includes/Pager.php

   1 <?php
   2
   3 /**
   4  * Basic pager interface.
   5  * @addtogroup Pager
   6  */
   7 interface Pager {
   8         function getNavigationBar();
   9         function getBody();
  10 }
  11
  12 /**
  13  * IndexPager is an efficient pager which uses a (roughly unique) index in the
  14  * data set to implement paging, rather than a "LIMIT offset,limit" clause.
  15  * In MySQL, such a limit/offset clause requires counting through the specified number
  16  * of offset rows to find the desired data, which can be expensive for large offsets.
  17  *
  18  * ReverseChronologicalPager is a child class of the abstract IndexPager, and contains
  19  * some formatting and display code which is specific to the use of timestamps as
  20  * indexes. Here is a synopsis of its operation:
  21  *
  22  *    * The query is specified by the offset, limit and direction (dir) parameters, in
  23  *      addition to any subclass-specific parameters.
  24  *
  25  *    * The offset is the non-inclusive start of the DB query. A row with an index value
  26  *      equal to the offset will never be shown.
  27  *
  28  *    * The query may either be done backwards, where the rows are returned by the database
  29  *      in the opposite order to which they are displayed to the user, or forwards. This is
  30  *      specified by the "dir" parameter, dir=prev means backwards, anything else means
  31  *      forwards. The offset value specifies the start of the database result set, which
  32  *      may be either the start or end of the displayed data set. This allows "previous"
  33  *      links to be implemented without knowledge of the index value at the start of the
  34  *      previous page.
  35  *
  36  *    * An additional row beyond the user-specified limit is always requested. This allows
  37  *      us to tell whether we should display a "next" link in the case of forwards mode,
  38  *      or a "previous" link in the case of backwards mode. Determining whether to
  39  *      display the other link (the one for the page before the start of the database
  40  *      result set) can be done heuristically by examining the offset.
  41  *
  42  *    * An empty offset indicates that the offset condition should be omitted from the query.
  43  *      This naturally produces either the first page or the last page depending on the
  44  *      dir parameter.
  45  *
  46  *  Subclassing the pager to implement concrete functionality should be fairly simple,
  47  *  please see the examples in PageHistory.php and SpecialIpblocklist.php. You just need
  48  *  to override formatRow(), getQueryInfo() and getIndexField(). Don't forget to call the
  49  *  parent constructor if you override it.
  50  *
  51  * @addtogroup Pager
  52  */
  53 abstract class IndexPager implements Pager {
  54         public $mRequest;
  55         public $mLimitsShown = array( 20, 50, 100, 250, 500 );
  56         public $mDefaultLimit = 50;
  57         public $mOffset, $mLimit;
  58         public $mQueryDone = false;
  59         public $mDb;
  60         public $mPastTheEndRow;
  61
  62         protected $mIndexField;
  63
  64         /**
  65          * Default query direction. false for ascending, true for descending
  66          */
  67         public $mDefaultDirection = false;
  68
  69         /**
  70          * Result object for the query. Warning: seek before use.
  71          */
  72         public $mResult;
  73
  74         function __construct() {
  75                 global $wgRequest;
  76                 $this->mRequest = $wgRequest;
  77
  78                 # NB: the offset is quoted, not validated. It is treated as an arbitrary string
  79                 # to support the widest variety of index types. Be careful outputting it into
  80                 # HTML!
  81                 $this->mOffset = $this->mRequest->getText( 'offset' );
  82                 $this->mLimit = $this->mRequest->getInt( 'limit', $this->mDefaultLimit );
  83                 if ( $this->mLimit <= 0 || $this->mLimit > 50000 ) {
  84                         $this->mLimit = $this->mDefaultLimit;
  85                 }
  86                 $this->mIsBackwards = ( $this->mRequest->getVal( 'dir' ) == 'prev' );
  87                 $this->mIndexField = $this->getIndexField();
  88                 $this->mDb = wfGetDB( DB_SLAVE );
  89         }
  90
  91         /**
  92          * Do the query, using information from the object context. This function
  93          * has been kept minimal to make it overridable if necessary, to allow for
  94          * result sets formed from multiple DB queries.
  95          */
  96         function doQuery() {
  97                 # Use the child class name for profiling
  98                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
  99                 wfProfileIn( $fname );
 100
 101                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 102                 # Plus an extra row so that we can tell the "next" link should be shown
 103                 $queryLimit = $this->mLimit + 1;
 104
 105                 $this->mResult = $this->reallyDoQuery( $this->mOffset, $queryLimit, $descending );
 106                 $this->extractResultInfo( $this->mOffset, $queryLimit, $this->mResult );
 107                 $this->mQueryDone = true;
 108
 109                 wfProfileOut( $fname );
 110         }
 111
 112         /**
 113          * Extract some useful data from the result object for use by
 114          * the navigation bar, put it into $this
 115          */
 116         function extractResultInfo( $offset, $limit, ResultWrapper $res ) {
 117                 $numRows = $res->numRows();
 118                 if ( $numRows ) {
 119                         $row = $res->fetchRow();
 120                         $firstIndex = $row[$this->mIndexField];
 121
 122                         # Discard the extra result row if there is one
 123                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 124                                 $res->seek( $numRows - 1 );
 125                                 $this->mPastTheEndRow = $res->fetchObject();
 126                                 $indexField = $this->mIndexField;
 127                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexField;
 128                                 $res->seek( $numRows - 2 );
 129                                 $row = $res->fetchRow();
 130                                 $lastIndex = $row[$this->mIndexField];
 131                         } else {
 132                                 $this->mPastTheEndRow = null;
 133                                 # Setting indexes to an empty string means that they will be omitted
 134                                 # if they would otherwise appear in URLs. It just so happens that this
 135                                 # is the right thing to do in the standard UI, in all the relevant cases.
 136                                 $this->mPastTheEndIndex = '';
 137                                 $res->seek( $numRows - 1 );
 138                                 $row = $res->fetchRow();
 139                                 $lastIndex = $row[$this->mIndexField];
 140                         }
 141                 } else {
 142                         $firstIndex = '';
 143                         $lastIndex = '';
 144                         $this->mPastTheEndRow = null;
 145                         $this->mPastTheEndIndex = '';
 146                 }
 147
 148                 if ( $this->mIsBackwards ) {
 149                         $this->mIsFirst = ( $numRows < $limit );
 150                         $this->mIsLast = ( $offset == '' );
 151                         $this->mLastShown = $firstIndex;
 152                         $this->mFirstShown = $lastIndex;
 153                 } else {
 154                         $this->mIsFirst = ( $offset == '' );
 155                         $this->mIsLast = ( $numRows < $limit );
 156                         $this->mLastShown = $lastIndex;
 157                         $this->mFirstShown = $firstIndex;
 158                 }
 159         }
 160
 161         /**
 162          * Do a query with specified parameters, rather than using the object context
 163          *
 164          * @param string $offset Index offset, inclusive
 165          * @param integer $limit Exact query limit
 166          * @param boolean $descending Query direction, false for ascending, true for descending
 167          * @return ResultWrapper
 168          */
 169         function reallyDoQuery( $offset, $limit, $ascending ) {
 170                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 171                 $info = $this->getQueryInfo();
 172                 $tables = $info['tables'];
 173                 $fields = $info['fields'];
 174                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 175                 $options = isset( $info['options'] ) ? $info['options'] : array();
 176                 if ( $ascending ) {
 177                         $options['ORDER BY'] = $this->mIndexField;
 178                         $operator = '>';
 179                 } else {
 180                         $options['ORDER BY'] = $this->mIndexField . ' DESC';
 181                         $operator = '<';
 182                 }
 183                 if ( $offset != '' ) {
 184                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 185                 }
 186                 $options['LIMIT'] = intval( $limit );
 187                 $res = $this->mDb->select( $tables, $fields, $conds, $fname, $options );
 188                 return new ResultWrapper( $this->mDb, $res );
 189         }
 190
 191         /**
 192          * Get the formatted result list. Calls getStartBody(), formatRow() and
 193          * getEndBody(), concatenates the results and returns them.
 194          */
 195         function getBody() {
 196                 if ( !$this->mQueryDone ) {
 197                         $this->doQuery();
 198                 }
 199                 # Don't use any extra rows returned by the query
 200                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 201
 202                 $s = $this->getStartBody();
 203                 if ( $numRows ) {
 204                         if ( $this->mIsBackwards ) {
 205                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 206                                         $this->mResult->seek( $i );
 207                                         $row = $this->mResult->fetchObject();
 208                                         $s .= $this->formatRow( $row );
 209                                 }
 210                         } else {
 211                                 $this->mResult->seek( 0 );
 212                                 for ( $i = 0; $i < $numRows; $i++ ) {
 213                                         $row = $this->mResult->fetchObject();
 214                                         $s .= $this->formatRow( $row );
 215                                 }
 216                         }
 217                 } else {
 218                         $s .= $this->getEmptyBody();
 219                 }
 220                 $s .= $this->getEndBody();
 221                 return $s;
 222         }
 223
 224         /**
 225          * Make a self-link
 226          */
 227         function makeLink($text, $query = NULL) {
 228                 if ( $query === null ) {
 229                         return $text;
 230                 } else {
 231                         return $this->getSkin()->makeKnownLinkObj( $this->getTitle(), $text,
 232                                 wfArrayToCGI( $query, $this->getDefaultQuery() ) );
 233                 }
 234         }
 235
 236         /**
 237          * Hook into getBody(), allows text to be inserted at the start. This
 238          * will be called even if there are no rows in the result set.
 239          */
 240         function getStartBody() {
 241                 return '';
 242         }
 243
 244         /**
 245          * Hook into getBody() for the end of the list
 246          */
 247         function getEndBody() {
 248                 return '';
 249         }
 250
 251         /**
 252          * Hook into getBody(), for the bit between the start and the
 253          * end when there are no rows
 254          */
 255         function getEmptyBody() {
 256                 return '';
 257         }
 258
 259         /**
 260          * Title used for self-links. Override this if you want to be able to
 261          * use a title other than $wgTitle
 262          */
 263         function getTitle() {
 264                 return $GLOBALS['wgTitle'];
 265         }
 266
 267         /**
 268          * Get the current skin. This can be overridden if necessary.
 269          */
 270         function getSkin() {
 271                 if ( !isset( $this->mSkin ) ) {
 272                         global $wgUser;
 273                         $this->mSkin = $wgUser->getSkin();
 274                 }
 275                 return $this->mSkin;
 276         }
 277
 278         /**
 279          * Get an array of query parameters that should be put into self-links.
 280          * By default, all parameters passed in the URL are used, except for a
 281          * short blacklist.
 282          */
 283         function getDefaultQuery() {
 284                 if ( !isset( $this->mDefaultQuery ) ) {
 285                         $this->mDefaultQuery = $_GET;
 286                         unset( $this->mDefaultQuery['title'] );
 287                         unset( $this->mDefaultQuery['dir'] );
 288                         unset( $this->mDefaultQuery['offset'] );
 289                         unset( $this->mDefaultQuery['limit'] );
 290                 }
 291                 return $this->mDefaultQuery;
 292         }
 293
 294         /**
 295          * Get the number of rows in the result set
 296          */
 297         function getNumRows() {
 298                 if ( !$this->mQueryDone ) {
 299                         $this->doQuery();
 300                 }
 301                 return $this->mResult->numRows();
 302         }
 303
 304         /**
 305          * Get a query array for the prev, next, first and last links.
 306          */
 307         function getPagingQueries() {
 308                 if ( !$this->mQueryDone ) {
 309                         $this->doQuery();
 310                 }
 311
 312                 # Don't announce the limit everywhere if it's the default
 313                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? '' : $this->mLimit;
 314
 315                 if ( $this->mIsFirst ) {
 316                         $prev = false;
 317                         $first = false;
 318                 } else {
 319                         $prev = array( 'dir' => 'prev', 'offset' => $this->mFirstShown, 'limit' => $urlLimit );
 320                         $first = array( 'limit' => $urlLimit );
 321                 }
 322                 if ( $this->mIsLast ) {
 323                         $next = false;
 324                         $last = false;
 325                 } else {
 326                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 327                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 328                 }
 329                 return array( 'prev' => $prev, 'next' => $next, 'first' => $first, 'last' => $last );
 330         }
 331
 332         /**
 333          * Get paging links. If a link is disabled, the item from $disabledTexts will
 334          * be used. If there is no such item, the unlinked text from $linkTexts will
 335          * be used. Both $linkTexts and $disabledTexts are arrays of HTML.
 336          */
 337         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 338                 $queries = $this->getPagingQueries();
 339                 $links = array();
 340                 foreach ( $queries as $type => $query ) {
 341                         if ( $query !== false ) {
 342                                 $links[$type] = $this->makeLink( $linkTexts[$type], $queries[$type] );
 343                         } elseif ( isset( $disabledTexts[$type] ) ) {
 344                                 $links[$type] = $disabledTexts[$type];
 345                         } else {
 346                                 $links[$type] = $linkTexts[$type];
 347                         }
 348                 }
 349                 return $links;
 350         }
 351
 352         function getLimitLinks() {
 353                 global $wgLang;
 354                 $links = array();
 355                 if ( $this->mIsBackwards ) {
 356                         $offset = $this->mPastTheEndIndex;
 357                 } else {
 358                         $offset = $this->mOffset;
 359                 }
 360                 foreach ( $this->mLimitsShown as $limit ) {
 361                         $links[] = $this->makeLink( $wgLang->formatNum( $limit ),
 362                                 array( 'offset' => $offset, 'limit' => $limit ) );
 363                 }
 364                 return $links;
 365         }
 366
 367         /**
 368          * Abstract formatting function. This should return an HTML string
 369          * representing the result row $row. Rows will be concatenated and
 370          * returned by getBody()
 371          */
 372         abstract function formatRow( $row );
 373
 374         /**
 375          * This function should be overridden to provide all parameters
 376          * needed for the main paged query. It returns an associative
 377          * array with the following elements:
 378          *    tables => Table(s) for passing to Database::select()
 379          *    fields => Field(s) for passing to Database::select(), may be *
 380          *    conds => WHERE conditions
 381          *    options => option array
 382          */
 383         abstract function getQueryInfo();
 384
 385         /**
 386          * This function should be overridden to return the name of the
 387          * index field.
 388          */
 389         abstract function getIndexField();
 390 }
 391
 392
 393 /**
 394  * IndexPager with an alphabetic list and a formatted navigation bar
 395  * @addtogroup Pager
 396  */
 397 abstract class AlphabeticPager extends IndexPager {
 398         public $mDefaultDirection = false;
 399
 400         function __construct() {
 401                 parent::__construct();
 402         }
 403
 404         /**
 405          * Shamelessly stolen bits from ReverseChronologicalPager, d
 406          * didn't want to do class magic as may be still revamped
 407          */
 408         function getNavigationBar() {
 409                 global $wgLang;
 410
 411                 $linkTexts = array(
 412                         'prev' => wfMsgHtml( "prevn", $this->mLimit ),
 413                         'next' => wfMsgHtml( 'nextn', $this->mLimit ),
 414                         'first' => wfMsgHtml('page_first'), /* Introduced the message */
 415                         'last' => wfMsgHtml( 'page_last' )  /* Introduced the message */
 416                 );
 417
 418                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 419                 $limitLinks = $this->getLimitLinks();
 420                 $limits = implode( ' | ', $limitLinks );
 421
 422                 $this->mNavigationBar = "({$pagingLinks['first']} | {$pagingLinks['last']}) " . wfMsgHtml("viewprevnext", $pagingLinks['prev'], $pagingLinks['next'], $limits);
 423                 return $this->mNavigationBar;
 424
 425         }
 426 }
 427
 428 /**
 429  * IndexPager with a formatted navigation bar
 430  * @addtogroup Pager
 431  */
 432 abstract class ReverseChronologicalPager extends IndexPager {
 433         public $mDefaultDirection = true;
 434
 435         function __construct() {
 436                 parent::__construct();
 437         }
 438
 439         function getNavigationBar() {
 440                 global $wgLang;
 441
 442                 if ( isset( $this->mNavigationBar ) ) {
 443                         return $this->mNavigationBar;
 444                 }
 445                 $linkTexts = array(
 446                         'prev' => wfMsgHtml( "prevn", $this->mLimit ),
 447                         'next' => wfMsgHtml( 'nextn', $this->mLimit ),
 448                         'first' => wfMsgHtml('histlast'),
 449                         'last' => wfMsgHtml( 'histfirst' )
 450                 );
 451
 452                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 453                 $limitLinks = $this->getLimitLinks();
 454                 $limits = implode( ' | ', $limitLinks );
 455
 456                 $this->mNavigationBar = "({$pagingLinks['first']} | {$pagingLinks['last']}) " .
 457                         wfMsgHtml("viewprevnext", $pagingLinks['prev'], $pagingLinks['next'], $limits);
 458                 return $this->mNavigationBar;
 459         }
 460 }
 461
 462 /**
 463  * Table-based display with a user-selectable sort order
 464  * @addtogroup Pager
 465  */
 466 abstract class TablePager extends IndexPager {
 467         var $mSort;
 468         var $mCurrentRow;
 469
 470         function __construct() {
 471                 global $wgRequest;
 472                 $this->mSort = $wgRequest->getText( 'sort' );
 473                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() ) ) {
 474                         $this->mSort = $this->getDefaultSort();
 475                 }
 476                 if ( $wgRequest->getBool( 'asc' ) ) {
 477                         $this->mDefaultDirection = false;
 478                 } elseif ( $wgRequest->getBool( 'desc' ) ) {
 479                         $this->mDefaultDirection = true;
 480                 } /* Else leave it at whatever the class default is */
 481
 482                 parent::__construct();
 483         }
 484
 485         function getStartBody() {
 486                 global $wgStylePath;
 487                 $tableClass = htmlspecialchars( $this->getTableClass() );
 488                 $sortClass = htmlspecialchars( $this->getSortHeaderClass() );
 489
 490                 $s = "<table border='1' class=\"$tableClass\"><thead><tr>\n";
 491                 $fields = $this->getFieldNames();
 492
 493                 # Make table header
 494                 foreach ( $fields as $field => $name ) {
 495                         if ( strval( $name ) == '' ) {
 496                                 $s .= "<th>&nbsp;</th>\n";
 497                         } elseif ( $this->isFieldSortable( $field ) ) {
 498                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 499                                 if ( $field == $this->mSort ) {
 500                                         # This is the sorted column
 501                                         # Prepare a link that goes in the other sort order
 502                                         if ( $this->mDefaultDirection ) {
 503                                                 # Descending
 504                                                 $image = 'Arr_u.png';
 505                                                 $query['asc'] = '1';
 506                                                 $query['desc'] = '';
 507                                                 $alt = htmlspecialchars( wfMsg( 'descending_abbrev' ) );
 508                                         } else {
 509                                                 # Ascending
 510                                                 $image = 'Arr_d.png';
 511                                                 $query['asc'] = '';
 512                                                 $query['desc'] = '1';
 513                                                 $alt = htmlspecialchars( wfMsg( 'ascending_abbrev' ) );
 514                                         }
 515                                         $image = htmlspecialchars( "$wgStylePath/common/images/$image" );
 516                                         $link = $this->makeLink(
 517                                                 "<img width=\"12\" height=\"12\" alt=\"$alt\" src=\"$image\" />" .
 518                                                 htmlspecialchars( $name ), $query );
 519                                         $s .= "<th class=\"$sortClass\">$link</th>\n";
 520                                 } else {
 521                                         $s .= '<th>' . $this->makeLink( htmlspecialchars( $name ), $query ) . "</th>\n";
 522                                 }
 523                         } else {
 524                                 $s .= '<th>' . htmlspecialchars( $name ) . "</th>\n";
 525                         }
 526                 }
 527                 $s .= "</tr></thead><tbody>\n";
 528                 return $s;
 529         }
 530
 531         function getEndBody() {
 532                 return "</tbody></table>\n";
 533         }
 534
 535         function getEmptyBody() {
 536                 $colspan = count( $this->getFieldNames() );
 537                 $msgEmpty = wfMsgHtml( 'table_pager_empty' );
 538                 return "<tr><td colspan=\"$colspan\">$msgEmpty</td></tr>\n";
 539         }
 540
 541         function formatRow( $row ) {
 542                 $s = "<tr>\n";
 543                 $fieldNames = $this->getFieldNames();
 544                 $this->mCurrentRow = $row;  # In case formatValue needs to know
 545                 foreach ( $fieldNames as $field => $name ) {
 546                         $value = isset( $row->$field ) ? $row->$field : null;
 547                         $formatted = strval( $this->formatValue( $field, $value ) );
 548                         if ( $formatted == '' ) {
 549                                 $formatted = '&nbsp;';
 550                         }
 551                         $class = 'TablePager_col_' . htmlspecialchars( $field );
 552                         $s .= "<td class=\"$class\">$formatted</td>\n";
 553                 }
 554                 $s .= "</tr>\n";
 555                 return $s;
 556         }
 557
 558         function getIndexField() {
 559                 return $this->mSort;
 560         }
 561
 562         function getTableClass() {
 563                 return 'TablePager';
 564         }
 565
 566         function getNavClass() {
 567                 return 'TablePager_nav';
 568         }
 569
 570         function getSortHeaderClass() {
 571                 return 'TablePager_sort';
 572         }
 573
 574         /**
 575          * A navigation bar with images
 576          */
 577         function getNavigationBar() {
 578                 global $wgStylePath, $wgContLang;
 579                 $path = "$wgStylePath/common/images";
 580                 $labels = array(
 581                         'first' => 'table_pager_first',
 582                         'prev' => 'table_pager_prev',
 583                         'next' => 'table_pager_next',
 584                         'last' => 'table_pager_last',
 585                 );
 586                 $images = array(
 587                         'first' => $wgContLang->isRTL() ? 'arrow_last_25.png' : 'arrow_first_25.png',
 588                         'prev' =>  $wgContLang->isRTL() ? 'arrow_right_25.png' : 'arrow_left_25.png',
 589                         'next' =>  $wgContLang->isRTL() ? 'arrow_left_25.png' : 'arrow_right_25.png',
 590                         'last' =>  $wgContLang->isRTL() ? 'arrow_first_25.png' : 'arrow_last_25.png',
 591                 );
 592                 $disabledImages = array(
 593                         'first' => $wgContLang->isRTL() ? 'arrow_disabled_last_25.png' : 'arrow_disabled_first_25.png',
 594                         'prev' =>  $wgContLang->isRTL() ? 'arrow_disabled_right_25.png' : 'arrow_disabled_left_25.png',
 595                         'next' =>  $wgContLang->isRTL() ? 'arrow_disabled_left_25.png' : 'arrow_disabled_right_25.png',
 596                         'last' =>  $wgContLang->isRTL() ? 'arrow_disabled_first_25.png' : 'arrow_disabled_last_25.png',
 597                 );
 598
 599                 $linkTexts = array();
 600                 $disabledTexts = array();
 601                 foreach ( $labels as $type => $label ) {
 602                         $msgLabel = wfMsgHtml( $label );
 603                         $linkTexts[$type] = "<img src=\"$path/{$images[$type]}\" alt=\"$msgLabel\"/><br/>$msgLabel";
 604                         $disabledTexts[$type] = "<img src=\"$path/{$disabledImages[$type]}\" alt=\"$msgLabel\"/><br/>$msgLabel";
 605                 }
 606                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
 607
 608                 $navClass = htmlspecialchars( $this->getNavClass() );
 609                 $s = "<table class=\"$navClass\" align=\"center\" cellpadding=\"3\"><tr>\n";
 610                 $cellAttrs = 'valign="top" align="center" width="' . 100 / count( $links ) . '%"';
 611                 foreach ( $labels as $type => $label ) {
 612                         $s .= "<td $cellAttrs>{$links[$type]}</td>\n";
 613                 }
 614                 $s .= "</tr></table>\n";
 615                 return $s;
 616         }
 617
 618         /**
 619          * Get a <select> element which has options for each of the allowed limits
 620          */
 621         function getLimitSelect() {
 622                 global $wgLang;
 623                 $s = "<select name=\"limit\">";
 624                 foreach ( $this->mLimitsShown as $limit ) {
 625                         $selected = $limit == $this->mLimit ? 'selected="selected"' : '';
 626                         $formattedLimit = $wgLang->formatNum( $limit );
 627                         $s .= "<option value=\"$limit\" $selected>$formattedLimit</option>\n";
 628                 }
 629                 $s .= "</select>";
 630                 return $s;
 631         }
 632
 633         /**
 634          * Get <input type="hidden"> elements for use in a method="get" form.
 635          * Resubmits all defined elements of the $_GET array, except for a
 636          * blacklist, passed in the $blacklist parameter.
 637          */
 638         function getHiddenFields( $blacklist = array() ) {
 639                 $blacklist = (array)$blacklist;
 640                 $query = $_GET;
 641                 foreach ( $blacklist as $name ) {
 642                         unset( $query[$name] );
 643                 }
 644                 $s = '';
 645                 foreach ( $query as $name => $value ) {
 646                         $encName = htmlspecialchars( $name );
 647                         $encValue = htmlspecialchars( $value );
 648                         $s .= "<input type=\"hidden\" name=\"$encName\" value=\"$encValue\"/>\n";
 649                 }
 650                 return $s;
 651         }
 652
 653         /**
 654          * Get a form containing a limit selection dropdown
 655          */
 656         function getLimitForm() {
 657                 # Make the select with some explanatory text
 658                 $url = $this->getTitle()->escapeLocalURL();
 659                 $msgSubmit = wfMsgHtml( 'table_pager_limit_submit' );
 660                 return
 661                         "<form method=\"get\" action=\"$url\">" .
 662                         wfMsgHtml( 'table_pager_limit', $this->getLimitSelect() ) .
 663                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
 664                         $this->getHiddenFields( 'limit' ) .
 665                         "</form>\n";
 666         }
 667
 668         /**
 669          * Return true if the named field should be sortable by the UI, false otherwise
 670          * @param string $field
 671          */
 672         abstract function isFieldSortable( $field );
 673
 674         /**
 675          * Format a table cell. The return value should be HTML, but use an empty string
 676          * not &nbsp; for empty cells. Do not include the <td> and </td>.
 677          *
 678          * @param string $name The database field name
 679          * @param string $value The value retrieved from the database
 680          *
 681          * The current result row is available as $this->mCurrentRow, in case you need
 682          * more context.
 683          */
 684         abstract function formatValue( $name, $value );
 685
 686         /**
 687          * The database field name used as a default sort order
 688          */
 689         abstract function getDefaultSort();
 690
 691         /**
 692          * An array mapping database field names to a textual description of the field
 693          * name, for use in the table header. The description should be plain text, it
 694          * will be HTML-escaped later.
 695          */
 696         abstract function getFieldNames();
 697 }
 698 ?>