includes/Pager.php

   1 <?php
   2 /**
   3  * Efficient paging for SQL queries.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Pager
  22  */
  23
  24 /**
  25  * @defgroup Pager Pager
  26  */
  27
  28 /**
  29  * Basic pager interface.
  30  * @ingroup Pager
  31  */
  32 interface Pager {
  33         function getNavigationBar();
  34         function getBody();
  35 }
  36
  37 /**
  38  * IndexPager is an efficient pager which uses a (roughly unique) index in the
  39  * data set to implement paging, rather than a "LIMIT offset,limit" clause.
  40  * In MySQL, such a limit/offset clause requires counting through the
  41  * specified number of offset rows to find the desired data, which can be
  42  * expensive for large offsets.
  43  *
  44  * ReverseChronologicalPager is a child class of the abstract IndexPager, and
  45  * contains  some formatting and display code which is specific to the use of
  46  * timestamps as  indexes. Here is a synopsis of its operation:
  47  *
  48  *    * The query is specified by the offset, limit and direction (dir)
  49  *      parameters, in addition to any subclass-specific parameters.
  50  *    * The offset is the non-inclusive start of the DB query. A row with an
  51  *      index value equal to the offset will never be shown.
  52  *    * The query may either be done backwards, where the rows are returned by
  53  *      the database in the opposite order to which they are displayed to the
  54  *      user, or forwards. This is specified by the "dir" parameter, dir=prev
  55  *      means backwards, anything else means forwards. The offset value
  56  *      specifies the start of the database result set, which may be either
  57  *      the start or end of the displayed data set. This allows "previous"
  58  *      links to be implemented without knowledge of the index value at the
  59  *      start of the previous page.
  60  *    * An additional row beyond the user-specified limit is always requested.
  61  *      This allows us to tell whether we should display a "next" link in the
  62  *      case of forwards mode, or a "previous" link in the case of backwards
  63  *      mode. Determining whether to display the other link (the one for the
  64  *      page before the start of the database result set) can be done
  65  *      heuristically by examining the offset.
  66  *
  67  *    * An empty offset indicates that the offset condition should be omitted
  68  *      from the query. This naturally produces either the first page or the
  69  *      last page depending on the dir parameter.
  70  *
  71  *  Subclassing the pager to implement concrete functionality should be fairly
  72  *  simple, please see the examples in HistoryPage.php and
  73  *  SpecialBlockList.php. You just need to override formatRow(),
  74  *  getQueryInfo() and getIndexField(). Don't forget to call the parent
  75  *  constructor if you override it.
  76  *
  77  * @ingroup Pager
  78  */
  79 abstract class IndexPager extends ContextSource implements Pager {
  80         public $mRequest;
  81         public $mLimitsShown = array( 20, 50, 100, 250, 500 );
  82         public $mDefaultLimit = 50;
  83         public $mOffset, $mLimit;
  84         public $mQueryDone = false;
  85         public $mDb;
  86         public $mPastTheEndRow;
  87
  88         /**
  89          * The index to actually be used for ordering. This is a single column,
  90          * for one ordering, even if multiple orderings are supported.
  91          */
  92         protected $mIndexField;
  93         /**
  94          * An array of secondary columns to order by. These fields are not part of the offset.
  95          * This is a column list for one ordering, even if multiple orderings are supported.
  96          */
  97         protected $mExtraSortFields;
  98         /** For pages that support multiple types of ordering, which one to use.
  99          */
 100         protected $mOrderType;
 101         /**
 102          * $mDefaultDirection gives the direction to use when sorting results:
 103          * false for ascending, true for descending.  If $mIsBackwards is set, we
 104          * start from the opposite end, but we still sort the page itself according
 105          * to $mDefaultDirection.  E.g., if $mDefaultDirection is false but we're
 106          * going backwards, we'll display the last page of results, but the last
 107          * result will be at the bottom, not the top.
 108          *
 109          * Like $mIndexField, $mDefaultDirection will be a single value even if the
 110          * class supports multiple default directions for different order types.
 111          */
 112         public $mDefaultDirection;
 113         public $mIsBackwards;
 114
 115         /** True if the current result set is the first one */
 116         public $mIsFirst;
 117         public $mIsLast;
 118
 119         protected $mLastShown, $mFirstShown, $mPastTheEndIndex, $mDefaultQuery, $mNavigationBar;
 120
 121         /**
 122          * Whether to include the offset in the query
 123          */
 124         protected $mIncludeOffset = false;
 125
 126         /**
 127          * Result object for the query. Warning: seek before use.
 128          *
 129          * @var ResultWrapper
 130          */
 131         public $mResult;
 132
 133         public function __construct( IContextSource $context = null ) {
 134                 if ( $context ) {
 135                         $this->setContext( $context );
 136                 }
 137
 138                 $this->mRequest = $this->getRequest();
 139
 140                 # NB: the offset is quoted, not validated. It is treated as an
 141                 # arbitrary string to support the widest variety of index types. Be
 142                 # careful outputting it into HTML!
 143                 $this->mOffset = $this->mRequest->getText( 'offset' );
 144
 145                 # Use consistent behavior for the limit options
 146                 $this->mDefaultLimit = $this->getUser()->getIntOption( 'rclimit' );
 147                 if ( !$this->mLimit ) {
 148                         // Don't override if a subclass calls $this->setLimit() in its constructor.
 149                         list( $this->mLimit, /* $offset */ ) = $this->mRequest->getLimitOffset();
 150                 }
 151
 152                 $this->mIsBackwards = ( $this->mRequest->getVal( 'dir' ) == 'prev' );
 153                 $this->mDb = wfGetDB( DB_SLAVE );
 154
 155                 $index = $this->getIndexField(); // column to sort on
 156                 $extraSort = $this->getExtraSortFields(); // extra columns to sort on for query planning
 157                 $order = $this->mRequest->getVal( 'order' );
 158                 if( is_array( $index ) && isset( $index[$order] ) ) {
 159                         $this->mOrderType = $order;
 160                         $this->mIndexField = $index[$order];
 161                         $this->mExtraSortFields = isset( $extraSort[$order] )
 162                                 ? (array)$extraSort[$order]
 163                                 : array();
 164                 } elseif( is_array( $index ) ) {
 165                         # First element is the default
 166                         reset( $index );
 167                         list( $this->mOrderType, $this->mIndexField ) = each( $index );
 168                         $this->mExtraSortFields = isset( $extraSort[$this->mOrderType] )
 169                                 ? (array)$extraSort[$this->mOrderType]
 170                                 : array();
 171                 } else {
 172                         # $index is not an array
 173                         $this->mOrderType = null;
 174                         $this->mIndexField = $index;
 175                         $this->mExtraSortFields = (array)$extraSort;
 176                 }
 177
 178                 if( !isset( $this->mDefaultDirection ) ) {
 179                         $dir = $this->getDefaultDirections();
 180                         $this->mDefaultDirection = is_array( $dir )
 181                                 ? $dir[$this->mOrderType]
 182                                 : $dir;
 183                 }
 184         }
 185
 186         /**
 187          * Get the Database object in use
 188          *
 189          * @return DatabaseBase
 190          */
 191         public function getDatabase() {
 192                 return $this->mDb;
 193         }
 194
 195         /**
 196          * Do the query, using information from the object context. This function
 197          * has been kept minimal to make it overridable if necessary, to allow for
 198          * result sets formed from multiple DB queries.
 199          */
 200         public function doQuery() {
 201                 # Use the child class name for profiling
 202                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 203                 wfProfileIn( $fname );
 204
 205                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 206                 # Plus an extra row so that we can tell the "next" link should be shown
 207                 $queryLimit = $this->mLimit + 1;
 208
 209                 $this->mResult = $this->reallyDoQuery(
 210                         $this->mOffset,
 211                         $queryLimit,
 212                         $descending
 213                 );
 214
 215                 $this->extractResultInfo( $this->mOffset, $queryLimit, $this->mResult );
 216                 $this->mQueryDone = true;
 217
 218                 $this->preprocessResults( $this->mResult );
 219                 $this->mResult->rewind(); // Paranoia
 220
 221                 wfProfileOut( $fname );
 222         }
 223
 224         /**
 225          * @return ResultWrapper The result wrapper.
 226          */
 227         function getResult() {
 228                 return $this->mResult;
 229         }
 230
 231         /**
 232          * Set the offset from an other source than the request
 233          *
 234          * @param $offset Int|String
 235          */
 236         function setOffset( $offset ) {
 237                 $this->mOffset = $offset;
 238         }
 239         /**
 240          * Set the limit from an other source than the request
 241          *
 242          * Verifies limit is between 1 and 5000
 243          *
 244          * @param $limit Int|String
 245          */
 246         function setLimit( $limit ) {
 247                 $limit = (int) $limit;
 248                 // WebRequest::getLimitOffset() puts a cap of 5000, so do same here.
 249                 if ( $limit > 5000 ) {
 250                         $limit = 5000;
 251                 }
 252                 if ( $limit > 0 ) {
 253                         $this->mLimit = $limit;
 254                 }
 255         }
 256
 257         /**
 258          * Set whether a row matching exactly the offset should be also included
 259          * in the result or not. By default this is not the case, but when the
 260          * offset is user-supplied this might be wanted.
 261          *
 262          * @param $include bool
 263          */
 264         public function setIncludeOffset( $include ) {
 265                 $this->mIncludeOffset = $include;
 266         }
 267
 268         /**
 269          * Extract some useful data from the result object for use by
 270          * the navigation bar, put it into $this
 271          *
 272          * @param string $offset index offset, inclusive
 273          * @param $limit Integer: exact query limit
 274          * @param $res ResultWrapper
 275          */
 276         function extractResultInfo( $offset, $limit, ResultWrapper $res ) {
 277                 $numRows = $res->numRows();
 278                 if ( $numRows ) {
 279                         # Remove any table prefix from index field
 280                         $parts = explode( '.', $this->mIndexField );
 281                         $indexColumn = end( $parts );
 282
 283                         $row = $res->fetchRow();
 284                         $firstIndex = $row[$indexColumn];
 285
 286                         # Discard the extra result row if there is one
 287                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 288                                 $res->seek( $numRows - 1 );
 289                                 $this->mPastTheEndRow = $res->fetchObject();
 290                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexColumn;
 291                                 $res->seek( $numRows - 2 );
 292                                 $row = $res->fetchRow();
 293                                 $lastIndex = $row[$indexColumn];
 294                         } else {
 295                                 $this->mPastTheEndRow = null;
 296                                 # Setting indexes to an empty string means that they will be
 297                                 # omitted if they would otherwise appear in URLs. It just so
 298                                 # happens that this  is the right thing to do in the standard
 299                                 # UI, in all the relevant cases.
 300                                 $this->mPastTheEndIndex = '';
 301                                 $res->seek( $numRows - 1 );
 302                                 $row = $res->fetchRow();
 303                                 $lastIndex = $row[$indexColumn];
 304                         }
 305                 } else {
 306                         $firstIndex = '';
 307                         $lastIndex = '';
 308                         $this->mPastTheEndRow = null;
 309                         $this->mPastTheEndIndex = '';
 310                 }
 311
 312                 if ( $this->mIsBackwards ) {
 313                         $this->mIsFirst = ( $numRows < $limit );
 314                         $this->mIsLast = ( $offset == '' );
 315                         $this->mLastShown = $firstIndex;
 316                         $this->mFirstShown = $lastIndex;
 317                 } else {
 318                         $this->mIsFirst = ( $offset == '' );
 319                         $this->mIsLast = ( $numRows < $limit );
 320                         $this->mLastShown = $lastIndex;
 321                         $this->mFirstShown = $firstIndex;
 322                 }
 323         }
 324
 325         /**
 326          * Get some text to go in brackets in the "function name" part of the SQL comment
 327          *
 328          * @return String
 329          */
 330         function getSqlComment() {
 331                 return get_class( $this );
 332         }
 333
 334         /**
 335          * Do a query with specified parameters, rather than using the object
 336          * context
 337          *
 338          * @param string $offset index offset, inclusive
 339          * @param $limit Integer: exact query limit
 340          * @param $descending Boolean: query direction, false for ascending, true for descending
 341          * @return ResultWrapper
 342          */
 343         public function reallyDoQuery( $offset, $limit, $descending ) {
 344                 list( $tables, $fields, $conds, $fname, $options, $join_conds ) = $this->buildQueryInfo( $offset, $limit, $descending );
 345                 return $this->mDb->select( $tables, $fields, $conds, $fname, $options, $join_conds );
 346         }
 347
 348         /**
 349          * Build variables to use by the database wrapper.
 350          *
 351          * @param string $offset index offset, inclusive
 352          * @param $limit Integer: exact query limit
 353          * @param $descending Boolean: query direction, false for ascending, true for descending
 354          * @return array
 355          */
 356         protected function buildQueryInfo( $offset, $limit, $descending ) {
 357                 $fname = __METHOD__ . ' (' . $this->getSqlComment() . ')';
 358                 $info = $this->getQueryInfo();
 359                 $tables = $info['tables'];
 360                 $fields = $info['fields'];
 361                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 362                 $options = isset( $info['options'] ) ? $info['options'] : array();
 363                 $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
 364                 $sortColumns = array_merge( array( $this->mIndexField ), $this->mExtraSortFields );
 365                 if ( $descending ) {
 366                         $options['ORDER BY'] = $sortColumns;
 367                         $operator = $this->mIncludeOffset ? '>=' : '>';
 368                 } else {
 369                         $orderBy = array();
 370                         foreach ( $sortColumns as $col ) {
 371                                 $orderBy[] = $col . ' DESC';
 372                         }
 373                         $options['ORDER BY'] = $orderBy;
 374                         $operator = $this->mIncludeOffset ? '<=' : '<';
 375                 }
 376                 if ( $offset != '' ) {
 377                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 378                 }
 379                 $options['LIMIT'] = intval( $limit );
 380                 return array( $tables, $fields, $conds, $fname, $options, $join_conds );
 381         }
 382
 383         /**
 384          * Pre-process results; useful for performing batch existence checks, etc.
 385          *
 386          * @param $result ResultWrapper
 387          */
 388         protected function preprocessResults( $result ) {}
 389
 390         /**
 391          * Get the formatted result list. Calls getStartBody(), formatRow() and
 392          * getEndBody(), concatenates the results and returns them.
 393          *
 394          * @return String
 395          */
 396         public function getBody() {
 397                 if ( !$this->mQueryDone ) {
 398                         $this->doQuery();
 399                 }
 400
 401                 if ( $this->mResult->numRows() ) {
 402                         # Do any special query batches before display
 403                         $this->doBatchLookups();
 404                 }
 405
 406                 # Don't use any extra rows returned by the query
 407                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 408
 409                 $s = $this->getStartBody();
 410                 if ( $numRows ) {
 411                         if ( $this->mIsBackwards ) {
 412                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 413                                         $this->mResult->seek( $i );
 414                                         $row = $this->mResult->fetchObject();
 415                                         $s .= $this->formatRow( $row );
 416                                 }
 417                         } else {
 418                                 $this->mResult->seek( 0 );
 419                                 for ( $i = 0; $i < $numRows; $i++ ) {
 420                                         $row = $this->mResult->fetchObject();
 421                                         $s .= $this->formatRow( $row );
 422                                 }
 423                         }
 424                 } else {
 425                         $s .= $this->getEmptyBody();
 426                 }
 427                 $s .= $this->getEndBody();
 428                 return $s;
 429         }
 430
 431         /**
 432          * Make a self-link
 433          *
 434          * @param string $text text displayed on the link
 435          * @param array $query associative array of parameter to be in the query string
 436          * @param string $type value of the "rel" attribute
 437          *
 438          * @return String: HTML fragment
 439          */
 440         function makeLink( $text, array $query = null, $type = null ) {
 441                 if ( $query === null ) {
 442                         return $text;
 443                 }
 444
 445                 $attrs = array();
 446                 if( in_array( $type, array( 'first', 'prev', 'next', 'last' ) ) ) {
 447                         # HTML5 rel attributes
 448                         $attrs['rel'] = $type;
 449                 }
 450
 451                 if( $type ) {
 452                         $attrs['class'] = "mw-{$type}link";
 453                 }
 454
 455                 return Linker::linkKnown(
 456                         $this->getTitle(),
 457                         $text,
 458                         $attrs,
 459                         $query + $this->getDefaultQuery()
 460                 );
 461         }
 462
 463         /**
 464          * Called from getBody(), before getStartBody() is called and
 465          * after doQuery() was called. This will be called only if there
 466          * are rows in the result set.
 467          *
 468          * @return void
 469          */
 470         protected function doBatchLookups() {}
 471
 472         /**
 473          * Hook into getBody(), allows text to be inserted at the start. This
 474          * will be called even if there are no rows in the result set.
 475          *
 476          * @return String
 477          */
 478         protected function getStartBody() {
 479                 return '';
 480         }
 481
 482         /**
 483          * Hook into getBody() for the end of the list
 484          *
 485          * @return String
 486          */
 487         protected function getEndBody() {
 488                 return '';
 489         }
 490
 491         /**
 492          * Hook into getBody(), for the bit between the start and the
 493          * end when there are no rows
 494          *
 495          * @return String
 496          */
 497         protected function getEmptyBody() {
 498                 return '';
 499         }
 500
 501         /**
 502          * Get an array of query parameters that should be put into self-links.
 503          * By default, all parameters passed in the URL are used, except for a
 504          * short blacklist.
 505          *
 506          * @return array Associative array
 507          */
 508         function getDefaultQuery() {
 509                 if ( !isset( $this->mDefaultQuery ) ) {
 510                         $this->mDefaultQuery = $this->getRequest()->getQueryValues();
 511                         unset( $this->mDefaultQuery['title'] );
 512                         unset( $this->mDefaultQuery['dir'] );
 513                         unset( $this->mDefaultQuery['offset'] );
 514                         unset( $this->mDefaultQuery['limit'] );
 515                         unset( $this->mDefaultQuery['order'] );
 516                         unset( $this->mDefaultQuery['month'] );
 517                         unset( $this->mDefaultQuery['year'] );
 518                 }
 519                 return $this->mDefaultQuery;
 520         }
 521
 522         /**
 523          * Get the number of rows in the result set
 524          *
 525          * @return Integer
 526          */
 527         function getNumRows() {
 528                 if ( !$this->mQueryDone ) {
 529                         $this->doQuery();
 530                 }
 531                 return $this->mResult->numRows();
 532         }
 533
 534         /**
 535          * Get a URL query array for the prev, next, first and last links.
 536          *
 537          * @return Array
 538          */
 539         function getPagingQueries() {
 540                 if ( !$this->mQueryDone ) {
 541                         $this->doQuery();
 542                 }
 543
 544                 # Don't announce the limit everywhere if it's the default
 545                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? null : $this->mLimit;
 546
 547                 if ( $this->mIsFirst ) {
 548                         $prev = false;
 549                         $first = false;
 550                 } else {
 551                         $prev = array(
 552                                 'dir' => 'prev',
 553                                 'offset' => $this->mFirstShown,
 554                                 'limit' => $urlLimit
 555                         );
 556                         $first = array( 'limit' => $urlLimit );
 557                 }
 558                 if ( $this->mIsLast ) {
 559                         $next = false;
 560                         $last = false;
 561                 } else {
 562                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 563                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 564                 }
 565                 return array(
 566                         'prev' => $prev,
 567                         'next' => $next,
 568                         'first' => $first,
 569                         'last' => $last
 570                 );
 571         }
 572
 573         /**
 574          * Returns whether to show the "navigation bar"
 575          *
 576          * @return Boolean
 577          */
 578         function isNavigationBarShown() {
 579                 if ( !$this->mQueryDone ) {
 580                         $this->doQuery();
 581                 }
 582                 // Hide navigation by default if there is nothing to page
 583                 return !($this->mIsFirst && $this->mIsLast);
 584         }
 585
 586         /**
 587          * Get paging links. If a link is disabled, the item from $disabledTexts
 588          * will be used. If there is no such item, the unlinked text from
 589          * $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays
 590          * of HTML.
 591          *
 592          * @param $linkTexts Array
 593          * @param $disabledTexts Array
 594          * @return Array
 595          */
 596         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 597                 $queries = $this->getPagingQueries();
 598                 $links = array();
 599
 600                 foreach ( $queries as $type => $query ) {
 601                         if ( $query !== false ) {
 602                                 $links[$type] = $this->makeLink(
 603                                         $linkTexts[$type],
 604                                         $queries[$type],
 605                                         $type
 606                                 );
 607                         } elseif ( isset( $disabledTexts[$type] ) ) {
 608                                 $links[$type] = $disabledTexts[$type];
 609                         } else {
 610                                 $links[$type] = $linkTexts[$type];
 611                         }
 612                 }
 613
 614                 return $links;
 615         }
 616
 617         function getLimitLinks() {
 618                 $links = array();
 619                 if ( $this->mIsBackwards ) {
 620                         $offset = $this->mPastTheEndIndex;
 621                 } else {
 622                         $offset = $this->mOffset;
 623                 }
 624                 foreach ( $this->mLimitsShown as $limit ) {
 625                         $links[] = $this->makeLink(
 626                                 $this->getLanguage()->formatNum( $limit ),
 627                                 array( 'offset' => $offset, 'limit' => $limit ),
 628                                 'num'
 629                         );
 630                 }
 631                 return $links;
 632         }
 633
 634         /**
 635          * Abstract formatting function. This should return an HTML string
 636          * representing the result row $row. Rows will be concatenated and
 637          * returned by getBody()
 638          *
 639          * @param $row Object: database row
 640          * @return String
 641          */
 642         abstract function formatRow( $row );
 643
 644         /**
 645          * This function should be overridden to provide all parameters
 646          * needed for the main paged query. It returns an associative
 647          * array with the following elements:
 648          *    tables => Table(s) for passing to Database::select()
 649          *    fields => Field(s) for passing to Database::select(), may be *
 650          *    conds => WHERE conditions
 651          *    options => option array
 652          *    join_conds => JOIN conditions
 653          *
 654          * @return Array
 655          */
 656         abstract function getQueryInfo();
 657
 658         /**
 659          * This function should be overridden to return the name of the index fi-
 660          * eld.  If the pager supports multiple orders, it may return an array of
 661          * 'querykey' => 'indexfield' pairs, so that a request with &count=querykey
 662          * will use indexfield to sort.  In this case, the first returned key is
 663          * the default.
 664          *
 665          * Needless to say, it's really not a good idea to use a non-unique index
 666          * for this!  That won't page right.
 667          *
 668          * @return string|Array
 669          */
 670         abstract function getIndexField();
 671
 672         /**
 673          * This function should be overridden to return the names of secondary columns
 674          * to order by in addition to the column in getIndexField(). These fields will
 675          * not be used in the pager offset or in any links for users.
 676          *
 677          * If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then
 678          * this must return a corresponding array of 'querykey' => array( fields...) pairs
 679          * in order for a request with &count=querykey to use array( fields...) to sort.
 680          *
 681          * This is useful for pagers that GROUP BY a unique column (say page_id)
 682          * and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on
 683          * page_len,page_id avoids temp tables (given a page_len index). This would
 684          * also work if page_id was non-unique but we had a page_len,page_id index.
 685          *
 686          * @return Array
 687          */
 688         protected function getExtraSortFields() { return array(); }
 689
 690         /**
 691          * Return the default sorting direction: false for ascending, true for
 692          * descending.  You can also have an associative array of ordertype => dir,
 693          * if multiple order types are supported.  In this case getIndexField()
 694          * must return an array, and the keys of that must exactly match the keys
 695          * of this.
 696          *
 697          * For backward compatibility, this method's return value will be ignored
 698          * if $this->mDefaultDirection is already set when the constructor is
 699          * called, for instance if it's statically initialized.  In that case the
 700          * value of that variable (which must be a boolean) will be used.
 701          *
 702          * Note that despite its name, this does not return the value of the
 703          * $this->mDefaultDirection member variable.  That's the default for this
 704          * particular instantiation, which is a single value.  This is the set of
 705          * all defaults for the class.
 706          *
 707          * @return Boolean
 708          */
 709         protected function getDefaultDirections() { return false; }
 710 }
 711
 712 /**
 713  * IndexPager with an alphabetic list and a formatted navigation bar
 714  * @ingroup Pager
 715  */
 716 abstract class AlphabeticPager extends IndexPager {
 717
 718         /**
 719          * Shamelessly stolen bits from ReverseChronologicalPager,
 720          * didn't want to do class magic as may be still revamped
 721          *
 722          * @return String HTML
 723          */
 724         function getNavigationBar() {
 725                 if ( !$this->isNavigationBarShown() ) {
 726                         return '';
 727                 }
 728
 729                 if( isset( $this->mNavigationBar ) ) {
 730                         return $this->mNavigationBar;
 731                 }
 732
 733                 $linkTexts = array(
 734                         'prev' => $this->msg( 'prevn' )->numParams( $this->mLimit )->escaped(),
 735                         'next' => $this->msg( 'nextn' )->numParams( $this->mLimit )->escaped(),
 736                         'first' => $this->msg( 'page_first' )->escaped(),
 737                         'last' => $this->msg( 'page_last' )->escaped()
 738                 );
 739
 740                 $lang = $this->getLanguage();
 741
 742                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 743                 $limitLinks = $this->getLimitLinks();
 744                 $limits = $lang->pipeList( $limitLinks );
 745
 746                 $this->mNavigationBar = $this->msg( 'parentheses' )->rawParams(
 747                         $lang->pipeList( array( $pagingLinks['first'],
 748                         $pagingLinks['last'] ) ) )->escaped() . " " .
 749                         $this->msg( 'viewprevnext' )->rawParams( $pagingLinks['prev'],
 750                                 $pagingLinks['next'], $limits )->escaped();
 751
 752                 if( !is_array( $this->getIndexField() ) ) {
 753                         # Early return to avoid undue nesting
 754                         return $this->mNavigationBar;
 755                 }
 756
 757                 $extra = '';
 758                 $first = true;
 759                 $msgs = $this->getOrderTypeMessages();
 760                 foreach( array_keys( $msgs ) as $order ) {
 761                         if( $first ) {
 762                                 $first = false;
 763                         } else {
 764                                 $extra .= $this->msg( 'pipe-separator' )->escaped();
 765                         }
 766
 767                         if( $order == $this->mOrderType ) {
 768                                 $extra .= $this->msg( $msgs[$order] )->escaped();
 769                         } else {
 770                                 $extra .= $this->makeLink(
 771                                         $this->msg( $msgs[$order] )->escaped(),
 772                                         array( 'order' => $order )
 773                                 );
 774                         }
 775                 }
 776
 777                 if( $extra !== '' ) {
 778                         $extra = ' ' . $this->msg( 'parentheses' )->rawParams( $extra )->escaped();
 779                         $this->mNavigationBar .= $extra;
 780                 }
 781
 782                 return $this->mNavigationBar;
 783         }
 784
 785         /**
 786          * If this supports multiple order type messages, give the message key for
 787          * enabling each one in getNavigationBar.  The return type is an associative
 788          * array whose keys must exactly match the keys of the array returned
 789          * by getIndexField(), and whose values are message keys.
 790          *
 791          * @return Array
 792          */
 793         protected function getOrderTypeMessages() {
 794                 return null;
 795         }
 796 }
 797
 798 /**
 799  * IndexPager with a formatted navigation bar
 800  * @ingroup Pager
 801  */
 802 abstract class ReverseChronologicalPager extends IndexPager {
 803         public $mDefaultDirection = true;
 804         public $mYear;
 805         public $mMonth;
 806
 807         function getNavigationBar() {
 808                 if ( !$this->isNavigationBarShown() ) {
 809                         return '';
 810                 }
 811
 812                 if ( isset( $this->mNavigationBar ) ) {
 813                         return $this->mNavigationBar;
 814                 }
 815
 816                 $linkTexts = array(
 817                         'prev' => $this->msg( 'pager-newer-n' )->numParams( $this->mLimit )->escaped(),
 818                         'next' => $this->msg( 'pager-older-n' )->numParams( $this->mLimit )->escaped(),
 819                         'first' => $this->msg( 'histlast' )->escaped(),
 820                         'last' => $this->msg( 'histfirst' )->escaped()
 821                 );
 822
 823                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 824                 $limitLinks = $this->getLimitLinks();
 825                 $limits = $this->getLanguage()->pipeList( $limitLinks );
 826                 $firstLastLinks = $this->msg( 'parentheses' )->rawParams( "{$pagingLinks['first']}" .
 827                         $this->msg( 'pipe-separator' )->escaped() .
 828                         "{$pagingLinks['last']}" )->escaped();
 829
 830                 $this->mNavigationBar = $firstLastLinks . ' ' .
 831                         $this->msg( 'viewprevnext' )->rawParams(
 832                                 $pagingLinks['prev'], $pagingLinks['next'], $limits )->escaped();
 833
 834                 return $this->mNavigationBar;
 835         }
 836
 837         function getDateCond( $year, $month ) {
 838                 $year = intval( $year );
 839                 $month = intval( $month );
 840
 841                 // Basic validity checks
 842                 $this->mYear = $year > 0 ? $year : false;
 843                 $this->mMonth = ( $month > 0 && $month < 13 ) ? $month : false;
 844
 845                 // Given an optional year and month, we need to generate a timestamp
 846                 // to use as "WHERE rev_timestamp <= result"
 847                 // Examples: year = 2006 equals < 20070101 (+000000)
 848                 // year=2005, month=1    equals < 20050201
 849                 // year=2005, month=12   equals < 20060101
 850                 if ( !$this->mYear && !$this->mMonth ) {
 851                         return;
 852                 }
 853
 854                 if ( $this->mYear ) {
 855                         $year = $this->mYear;
 856                 } else {
 857                         // If no year given, assume the current one
 858                         $year = gmdate( 'Y' );
 859                         // If this month hasn't happened yet this year, go back to last year's month
 860                         if( $this->mMonth > gmdate( 'n' ) ) {
 861                                 $year--;
 862                         }
 863                 }
 864
 865                 if ( $this->mMonth ) {
 866                         $month = $this->mMonth + 1;
 867                         // For December, we want January 1 of the next year
 868                         if ( $month > 12 ) {
 869                                 $month = 1;
 870                                 $year++;
 871                         }
 872                 } else {
 873                         // No month implies we want up to the end of the year in question
 874                         $month = 1;
 875                         $year++;
 876                 }
 877
 878                 // Y2K38 bug
 879                 if ( $year > 2032 ) {
 880                         $year = 2032;
 881                 }
 882
 883                 $ymd = (int)sprintf( "%04d%02d01", $year, $month );
 884
 885                 if ( $ymd > 20320101 ) {
 886                         $ymd = 20320101;
 887                 }
 888
 889                 $this->mOffset = $this->mDb->timestamp( "${ymd}000000" );
 890         }
 891 }
 892
 893 /**
 894  * Table-based display with a user-selectable sort order
 895  * @ingroup Pager
 896  */
 897 abstract class TablePager extends IndexPager {
 898         var $mSort;
 899         var $mCurrentRow;
 900
 901         public function __construct( IContextSource $context = null ) {
 902                 if ( $context ) {
 903                         $this->setContext( $context );
 904                 }
 905
 906                 $this->mSort = $this->getRequest()->getText( 'sort' );
 907                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() ) ) {
 908                         $this->mSort = $this->getDefaultSort();
 909                 }
 910                 if ( $this->getRequest()->getBool( 'asc' ) ) {
 911                         $this->mDefaultDirection = false;
 912                 } elseif ( $this->getRequest()->getBool( 'desc' ) ) {
 913                         $this->mDefaultDirection = true;
 914                 } /* Else leave it at whatever the class default is */
 915
 916                 parent::__construct();
 917         }
 918
 919         /**
 920          * @protected
 921          * @return string
 922          */
 923         function getStartBody() {
 924                 global $wgStylePath;
 925                 $sortClass = $this->getSortHeaderClass();
 926
 927                 $s = '';
 928                 $fields = $this->getFieldNames();
 929
 930                 # Make table header
 931                 foreach ( $fields as $field => $name ) {
 932                         if ( strval( $name ) == '' ) {
 933                                 $s .= Html::rawElement( 'th', array(), '&#160;' ) . "\n";
 934                         } elseif ( $this->isFieldSortable( $field ) ) {
 935                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 936                                 if ( $field == $this->mSort ) {
 937                                         # This is the sorted column
 938                                         # Prepare a link that goes in the other sort order
 939                                         if ( $this->mDefaultDirection ) {
 940                                                 # Descending
 941                                                 $image = 'Arr_d.png';
 942                                                 $query['asc'] = '1';
 943                                                 $query['desc'] = '';
 944                                                 $alt = $this->msg( 'descending_abbrev' )->escaped();
 945                                         } else {
 946                                                 # Ascending
 947                                                 $image = 'Arr_u.png';
 948                                                 $query['asc'] = '';
 949                                                 $query['desc'] = '1';
 950                                                 $alt = $this->msg( 'ascending_abbrev' )->escaped();
 951                                         }
 952                                         $image = "$wgStylePath/common/images/$image";
 953                                         $link = $this->makeLink(
 954                                                 Html::element( 'img', array( 'width' => 12, 'height' => 12,
 955                                                         'alt' => $alt, 'src' => $image ) ) . htmlspecialchars( $name ), $query );
 956                                         $s .= Html::rawElement( 'th', array( 'class' => $sortClass ), $link ) . "\n";
 957                                 } else {
 958                                         $s .= Html::rawElement( 'th', array(),
 959                                                 $this->makeLink( htmlspecialchars( $name ), $query ) ) . "\n";
 960                                 }
 961                         } else {
 962                                 $s .= Html::element( 'th', array(), $name ) . "\n";
 963                         }
 964                 }
 965
 966                 $tableClass = $this->getTableClass();
 967                 $ret = Html::openElement( 'table', array( 'style' => 'border:1px;', 'class' => "mw-datatable $tableClass" ) );
 968                 $ret .= Html::rawElement( 'thead', array(), Html::rawElement( 'tr', array(), "\n" . $s . "\n" ) );
 969                 $ret .= Html::openElement( 'tbody' ) . "\n";
 970
 971                 return $ret;
 972         }
 973
 974         /**
 975          * @protected
 976          * @return string
 977          */
 978         function getEndBody() {
 979                 return "</tbody></table>\n";
 980         }
 981
 982         /**
 983          * @protected
 984          * @return string
 985          */
 986         function getEmptyBody() {
 987                 $colspan = count( $this->getFieldNames() );
 988                 $msgEmpty = $this->msg( 'table_pager_empty' )->text();
 989                 return Html::rawElement( 'tr', array(),
 990                         Html::element( 'td', array( 'colspan' => $colspan ), $msgEmpty ) );
 991         }
 992
 993         /**
 994          * @protected
 995          * @param stdClass $row
 996          * @return String HTML
 997          */
 998         function formatRow( $row ) {
 999                 $this->mCurrentRow = $row; // In case formatValue etc need to know
1000                 $s = Html::openElement( 'tr', $this->getRowAttrs( $row ) ) . "\n";
1001                 $fieldNames = $this->getFieldNames();
1002
1003                 foreach ( $fieldNames as $field => $name ) {
1004                         $value = isset( $row->$field ) ? $row->$field : null;
1005                         $formatted = strval( $this->formatValue( $field, $value ) );
1006
1007                         if ( $formatted == '' ) {
1008                                 $formatted = '&#160;';
1009                         }
1010
1011                         $s .= Html::rawElement( 'td', $this->getCellAttrs( $field, $value ), $formatted ) . "\n";
1012                 }
1013
1014                 $s .= Html::closeElement( 'tr' ) . "\n";
1015
1016                 return $s;
1017         }
1018
1019         /**
1020          * Get a class name to be applied to the given row.
1021          *
1022          * @protected
1023          *
1024          * @param $row Object: the database result row
1025          * @return String
1026          */
1027         function getRowClass( $row ) {
1028                 return '';
1029         }
1030
1031         /**
1032          * Get attributes to be applied to the given row.
1033          *
1034          * @protected
1035          *
1036          * @param $row Object: the database result row
1037          * @return Array of attribute => value
1038          */
1039         function getRowAttrs( $row ) {
1040                 $class = $this->getRowClass( $row );
1041                 if ( $class === '' ) {
1042                         // Return an empty array to avoid clutter in HTML like class=""
1043                         return array();
1044                 } else {
1045                         return array( 'class' => $this->getRowClass( $row ) );
1046                 }
1047         }
1048
1049         /**
1050          * Get any extra attributes to be applied to the given cell. Don't
1051          * take this as an excuse to hardcode styles; use classes and
1052          * CSS instead.  Row context is available in $this->mCurrentRow
1053          *
1054          * @protected
1055          *
1056          * @param string $field The column
1057          * @param string $value The cell contents
1058          * @return Array of attr => value
1059          */
1060         function getCellAttrs( $field, $value ) {
1061                 return array( 'class' => 'TablePager_col_' . $field );
1062         }
1063
1064         /**
1065          * @protected
1066          * @return string
1067          */
1068         function getIndexField() {
1069                 return $this->mSort;
1070         }
1071
1072         /**
1073          * @protected
1074          * @return string
1075          */
1076         function getTableClass() {
1077                 return 'TablePager';
1078         }
1079
1080         /**
1081          * @protected
1082          * @return string
1083          */
1084         function getNavClass() {
1085                 return 'TablePager_nav';
1086         }
1087
1088         /**
1089          * @protected
1090          * @return string
1091          */
1092         function getSortHeaderClass() {
1093                 return 'TablePager_sort';
1094         }
1095
1096         /**
1097          * A navigation bar with images
1098          * @return String HTML
1099          */
1100         public function getNavigationBar() {
1101                 global $wgStylePath;
1102
1103                 if ( !$this->isNavigationBarShown() ) {
1104                         return '';
1105                 }
1106
1107                 $path = "$wgStylePath/common/images";
1108                 $labels = array(
1109                         'first' => 'table_pager_first',
1110                         'prev' => 'table_pager_prev',
1111                         'next' => 'table_pager_next',
1112                         'last' => 'table_pager_last',
1113                 );
1114                 $images = array(
1115                         'first' => 'arrow_first_25.png',
1116                         'prev' => 'arrow_left_25.png',
1117                         'next' => 'arrow_right_25.png',
1118                         'last' => 'arrow_last_25.png',
1119                 );
1120                 $disabledImages = array(
1121                         'first' => 'arrow_disabled_first_25.png',
1122                         'prev' => 'arrow_disabled_left_25.png',
1123                         'next' => 'arrow_disabled_right_25.png',
1124                         'last' => 'arrow_disabled_last_25.png',
1125                 );
1126                 if( $this->getLanguage()->isRTL() ) {
1127                         $keys = array_keys( $labels );
1128                         $images = array_combine( $keys, array_reverse( $images ) );
1129                         $disabledImages = array_combine( $keys, array_reverse( $disabledImages ) );
1130                 }
1131
1132                 $linkTexts = array();
1133                 $disabledTexts = array();
1134                 foreach ( $labels as $type => $label ) {
1135                         $msgLabel = $this->msg( $label )->escaped();
1136                         $linkTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$images[$type]}",
1137                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1138                         $disabledTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$disabledImages[$type]}",
1139                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1140                 }
1141                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
1142
1143                 $s = Html::openElement( 'table', array( 'class' => $this->getNavClass() ) );
1144                 $s .= Html::openElement( 'tr' ) . "\n";
1145                 $width = 100 / count( $links ) . '%';
1146                 foreach ( $labels as $type => $label ) {
1147                         $s .= Html::rawElement( 'td', array( 'style' => "width:$width;" ), $links[$type] ) . "\n";
1148                 }
1149                 $s .= Html::closeElement( 'tr' ) . Html::closeElement( 'table' ) . "\n";
1150                 return $s;
1151         }
1152
1153         /**
1154          * Get a "<select>" element which has options for each of the allowed limits
1155          *
1156          * @return String: HTML fragment
1157          */
1158         public function getLimitSelect() {
1159                 # Add the current limit from the query string
1160                 # to avoid that the limit is lost after clicking Go next time
1161                 if ( !in_array( $this->mLimit, $this->mLimitsShown ) ) {
1162                         $this->mLimitsShown[] = $this->mLimit;
1163                         sort( $this->mLimitsShown );
1164                 }
1165                 $s = Html::openElement( 'select', array( 'name' => 'limit' ) ) . "\n";
1166                 foreach ( $this->mLimitsShown as $key => $value ) {
1167                         # The pair is either $index => $limit, in which case the $value
1168                         # will be numeric, or $limit => $text, in which case the $value
1169                         # will be a string.
1170                         if( is_int( $value ) ) {
1171                                 $limit = $value;
1172                                 $text = $this->getLanguage()->formatNum( $limit );
1173                         } else {
1174                                 $limit = $key;
1175                                 $text = $value;
1176                         }
1177                         $s .= Xml::option( $text, $limit, $limit == $this->mLimit ) . "\n";
1178                 }
1179                 $s .= Html::closeElement( 'select' );
1180                 return $s;
1181         }
1182
1183         /**
1184          * Get \<input type="hidden"\> elements for use in a method="get" form.
1185          * Resubmits all defined elements of the query string, except for a
1186          * blacklist, passed in the $blacklist parameter.
1187          *
1188          * @param array $blacklist parameters from the request query which should not be resubmitted
1189          * @return String: HTML fragment
1190          */
1191         function getHiddenFields( $blacklist = array() ) {
1192                 $blacklist = (array)$blacklist;
1193                 $query = $this->getRequest()->getQueryValues();
1194                 foreach ( $blacklist as $name ) {
1195                         unset( $query[$name] );
1196                 }
1197                 $s = '';
1198                 foreach ( $query as $name => $value ) {
1199                         $s .= Html::hidden( $name, $value ) . "\n";
1200                 }
1201                 return $s;
1202         }
1203
1204         /**
1205          * Get a form containing a limit selection dropdown
1206          *
1207          * @return String: HTML fragment
1208          */
1209         function getLimitForm() {
1210                 global $wgScript;
1211
1212                 return Html::rawElement(
1213                         'form',
1214                         array(
1215                                 'method' => 'get',
1216                                 'action' => $wgScript
1217                         ),
1218                         "\n" . $this->getLimitDropdown()
1219                 ) . "\n";
1220         }
1221
1222         /**
1223          * Gets a limit selection dropdown
1224          *
1225          * @return string
1226          */
1227         function getLimitDropdown() {
1228                 # Make the select with some explanatory text
1229                 $msgSubmit = $this->msg( 'table_pager_limit_submit' )->escaped();
1230
1231                 return $this->msg( 'table_pager_limit' )
1232                         ->rawParams( $this->getLimitSelect() )->escaped() .
1233                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
1234                         $this->getHiddenFields( array( 'limit' ) );
1235         }
1236
1237         /**
1238          * Return true if the named field should be sortable by the UI, false
1239          * otherwise
1240          *
1241          * @param $field String
1242          */
1243         abstract function isFieldSortable( $field );
1244
1245         /**
1246          * Format a table cell. The return value should be HTML, but use an empty
1247          * string not &#160; for empty cells. Do not include the <td> and </td>.
1248          *
1249          * The current result row is available as $this->mCurrentRow, in case you
1250          * need more context.
1251          *
1252          * @protected
1253          *
1254          * @param string $name the database field name
1255          * @param string $value the value retrieved from the database
1256          */
1257         abstract function formatValue( $name, $value );
1258
1259         /**
1260          * The database field name used as a default sort order.
1261          *
1262          * @protected
1263          *
1264          * @return string
1265          */
1266         abstract function getDefaultSort();
1267
1268         /**
1269          * An array mapping database field names to a textual description of the
1270          * field name, for use in the table header. The description should be plain
1271          * text, it will be HTML-escaped later.
1272          *
1273          * @return Array
1274          */
1275         abstract function getFieldNames();
1276 }