          *
 975                          * Throughout this code, $i and $j are adjusted together so that
 976                          * the first $i elements of $changed and the first $j elements
 977                          * of $other_changed both contain the same number of zeros
 978                          * (unchanged lines).
 979                          * Furthermore, $j is always kept so that $j == $other_len or
 980                          * $other_changed[$j] == false.
 981                          */
 982                         while ($j < $other_len && $other_changed[$j])
 983                                 $j++;
 984
 985                         while ($i < $len && ! $changed[$i]) {
 986                                 USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
 987                                 $i++; $j++;
 988                                 while ($j < $other_len && $other_changed[$j])
 989                                         $j++;
 990                         }
 991
 992                         if ($i == $len)
 993                                 break;
 994
 995                         $start = $i;
 996
 997                         // Find the end of this run of changes.
 998                         while (++$i < $len && $changed[$i])
 999                                 continue;
1000
1001                         do {
1002                                 /*
1003                                  * Record the length of this run of changes, so that
1004                                  * we can later determine whether the run has grown.
1005                                  */
1006                                 $runlength = $i - $start;
1007
1008                                 /*
1009                                  * Move the changed region back, so long as the
1010                                  * previous unchanged line matches the last changed one.
1011                                  * This merges with previous changed regions.
1012                                  */
1013                                 while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) {
1014                                         $changed[--$start] = 1;
1015                                         $changed[--$i] = false;
1016                                         while ($start > 0 && $changed[$start - 1])
1017                                                 $start--;
1018                                         USE_ASSERTS && assert('$j > 0');
1019                                         while ($other_changed[--$j])
1020                                                 continue;
1021                                         USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1022                                 }
1023
1024                                 /*
1025                                  * Set CORRESPONDING to the end of the changed run, at the last
1026                                  * point where it corresponds to a changed run in the other file.
1027                                  * CORRESPONDING == LEN means no such point has been found.
1028                                  */
1029                                 $corresponding = $j < $other_len ? $i : $len;
1030
1031                                 /*
1032                                  * Move the changed region forward, so long as the
1033                                  * first changed line matches the following unchanged one.
1034                                  * This merges with following changed regions.
1035                                  * Do this second, so that if there are no merges,
1036                                  * the changed region is moved forward as far as possible.
1037                                  */
1038                                 while ($i < $len && $lines[$start] == $lines[$i]) {
1039                                         $changed[$start++] = false;
1040                                         $changed[$i++] = 1;
1041                                         while ($i < $len && $changed[$i])
1042                                                 $i++;
1043
1044                                         USE_ASSERTS && assert('$j < $other_len && ! $other_changed[$j]');
1045                                         $j++;
1046                                         if ($j < $other_len && $other_changed[$j]) {
1047                                                 $corresponding = $i;
1048                                                 while ($j < $other_len && $other_changed[$j])
1049                                                         $j++;
1050                                         }
1051                                 }
1052                         } while ($runlength != $i - $start);
1053
1054                         /*
1055                          * If possible, move the fully-merged run of changes
1056                          * back to a corresponding run in the other file.
1057                          */
1058                         while ($corresponding < $i) {
1059                                 $changed[--$start] = 1;
1060                                 $changed[--$i] = 0;
1061                                 USE_ASSERTS && assert('$j > 0');
1062                                 while ($other_changed[--$j])
1063                                         continue;
1064                                 USE_ASSERTS && assert('$j >= 0 && !$other_changed[$j]');
1065                         }
1066                 }
1067                 wfProfileOut( $fname );
1068         }
1069 }
1070
1071 /**
1072  * Class representing a 'diff' between two sequences of strings.
1073  * @todo document
1074  * @access private
1075  * @package MediaWiki
1076  * @subpackage DifferenceEngine
1077  */
1078 class Diff
1079 {
1080         var $edits;
1081
1082         /**
1083          * Constructor.
1084          * Computes diff between sequences of strings.
1085          *
1086          * @param $from_lines array An array of strings.
1087          *                (Typically these are lines from a file.)
1088          * @param $to_lines array An array of strings.
1089          */
1090         function Diff($from_lines, $to_lines) {
1091                 $eng = new _DiffEngine;
1092                 $this->edits = $eng->diff($from_lines, $to_lines);
1093                 //$this->_check($from_lines, $to_lines);
1094         }
1095
1096         /**
1097          * Compute reversed Diff.
1098          *
1099          * SYNOPSIS:
1100          *
1101          *      $diff = new Diff($lines1, $lines2);
1102          *      $rev = $diff->reverse();
1103          * @return object A Diff object representing the inverse of the
1104          *                                original diff.
1105          */
1106         function reverse () {
1107                 $rev = $this;
1108                 $rev->edits = array();
1109                 foreach ($this->edits as $edit) {
1110                         $rev->edits[] = $edit->reverse();
1111                 }
1112                 return $rev;
1113         }
1114
1115         /**
1116          * Check for empty diff.
1117          *
1118          * @return bool True iff two sequences were identical.
1119          */
1120         function isEmpty () {
1121                 foreach ($this->edits as $edit) {
1122                         if ($edit->type != 'copy')
1123                                 return false;
1124                 }
1125                 return true;
1126         }
1127
1128         /**
1129          * Compute the length of the Longest Common Subsequence (LCS).
1130          *
1131          * This is mostly for diagnostic purposed.
1132          *
1133          * @return int The length of the LCS.
1134          */
1135         function lcs () {
1136                 $lcs = 0;
1137                 foreach ($this->edits as $edit) {
1138                         if ($edit->type == 'copy')
1139                                 $lcs += sizeof($edit->orig);
1140                 }
1141                 return $lcs;
1142         }
1143
1144         /**
1145          * Get the original set of lines.
1146          *
1147          * This reconstructs the $from_lines parameter passed to the
1148          * constructor.
1149          *
1150          * @return array The original sequence of strings.
1151          */
1152         function orig() {
1153                 $lines = array();
1154
1155                 foreach ($this->edits as $edit) {
1156                         if ($edit->orig)
1157                                 array_splice($lines, sizeof($lines), 0, $edit->orig);
1158                 }
1159                 return $lines;
1160         }
1161
1162         /**
1163          * Get the closing set of lines.
1164          *
1165          * This reconstructs the $to_lines parameter passed to the
1166          * constructor.
1167          *
1168          * @return array The sequence of strings.
1169          */
1170         function closing() {
1171                 $lines = array();
1172
1173                 foreach ($this->edits as $edit) {
1174                         if ($edit->closing)
1175                                 array_splice($lines, sizeof($lines), 0, $edit->closing);
1176                 }
1177                 return $lines;
1178         }
1179
1180         /**
1181          * Check a Diff for validity.
1182          *
1183          * This is here only for debugging purposes.
1184          */
1185         function _check ($from_lines, $to_lines) {
1186                 $fname = 'Diff::_check';
1187                 wfProfileIn( $fname );
1188                 if (serialize($from_lines) != serialize($this->orig()))
1189                         trigger_error("Reconstructed original doesn't match", E_USER_ERROR);
1190                 if (serialize($to_lines) != serialize($this->closing()))
1191                         trigger_error("Reconstructed closing doesn't match", E_USER_ERROR);
1192
1193                 $rev = $this->reverse();
1194                 if (serialize($to_lines) != serialize($rev->orig()))
1195                         trigger_error("Reversed original doesn't match", E_USER_ERROR);
1196                 if (serialize($from_lines) != serialize($rev->closing()))
1197                         trigger_error("Reversed closing doesn't match", E_USER_ERROR);
1198
1199
1200                 $prevtype = 'none';
1201                 foreach ($this->edits as $edit) {
1202                         if ( $prevtype == $edit->type )
1203                                 trigger_error("Edit sequence is non-optimal", E_USER_ERROR);
1204                         $prevtype = $edit->type;
1205                 }
1206
1207                 $lcs = $this->lcs();
1208                 trigger_error('Diff okay: LCS = '.$lcs, E_USER_NOTICE);
1209                 wfProfileOut( $fname );
1210         }
1211 }
1212
1213 /**
1214  * FIXME: bad name.
1215  * @todo document
1216  * @access private
1217  * @package MediaWiki
1218  * @subpackage DifferenceEngine
1219  */
1220 class MappedDiff extends Diff
1221 {
1222         /**
1223          * Constructor.
1224          *
1225          * Computes diff between sequences of strings.
1226          *
1227          * This can be used to compute things like
1228          * case-insensitve diffs, or diffs which ignore
1229          * changes in white-space.
1230          *
1231          * @param $from_lines array An array of strings.
1232          *      (Typically these are lines from a file.)
1233          *
1234          * @param $to_lines array An array of strings.
1235          *
1236          * @param $mapped_from_lines array This array should
1237          *      have the same size number of elements as $from_lines.
1238          *      The elements in $mapped_from_lines and
1239          *      $mapped_to_lines are what is actually compared
1240          *      when computing the diff.
1241          *
1242          * @param $mapped_to_lines array This array should
1243          *      have the same number of elements as $to_lines.
1244          */
1245         function MappedDiff($from_lines, $to_lines,
1246                                                 $mapped_from_lines, $mapped_to_lines) {
1247                 $fname = 'MappedDiff::MappedDiff';
1248                 wfProfileIn( $fname );
1249
1250                 assert(sizeof($from_lines) == sizeof($mapped_from_lines));
1251                 assert(sizeof($to_lines) == sizeof($mapped_to_lines));
1252
1253                 $this->Diff($mapped_from_lines, $mapped_to_lines);
1254
1255                 $xi = $yi = 0;
1256                 for ($i = 0; $i < sizeof($this->edits); $i++) {
1257                         $orig = &$this->edits[$i]->orig;
1258                         if (is_array($orig)) {
1259                                 $orig = array_slice($from_lines, $xi, sizeof($orig));
1260                                 $xi += sizeof($orig);
1261                         }
1262
1263                         $closing = &$this->edits[$i]->closing;
1264                         if (is_array($closing)) {
1265                                 $closing = array_slice($to_lines, $yi, sizeof($closing));
1266                                 $yi += sizeof($closing);
1267                         }
1268                 }
1269                 wfProfileOut( $fname );
1270         }
1271 }
1272
1273 /**
1274  * A class to format Diffs
1275  *
1276  * This class formats the diff in classic diff format.
1277  * It is intended that this class be customized via inheritance,
1278  * to obtain fancier outputs.
1279  * @todo document
1280  * @access private
1281  * @package MediaWiki
1282  * @subpackage DifferenceEngine
1283  */
1284 class DiffFormatter
1285 {
1286         /**
1287          * Number of leading context "lines" to preserve.
1288          *
1289          * This should be left at zero for this class, but subclasses
1290          * may want to set this to other values.
1291          */
1292         var $leading_context_lines = 0;
1293
1294         /**
1295          * Number of trailing context "lines" to preserve.
1296          *
1297          * This should be left at zero for this class, but subclasses
1298          * may want to set this to other values.
1299          */
1300         var $trailing_context_lines = 0;
1301
1302         /**
1303          * Format a diff.
1304          *
1305          * @param $diff object A Diff object.
1306          * @return string The formatted output.
1307          */
1308         function format($diff) {
1309                 $fname = 'DiffFormatter::format';
1310                 wfProfileIn( $fname );
1311
1312                 $xi = $yi = 1;
1313                 $block = false;
1314                 $context = array();
1315
1316                 $nlead = $this->leading_context_lines;
1317                 $ntrail = $this->trailing_context_lines;
1318
1319                 $this->_start_diff();
1320
1321                 foreach ($diff->edits as $edit) {
1322                         if ($edit->type == 'copy') {
1323                                 if (is_array($block)) {
1324                                         if (sizeof($edit->orig) <= $nlead + $ntrail) {
1325                                                 $block[] = $edit;
1326                                         }
1327                                         else{
1328                                                 if ($ntrail) {
1329                                                         $context = array_slice($edit->orig, 0, $ntrail);
1330                                                         $block[] = new _DiffOp_Copy($context);
1331                                                 }
1332                                                 $this->_block($x0, $ntrail + $xi - $x0,
1333                                                                           $y0, $ntrail + $yi - $y0,
1334                                                                           $block);
1335                                                 $block = false;
1336                                         }
1337                                 }
1338                                 $context = $edit->orig;
1339                         }
1340                         else {
1341                                 if (! is_array($block)) {
1342                                         $context = array_slice($context, sizeof($context) - $nlead);
1343                                         $x0 = $xi - sizeof($context);
1344                                         $y0 = $yi - sizeof($context);
1345                                         $block = array();
1346                                         if ($context)
1347                                                 $block[] = new _DiffOp_Copy($context);
1348                                 }
1349                                 $block[] = $edit;
1350                         }
1351
1352                         if ($edit->orig)
1353                                 $xi += sizeof($edit->orig);
1354                         if ($edit->closing)
1355                                 $yi += sizeof($edit->closing);
1356                 }
1357
1358                 if (is_array($block))
1359                         $this->_block($x0, $xi - $x0,
1360                                                   $y0, $yi - $y0,
1361                                                   $block);
1362
1363                 $end = $this->_end_diff();
1364                 wfProfileOut( $fname );
1365                 return $end;
1366         }
1367
1368         function _block($xbeg, $xlen, $ybeg, $ylen, &$edits) {
1369                 $fname = 'DiffFormatter::_block';
1370                 wfProfileIn( $fname );
1371                 $this->_start_block($this->_block_header($xbeg, $xlen, $ybeg, $ylen));
1372                 foreach ($edits as $edit) {
1373                         if ($edit->type == 'copy')
1374                                 $this->_context($edit->orig);
1375                         elseif ($edit->type == 'add')
1376                                 $this->_added($edit->closing);
1377                         elseif ($edit->type == 'delete')
1378                                 $this->_deleted($edit->orig);
1379                         elseif ($edit->type == 'change')
1380                                 $this->_changed($edit->orig, $edit->closing);
1381                         else
1382                                 trigger_error('Unknown edit type', E_USER_ERROR);
1383                 }
1384                 $this->_end_block();
1385                 wfProfileOut( $fname );
1386         }
1387
1388         function _start_diff() {
1389                 ob_start();
1390         }
1391
1392         function _end_diff() {
1393                 $val = ob_get_contents();
1394                 ob_end_clean();
1395                 return $val;
1396         }
1397
1398         function _block_header($xbeg, $xlen, $ybeg, $ylen) {
1399                 if ($xlen > 1)
1400                         $xbeg .= "," . ($xbeg + $xlen - 1);
1401                 if ($ylen > 1)
1402                         $ybeg .= "," . ($ybeg + $ylen - 1);
1403
1404                 return $xbeg . ($xlen ? ($ylen ? 'c' : 'd') : 'a') . $ybeg;
1405         }
1406
1407         function _start_block($header) {
1408                 echo $header;
1409         }
1410
1411         function _end_block() {
1412         }
1413
1414         function _lines($lines, $prefix = ' ') {
1415                 foreach ($lines as $line)
1416                         echo "$prefix $line\n";
1417         }
1418
1419         function _context($lines) {
1420                 $this->_lines($lines);
1421         }
1422
1423         function _added($lines) {
1424                 $this->_lines($lines, '>');
1425         }
1426         function _deleted($lines) {
1427                 $this->_lines($lines, '<');
1428         }
1429
1430         function _changed($orig, $closing) {
1431                 $this->_deleted($orig);
1432                 echo "---\n";
1433                 $this->_added($closing);
1434         }
1435 }
1436
1437
1438 /**
1439  *      Additions by Axel Boldt follow, partly taken from diff.php, phpwiki-1.3.3
1440  *
1441  */
1442
1443 define('NBSP', '&#160;');                       // iso-8859-x non-breaking space.
1444
1445 /**
1446  * @todo document
1447  * @access private
1448  * @package MediaWiki
1449  * @subpackage DifferenceEngine
1450  */
1451 class _HWLDF_WordAccumulator {
1452         function _HWLDF_WordAccumulator () {
1453                 $this->_lines = array();
1454                 $this->_line = '';
1455                 $this->_group = '';
1456                 $this->_tag = '';
1457         }
1458
1459         function _flushGroup ($new_tag) {
1460                 if ($this->_group !== '') {
1461                         if ($this->_tag == 'mark')
1462                                 $this->_line .= '<span class="diffchange">' .
1463                                         htmlspecialchars ( $this->_group ) . '</span>';
1464                         else
1465                                 $this->_line .= htmlspecialchars ( $this->_group );
1466                 }
1467                 $this->_group = '';
1468                 $this->_tag = $new_tag;
1469         }
1470
1471         function _flushLine ($new_tag) {
1472                 $this->_flushGroup($new_tag);
1473                 if ($this->_line != '')
1474                         array_push ( $this->_lines, $this->_line );
1475                 else
1476                         # make empty lines visible by inserting an NBSP
1477                         array_push ( $this->_lines, NBSP );
1478                 $this->_line = '';
1479         }
1480
1481         function addWords ($words, $tag = '') {
1482                 if ($tag != $this->_tag)
1483                         $this->_flushGroup($tag);
1484
1485                 foreach ($words as $word) {
1486                         // new-line should only come as first char of word.
1487                         if ($word == '')
1488                                 continue;
1489                         if ($word[0] == "\n") {
1490                                 $this->_flushLine($tag);
1491                                 $word = substr($word, 1);
1492                         }
1493                         assert(!strstr($word, "\n"));
1494                         $this->_group .= $word;
1495                 }
1496         }
1497
1498         function getLines() {
1499                 $this->_flushLine('~done');
1500                 return $this->_lines;
1501         }
1502 }
1503
1504 /**
1505  * @todo document
1506  * @access private
1507  * @package MediaWiki
1508  * @subpackage DifferenceEngine
1509  */
1510 class WordLevelDiff extends MappedDiff
1511 {
1512         function WordLevelDiff ($orig_lines, $closing_lines) {
1513                 $fname = 'WordLevelDiff::WordLevelDiff';
1514                 wfProfileIn( $fname );
1515
1516                 list ($orig_words, $orig_stripped) = $this->_split($orig_lines);
1517                 list ($closing_words, $closing_stripped) = $this->_split($closing_lines);
1518
1519                 $this->MappedDiff($orig_words, $closing_words,
1520                                                   $orig_stripped, $closing_stripped);
1521                 wfProfileOut( $fname );
1522         }
1523
1524         function _split($lines) {
1525                 $fname = 'WordLevelDiff::_split';
1526                 wfProfileIn( $fname );
1527
1528                 $words = array();
1529                 $stripped = array();
1530                 $first = true;
1531                 foreach ( $lines as $line ) {
1532                         # If the line is too long, just pretend the entire line is one big word
1533                         # This prevents resource exhaustion problems
1534                         if ( $first ) {
1535                                 $first = false;
1536                         } else {
1537                                 $words[] = "\n";
1538                                 $stripped[] = "\n";
1539                         }
1540                         if ( strlen( $line ) > MAX_DIFF_LINE ) {
1541                                 $words[] = $line;
1542                                 $stripped[] = $line;
1543                         } else {
1544                                 if (preg_match_all('/ ( [^\S\n]+ | [0-9_A-Za-z\x80-\xff]+ | . ) (?: (?!< \n) [^\S\n])? /xs',
1545                                         $line, $m))
1546                                 {
1547                                         $words = array_merge( $words, $m[0] );
1548                                         $stripped = array_merge( $stripped, $m[1] );
1549                                 }
1550                         }
1551                 }
1552                 wfProfileOut( $fname );
1553                 return array($words, $stripped);
1554         }
1555
1556         function orig () {
1557                 $fname = 'WordLevelDiff::orig';
1558                 wfProfileIn( $fname );
1559                 $orig = new _HWLDF_WordAccumulator;
1560
1561                 foreach ($this->edits as $edit) {
1562                         if ($edit->type == 'copy')
1563                                 $orig->addWords($edit->orig);
1564                         elseif ($edit->orig)
1565                                 $orig->addWords($edit->orig, 'mark');
1566                 }
1567                 $lines = $orig->getLines();
1568                 wfProfileOut( $fname );
1569                 return $lines;
1570         }
1571
1572         function closing () {
1573                 $fname = 'WordLevelDiff::closing';
1574                 wfProfileIn( $fname );
1575                 $closing = new _HWLDF_WordAccumulator;
1576
1577                 foreach ($this->edits as $edit) {
1578                         if ($edit->type == 'copy')
1579                                 $closing->addWords($edit->closing);
1580                         elseif ($edit->closing)
1581                                 $closing->addWords($edit->closing, 'mark');
1582                 }
1583                 $lines = $closing->getLines();
1584                 wfProfileOut( $fname );
1585                 return $lines;
1586         }
1587 }
1588
1589 /**
1590  *      Wikipedia Table style diff formatter.
1591  * @todo document
1592  * @access private
1593  * @package MediaWiki
1594  * @subpackage DifferenceEngine
1595  */
1596 class TableDiffFormatter extends DiffFormatter
1597 {
1598         function TableDiffFormatter() {
1599                 $this->leading_context_lines = 2;
1600                 $this->trailing_context_lines = 2;
1601         }
1602
1603         function _block_header( $xbeg, $xlen, $ybeg, $ylen ) {
1604                 $l1 = wfMsg( 'lineno', $xbeg );
1605                 $l2 = wfMsg( 'lineno', $ybeg );
1606
1607                 $r = '<tr><td colspan="2" align="left"><strong>'.$l1."</strong></td>\n" .
1608                   '<td colspan="2" align="left"><strong>'.$l2."</strong></td></tr>\n";
1609                 return $r;
1610         }
1611
1612         function _start_block( $header ) {
1613                 global $wgOut;
1614                 echo $header;
1615         }
1616
1617         function _end_block() {
1618         }
1619
1620         function _lines( $lines, $prefix=' ', $color='white' ) {
1621         }
1622
1623         # HTML-escape parameter before calling this
1624         function addedLine( $line ) {
1625                 return "<td>+</td><td class='diff-addedline'>{$line}</td>";
1626         }
1627
1628         # HTML-escape parameter before calling this
1629         function deletedLine( $line ) {
1630                 return "<td>-</td><td class='diff-deletedline'>{$line}</td>";
1631         }
1632
1633         # HTML-escape parameter before calling this
1634         function contextLine( $line ) {
1635                 return "<td> </td><td class='diff-context'>{$line}</td>";
1636         }
1637
1638         function emptyLine() {
1639                 return '<td colspan="2">&nbsp;</td>';
1640         }
1641
1642         function _added( $lines ) {
1643                 foreach ($lines as $line) {
1644                         echo '<tr>' . $this->emptyLine() .
1645                                 $this->addedLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1646                 }
1647         }
1648
1649         function _deleted($lines) {
1650                 foreach ($lines as $line) {
1651                         echo '<tr>' . $this->deletedLine( htmlspecialchars ( $line ) ) .
1652                           $this->emptyLine() . "</tr>\n";
1653                 }
1654         }
1655
1656         function _context( $lines ) {
1657                 foreach ($lines as $line) {
1658                         echo '<tr>' .
1659                                 $this->contextLine( htmlspecialchars ( $line ) ) .
1660                                 $this->contextLine( htmlspecialchars ( $line ) ) . "</tr>\n";
1661                 }
1662         }
1663
1664         function _changed( $orig, $closing ) {
1665                 $fname = 'TableDiffFormatter::_changed';
1666                 wfProfileIn( $fname );
1667
1668                 $diff = new WordLevelDiff( $orig, $closing );
1669                 $del = $diff->orig();
1670                 $add = $diff->closing();
1671
1672                 # Notice that WordLevelDiff returns HTML-escaped output.
1673                 # Hence, we will be calling addedLine/deletedLine without HTML-escaping.
1674
1675                 while ( $line = array_shift( $del ) ) {
1676                         $aline = array_shift( $add );
1677                         echo '<tr>' . $this->deletedLine( $line ) .
1678                                 $this->addedLine( $aline ) . "</tr>\n";
1679                 }
1680                 foreach ($add as $line) {       # If any leftovers
1681                         echo '<tr>' . $this->emptyLine() .
1682                                 $this->addedLine( $line ) . "</tr>\n";
1683                 }
1684                 wfProfileOut( $fname );
1685         }
1686 }
1687
1688 ?>