includes/Pager.php

   1 <?php
   2 /**
   3  * @defgroup Pager Pager
   4  *
   5  * @file
   6  * @ingroup Pager
   7  */
   8
   9 /**
  10  * Basic pager interface.
  11  * @ingroup Pager
  12  */
  13 interface Pager {
  14         function getNavigationBar();
  15         function getBody();
  16 }
  17
  18 /**
  19  * IndexPager is an efficient pager which uses a (roughly unique) index in the
  20  * data set to implement paging, rather than a "LIMIT offset,limit" clause.
  21  * In MySQL, such a limit/offset clause requires counting through the
  22  * specified number of offset rows to find the desired data, which can be
  23  * expensive for large offsets.
  24  *
  25  * ReverseChronologicalPager is a child class of the abstract IndexPager, and
  26  * contains  some formatting and display code which is specific to the use of
  27  * timestamps as  indexes. Here is a synopsis of its operation:
  28  *
  29  *    * The query is specified by the offset, limit and direction (dir)
  30  *      parameters, in addition to any subclass-specific parameters.
  31  *    * The offset is the non-inclusive start of the DB query. A row with an
  32  *      index value equal to the offset will never be shown.
  33  *    * The query may either be done backwards, where the rows are returned by
  34  *      the database in the opposite order to which they are displayed to the
  35  *      user, or forwards. This is specified by the "dir" parameter, dir=prev
  36  *      means backwards, anything else means forwards. The offset value
  37  *      specifies the start of the database result set, which may be either
  38  *      the start or end of the displayed data set. This allows "previous"
  39  *      links to be implemented without knowledge of the index value at the
  40  *      start of the previous page.
  41  *    * An additional row beyond the user-specified limit is always requested.
  42  *      This allows us to tell whether we should display a "next" link in the
  43  *      case of forwards mode, or a "previous" link in the case of backwards
  44  *      mode. Determining whether to display the other link (the one for the
  45  *      page before the start of the database result set) can be done
  46  *      heuristically by examining the offset.
  47  *
  48  *    * An empty offset indicates that the offset condition should be omitted
  49  *      from the query. This naturally produces either the first page or the
  50  *      last page depending on the dir parameter.
  51  *
  52  *  Subclassing the pager to implement concrete functionality should be fairly
  53  *  simple, please see the examples in HistoryPage.php and
  54  *  SpecialBlockList.php. You just need to override formatRow(),
  55  *  getQueryInfo() and getIndexField(). Don't forget to call the parent
  56  *  constructor if you override it.
  57  *
  58  * @ingroup Pager
  59  */
  60 abstract class IndexPager extends ContextSource implements Pager {
  61         public $mRequest;
  62         public $mLimitsShown = array( 20, 50, 100, 250, 500 );
  63         public $mDefaultLimit = 50;
  64         public $mOffset, $mLimit;
  65         public $mQueryDone = false;
  66         public $mDb;
  67         public $mPastTheEndRow;
  68
  69         /**
  70          * The index to actually be used for ordering. This is a single column,
  71          * for one ordering, even if multiple orderings are supported.
  72          */
  73         protected $mIndexField;
  74         /**
  75          * An array of secondary columns to order by. These fields are not part of the offset.
  76          * This is a column list for one ordering, even if multiple orderings are supported.
  77          */
  78         protected $mExtraSortFields;
  79         /** For pages that support multiple types of ordering, which one to use.
  80          */
  81         protected $mOrderType;
  82         /**
  83          * $mDefaultDirection gives the direction to use when sorting results:
  84          * false for ascending, true for descending.  If $mIsBackwards is set, we
  85          * start from the opposite end, but we still sort the page itself according
  86          * to $mDefaultDirection.  E.g., if $mDefaultDirection is false but we're
  87          * going backwards, we'll display the last page of results, but the last
  88          * result will be at the bottom, not the top.
  89          *
  90          * Like $mIndexField, $mDefaultDirection will be a single value even if the
  91          * class supports multiple default directions for different order types.
  92          */
  93         public $mDefaultDirection;
  94         public $mIsBackwards;
  95
  96         /** True if the current result set is the first one */
  97         public $mIsFirst;
  98         public $mIsLast;
  99
 100         protected $mLastShown, $mFirstShown, $mPastTheEndIndex, $mDefaultQuery, $mNavigationBar;
 101
 102         /**
 103          * HTMLForm object
 104          *
 105          * @var HTMLForm
 106          */
 107         protected $mHTMLForm;
 108
 109         /**
 110          * Result object for the query. Warning: seek before use.
 111          *
 112          * @var ResultWrapper
 113          */
 114         public $mResult;
 115
 116         public function __construct( IContextSource $context = null ) {
 117                 if ( $context ) {
 118                         $this->setContext( $context );
 119                 }
 120
 121                 $this->mRequest = $this->getRequest();
 122
 123                 # NB: the offset is quoted, not validated. It is treated as an
 124                 # arbitrary string to support the widest variety of index types. Be
 125                 # careful outputting it into HTML!
 126                 $this->mOffset = $this->mRequest->getText( 'offset' );
 127
 128                 # Use consistent behavior for the limit options
 129                 $this->mDefaultLimit = intval( $this->getUser()->getOption( 'rclimit' ) );
 130                 list( $this->mLimit, /* $offset */ ) = $this->mRequest->getLimitOffset();
 131
 132                 $this->mIsBackwards = ( $this->mRequest->getVal( 'dir' ) == 'prev' );
 133                 $this->mDb = wfGetDB( DB_SLAVE );
 134
 135                 $index = $this->getIndexField(); // column to sort on
 136                 $extraSort = $this->getExtraSortFields(); // extra columns to sort on for query planning
 137                 $order = $this->mRequest->getVal( 'order' );
 138                 if( is_array( $index ) && isset( $index[$order] ) ) {
 139                         $this->mOrderType = $order;
 140                         $this->mIndexField = $index[$order];
 141                         $this->mExtraSortFields = isset( $extraSort[$order] )
 142                                 ? (array)$extraSort[$order]
 143                                 : array();
 144                 } elseif( is_array( $index ) ) {
 145                         # First element is the default
 146                         reset( $index );
 147                         list( $this->mOrderType, $this->mIndexField ) = each( $index );
 148                         $this->mExtraSortFields = isset( $extraSort[$this->mOrderType] )
 149                                 ? (array)$extraSort[$this->mOrderType]
 150                                 : array();
 151                 } else {
 152                         # $index is not an array
 153                         $this->mOrderType = null;
 154                         $this->mIndexField = $index;
 155                         $this->mExtraSortFields = (array)$extraSort;
 156                 }
 157
 158                 if( !isset( $this->mDefaultDirection ) ) {
 159                         $dir = $this->getDefaultDirections();
 160                         $this->mDefaultDirection = is_array( $dir )
 161                                 ? $dir[$this->mOrderType]
 162                                 : $dir;
 163                 }
 164         }
 165
 166         /**
 167          * Do the query, using information from the object context. This function
 168          * has been kept minimal to make it overridable if necessary, to allow for
 169          * result sets formed from multiple DB queries.
 170          */
 171         public function doQuery() {
 172                 # Use the child class name for profiling
 173                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 174                 wfProfileIn( $fname );
 175
 176                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 177                 # Plus an extra row so that we can tell the "next" link should be shown
 178                 $queryLimit = $this->mLimit + 1;
 179
 180                 $this->mResult = $this->reallyDoQuery(
 181                         $this->mOffset,
 182                         $queryLimit,
 183                         $descending
 184                 );
 185                 $this->extractResultInfo( $this->mOffset, $queryLimit, $this->mResult );
 186                 $this->mQueryDone = true;
 187
 188                 $this->preprocessResults( $this->mResult );
 189                 $this->mResult->rewind(); // Paranoia
 190
 191                 wfProfileOut( $fname );
 192         }
 193
 194         /**
 195          * @return ResultWrapper The result wrapper.
 196          */
 197         function getResult() {
 198                 return $this->mResult;
 199         }
 200
 201         /**
 202          * Set the offset from an other source than the request
 203          *
 204          * @param $offset Int|String
 205          */
 206         function setOffset( $offset ) {
 207                 $this->mOffset = $offset;
 208         }
 209         /**
 210          * Set the limit from an other source than the request
 211          *
 212          * @param $limit Int|String
 213          */
 214         function setLimit( $limit ) {
 215                 $this->mLimit = $limit;
 216         }
 217
 218         /**
 219          * Extract some useful data from the result object for use by
 220          * the navigation bar, put it into $this
 221          *
 222          * @param $offset String: index offset, inclusive
 223          * @param $limit Integer: exact query limit
 224          * @param $res ResultWrapper
 225          */
 226         function extractResultInfo( $offset, $limit, ResultWrapper $res ) {
 227                 $numRows = $res->numRows();
 228                 if ( $numRows ) {
 229                         # Remove any table prefix from index field
 230                         $parts = explode( '.', $this->mIndexField );
 231                         $indexColumn = end( $parts );
 232
 233                         $row = $res->fetchRow();
 234                         $firstIndex = $row[$indexColumn];
 235
 236                         # Discard the extra result row if there is one
 237                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 238                                 $res->seek( $numRows - 1 );
 239                                 $this->mPastTheEndRow = $res->fetchObject();
 240                                 $indexField = $this->mIndexField;
 241                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexField;
 242                                 $res->seek( $numRows - 2 );
 243                                 $row = $res->fetchRow();
 244                                 $lastIndex = $row[$indexColumn];
 245                         } else {
 246                                 $this->mPastTheEndRow = null;
 247                                 # Setting indexes to an empty string means that they will be
 248                                 # omitted if they would otherwise appear in URLs. It just so
 249                                 # happens that this  is the right thing to do in the standard
 250                                 # UI, in all the relevant cases.
 251                                 $this->mPastTheEndIndex = '';
 252                                 $res->seek( $numRows - 1 );
 253                                 $row = $res->fetchRow();
 254                                 $lastIndex = $row[$indexColumn];
 255                         }
 256                 } else {
 257                         $firstIndex = '';
 258                         $lastIndex = '';
 259                         $this->mPastTheEndRow = null;
 260                         $this->mPastTheEndIndex = '';
 261                 }
 262
 263                 if ( $this->mIsBackwards ) {
 264                         $this->mIsFirst = ( $numRows < $limit );
 265                         $this->mIsLast = ( $offset == '' );
 266                         $this->mLastShown = $firstIndex;
 267                         $this->mFirstShown = $lastIndex;
 268                 } else {
 269                         $this->mIsFirst = ( $offset == '' );
 270                         $this->mIsLast = ( $numRows < $limit );
 271                         $this->mLastShown = $lastIndex;
 272                         $this->mFirstShown = $firstIndex;
 273                 }
 274         }
 275
 276         /**
 277          * Get some text to go in brackets in the "function name" part of the SQL comment
 278          *
 279          * @return String
 280          */
 281         function getSqlComment() {
 282                 return get_class( $this );
 283         }
 284
 285         /**
 286          * Do a query with specified parameters, rather than using the object
 287          * context
 288          *
 289          * @param $offset String: index offset, inclusive
 290          * @param $limit Integer: exact query limit
 291          * @param $descending Boolean: query direction, false for ascending, true for descending
 292          * @return ResultWrapper
 293          */
 294         function reallyDoQuery( $offset, $limit, $descending ) {
 295                 $fname = __METHOD__ . ' (' . $this->getSqlComment() . ')';
 296                 $info = $this->getQueryInfo();
 297                 $tables = $info['tables'];
 298                 $fields = $info['fields'];
 299                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 300                 $options = isset( $info['options'] ) ? $info['options'] : array();
 301                 $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
 302                 $sortColumns = array_merge( array( $this->mIndexField ), $this->mExtraSortFields );
 303                 if ( $descending ) {
 304                         $options['ORDER BY'] = implode( ',', $sortColumns );
 305                         $operator = '>';
 306                 } else {
 307                         $orderBy = array();
 308                         foreach ( $sortColumns as $col ) {
 309                                 $orderBy[] = $col . ' DESC';
 310                         }
 311                         $options['ORDER BY'] = implode( ',', $orderBy );
 312                         $operator = '<';
 313                 }
 314                 if ( $offset != '' ) {
 315                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 316                 }
 317                 $options['LIMIT'] = intval( $limit );
 318                 $res = $this->mDb->select( $tables, $fields, $conds, $fname, $options, $join_conds );
 319                 return new ResultWrapper( $this->mDb, $res );
 320         }
 321
 322         /**
 323          * Pre-process results; useful for performing batch existence checks, etc.
 324          *
 325          * @param $result ResultWrapper
 326          */
 327         protected function preprocessResults( $result ) {}
 328
 329         /**
 330          * Get the formatted result list. Calls getStartBody(), formatRow() and
 331          * getEndBody(), concatenates the results and returns them.
 332          *
 333          * @return String
 334          */
 335         public function getBody() {
 336                 if ( !$this->mQueryDone ) {
 337                         $this->doQuery();
 338                 }
 339
 340                 if ( $this->mResult->numRows() ) {
 341                         # Do any special query batches before display
 342                         $this->doBatchLookups();
 343                 }
 344
 345                 # Don't use any extra rows returned by the query
 346                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 347
 348                 $s = $this->getStartBody();
 349                 if ( $numRows ) {
 350                         if ( $this->mIsBackwards ) {
 351                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 352                                         $this->mResult->seek( $i );
 353                                         $row = $this->mResult->fetchObject();
 354                                         $s .= $this->formatRow( $row );
 355                                 }
 356                         } else {
 357                                 $this->mResult->seek( 0 );
 358                                 for ( $i = 0; $i < $numRows; $i++ ) {
 359                                         $row = $this->mResult->fetchObject();
 360                                         $s .= $this->formatRow( $row );
 361                                 }
 362                         }
 363                 } else {
 364                         $s .= $this->getEmptyBody();
 365                 }
 366                 $s .= $this->getEndBody();
 367                 return $s;
 368         }
 369
 370         /**
 371          * Make a self-link
 372          *
 373          * @param $text String: text displayed on the link
 374          * @param $query Array: associative array of paramter to be in the query string
 375          * @param $type String: value of the "rel" attribute
 376          * @return String: HTML fragment
 377          */
 378         function makeLink($text, $query = null, $type=null) {
 379                 if ( $query === null ) {
 380                         return $text;
 381                 }
 382
 383                 $attrs = array();
 384                 if( in_array( $type, array( 'first', 'prev', 'next', 'last' ) ) ) {
 385                         # HTML5 rel attributes
 386                         $attrs['rel'] = $type;
 387                 }
 388
 389                 if( $type ) {
 390                         $attrs['class'] = "mw-{$type}link";
 391                 }
 392                 return Linker::linkKnown(
 393                         $this->getTitle(),
 394                         $text,
 395                         $attrs,
 396                         $query + $this->getDefaultQuery()
 397                 );
 398         }
 399
 400         /**
 401          * Called from getBody(), before getStartBody() is called and
 402          * after doQuery() was called. This will be called only if there
 403          * are rows in the result set.
 404          *
 405          * @return void
 406          */
 407         protected function doBatchLookups() {}
 408
 409         /**
 410          * Hook into getBody(), allows text to be inserted at the start. This
 411          * will be called even if there are no rows in the result set.
 412          *
 413          * @return String
 414          */
 415         protected function getStartBody() {
 416                 return '';
 417         }
 418
 419         /**
 420          * Hook into getBody() for the end of the list
 421          *
 422          * @return String
 423          */
 424         protected function getEndBody() {
 425                 return '';
 426         }
 427
 428         /**
 429          * Hook into getBody(), for the bit between the start and the
 430          * end when there are no rows
 431          *
 432          * @return String
 433          */
 434         protected function getEmptyBody() {
 435                 return '';
 436         }
 437
 438         /**
 439          * Get an array of query parameters that should be put into self-links.
 440          * By default, all parameters passed in the URL are used, except for a
 441          * short blacklist.
 442          *
 443          * @return Associative array
 444          */
 445         function getDefaultQuery() {
 446                 if ( !isset( $this->mDefaultQuery ) ) {
 447                         $this->mDefaultQuery = $this->getRequest()->getQueryValues();
 448                         unset( $this->mDefaultQuery['title'] );
 449                         unset( $this->mDefaultQuery['dir'] );
 450                         unset( $this->mDefaultQuery['offset'] );
 451                         unset( $this->mDefaultQuery['limit'] );
 452                         unset( $this->mDefaultQuery['order'] );
 453                         unset( $this->mDefaultQuery['month'] );
 454                         unset( $this->mDefaultQuery['year'] );
 455                 }
 456                 return $this->mDefaultQuery;
 457         }
 458
 459         /**
 460          * Get the number of rows in the result set
 461          *
 462          * @return Integer
 463          */
 464         function getNumRows() {
 465                 if ( !$this->mQueryDone ) {
 466                         $this->doQuery();
 467                 }
 468                 return $this->mResult->numRows();
 469         }
 470
 471         /**
 472          * Get a URL query array for the prev, next, first and last links.
 473          *
 474          * @return Array
 475          */
 476         function getPagingQueries() {
 477                 if ( !$this->mQueryDone ) {
 478                         $this->doQuery();
 479                 }
 480
 481                 # Don't announce the limit everywhere if it's the default
 482                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? '' : $this->mLimit;
 483
 484                 if ( $this->mIsFirst ) {
 485                         $prev = false;
 486                         $first = false;
 487                 } else {
 488                         $prev = array(
 489                                 'dir' => 'prev',
 490                                 'offset' => $this->mFirstShown,
 491                                 'limit' => $urlLimit
 492                         );
 493                         $first = array( 'limit' => $urlLimit );
 494                 }
 495                 if ( $this->mIsLast ) {
 496                         $next = false;
 497                         $last = false;
 498                 } else {
 499                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 500                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 501                 }
 502                 return array(
 503                         'prev' => $prev,
 504                         'next' => $next,
 505                         'first' => $first,
 506                         'last' => $last
 507                 );
 508         }
 509
 510         /**
 511          * Returns whether to show the "navigation bar"
 512          *
 513          * @return Boolean
 514          */
 515         function isNavigationBarShown() {
 516                 if ( !$this->mQueryDone ) {
 517                         $this->doQuery();
 518                 }
 519                 // Hide navigation by default if there is nothing to page
 520                 return !($this->mIsFirst && $this->mIsLast);
 521         }
 522
 523         /**
 524          * Get paging links. If a link is disabled, the item from $disabledTexts
 525          * will be used. If there is no such item, the unlinked text from
 526          * $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays
 527          * of HTML.
 528          *
 529          * @param $linkTexts Array
 530          * @param $disabledTexts Array
 531          * @return Array
 532          */
 533         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 534                 $queries = $this->getPagingQueries();
 535                 $links = array();
 536                 foreach ( $queries as $type => $query ) {
 537                         if ( $query !== false ) {
 538                                 $links[$type] = $this->makeLink(
 539                                         $linkTexts[$type],
 540                                         $queries[$type],
 541                                         $type
 542                                 );
 543                         } elseif ( isset( $disabledTexts[$type] ) ) {
 544                                 $links[$type] = $disabledTexts[$type];
 545                         } else {
 546                                 $links[$type] = $linkTexts[$type];
 547                         }
 548                 }
 549                 return $links;
 550         }
 551
 552         function getLimitLinks() {
 553                 $links = array();
 554                 if ( $this->mIsBackwards ) {
 555                         $offset = $this->mPastTheEndIndex;
 556                 } else {
 557                         $offset = $this->mOffset;
 558                 }
 559                 foreach ( $this->mLimitsShown as $limit ) {
 560                         $links[] = $this->makeLink(
 561                                 $this->getLanguage()->formatNum( $limit ),
 562                                 array( 'offset' => $offset, 'limit' => $limit ),
 563                                 'num'
 564                         );
 565                 }
 566                 return $links;
 567         }
 568
 569         /**
 570          * Assembles an HTMLForm for the Pager and returns the HTML
 571          *
 572          * @return string
 573          */
 574         public function buildHTMLForm() {
 575                 if ( $this->getHTMLFormFields() === null ) {
 576                         throw new MWException( __METHOD__ . " was called without any form fields being defined" );
 577                 }
 578
 579                 $this->mHTMLForm = new HTMLForm( $this->getHTMLFormFields(), $this->getContext() );
 580                 $this->mHTMLForm->setMethod( 'get' );
 581                 $this->mHTMLForm->setWrapperLegendMsg( $this->getHTMLFormLegend() );
 582                 $this->mHTMLForm->setSubmitTextMsg( $this->getHTMLFormSubmit() );
 583                 $this->addHiddenFields();
 584                 $this->modifyHTMLForm( $this->mHTMLForm );
 585                 $this->mHTMLForm->prepareForm();
 586
 587                 return $this->mHTMLForm->getHTML( '' );
 588         }
 589
 590         /**
 591          * Adds hidden elements to forms for things that are in the query string.
 592          * This is so that parameters like offset stick through form submissions
 593          */
 594         protected function addHiddenFields() {
 595                 $query = $this->getRequest()->getQueryValues();
 596                 $fieldsBlacklist = array( 'title' );
 597                 $fields = $this->mHTMLForm->getFlatFields();
 598                 foreach ( $fields as $name => $field ) {
 599                         $fieldsBlacklist[] = $field->getName();
 600                 }
 601                 foreach ( $query as $name => $value ) {
 602                         if ( in_array( $name, $fieldsBlacklist ) ) {
 603                                 continue;
 604                         }
 605                         $this->mHTMLForm->addHiddenField( $name, $value );
 606                 }
 607         }
 608
 609         /**
 610          * Abstract formatting function. This should return an HTML string
 611          * representing the result row $row. Rows will be concatenated and
 612          * returned by getBody()
 613          *
 614          * @param $row Object: database row
 615          * @return String
 616          */
 617         abstract function formatRow( $row );
 618
 619         /**
 620          * This function should be overridden to provide all parameters
 621          * needed for the main paged query. It returns an associative
 622          * array with the following elements:
 623          *    tables => Table(s) for passing to Database::select()
 624          *    fields => Field(s) for passing to Database::select(), may be *
 625          *    conds => WHERE conditions
 626          *    options => option array
 627          *    join_conds => JOIN conditions
 628          *
 629          * @return Array
 630          */
 631         abstract function getQueryInfo();
 632
 633         /**
 634          * This function should be overridden to return the name of the index fi-
 635          * eld.  If the pager supports multiple orders, it may return an array of
 636          * 'querykey' => 'indexfield' pairs, so that a request with &count=querykey
 637          * will use indexfield to sort.  In this case, the first returned key is
 638          * the default.
 639          *
 640          * Needless to say, it's really not a good idea to use a non-unique index
 641          * for this!  That won't page right.
 642          *
 643          * @return string|Array
 644          */
 645         abstract function getIndexField();
 646
 647         /**
 648          * This function should be overridden to return the names of secondary columns
 649          * to order by in addition to the column in getIndexField(). These fields will
 650          * not be used in the pager offset or in any links for users.
 651          *
 652          * If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then
 653          * this must return a corresponding array of 'querykey' => array( fields...) pairs
 654          * in order for a request with &count=querykey to use array( fields...) to sort.
 655          *
 656          * This is useful for pagers that GROUP BY a unique column (say page_id)
 657          * and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on
 658          * page_len,page_id avoids temp tables (given a page_len index). This would
 659          * also work if page_id was non-unique but we had a page_len,page_id index.
 660          *
 661          * @return Array
 662          */
 663         protected function getExtraSortFields() { return array(); }
 664
 665         /**
 666          * Return the default sorting direction: false for ascending, true for de-
 667          * scending.  You can also have an associative array of ordertype => dir,
 668          * if multiple order types are supported.  In this case getIndexField()
 669          * must return an array, and the keys of that must exactly match the keys
 670          * of this.
 671          *
 672          * For backward compatibility, this method's return value will be ignored
 673          * if $this->mDefaultDirection is already set when the constructor is
 674          * called, for instance if it's statically initialized.  In that case the
 675          * value of that variable (which must be a boolean) will be used.
 676          *
 677          * Note that despite its name, this does not return the value of the
 678          * $this->mDefaultDirection member variable.  That's the default for this
 679          * particular instantiation, which is a single value.  This is the set of
 680          * all defaults for the class.
 681          *
 682          * @return Boolean
 683          */
 684         protected function getDefaultDirections() { return false; }
 685
 686         /**
 687          * Returns an array for HTMLForm fields for the pager
 688          *
 689          * Only used if the pager makes use of HTMLForms
 690          *
 691          * @return array|null
 692          */
 693         protected function getHTMLFormFields() { return null; }
 694
 695         /**
 696          * Message name for the fieldset legend text
 697          *
 698          * Only used if the pager makes use of HTMLForms
 699          *
 700          * @return string
 701          */
 702         protected function getHTMLFormLegend() { return ''; }
 703
 704         /**
 705          * Message name for the submit button text
 706          *
 707          * Only used if the pager makes use of HTMLForms
 708          *
 709          * @return string
 710          */
 711         protected function getHTMLFormSubmit() { return ''; }
 712
 713         /**
 714          * If the pager needs to do any modifications to the Form, override this
 715          * function.
 716          *
 717          * Only used if the pager makes use of HTMLForms
 718          *
 719          * @param HTMLForm $form
 720          */
 721         protected function modifyHTMLForm( HTMLForm $form ) {}
 722 }
 723
 724
 725 /**
 726  * IndexPager with an alphabetic list and a formatted navigation bar
 727  * @ingroup Pager
 728  */
 729 abstract class AlphabeticPager extends IndexPager {
 730
 731         /**
 732          * Shamelessly stolen bits from ReverseChronologicalPager,
 733          * didn't want to do class magic as may be still revamped
 734          *
 735          * @return String HTML
 736          */
 737         function getNavigationBar() {
 738                 if ( !$this->isNavigationBarShown() ) return '';
 739
 740                 if( isset( $this->mNavigationBar ) ) {
 741                         return $this->mNavigationBar;
 742                 }
 743
 744                 $lang = $this->getLanguage();
 745
 746                 $opts = array( 'parsemag', 'escapenoentities' );
 747                 $linkTexts = array(
 748                         'prev' => wfMsgExt(
 749                                 'prevn',
 750                                 $opts,
 751                                 $lang->formatNum( $this->mLimit )
 752                         ),
 753                         'next' => wfMsgExt(
 754                                 'nextn',
 755                                 $opts,
 756                                 $lang->formatNum($this->mLimit )
 757                         ),
 758                         'first' => wfMsgExt( 'page_first', $opts ),
 759                         'last' => wfMsgExt( 'page_last', $opts )
 760                 );
 761
 762                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 763                 $limitLinks = $this->getLimitLinks();
 764                 $limits = $lang->pipeList( $limitLinks );
 765
 766                 $this->mNavigationBar =
 767                         "(" . $lang->pipeList(
 768                                 array( $pagingLinks['first'],
 769                                 $pagingLinks['last'] )
 770                         ) . ") " .
 771                         wfMsgHtml( 'viewprevnext', $pagingLinks['prev'],
 772                         $pagingLinks['next'], $limits );
 773
 774                 if( !is_array( $this->getIndexField() ) ) {
 775                         # Early return to avoid undue nesting
 776                         return $this->mNavigationBar;
 777                 }
 778
 779                 $extra = '';
 780                 $first = true;
 781                 $msgs = $this->getOrderTypeMessages();
 782                 foreach( array_keys( $msgs ) as $order ) {
 783                         if( $first ) {
 784                                 $first = false;
 785                         } else {
 786                                 $extra .= wfMsgExt( 'pipe-separator' , 'escapenoentities' );
 787                         }
 788
 789                         if( $order == $this->mOrderType ) {
 790                                 $extra .= wfMsgHTML( $msgs[$order] );
 791                         } else {
 792                                 $extra .= $this->makeLink(
 793                                         wfMsgHTML( $msgs[$order] ),
 794                                         array( 'order' => $order )
 795                                 );
 796                         }
 797                 }
 798
 799                 if( $extra !== '' ) {
 800                         $this->mNavigationBar .= " ($extra)";
 801                 }
 802
 803                 return $this->mNavigationBar;
 804         }
 805
 806         /**
 807          * If this supports multiple order type messages, give the message key for
 808          * enabling each one in getNavigationBar.  The return type is an associa-
 809          * tive array whose keys must exactly match the keys of the array returned
 810          * by getIndexField(), and whose values are message keys.
 811          *
 812          * @return Array
 813          */
 814         protected function getOrderTypeMessages() {
 815                 return null;
 816         }
 817 }
 818
 819 /**
 820  * IndexPager with a formatted navigation bar
 821  * @ingroup Pager
 822  */
 823 abstract class ReverseChronologicalPager extends IndexPager {
 824         public $mDefaultDirection = true;
 825         public $mYear;
 826         public $mMonth;
 827
 828         function getNavigationBar() {
 829                 if ( !$this->isNavigationBarShown() ) {
 830                         return '';
 831                 }
 832
 833                 if ( isset( $this->mNavigationBar ) ) {
 834                         return $this->mNavigationBar;
 835                 }
 836
 837                 $nicenumber = $this->getLanguage()->formatNum( $this->mLimit );
 838                 $linkTexts = array(
 839                         'prev' => wfMsgExt(
 840                                 'pager-newer-n',
 841                                 array( 'parsemag', 'escape' ),
 842                                 $nicenumber
 843                         ),
 844                         'next' => wfMsgExt(
 845                                 'pager-older-n',
 846                                 array( 'parsemag', 'escape' ),
 847                                 $nicenumber
 848                         ),
 849                         'first' => wfMsgHtml( 'histlast' ),
 850                         'last' => wfMsgHtml( 'histfirst' )
 851                 );
 852
 853                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 854                 $limitLinks = $this->getLimitLinks();
 855                 $limits = $this->getLanguage()->pipeList( $limitLinks );
 856
 857                 $this->mNavigationBar = "({$pagingLinks['first']}" .
 858                         wfMsgExt( 'pipe-separator' , 'escapenoentities' ) .
 859                         "{$pagingLinks['last']}) " .
 860                         wfMsgHTML(
 861                                 'viewprevnext',
 862                                 $pagingLinks['prev'], $pagingLinks['next'],
 863                                 $limits
 864                         );
 865                 return $this->mNavigationBar;
 866         }
 867
 868         function getDateCond( $year, $month ) {
 869                 $year = intval($year);
 870                 $month = intval($month);
 871                 // Basic validity checks
 872                 $this->mYear = $year > 0 ? $year : false;
 873                 $this->mMonth = ($month > 0 && $month < 13) ? $month : false;
 874                 // Given an optional year and month, we need to generate a timestamp
 875                 // to use as "WHERE rev_timestamp <= result"
 876                 // Examples: year = 2006 equals < 20070101 (+000000)
 877                 // year=2005, month=1    equals < 20050201
 878                 // year=2005, month=12   equals < 20060101
 879                 if ( !$this->mYear && !$this->mMonth ) {
 880                         return;
 881                 }
 882                 if ( $this->mYear ) {
 883                         $year = $this->mYear;
 884                 } else {
 885                         // If no year given, assume the current one
 886                         $year = gmdate( 'Y' );
 887                         // If this month hasn't happened yet this year, go back to last year's month
 888                         if( $this->mMonth > gmdate( 'n' ) ) {
 889                                 $year--;
 890                         }
 891                 }
 892                 if ( $this->mMonth ) {
 893                         $month = $this->mMonth + 1;
 894                         // For December, we want January 1 of the next year
 895                         if ($month > 12) {
 896                                 $month = 1;
 897                                 $year++;
 898                         }
 899                 } else {
 900                         // No month implies we want up to the end of the year in question
 901                         $month = 1;
 902                         $year++;
 903                 }
 904                 // Y2K38 bug
 905                 if ( $year > 2032 ) {
 906                         $year = 2032;
 907                 }
 908                 $ymd = (int)sprintf( "%04d%02d01", $year, $month );
 909                 if ( $ymd > 20320101 ) {
 910                         $ymd = 20320101;
 911                 }
 912                 $this->mOffset = $this->mDb->timestamp( "${ymd}000000" );
 913         }
 914 }
 915
 916 /**
 917  * Table-based display with a user-selectable sort order
 918  * @ingroup Pager
 919  */
 920 abstract class TablePager extends IndexPager {
 921         var $mSort;
 922         var $mCurrentRow;
 923
 924         function __construct( IContextSource $context = null ) {
 925                 if ( $context ) {
 926                         $this->setContext( $context );
 927                 }
 928
 929                 $this->mSort = $this->getRequest()->getText( 'sort' );
 930                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() ) ) {
 931                         $this->mSort = $this->getDefaultSort();
 932                 }
 933                 if ( $this->getRequest()->getBool( 'asc' ) ) {
 934                         $this->mDefaultDirection = false;
 935                 } elseif ( $this->getRequest()->getBool( 'desc' ) ) {
 936                         $this->mDefaultDirection = true;
 937                 } /* Else leave it at whatever the class default is */
 938
 939                 parent::__construct();
 940         }
 941
 942         function getStartBody() {
 943                 global $wgStylePath;
 944                 $tableClass = htmlspecialchars( $this->getTableClass() );
 945                 $sortClass = htmlspecialchars( $this->getSortHeaderClass() );
 946
 947                 $s = "<table style='border:1;' class=\"mw-datatable $tableClass\"><thead><tr>\n";
 948                 $fields = $this->getFieldNames();
 949
 950                 # Make table header
 951                 foreach ( $fields as $field => $name ) {
 952                         if ( strval( $name ) == '' ) {
 953                                 $s .= "<th>&#160;</th>\n";
 954                         } elseif ( $this->isFieldSortable( $field ) ) {
 955                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 956                                 if ( $field == $this->mSort ) {
 957                                         # This is the sorted column
 958                                         # Prepare a link that goes in the other sort order
 959                                         if ( $this->mDefaultDirection ) {
 960                                                 # Descending
 961                                                 $image = 'Arr_d.png';
 962                                                 $query['asc'] = '1';
 963                                                 $query['desc'] = '';
 964                                                 $alt = htmlspecialchars( wfMsg( 'descending_abbrev' ) );
 965                                         } else {
 966                                                 # Ascending
 967                                                 $image = 'Arr_u.png';
 968                                                 $query['asc'] = '';
 969                                                 $query['desc'] = '1';
 970                                                 $alt = htmlspecialchars( wfMsg( 'ascending_abbrev' ) );
 971                                         }
 972                                         $image = htmlspecialchars( "$wgStylePath/common/images/$image" );
 973                                         $link = $this->makeLink(
 974                                                 "<img width=\"12\" height=\"12\" alt=\"$alt\" src=\"$image\" />" .
 975                                                 htmlspecialchars( $name ), $query );
 976                                         $s .= "<th class=\"$sortClass\">$link</th>\n";
 977                                 } else {
 978                                         $s .= '<th>' . $this->makeLink( htmlspecialchars( $name ), $query ) . "</th>\n";
 979                                 }
 980                         } else {
 981                                 $s .= '<th>' . htmlspecialchars( $name ) . "</th>\n";
 982                         }
 983                 }
 984                 $s .= "</tr></thead><tbody>\n";
 985                 return $s;
 986         }
 987
 988         function getEndBody() {
 989                 return "</tbody></table>\n";
 990         }
 991
 992         function getEmptyBody() {
 993                 $colspan = count( $this->getFieldNames() );
 994                 $msgEmpty = wfMsgHtml( 'table_pager_empty' );
 995                 return "<tr><td colspan=\"$colspan\">$msgEmpty</td></tr>\n";
 996         }
 997
 998         /**
 999          * @param $row Array
1000          * @return String HTML
1001          */
1002         function formatRow( $row ) {
1003                 $this->mCurrentRow = $row;      # In case formatValue etc need to know
1004                 $s = Xml::openElement( 'tr', $this->getRowAttrs( $row ) );
1005                 $fieldNames = $this->getFieldNames();
1006                 foreach ( $fieldNames as $field => $name ) {
1007                         $value = isset( $row->$field ) ? $row->$field : null;
1008                         $formatted = strval( $this->formatValue( $field, $value ) );
1009                         if ( $formatted == '' ) {
1010                                 $formatted = '&#160;';
1011                         }
1012                         $s .= Xml::tags( 'td', $this->getCellAttrs( $field, $value ), $formatted );
1013                 }
1014                 $s .= "</tr>\n";
1015                 return $s;
1016         }
1017
1018         /**
1019          * Get a class name to be applied to the given row.
1020          *
1021          * @param $row Object: the database result row
1022          * @return String
1023          */
1024         function getRowClass( $row ) {
1025                 return '';
1026         }
1027
1028         /**
1029          * Get attributes to be applied to the given row.
1030          *
1031          * @param $row Object: the database result row
1032          * @return Array of <attr> => <value>
1033          */
1034         function getRowAttrs( $row ) {
1035                 $class = $this->getRowClass( $row );
1036                 if ( $class === '' ) {
1037                         // Return an empty array to avoid clutter in HTML like class=""
1038                         return array();
1039                 } else {
1040                         return array( 'class' => $this->getRowClass( $row ) );
1041                 }
1042         }
1043
1044         /**
1045          * Get any extra attributes to be applied to the given cell. Don't
1046          * take this as an excuse to hardcode styles; use classes and
1047          * CSS instead.  Row context is available in $this->mCurrentRow
1048          *
1049          * @param $field String The column
1050          * @param $value String The cell contents
1051          * @return Array of attr => value
1052          */
1053         function getCellAttrs( $field, $value ) {
1054                 return array( 'class' => 'TablePager_col_' . $field );
1055         }
1056
1057         function getIndexField() {
1058                 return $this->mSort;
1059         }
1060
1061         function getTableClass() {
1062                 return 'TablePager';
1063         }
1064
1065         function getNavClass() {
1066                 return 'TablePager_nav';
1067         }
1068
1069         function getSortHeaderClass() {
1070                 return 'TablePager_sort';
1071         }
1072
1073         /**
1074          * A navigation bar with images
1075          * @return String HTML
1076          */
1077         function getNavigationBar() {
1078                 global $wgStylePath;
1079
1080                 if ( !$this->isNavigationBarShown() ) {
1081                         return '';
1082                 }
1083
1084                 $path = "$wgStylePath/common/images";
1085                 $labels = array(
1086                         'first' => 'table_pager_first',
1087                         'prev' => 'table_pager_prev',
1088                         'next' => 'table_pager_next',
1089                         'last' => 'table_pager_last',
1090                 );
1091                 $images = array(
1092                         'first' => 'arrow_first_25.png',
1093                         'prev' => 'arrow_left_25.png',
1094                         'next' => 'arrow_right_25.png',
1095                         'last' => 'arrow_last_25.png',
1096                 );
1097                 $disabledImages = array(
1098                         'first' => 'arrow_disabled_first_25.png',
1099                         'prev' => 'arrow_disabled_left_25.png',
1100                         'next' => 'arrow_disabled_right_25.png',
1101                         'last' => 'arrow_disabled_last_25.png',
1102                 );
1103                 if( $this->getLanguage()->isRTL() ) {
1104                         $keys = array_keys( $labels );
1105                         $images = array_combine( $keys, array_reverse( $images ) );
1106                         $disabledImages = array_combine( $keys, array_reverse( $disabledImages ) );
1107                 }
1108
1109                 $linkTexts = array();
1110                 $disabledTexts = array();
1111                 foreach ( $labels as $type => $label ) {
1112                         $msgLabel = wfMsgHtml( $label );
1113                         $linkTexts[$type] = "<img src=\"$path/{$images[$type]}\" alt=\"$msgLabel\"/><br />$msgLabel";
1114                         $disabledTexts[$type] = "<img src=\"$path/{$disabledImages[$type]}\" alt=\"$msgLabel\"/><br />$msgLabel";
1115                 }
1116                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
1117
1118                 $navClass = htmlspecialchars( $this->getNavClass() );
1119                 $s = "<table class=\"$navClass\"><tr>\n";
1120                 $width = 100 / count( $links ) . '%';
1121                 foreach ( $labels as $type => $label ) {
1122                         $s .= "<td style='width:$width;'>{$links[$type]}</td>\n";
1123                 }
1124                 $s .= "</tr></table>\n";
1125                 return $s;
1126         }
1127
1128         /**
1129          * Get a <select> element which has options for each of the allowed limits
1130          *
1131          * @return String: HTML fragment
1132          */
1133         function getLimitSelect() {
1134                 # Add the current limit from the query string
1135                 # to avoid that the limit is lost after clicking Go next time
1136                 if ( !in_array( $this->mLimit, $this->mLimitsShown ) ) {
1137                         $this->mLimitsShown[] = $this->mLimit;
1138                         sort( $this->mLimitsShown );
1139                 }
1140                 $s = Html::openElement( 'select', array( 'name' => 'limit' ) ) . "\n";
1141                 foreach ( $this->mLimitsShown as $key => $value ) {
1142                         # The pair is either $index => $limit, in which case the $value
1143                         # will be numeric, or $limit => $text, in which case the $value
1144                         # will be a string.
1145                         if( is_int( $value ) ){
1146                                 $limit = $value;
1147                                 $text = $this->getLanguage()->formatNum( $limit );
1148                         } else {
1149                                 $limit = $key;
1150                                 $text = $value;
1151                         }
1152                         $s .= Xml::option( $text, $limit, $limit == $this->mLimit ) . "\n";
1153                 }
1154                 $s .= Html::closeElement( 'select' );
1155                 return $s;
1156         }
1157
1158         /**
1159          * Returns an HTMLFormField definition for the "Items per page:" dropdown
1160          *
1161          * @return array
1162          */
1163         protected function getHTMLFormLimitSelect() {
1164                 $f = array(
1165                         'class' => 'HTMLItemsPerPageField',
1166                         'label-message' => 'table_pager_limit_label',
1167                         'options' => array(),
1168                         'default' => $this->mDefaultLimit,
1169                         'name' => 'limit',
1170                 );
1171
1172                 foreach( $this->mLimitsShown as $limit ) {
1173                         $f['options'][$this->getLanguage()->formatNum( $limit )] = $limit;
1174                 }
1175
1176                 return $f;
1177         }
1178
1179         /**
1180          * Get <input type="hidden"> elements for use in a method="get" form.
1181          * Resubmits all defined elements of the query string, except for a
1182          * blacklist, passed in the $blacklist parameter.
1183          *
1184          * @param $blacklist Array parameters from the request query which should not be resubmitted
1185          * @return String: HTML fragment
1186          */
1187         function getHiddenFields( $blacklist = array() ) {
1188                 $blacklist = (array)$blacklist;
1189                 $query = $this->getRequest()->getQueryValues();
1190                 foreach ( $blacklist as $name ) {
1191                         unset( $query[$name] );
1192                 }
1193                 $s = '';
1194                 foreach ( $query as $name => $value ) {
1195                         $encName = htmlspecialchars( $name );
1196                         $encValue = htmlspecialchars( $value );
1197                         $s .= "<input type=\"hidden\" name=\"$encName\" value=\"$encValue\"/>\n";
1198                 }
1199                 return $s;
1200         }
1201
1202         /**
1203          * Get a form containing a limit selection dropdown
1204          *
1205          * @return String: HTML fragment
1206          */
1207         function getLimitForm() {
1208                 global $wgScript;
1209
1210                 return Xml::openElement(
1211                         'form',
1212                         array(
1213                                 'method' => 'get',
1214                                 'action' => $wgScript
1215                         ) ) . "\n" . $this->getLimitDropdown() . "</form>\n";
1216         }
1217
1218         /**
1219          * Gets a limit selection dropdown
1220          *
1221          * @return string
1222          */
1223         function getLimitDropdown() {
1224                 # Make the select with some explanatory text
1225                 $msgSubmit = wfMsgHtml( 'table_pager_limit_submit' );
1226
1227                 return wfMsgHtml( 'table_pager_limit', $this->getLimitSelect() ) .
1228                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
1229                         $this->getHiddenFields( array( 'limit' ) );
1230         }
1231
1232         /**
1233          * Return true if the named field should be sortable by the UI, false
1234          * otherwise
1235          *
1236          * @param $field String
1237          */
1238         abstract function isFieldSortable( $field );
1239
1240         /**
1241          * Format a table cell. The return value should be HTML, but use an empty
1242          * string not &#160; for empty cells. Do not include the <td> and </td>.
1243          *
1244          * The current result row is available as $this->mCurrentRow, in case you
1245          * need more context.
1246          *
1247          * @param $name String: the database field name
1248          * @param $value String: the value retrieved from the database
1249          */
1250         abstract function formatValue( $name, $value );
1251
1252         /**
1253          * The database field name used as a default sort order
1254          */
1255         abstract function getDefaultSort();
1256
1257         /**
1258          * An array mapping database field names to a textual description of the
1259          * field name, for use in the table header. The description should be plain
1260          * text, it will be HTML-escaped later.
1261          *
1262          * @return Array
1263          */
1264         abstract function getFieldNames();
1265 }
1266
1267 /**
1268  * Items per page dropdown for HTMLForm
1269  */
1270 class HTMLItemsPerPageField extends HTMLSelectField {
1271         /**
1272          * Basically don't do any validation. If it's a number that's fine. Also,
1273          * add it to the list if it's not there already
1274          *
1275          * @param $value
1276          * @param $alldata
1277          * @return bool
1278          */
1279         function validate( $value, $alldata ) {
1280                 if ( $value == '' ) {
1281                         return true;
1282                 }
1283
1284                 if ( !in_array( $value, $this->mParams['options'] ) ) {
1285                         $this->mParams['options'][ $this->mParent->getLanguage()->formatNum( $value ) ] = intval($value);
1286                         asort( $this->mParams['options'] );
1287                 }
1288
1289                 return true;
1290         }
1291
1292 }