includes/Pager.php

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