includes/Pager.php

   1 <?php
   2 /**
   3  * @defgroup Pager Pager
   4  *
   5  * @file
   6  * @ingroup Pager
   7  */
   8
   9 /**
  10  * Basic pager interface.
  11  * @ingroup Pager
  12  */
  13 interface Pager {
  14         function getNavigationBar();
  15         function getBody();
  16 }
  17
  18 /**
  19  * IndexPager is an efficient pager which uses a (roughly unique) index in the
  20  * data set to implement paging, rather than a "LIMIT offset,limit" clause.
  21  * In MySQL, such a limit/offset clause requires counting through the
  22  * specified number of offset rows to find the desired data, which can be
  23  * expensive for large offsets.
  24  *
  25  * ReverseChronologicalPager is a child class of the abstract IndexPager, and
  26  * contains  some formatting and display code which is specific to the use of
  27  * timestamps as  indexes. Here is a synopsis of its operation:
  28  *
  29  *    * The query is specified by the offset, limit and direction (dir)
  30  *      parameters, in addition to any subclass-specific parameters.
  31  *    * The offset is the non-inclusive start of the DB query. A row with an
  32  *      index value equal to the offset will never be shown.
  33  *    * The query may either be done backwards, where the rows are returned by
  34  *      the database in the opposite order to which they are displayed to the
  35  *      user, or forwards. This is specified by the "dir" parameter, dir=prev
  36  *      means backwards, anything else means forwards. The offset value
  37  *      specifies the start of the database result set, which may be either
  38  *      the start or end of the displayed data set. This allows "previous"
  39  *      links to be implemented without knowledge of the index value at the
  40  *      start of the previous page.
  41  *    * An additional row beyond the user-specified limit is always requested.
  42  *      This allows us to tell whether we should display a "next" link in the
  43  *      case of forwards mode, or a "previous" link in the case of backwards
  44  *      mode. Determining whether to display the other link (the one for the
  45  *      page before the start of the database result set) can be done
  46  *      heuristically by examining the offset.
  47  *
  48  *    * An empty offset indicates that the offset condition should be omitted
  49  *      from the query. This naturally produces either the first page or the
  50  *      last page depending on the dir parameter.
  51  *
  52  *  Subclassing the pager to implement concrete functionality should be fairly
  53  *  simple, please see the examples in PageHistory.php and
  54  *  SpecialIpblocklist.php. You just need to override formatRow(),
  55  *  getQueryInfo() and getIndexField(). Don't forget to call the parent
  56  *  constructor if you override it.
  57  *
  58  * @ingroup Pager
  59  */
  60 abstract class IndexPager implements Pager {
  61         public $mRequest;
  62         public $mLimitsShown = array( 20, 50, 100, 250, 500 );
  63         public $mDefaultLimit = 50;
  64         public $mOffset, $mLimit;
  65         public $mQueryDone = false;
  66         public $mDb;
  67         public $mPastTheEndRow;
  68
  69         /**
  70          * The index to actually be used for ordering.  This is a single string e-
  71          * ven if multiple orderings are supported.
  72          */
  73         protected $mIndexField;
  74         /** For pages that support multiple types of ordering, which one to use. */
  75         protected $mOrderType;
  76         /**
  77          * $mDefaultDirection gives the direction to use when sorting results:
  78          * false for ascending, true for descending.  If $mIsBackwards is set, we
  79          * start from the opposite end, but we still sort the page itself according
  80          * to $mDefaultDirection.  E.g., if $mDefaultDirection is false but we're
  81          * going backwards, we'll display the last page of results, but the last
  82          * result will be at the bottom, not the top.
  83          *
  84          * Like $mIndexField, $mDefaultDirection will be a single value even if the
  85          * class supports multiple default directions for different order types.
  86          */
  87         public $mDefaultDirection;
  88         public $mIsBackwards;
  89
  90         /**
  91          * Result object for the query. Warning: seek before use.
  92          */
  93         public $mResult;
  94
  95         public function __construct() {
  96                 global $wgRequest, $wgUser;
  97                 $this->mRequest = $wgRequest;
  98
  99                 # NB: the offset is quoted, not validated. It is treated as an
 100                 # arbitrary string to support the widest variety of index types. Be
 101                 # careful outputting it into HTML!
 102                 $this->mOffset = $this->mRequest->getText( 'offset' );
 103
 104                 # Use consistent behavior for the limit options
 105                 $this->mDefaultLimit = intval( $wgUser->getOption( 'rclimit' ) );
 106                 list( $this->mLimit, /* $offset */ ) = $this->mRequest->getLimitOffset();
 107
 108                 $this->mIsBackwards = ( $this->mRequest->getVal( 'dir' ) == 'prev' );
 109                 $this->mDb = wfGetDB( DB_SLAVE );
 110
 111                 $index = $this->getIndexField();
 112                 $order = $this->mRequest->getVal( 'order' );
 113                 if( is_array( $index ) && isset( $index[$order] ) ) {
 114                         $this->mOrderType = $order;
 115                         $this->mIndexField = $index[$order];
 116                 } elseif( is_array( $index ) ) {
 117                         # First element is the default
 118                         reset( $index );
 119                         list( $this->mOrderType, $this->mIndexField ) = each( $index );
 120                 } else {
 121                         # $index is not an array
 122                         $this->mOrderType = null;
 123                         $this->mIndexField = $index;
 124                 }
 125
 126                 if( !isset( $this->mDefaultDirection ) ) {
 127                         $dir = $this->getDefaultDirections();
 128                         $this->mDefaultDirection = is_array( $dir )
 129                                 ? $dir[$this->mOrderType]
 130                                 : $dir;
 131                 }
 132         }
 133
 134         /**
 135          * Do the query, using information from the object context. This function
 136          * has been kept minimal to make it overridable if necessary, to allow for
 137          * result sets formed from multiple DB queries.
 138          */
 139         function doQuery() {
 140                 # Use the child class name for profiling
 141                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 142                 wfProfileIn( $fname );
 143
 144                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 145                 # Plus an extra row so that we can tell the "next" link should be shown
 146                 $queryLimit = $this->mLimit + 1;
 147
 148                 $this->mResult = $this->reallyDoQuery( $this->mOffset, $queryLimit, $descending );
 149                 $this->extractResultInfo( $this->mOffset, $queryLimit, $this->mResult );
 150                 $this->mQueryDone = true;
 151
 152                 $this->preprocessResults( $this->mResult );
 153                 $this->mResult->rewind(); // Paranoia
 154
 155                 wfProfileOut( $fname );
 156         }
 157
 158         /**
 159          * Extract some useful data from the result object for use by
 160          * the navigation bar, put it into $this
 161          */
 162         function extractResultInfo( $offset, $limit, ResultWrapper $res ) {
 163                 $numRows = $res->numRows();
 164                 if ( $numRows ) {
 165                         $row = $res->fetchRow();
 166                         $firstIndex = $row[$this->mIndexField];
 167
 168                         # Discard the extra result row if there is one
 169                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 170                                 $res->seek( $numRows - 1 );
 171                                 $this->mPastTheEndRow = $res->fetchObject();
 172                                 $indexField = $this->mIndexField;
 173                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexField;
 174                                 $res->seek( $numRows - 2 );
 175                                 $row = $res->fetchRow();
 176                                 $lastIndex = $row[$this->mIndexField];
 177                         } else {
 178                                 $this->mPastTheEndRow = null;
 179                                 # Setting indexes to an empty string means that they will be
 180                                 # omitted if they would otherwise appear in URLs. It just so
 181                                 # happens that this  is the right thing to do in the standard
 182                                 # UI, in all the relevant cases.
 183                                 $this->mPastTheEndIndex = '';
 184                                 $res->seek( $numRows - 1 );
 185                                 $row = $res->fetchRow();
 186                                 $lastIndex = $row[$this->mIndexField];
 187                         }
 188                 } else {
 189                         $firstIndex = '';
 190                         $lastIndex = '';
 191                         $this->mPastTheEndRow = null;
 192                         $this->mPastTheEndIndex = '';
 193                 }
 194
 195                 if ( $this->mIsBackwards ) {
 196                         $this->mIsFirst = ( $numRows < $limit );
 197                         $this->mIsLast = ( $offset == '' );
 198                         $this->mLastShown = $firstIndex;
 199                         $this->mFirstShown = $lastIndex;
 200                 } else {
 201                         $this->mIsFirst = ( $offset == '' );
 202                         $this->mIsLast = ( $numRows < $limit );
 203                         $this->mLastShown = $lastIndex;
 204                         $this->mFirstShown = $firstIndex;
 205                 }
 206         }
 207
 208         /**
 209          * Do a query with specified parameters, rather than using the object
 210          * context
 211          *
 212          * @param string $offset Index offset, inclusive
 213          * @param integer $limit Exact query limit
 214          * @param boolean $descending Query direction, false for ascending, true for descending
 215          * @return ResultWrapper
 216          */
 217         function reallyDoQuery( $offset, $limit, $descending ) {
 218                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 219                 $info = $this->getQueryInfo();
 220                 $tables = $info['tables'];
 221                 $fields = $info['fields'];
 222                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 223                 $options = isset( $info['options'] ) ? $info['options'] : array();
 224                 $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
 225                 if ( $descending ) {
 226                         $options['ORDER BY'] = $this->mIndexField;
 227                         $operator = '>';
 228                 } else {
 229                         $options['ORDER BY'] = $this->mIndexField . ' DESC';
 230                         $operator = '<';
 231                 }
 232                 if ( $offset != '' ) {
 233                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 234                 }
 235                 $options['LIMIT'] = intval( $limit );
 236                 $res = $this->mDb->select( $tables, $fields, $conds, $fname, $options, $join_conds );
 237                 return new ResultWrapper( $this->mDb, $res );
 238         }
 239
 240         /**
 241          * Pre-process results; useful for performing batch existence checks, etc.
 242          *
 243          * @param ResultWrapper $result Result wrapper
 244          */
 245         protected function preprocessResults( $result ) {}
 246
 247         /**
 248          * Get the formatted result list. Calls getStartBody(), formatRow() and
 249          * getEndBody(), concatenates the results and returns them.
 250          */
 251         function getBody() {
 252                 if ( !$this->mQueryDone ) {
 253                         $this->doQuery();
 254                 }
 255                 # Don't use any extra rows returned by the query
 256                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 257
 258                 $s = $this->getStartBody();
 259                 if ( $numRows ) {
 260                         if ( $this->mIsBackwards ) {
 261                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 262                                         $this->mResult->seek( $i );
 263                                         $row = $this->mResult->fetchObject();
 264                                         $s .= $this->formatRow( $row );
 265                                 }
 266                         } else {
 267                                 $this->mResult->seek( 0 );
 268                                 for ( $i = 0; $i < $numRows; $i++ ) {
 269                                         $row = $this->mResult->fetchObject();
 270                                         $s .= $this->formatRow( $row );
 271                                 }
 272                         }
 273                 } else {
 274                         $s .= $this->getEmptyBody();
 275                 }
 276                 $s .= $this->getEndBody();
 277                 return $s;
 278         }
 279
 280         /**
 281          * Make a self-link
 282          */
 283         function makeLink($text, $query = null, $type=null) {
 284                 if ( $query === null ) {
 285                         return $text;
 286                 }
 287                 if( $type == 'prev' || $type == 'next' ) {
 288                         $attrs = "rel=\"$type\"";
 289                 } elseif( $type == 'first' ) {
 290                         $attrs = "rel=\"start\"";
 291                 } else {
 292                         # HTML 4 has no rel="end" . . .
 293                         $attrs = '';
 294                 }
 295                 return $this->getSkin()->makeKnownLinkObj( $this->getTitle(), $text,
 296                                 wfArrayToCGI( $query, $this->getDefaultQuery() ), '', '',
 297                                 $attrs );
 298         }
 299
 300         /**
 301          * Hook into getBody(), allows text to be inserted at the start. This
 302          * will be called even if there are no rows in the result set.
 303          */
 304         function getStartBody() {
 305                 return '';
 306         }
 307
 308         /**
 309          * Hook into getBody() for the end of the list
 310          */
 311         function getEndBody() {
 312                 return '';
 313         }
 314
 315         /**
 316          * Hook into getBody(), for the bit between the start and the
 317          * end when there are no rows
 318          */
 319         function getEmptyBody() {
 320                 return '';
 321         }
 322
 323         /**
 324          * Title used for self-links. Override this if you want to be able to
 325          * use a title other than $wgTitle
 326          */
 327         function getTitle() {
 328                 return $GLOBALS['wgTitle'];
 329         }
 330
 331         /**
 332          * Get the current skin. This can be overridden if necessary.
 333          */
 334         function getSkin() {
 335                 if ( !isset( $this->mSkin ) ) {
 336                         global $wgUser;
 337                         $this->mSkin = $wgUser->getSkin();
 338                 }
 339                 return $this->mSkin;
 340         }
 341
 342         /**
 343          * Get an array of query parameters that should be put into self-links.
 344          * By default, all parameters passed in the URL are used, except for a
 345          * short blacklist.
 346          */
 347         function getDefaultQuery() {
 348                 if ( !isset( $this->mDefaultQuery ) ) {
 349                         $this->mDefaultQuery = $_GET;
 350                         unset( $this->mDefaultQuery['title'] );
 351                         unset( $this->mDefaultQuery['dir'] );
 352                         unset( $this->mDefaultQuery['offset'] );
 353                         unset( $this->mDefaultQuery['limit'] );
 354                         unset( $this->mDefaultQuery['order'] );
 355                 }
 356                 return $this->mDefaultQuery;
 357         }
 358
 359         /**
 360          * Get the number of rows in the result set
 361          */
 362         function getNumRows() {
 363                 if ( !$this->mQueryDone ) {
 364                         $this->doQuery();
 365                 }
 366                 return $this->mResult->numRows();
 367         }
 368
 369         /**
 370          * Get a URL query array for the prev, next, first and last links.
 371          */
 372         function getPagingQueries() {
 373                 if ( !$this->mQueryDone ) {
 374                         $this->doQuery();
 375                 }
 376
 377                 # Don't announce the limit everywhere if it's the default
 378                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? '' : $this->mLimit;
 379
 380                 if ( $this->mIsFirst ) {
 381                         $prev = false;
 382                         $first = false;
 383                 } else {
 384                         $prev = array( 'dir' => 'prev', 'offset' => $this->mFirstShown, 'limit' => $urlLimit );
 385                         $first = array( 'limit' => $urlLimit );
 386                 }
 387                 if ( $this->mIsLast ) {
 388                         $next = false;
 389                         $last = false;
 390                 } else {
 391                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 392                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 393                 }
 394                 return array( 'prev' => $prev, 'next' => $next, 'first' => $first, 'last' => $last );
 395         }
 396
 397         /**
 398          * Get paging links. If a link is disabled, the item from $disabledTexts
 399          * will be used. If there is no such item, the unlinked text from
 400          * $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays
 401          * of HTML.
 402          */
 403         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 404                 $queries = $this->getPagingQueries();
 405                 $links = array();
 406                 foreach ( $queries as $type => $query ) {
 407                         if ( $query !== false ) {
 408                                 $links[$type] = "<span class='mw-pager-pagerlink-enabled'>" .
 409                                         $this->makeLink( $linkTexts[$type], $queries[$type], $type ) .
 410                                         "</span>";
 411                         } elseif ( isset( $disabledTexts[$type] ) ) {
 412                                 $links[$type] = "<span class='mw-pager-pagerlink-disabled'>" .
 413                                         $disabledTexts[$type] .
 414                                         "</span>";
 415                         } else {
 416                                 $links[$type] = "<span class='mw-pager-pagerlink-disabled'>" .
 417                                         $linkTexts[$type] .
 418                                         "</span>";
 419                         }
 420                 }
 421                 return $links;
 422         }
 423
 424         function getLimitLinks() {
 425                 global $wgLang;
 426                 $links = array();
 427                 if ( $this->mIsBackwards ) {
 428                         $offset = $this->mPastTheEndIndex;
 429                 } else {
 430                         $offset = $this->mOffset;
 431                 }
 432                 foreach ( $this->mLimitsShown as $limit ) {
 433                         $links[] = $this->makeLink( $wgLang->formatNum( $limit ),
 434                                 array( 'offset' => $offset, 'limit' => $limit ) );
 435                 }
 436                 return $links;
 437         }
 438
 439         /**
 440          * Abstract formatting function. This should return an HTML string
 441          * representing the result row $row. Rows will be concatenated and
 442          * returned by getBody()
 443          */
 444         abstract function formatRow( $row );
 445
 446         /**
 447          * This function should be overridden to provide all parameters
 448          * needed for the main paged query. It returns an associative
 449          * array with the following elements:
 450          *    tables => Table(s) for passing to Database::select()
 451          *    fields => Field(s) for passing to Database::select(), may be *
 452          *    conds => WHERE conditions
 453          *    options => option array
 454          */
 455         abstract function getQueryInfo();
 456
 457         /**
 458          * This function should be overridden to return the name of the index fi-
 459          * eld.  If the pager supports multiple orders, it may return an array of
 460          * 'querykey' => 'indexfield' pairs, so that a request with &count=querykey
 461          * will use indexfield to sort.  In this case, the first returned key is
 462          * the default.
 463          *
 464          * Needless to say, it's really not a good idea to use a non-unique index
 465          * for this!  That won't page right.
 466          */
 467         abstract function getIndexField();
 468
 469         /**
 470          * Return the default sorting direction: false for ascending, true for de-
 471          * scending.  You can also have an associative array of ordertype => dir,
 472          * if multiple order types are supported.  In this case getIndexField()
 473          * must return an array, and the keys of that must exactly match the keys
 474          * of this.
 475          *
 476          * For backward compatibility, this method's return value will be ignored
 477          * if $this->mDefaultDirection is already set when the constructor is
 478          * called, for instance if it's statically initialized.  In that case the
 479          * value of that variable (which must be a boolean) will be used.
 480          *
 481          * Note that despite its name, this does not return the value of the
 482          * $this->mDefaultDirection member variable.  That's the default for this
 483          * particular instantiation, which is a single value.  This is the set of
 484          * all defaults for the class.
 485          */
 486         protected function getDefaultDirections() { return false; }
 487 }
 488
 489
 490 /**
 491  * IndexPager with an alphabetic list and a formatted navigation bar
 492  * @ingroup Pager
 493  */
 494 abstract class AlphabeticPager extends IndexPager {
 495         function __construct() {
 496                 parent::__construct();
 497         }
 498
 499         /**
 500          * Shamelessly stolen bits from ReverseChronologicalPager,
 501          * didn't want to do class magic as may be still revamped
 502          */
 503         function getNavigationBar() {
 504                 global $wgLang;
 505
 506                 if( isset( $this->mNavigationBar ) ) {
 507                         return $this->mNavigationBar;
 508                 }
 509
 510                 $linkTexts = array(
 511                         'prev' => wfMsgHtml( 'prevn', $wgLang->formatNum( $this->mLimit ) ),
 512                         'next' => wfMsgHtml( 'nextn', $wgLang->formatNum($this->mLimit ) ),
 513                         'first' => wfMsgHtml( 'page_first' ),
 514                         'last' => wfMsgHtml( 'page_last' )
 515                 );
 516
 517                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 518                 $limitLinks = $this->getLimitLinks();
 519                 $limits = implode( ' | ', $limitLinks );
 520
 521                 $this->mNavigationBar =
 522                         "({$pagingLinks['first']} | {$pagingLinks['last']}) " .
 523                         wfMsgHtml( 'viewprevnext', $pagingLinks['prev'],
 524                         $pagingLinks['next'], $limits );
 525
 526                 if( !is_array( $this->getIndexField() ) ) {
 527                         # Early return to avoid undue nesting
 528                         return $this->mNavigationBar;
 529                 }
 530
 531                 $extra = '';
 532                 $first = true;
 533                 $msgs = $this->getOrderTypeMessages();
 534                 foreach( array_keys( $msgs ) as $order ) {
 535                         if( $first ) {
 536                                 $first = false;
 537                         } else {
 538                                 $extra .= ' | ';
 539                         }
 540
 541                         if( $order == $this->mOrderType ) {
 542                                 $extra .= wfMsgHTML( $msgs[$order] );
 543                         } else {
 544                                 $extra .= $this->makeLink(
 545                                         wfMsgHTML( $msgs[$order] ),
 546                                         array( 'order' => $order )
 547                                 );
 548                         }
 549                 }
 550
 551                 if( $extra !== '' ) {
 552                         $this->mNavigationBar .= " ($extra)";
 553                 }
 554
 555                 return $this->mNavigationBar;
 556         }
 557
 558         /**
 559          * If this supports multiple order type messages, give the message key for
 560          * enabling each one in getNavigationBar.  The return type is an associa-
 561          * tive array whose keys must exactly match the keys of the array returned
 562          * by getIndexField(), and whose values are message keys.
 563          * @return array
 564          */
 565         protected function getOrderTypeMessages() {
 566                 return null;
 567         }
 568 }
 569
 570 /**
 571  * IndexPager with a formatted navigation bar
 572  * @ingroup Pager
 573  */
 574 abstract class ReverseChronologicalPager extends IndexPager {
 575         public $mDefaultDirection = true;
 576
 577         function __construct() {
 578                 parent::__construct();
 579         }
 580
 581         function getNavigationBar() {
 582                 global $wgLang;
 583
 584                 if ( isset( $this->mNavigationBar ) ) {
 585                         return $this->mNavigationBar;
 586                 }
 587                 $nicenumber = $wgLang->formatNum( $this->mLimit );
 588                 $linkTexts = array(
 589                         'prev' => wfMsgExt( 'pager-newer-n', array( 'parsemag' ), $nicenumber ),
 590                         'next' => wfMsgExt( 'pager-older-n', array( 'parsemag' ), $nicenumber ),
 591                         'first' => wfMsgHtml( 'histlast' ),
 592                         'last' => wfMsgHtml( 'histfirst' )
 593                 );
 594
 595                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 596                 $limitLinks = $this->getLimitLinks();
 597                 $limits = implode( ' | ', $limitLinks );
 598
 599                 $this->mNavigationBar = "({$pagingLinks['first']} | {$pagingLinks['last']}) " .
 600                         wfMsgHtml("viewprevnext", $pagingLinks['prev'], $pagingLinks['next'], $limits);
 601                 return $this->mNavigationBar;
 602         }
 603 }
 604
 605 /**
 606  * Table-based display with a user-selectable sort order
 607  * @ingroup Pager
 608  */
 609 abstract class TablePager extends IndexPager {
 610         var $mSort;
 611         var $mCurrentRow;
 612
 613         function __construct() {
 614                 global $wgRequest;
 615                 $this->mSort = $wgRequest->getText( 'sort' );
 616                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() ) ) {
 617                         $this->mSort = $this->getDefaultSort();
 618                 }
 619                 if ( $wgRequest->getBool( 'asc' ) ) {
 620                         $this->mDefaultDirection = false;
 621                 } elseif ( $wgRequest->getBool( 'desc' ) ) {
 622                         $this->mDefaultDirection = true;
 623                 } /* Else leave it at whatever the class default is */
 624
 625                 parent::__construct();
 626         }
 627
 628         function getStartBody() {
 629                 global $wgStylePath;
 630                 $tableClass = htmlspecialchars( $this->getTableClass() );
 631                 $sortClass = htmlspecialchars( $this->getSortHeaderClass() );
 632
 633                 $s = "<table border='1' class=\"$tableClass\"><thead><tr>\n";
 634                 $fields = $this->getFieldNames();
 635
 636                 # Make table header
 637                 foreach ( $fields as $field => $name ) {
 638                         if ( strval( $name ) == '' ) {
 639                                 $s .= "<th>&nbsp;</th>\n";
 640                         } elseif ( $this->isFieldSortable( $field ) ) {
 641                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 642                                 if ( $field == $this->mSort ) {
 643                                         # This is the sorted column
 644                                         # Prepare a link that goes in the other sort order
 645                                         if ( $this->mDefaultDirection ) {
 646                                                 # Descending
 647                                                 $image = 'Arr_u.png';
 648                                                 $query['asc'] = '1';
 649                                                 $query['desc'] = '';
 650                                                 $alt = htmlspecialchars( wfMsg( 'descending_abbrev' ) );
 651                                         } else {
 652                                                 # Ascending
 653                                                 $image = 'Arr_d.png';
 654                                                 $query['asc'] = '';
 655                                                 $query['desc'] = '1';
 656                                                 $alt = htmlspecialchars( wfMsg( 'ascending_abbrev' ) );
 657                                         }
 658                                         $image = htmlspecialchars( "$wgStylePath/common/images/$image" );
 659                                         $link = $this->makeLink(
 660                                                 "<img width=\"12\" height=\"12\" alt=\"$alt\" src=\"$image\" />" .
 661                                                 htmlspecialchars( $name ), $query );
 662                                         $s .= "<th class=\"$sortClass\">$link</th>\n";
 663                                 } else {
 664                                         $s .= '<th>' . $this->makeLink( htmlspecialchars( $name ), $query ) . "</th>\n";
 665                                 }
 666                         } else {
 667                                 $s .= '<th>' . htmlspecialchars( $name ) . "</th>\n";
 668                         }
 669                 }
 670                 $s .= "</tr></thead><tbody>\n";
 671                 return $s;
 672         }
 673
 674         function getEndBody() {
 675                 return "</tbody></table>\n";
 676         }
 677
 678         function getEmptyBody() {
 679                 $colspan = count( $this->getFieldNames() );
 680                 $msgEmpty = wfMsgHtml( 'table_pager_empty' );
 681                 return "<tr><td colspan=\"$colspan\">$msgEmpty</td></tr>\n";
 682         }
 683
 684         function formatRow( $row ) {
 685                 $s = "<tr>\n";
 686                 $fieldNames = $this->getFieldNames();
 687                 $this->mCurrentRow = $row;  # In case formatValue needs to know
 688                 foreach ( $fieldNames as $field => $name ) {
 689                         $value = isset( $row->$field ) ? $row->$field : null;
 690                         $formatted = strval( $this->formatValue( $field, $value ) );
 691                         if ( $formatted == '' ) {
 692                                 $formatted = '&nbsp;';
 693                         }
 694                         $class = 'TablePager_col_' . htmlspecialchars( $field );
 695                         $s .= "<td class=\"$class\">$formatted</td>\n";
 696                 }
 697                 $s .= "</tr>\n";
 698                 return $s;
 699         }
 700
 701         function getIndexField() {
 702                 return $this->mSort;
 703         }
 704
 705         function getTableClass() {
 706                 return 'TablePager';
 707         }
 708
 709         function getNavClass() {
 710                 return 'TablePager_nav';
 711         }
 712
 713         function getSortHeaderClass() {
 714                 return 'TablePager_sort';
 715         }
 716
 717         /**
 718          * A navigation bar with images
 719          */
 720         function getNavigationBar() {
 721                 global $wgStylePath, $wgContLang;
 722                 $path = "$wgStylePath/common/images";
 723                 $labels = array(
 724                         'first' => 'table_pager_first',
 725                         'prev' => 'table_pager_prev',
 726                         'next' => 'table_pager_next',
 727                         'last' => 'table_pager_last',
 728                 );
 729                 $images = array(
 730                         'first' => $wgContLang->isRTL() ? 'arrow_last_25.png' : 'arrow_first_25.png',
 731                         'prev' =>  $wgContLang->isRTL() ? 'arrow_right_25.png' : 'arrow_left_25.png',
 732                         'next' =>  $wgContLang->isRTL() ? 'arrow_left_25.png' : 'arrow_right_25.png',
 733                         'last' =>  $wgContLang->isRTL() ? 'arrow_first_25.png' : 'arrow_last_25.png',
 734                 );
 735                 $disabledImages = array(
 736                         'first' => $wgContLang->isRTL() ? 'arrow_disabled_last_25.png' : 'arrow_disabled_first_25.png',
 737                         'prev' =>  $wgContLang->isRTL() ? 'arrow_disabled_right_25.png' : 'arrow_disabled_left_25.png',
 738                         'next' =>  $wgContLang->isRTL() ? 'arrow_disabled_left_25.png' : 'arrow_disabled_right_25.png',
 739                         'last' =>  $wgContLang->isRTL() ? 'arrow_disabled_first_25.png' : 'arrow_disabled_last_25.png',
 740                 );
 741
 742                 $linkTexts = array();
 743                 $disabledTexts = array();
 744                 foreach ( $labels as $type => $label ) {
 745                         $msgLabel = wfMsgHtml( $label );
 746                         $linkTexts[$type] = "<img src=\"$path/{$images[$type]}\" alt=\"$msgLabel\"/><br/>$msgLabel";
 747                         $disabledTexts[$type] = "<img src=\"$path/{$disabledImages[$type]}\" alt=\"$msgLabel\"/><br/>$msgLabel";
 748                 }
 749                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
 750
 751                 $navClass = htmlspecialchars( $this->getNavClass() );
 752                 $s = "<table class=\"$navClass\" align=\"center\" cellpadding=\"3\"><tr>\n";
 753                 $cellAttrs = 'valign="top" align="center" width="' . 100 / count( $links ) . '%"';
 754                 foreach ( $labels as $type => $label ) {
 755                         $s .= "<td $cellAttrs>{$links[$type]}</td>\n";
 756                 }
 757                 $s .= "</tr></table>\n";
 758                 return $s;
 759         }
 760
 761         /**
 762          * Get a <select> element which has options for each of the allowed limits
 763          */
 764         function getLimitSelect() {
 765                 global $wgLang;
 766                 $s = "<select name=\"limit\">";
 767                 foreach ( $this->mLimitsShown as $limit ) {
 768                         $selected = $limit == $this->mLimit ? 'selected="selected"' : '';
 769                         $formattedLimit = $wgLang->formatNum( $limit );
 770                         $s .= "<option value=\"$limit\" $selected>$formattedLimit</option>\n";
 771                 }
 772                 $s .= "</select>";
 773                 return $s;
 774         }
 775
 776         /**
 777          * Get <input type="hidden"> elements for use in a method="get" form.
 778          * Resubmits all defined elements of the $_GET array, except for a
 779          * blacklist, passed in the $blacklist parameter.
 780          */
 781         function getHiddenFields( $blacklist = array() ) {
 782                 $blacklist = (array)$blacklist;
 783                 $query = $_GET;
 784                 foreach ( $blacklist as $name ) {
 785                         unset( $query[$name] );
 786                 }
 787                 $s = '';
 788                 foreach ( $query as $name => $value ) {
 789                         $encName = htmlspecialchars( $name );
 790                         $encValue = htmlspecialchars( $value );
 791                         $s .= "<input type=\"hidden\" name=\"$encName\" value=\"$encValue\"/>\n";
 792                 }
 793                 return $s;
 794         }
 795
 796         /**
 797          * Get a form containing a limit selection dropdown
 798          */
 799         function getLimitForm() {
 800                 # Make the select with some explanatory text
 801                 $url = $this->getTitle()->escapeLocalURL();
 802                 $msgSubmit = wfMsgHtml( 'table_pager_limit_submit' );
 803                 return
 804                         "<form method=\"get\" action=\"$url\">" .
 805                         wfMsgHtml( 'table_pager_limit', $this->getLimitSelect() ) .
 806                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
 807                         $this->getHiddenFields( 'limit' ) .
 808                         "</form>\n";
 809         }
 810
 811         /**
 812          * Return true if the named field should be sortable by the UI, false
 813          * otherwise
 814          *
 815          * @param string $field
 816          */
 817         abstract function isFieldSortable( $field );
 818
 819         /**
 820          * Format a table cell. The return value should be HTML, but use an empty
 821          * string not &nbsp; for empty cells. Do not include the <td> and </td>.
 822          *
 823          * The current result row is available as $this->mCurrentRow, in case you
 824          * need more context.
 825          *
 826          * @param string $name The database field name
 827          * @param string $value The value retrieved from the database
 828          */
 829         abstract function formatValue( $name, $value );
 830
 831         /**
 832          * The database field name used as a default sort order
 833          */
 834         abstract function getDefaultSort();
 835
 836         /**
 837          * An array mapping database field names to a textual description of the
 838          * field name, for use in the table header. The description should be plain
 839          * text, it will be HTML-escaped later.
 840          */
 841         abstract function getFieldNames();
 842 }