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