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 HistoryAction.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                 # Let the subclass set the DB here; otherwise use a slave DB for the current wiki
 154                 $this->mDb = $this->mDb ?: wfGetDB( DB_SLAVE );
 155
 156                 $index = $this->getIndexField(); // column to sort on
 157                 $extraSort = $this->getExtraSortFields(); // extra columns to sort on for query planning
 158                 $order = $this->mRequest->getVal( 'order' );
 159                 if ( is_array( $index ) && isset( $index[$order] ) ) {
 160                         $this->mOrderType = $order;
 161                         $this->mIndexField = $index[$order];
 162                         $this->mExtraSortFields = isset( $extraSort[$order] )
 163                                 ? (array)$extraSort[$order]
 164                                 : array();
 165                 } elseif ( is_array( $index ) ) {
 166                         # First element is the default
 167                         reset( $index );
 168                         list( $this->mOrderType, $this->mIndexField ) = each( $index );
 169                         $this->mExtraSortFields = isset( $extraSort[$this->mOrderType] )
 170                                 ? (array)$extraSort[$this->mOrderType]
 171                                 : array();
 172                 } else {
 173                         # $index is not an array
 174                         $this->mOrderType = null;
 175                         $this->mIndexField = $index;
 176                         $this->mExtraSortFields = (array)$extraSort;
 177                 }
 178
 179                 if ( !isset( $this->mDefaultDirection ) ) {
 180                         $dir = $this->getDefaultDirections();
 181                         $this->mDefaultDirection = is_array( $dir )
 182                                 ? $dir[$this->mOrderType]
 183                                 : $dir;
 184                 }
 185         }
 186
 187         /**
 188          * Get the Database object in use
 189          *
 190          * @return DatabaseBase
 191          */
 192         public function getDatabase() {
 193                 return $this->mDb;
 194         }
 195
 196         /**
 197          * Do the query, using information from the object context. This function
 198          * has been kept minimal to make it overridable if necessary, to allow for
 199          * result sets formed from multiple DB queries.
 200          */
 201         public function doQuery() {
 202                 # Use the child class name for profiling
 203                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 204                 wfProfileIn( $fname );
 205
 206                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 207                 # Plus an extra row so that we can tell the "next" link should be shown
 208                 $queryLimit = $this->mLimit + 1;
 209
 210                 if ( $this->mOffset == '' ) {
 211                         $isFirst = true;
 212                 } else {
 213                         // If there's an offset, we may or may not be at the first entry.
 214                         // The only way to tell is to run the query in the opposite
 215                         // direction see if we get a row.
 216                         $oldIncludeOffset = $this->mIncludeOffset;
 217                         $this->mIncludeOffset = !$this->mIncludeOffset;
 218                         $isFirst = !$this->reallyDoQuery( $this->mOffset, 1, !$descending )->numRows();
 219                         $this->mIncludeOffset = $oldIncludeOffset;
 220                 }
 221
 222                 $this->mResult = $this->reallyDoQuery(
 223                         $this->mOffset,
 224                         $queryLimit,
 225                         $descending
 226                 );
 227
 228                 $this->extractResultInfo( $isFirst, $queryLimit, $this->mResult );
 229                 $this->mQueryDone = true;
 230
 231                 $this->preprocessResults( $this->mResult );
 232                 $this->mResult->rewind(); // Paranoia
 233
 234                 wfProfileOut( $fname );
 235         }
 236
 237         /**
 238          * @return ResultWrapper The result wrapper.
 239          */
 240         function getResult() {
 241                 return $this->mResult;
 242         }
 243
 244         /**
 245          * Set the offset from an other source than the request
 246          *
 247          * @param int|string $offset
 248          */
 249         function setOffset( $offset ) {
 250                 $this->mOffset = $offset;
 251         }
 252
 253         /**
 254          * Set the limit from an other source than the request
 255          *
 256          * Verifies limit is between 1 and 5000
 257          *
 258          * @param int|string $limit
 259          */
 260         function setLimit( $limit ) {
 261                 $limit = (int)$limit;
 262                 // WebRequest::getLimitOffset() puts a cap of 5000, so do same here.
 263                 if ( $limit > 5000 ) {
 264                         $limit = 5000;
 265                 }
 266                 if ( $limit > 0 ) {
 267                         $this->mLimit = $limit;
 268                 }
 269         }
 270
 271         /**
 272          * Get the current limit
 273          *
 274          * @return int
 275          */
 276         function getLimit() {
 277                 return $this->mLimit;
 278         }
 279
 280         /**
 281          * Set whether a row matching exactly the offset should be also included
 282          * in the result or not. By default this is not the case, but when the
 283          * offset is user-supplied this might be wanted.
 284          *
 285          * @param bool $include
 286          */
 287         public function setIncludeOffset( $include ) {
 288                 $this->mIncludeOffset = $include;
 289         }
 290
 291         /**
 292          * Extract some useful data from the result object for use by
 293          * the navigation bar, put it into $this
 294          *
 295          * @param bool $isFirst False if there are rows before those fetched (i.e.
 296          *     if a "previous" link would make sense)
 297          * @param int $limit Exact query limit
 298          * @param ResultWrapper $res
 299          */
 300         function extractResultInfo( $isFirst, $limit, ResultWrapper $res ) {
 301                 $numRows = $res->numRows();
 302                 if ( $numRows ) {
 303                         # Remove any table prefix from index field
 304                         $parts = explode( '.', $this->mIndexField );
 305                         $indexColumn = end( $parts );
 306
 307                         $row = $res->fetchRow();
 308                         $firstIndex = $row[$indexColumn];
 309
 310                         # Discard the extra result row if there is one
 311                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 312                                 $res->seek( $numRows - 1 );
 313                                 $this->mPastTheEndRow = $res->fetchObject();
 314                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexColumn;
 315                                 $res->seek( $numRows - 2 );
 316                                 $row = $res->fetchRow();
 317                                 $lastIndex = $row[$indexColumn];
 318                         } else {
 319                                 $this->mPastTheEndRow = null;
 320                                 # Setting indexes to an empty string means that they will be
 321                                 # omitted if they would otherwise appear in URLs. It just so
 322                                 # happens that this  is the right thing to do in the standard
 323                                 # UI, in all the relevant cases.
 324                                 $this->mPastTheEndIndex = '';
 325                                 $res->seek( $numRows - 1 );
 326                                 $row = $res->fetchRow();
 327                                 $lastIndex = $row[$indexColumn];
 328                         }
 329                 } else {
 330                         $firstIndex = '';
 331                         $lastIndex = '';
 332                         $this->mPastTheEndRow = null;
 333                         $this->mPastTheEndIndex = '';
 334                 }
 335
 336                 if ( $this->mIsBackwards ) {
 337                         $this->mIsFirst = ( $numRows < $limit );
 338                         $this->mIsLast = $isFirst;
 339                         $this->mLastShown = $firstIndex;
 340                         $this->mFirstShown = $lastIndex;
 341                 } else {
 342                         $this->mIsFirst = $isFirst;
 343                         $this->mIsLast = ( $numRows < $limit );
 344                         $this->mLastShown = $lastIndex;
 345                         $this->mFirstShown = $firstIndex;
 346                 }
 347         }
 348
 349         /**
 350          * Get some text to go in brackets in the "function name" part of the SQL comment
 351          *
 352          * @return string
 353          */
 354         function getSqlComment() {
 355                 return get_class( $this );
 356         }
 357
 358         /**
 359          * Do a query with specified parameters, rather than using the object
 360          * context
 361          *
 362          * @param string $offset Index offset, inclusive
 363          * @param int $limit Exact query limit
 364          * @param bool $descending Query direction, false for ascending, true for descending
 365          * @return ResultWrapper
 366          */
 367         public function reallyDoQuery( $offset, $limit, $descending ) {
 368                 list( $tables, $fields, $conds, $fname, $options, $join_conds ) =
 369                         $this->buildQueryInfo( $offset, $limit, $descending );
 370
 371                 return $this->mDb->select( $tables, $fields, $conds, $fname, $options, $join_conds );
 372         }
 373
 374         /**
 375          * Build variables to use by the database wrapper.
 376          *
 377          * @param string $offset Index offset, inclusive
 378          * @param int $limit Exact query limit
 379          * @param bool $descending Query direction, false for ascending, true for descending
 380          * @return array
 381          */
 382         protected function buildQueryInfo( $offset, $limit, $descending ) {
 383                 $fname = __METHOD__ . ' (' . $this->getSqlComment() . ')';
 384                 $info = $this->getQueryInfo();
 385                 $tables = $info['tables'];
 386                 $fields = $info['fields'];
 387                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 388                 $options = isset( $info['options'] ) ? $info['options'] : array();
 389                 $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
 390                 $sortColumns = array_merge( array( $this->mIndexField ), $this->mExtraSortFields );
 391                 if ( $descending ) {
 392                         $options['ORDER BY'] = $sortColumns;
 393                         $operator = $this->mIncludeOffset ? '>=' : '>';
 394                 } else {
 395                         $orderBy = array();
 396                         foreach ( $sortColumns as $col ) {
 397                                 $orderBy[] = $col . ' DESC';
 398                         }
 399                         $options['ORDER BY'] = $orderBy;
 400                         $operator = $this->mIncludeOffset ? '<=' : '<';
 401                 }
 402                 if ( $offset != '' ) {
 403                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 404                 }
 405                 $options['LIMIT'] = intval( $limit );
 406                 return array( $tables, $fields, $conds, $fname, $options, $join_conds );
 407         }
 408
 409         /**
 410          * Pre-process results; useful for performing batch existence checks, etc.
 411          *
 412          * @param ResultWrapper $result
 413          */
 414         protected function preprocessResults( $result ) {
 415         }
 416
 417         /**
 418          * Get the formatted result list. Calls getStartBody(), formatRow() and
 419          * getEndBody(), concatenates the results and returns them.
 420          *
 421          * @return string
 422          */
 423         public function getBody() {
 424                 if ( !$this->mQueryDone ) {
 425                         $this->doQuery();
 426                 }
 427
 428                 if ( $this->mResult->numRows() ) {
 429                         # Do any special query batches before display
 430                         $this->doBatchLookups();
 431                 }
 432
 433                 # Don't use any extra rows returned by the query
 434                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 435
 436                 $s = $this->getStartBody();
 437                 if ( $numRows ) {
 438                         if ( $this->mIsBackwards ) {
 439                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 440                                         $this->mResult->seek( $i );
 441                                         $row = $this->mResult->fetchObject();
 442                                         $s .= $this->formatRow( $row );
 443                                 }
 444                         } else {
 445                                 $this->mResult->seek( 0 );
 446                                 for ( $i = 0; $i < $numRows; $i++ ) {
 447                                         $row = $this->mResult->fetchObject();
 448                                         $s .= $this->formatRow( $row );
 449                                 }
 450                         }
 451                 } else {
 452                         $s .= $this->getEmptyBody();
 453                 }
 454                 $s .= $this->getEndBody();
 455                 return $s;
 456         }
 457
 458         /**
 459          * Make a self-link
 460          *
 461          * @param string $text Text displayed on the link
 462          * @param array $query Associative array of parameter to be in the query string
 463          * @param string $type Value of the "rel" attribute
 464          *
 465          * @return string HTML fragment
 466          */
 467         function makeLink( $text, array $query = null, $type = null ) {
 468                 if ( $query === null ) {
 469                         return $text;
 470                 }
 471
 472                 $attrs = array();
 473                 if ( in_array( $type, array( 'first', 'prev', 'next', 'last' ) ) ) {
 474                         # HTML5 rel attributes
 475                         $attrs['rel'] = $type;
 476                 }
 477
 478                 if ( $type ) {
 479                         $attrs['class'] = "mw-{$type}link";
 480                 }
 481
 482                 return Linker::linkKnown(
 483                         $this->getTitle(),
 484                         $text,
 485                         $attrs,
 486                         $query + $this->getDefaultQuery()
 487                 );
 488         }
 489
 490         /**
 491          * Called from getBody(), before getStartBody() is called and
 492          * after doQuery() was called. This will be called only if there
 493          * are rows in the result set.
 494          *
 495          * @return void
 496          */
 497         protected function doBatchLookups() {
 498         }
 499
 500         /**
 501          * Hook into getBody(), allows text to be inserted at the start. This
 502          * will be called even if there are no rows in the result set.
 503          *
 504          * @return string
 505          */
 506         protected function getStartBody() {
 507                 return '';
 508         }
 509
 510         /**
 511          * Hook into getBody() for the end of the list
 512          *
 513          * @return string
 514          */
 515         protected function getEndBody() {
 516                 return '';
 517         }
 518
 519         /**
 520          * Hook into getBody(), for the bit between the start and the
 521          * end when there are no rows
 522          *
 523          * @return string
 524          */
 525         protected function getEmptyBody() {
 526                 return '';
 527         }
 528
 529         /**
 530          * Get an array of query parameters that should be put into self-links.
 531          * By default, all parameters passed in the URL are used, except for a
 532          * short blacklist.
 533          *
 534          * @return array Associative array
 535          */
 536         function getDefaultQuery() {
 537                 if ( !isset( $this->mDefaultQuery ) ) {
 538                         $this->mDefaultQuery = $this->getRequest()->getQueryValues();
 539                         unset( $this->mDefaultQuery['title'] );
 540                         unset( $this->mDefaultQuery['dir'] );
 541                         unset( $this->mDefaultQuery['offset'] );
 542                         unset( $this->mDefaultQuery['limit'] );
 543                         unset( $this->mDefaultQuery['order'] );
 544                         unset( $this->mDefaultQuery['month'] );
 545                         unset( $this->mDefaultQuery['year'] );
 546                 }
 547                 return $this->mDefaultQuery;
 548         }
 549
 550         /**
 551          * Get the number of rows in the result set
 552          *
 553          * @return int
 554          */
 555         function getNumRows() {
 556                 if ( !$this->mQueryDone ) {
 557                         $this->doQuery();
 558                 }
 559                 return $this->mResult->numRows();
 560         }
 561
 562         /**
 563          * Get a URL query array for the prev, next, first and last links.
 564          *
 565          * @return array
 566          */
 567         function getPagingQueries() {
 568                 if ( !$this->mQueryDone ) {
 569                         $this->doQuery();
 570                 }
 571
 572                 # Don't announce the limit everywhere if it's the default
 573                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? null : $this->mLimit;
 574
 575                 if ( $this->mIsFirst ) {
 576                         $prev = false;
 577                         $first = false;
 578                 } else {
 579                         $prev = array(
 580                                 'dir' => 'prev',
 581                                 'offset' => $this->mFirstShown,
 582                                 'limit' => $urlLimit
 583                         );
 584                         $first = array( 'limit' => $urlLimit );
 585                 }
 586                 if ( $this->mIsLast ) {
 587                         $next = false;
 588                         $last = false;
 589                 } else {
 590                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 591                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 592                 }
 593                 return array(
 594                         'prev' => $prev,
 595                         'next' => $next,
 596                         'first' => $first,
 597                         'last' => $last
 598                 );
 599         }
 600
 601         /**
 602          * Returns whether to show the "navigation bar"
 603          *
 604          * @return bool
 605          */
 606         function isNavigationBarShown() {
 607                 if ( !$this->mQueryDone ) {
 608                         $this->doQuery();
 609                 }
 610                 // Hide navigation by default if there is nothing to page
 611                 return !( $this->mIsFirst && $this->mIsLast );
 612         }
 613
 614         /**
 615          * Get paging links. If a link is disabled, the item from $disabledTexts
 616          * will be used. If there is no such item, the unlinked text from
 617          * $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays
 618          * of HTML.
 619          *
 620          * @param array $linkTexts
 621          * @param array $disabledTexts
 622          * @return array
 623          */
 624         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 625                 $queries = $this->getPagingQueries();
 626                 $links = array();
 627
 628                 foreach ( $queries as $type => $query ) {
 629                         if ( $query !== false ) {
 630                                 $links[$type] = $this->makeLink(
 631                                         $linkTexts[$type],
 632                                         $queries[$type],
 633                                         $type
 634                                 );
 635                         } elseif ( isset( $disabledTexts[$type] ) ) {
 636                                 $links[$type] = $disabledTexts[$type];
 637                         } else {
 638                                 $links[$type] = $linkTexts[$type];
 639                         }
 640                 }
 641
 642                 return $links;
 643         }
 644
 645         function getLimitLinks() {
 646                 $links = array();
 647                 if ( $this->mIsBackwards ) {
 648                         $offset = $this->mPastTheEndIndex;
 649                 } else {
 650                         $offset = $this->mOffset;
 651                 }
 652                 foreach ( $this->mLimitsShown as $limit ) {
 653                         $links[] = $this->makeLink(
 654                                 $this->getLanguage()->formatNum( $limit ),
 655                                 array( 'offset' => $offset, 'limit' => $limit ),
 656                                 'num'
 657                         );
 658                 }
 659                 return $links;
 660         }
 661
 662         /**
 663          * Abstract formatting function. This should return an HTML string
 664          * representing the result row $row. Rows will be concatenated and
 665          * returned by getBody()
 666          *
 667          * @param array|stdClass $row Database row
 668          * @return string
 669          */
 670         abstract function formatRow( $row );
 671
 672         /**
 673          * This function should be overridden to provide all parameters
 674          * needed for the main paged query. It returns an associative
 675          * array with the following elements:
 676          *    tables => Table(s) for passing to Database::select()
 677          *    fields => Field(s) for passing to Database::select(), may be *
 678          *    conds => WHERE conditions
 679          *    options => option array
 680          *    join_conds => JOIN conditions
 681          *
 682          * @return array
 683          */
 684         abstract function getQueryInfo();
 685
 686         /**
 687          * This function should be overridden to return the name of the index fi-
 688          * eld.  If the pager supports multiple orders, it may return an array of
 689          * 'querykey' => 'indexfield' pairs, so that a request with &count=querykey
 690          * will use indexfield to sort.  In this case, the first returned key is
 691          * the default.
 692          *
 693          * Needless to say, it's really not a good idea to use a non-unique index
 694          * for this!  That won't page right.
 695          *
 696          * @return string|array
 697          */
 698         abstract function getIndexField();
 699
 700         /**
 701          * This function should be overridden to return the names of secondary columns
 702          * to order by in addition to the column in getIndexField(). These fields will
 703          * not be used in the pager offset or in any links for users.
 704          *
 705          * If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then
 706          * this must return a corresponding array of 'querykey' => array( fields...) pairs
 707          * in order for a request with &count=querykey to use array( fields...) to sort.
 708          *
 709          * This is useful for pagers that GROUP BY a unique column (say page_id)
 710          * and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on
 711          * page_len,page_id avoids temp tables (given a page_len index). This would
 712          * also work if page_id was non-unique but we had a page_len,page_id index.
 713          *
 714          * @return array
 715          */
 716         protected function getExtraSortFields() {
 717                 return array();
 718         }
 719
 720         /**
 721          * Return the default sorting direction: false for ascending, true for
 722          * descending.  You can also have an associative array of ordertype => dir,
 723          * if multiple order types are supported.  In this case getIndexField()
 724          * must return an array, and the keys of that must exactly match the keys
 725          * of this.
 726          *
 727          * For backward compatibility, this method's return value will be ignored
 728          * if $this->mDefaultDirection is already set when the constructor is
 729          * called, for instance if it's statically initialized.  In that case the
 730          * value of that variable (which must be a boolean) will be used.
 731          *
 732          * Note that despite its name, this does not return the value of the
 733          * $this->mDefaultDirection member variable.  That's the default for this
 734          * particular instantiation, which is a single value.  This is the set of
 735          * all defaults for the class.
 736          *
 737          * @return bool
 738          */
 739         protected function getDefaultDirections() {
 740                 return false;
 741         }
 742 }
 743
 744 /**
 745  * IndexPager with an alphabetic list and a formatted navigation bar
 746  * @ingroup Pager
 747  */
 748 abstract class AlphabeticPager extends IndexPager {
 749
 750         /**
 751          * Shamelessly stolen bits from ReverseChronologicalPager,
 752          * didn't want to do class magic as may be still revamped
 753          *
 754          * @return string HTML
 755          */
 756         function getNavigationBar() {
 757                 if ( !$this->isNavigationBarShown() ) {
 758                         return '';
 759                 }
 760
 761                 if ( isset( $this->mNavigationBar ) ) {
 762                         return $this->mNavigationBar;
 763                 }
 764
 765                 $linkTexts = array(
 766                         'prev' => $this->msg( 'prevn' )->numParams( $this->mLimit )->escaped(),
 767                         'next' => $this->msg( 'nextn' )->numParams( $this->mLimit )->escaped(),
 768                         'first' => $this->msg( 'page_first' )->escaped(),
 769                         'last' => $this->msg( 'page_last' )->escaped()
 770                 );
 771
 772                 $lang = $this->getLanguage();
 773
 774                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 775                 $limitLinks = $this->getLimitLinks();
 776                 $limits = $lang->pipeList( $limitLinks );
 777
 778                 $this->mNavigationBar = $this->msg( 'parentheses' )->rawParams(
 779                         $lang->pipeList( array( $pagingLinks['first'],
 780                         $pagingLinks['last'] ) ) )->escaped() . " " .
 781                         $this->msg( 'viewprevnext' )->rawParams( $pagingLinks['prev'],
 782                                 $pagingLinks['next'], $limits )->escaped();
 783
 784                 if ( !is_array( $this->getIndexField() ) ) {
 785                         # Early return to avoid undue nesting
 786                         return $this->mNavigationBar;
 787                 }
 788
 789                 $extra = '';
 790                 $first = true;
 791                 $msgs = $this->getOrderTypeMessages();
 792                 foreach ( array_keys( $msgs ) as $order ) {
 793                         if ( $first ) {
 794                                 $first = false;
 795                         } else {
 796                                 $extra .= $this->msg( 'pipe-separator' )->escaped();
 797                         }
 798
 799                         if ( $order == $this->mOrderType ) {
 800                                 $extra .= $this->msg( $msgs[$order] )->escaped();
 801                         } else {
 802                                 $extra .= $this->makeLink(
 803                                         $this->msg( $msgs[$order] )->escaped(),
 804                                         array( 'order' => $order )
 805                                 );
 806                         }
 807                 }
 808
 809                 if ( $extra !== '' ) {
 810                         $extra = ' ' . $this->msg( 'parentheses' )->rawParams( $extra )->escaped();
 811                         $this->mNavigationBar .= $extra;
 812                 }
 813
 814                 return $this->mNavigationBar;
 815         }
 816
 817         /**
 818          * If this supports multiple order type messages, give the message key for
 819          * enabling each one in getNavigationBar.  The return type is an associative
 820          * array whose keys must exactly match the keys of the array returned
 821          * by getIndexField(), and whose values are message keys.
 822          *
 823          * @return array
 824          */
 825         protected function getOrderTypeMessages() {
 826                 return null;
 827         }
 828 }
 829
 830 /**
 831  * IndexPager with a formatted navigation bar
 832  * @ingroup Pager
 833  */
 834 abstract class ReverseChronologicalPager extends IndexPager {
 835         public $mDefaultDirection = true;
 836         public $mYear;
 837         public $mMonth;
 838
 839         function getNavigationBar() {
 840                 if ( !$this->isNavigationBarShown() ) {
 841                         return '';
 842                 }
 843
 844                 if ( isset( $this->mNavigationBar ) ) {
 845                         return $this->mNavigationBar;
 846                 }
 847
 848                 $linkTexts = array(
 849                         'prev' => $this->msg( 'pager-newer-n' )->numParams( $this->mLimit )->escaped(),
 850                         'next' => $this->msg( 'pager-older-n' )->numParams( $this->mLimit )->escaped(),
 851                         'first' => $this->msg( 'histlast' )->escaped(),
 852                         'last' => $this->msg( 'histfirst' )->escaped()
 853                 );
 854
 855                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 856                 $limitLinks = $this->getLimitLinks();
 857                 $limits = $this->getLanguage()->pipeList( $limitLinks );
 858                 $firstLastLinks = $this->msg( 'parentheses' )->rawParams( "{$pagingLinks['first']}" .
 859                         $this->msg( 'pipe-separator' )->escaped() .
 860                         "{$pagingLinks['last']}" )->escaped();
 861
 862                 $this->mNavigationBar = $firstLastLinks . ' ' .
 863                         $this->msg( 'viewprevnext' )->rawParams(
 864                                 $pagingLinks['prev'], $pagingLinks['next'], $limits )->escaped();
 865
 866                 return $this->mNavigationBar;
 867         }
 868
 869         function getDateCond( $year, $month ) {
 870                 $year = intval( $year );
 871                 $month = intval( $month );
 872
 873                 // Basic validity checks
 874                 $this->mYear = $year > 0 ? $year : false;
 875                 $this->mMonth = ( $month > 0 && $month < 13 ) ? $month : false;
 876
 877                 // Given an optional year and month, we need to generate a timestamp
 878                 // to use as "WHERE rev_timestamp <= result"
 879                 // Examples: year = 2006 equals < 20070101 (+000000)
 880                 // year=2005, month=1    equals < 20050201
 881                 // year=2005, month=12   equals < 20060101
 882                 if ( !$this->mYear && !$this->mMonth ) {
 883                         return;
 884                 }
 885
 886                 if ( $this->mYear ) {
 887                         $year = $this->mYear;
 888                 } else {
 889                         // If no year given, assume the current one
 890                         $timestamp = MWTimestamp::getInstance();
 891                         $year = $timestamp->format( 'Y' );
 892                         // If this month hasn't happened yet this year, go back to last year's month
 893                         if ( $this->mMonth > $timestamp->format( 'n' ) ) {
 894                                 $year--;
 895                         }
 896                 }
 897
 898                 if ( $this->mMonth ) {
 899                         $month = $this->mMonth + 1;
 900                         // For December, we want January 1 of the next year
 901                         if ( $month > 12 ) {
 902                                 $month = 1;
 903                                 $year++;
 904                         }
 905                 } else {
 906                         // No month implies we want up to the end of the year in question
 907                         $month = 1;
 908                         $year++;
 909                 }
 910
 911                 // Y2K38 bug
 912                 if ( $year > 2032 ) {
 913                         $year = 2032;
 914                 }
 915
 916                 $ymd = (int)sprintf( "%04d%02d01", $year, $month );
 917
 918                 if ( $ymd > 20320101 ) {
 919                         $ymd = 20320101;
 920                 }
 921
 922                 $this->mOffset = $this->mDb->timestamp( "${ymd}000000" );
 923         }
 924 }
 925
 926 /**
 927  * Table-based display with a user-selectable sort order
 928  * @ingroup Pager
 929  */
 930 abstract class TablePager extends IndexPager {
 931         protected $mSort;
 932
 933         protected $mCurrentRow;
 934
 935         public function __construct( IContextSource $context = null ) {
 936                 if ( $context ) {
 937                         $this->setContext( $context );
 938                 }
 939
 940                 $this->mSort = $this->getRequest()->getText( 'sort' );
 941                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() )
 942                         || !$this->isFieldSortable( $this->mSort )
 943                 ) {
 944                         $this->mSort = $this->getDefaultSort();
 945                 }
 946                 if ( $this->getRequest()->getBool( 'asc' ) ) {
 947                         $this->mDefaultDirection = false;
 948                 } elseif ( $this->getRequest()->getBool( 'desc' ) ) {
 949                         $this->mDefaultDirection = true;
 950                 } /* Else leave it at whatever the class default is */
 951
 952                 parent::__construct();
 953         }
 954
 955         /**
 956          * @protected
 957          * @return string
 958          */
 959         function getStartBody() {
 960                 global $wgStylePath;
 961                 $sortClass = $this->getSortHeaderClass();
 962
 963                 $s = '';
 964                 $fields = $this->getFieldNames();
 965
 966                 # Make table header
 967                 foreach ( $fields as $field => $name ) {
 968                         if ( strval( $name ) == '' ) {
 969                                 $s .= Html::rawElement( 'th', array(), '&#160;' ) . "\n";
 970                         } elseif ( $this->isFieldSortable( $field ) ) {
 971                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 972                                 if ( $field == $this->mSort ) {
 973                                         # This is the sorted column
 974                                         # Prepare a link that goes in the other sort order
 975                                         if ( $this->mDefaultDirection ) {
 976                                                 # Descending
 977                                                 $image = 'Arr_d.png';
 978                                                 $query['asc'] = '1';
 979                                                 $query['desc'] = '';
 980                                                 $alt = $this->msg( 'descending_abbrev' )->escaped();
 981                                         } else {
 982                                                 # Ascending
 983                                                 $image = 'Arr_u.png';
 984                                                 $query['asc'] = '';
 985                                                 $query['desc'] = '1';
 986                                                 $alt = $this->msg( 'ascending_abbrev' )->escaped();
 987                                         }
 988                                         $image = "$wgStylePath/common/images/$image";
 989                                         $link = $this->makeLink(
 990                                                 Html::element( 'img', array( 'width' => 12, 'height' => 12,
 991                                                         'alt' => $alt, 'src' => $image ) ) . htmlspecialchars( $name ), $query );
 992                                         $s .= Html::rawElement( 'th', array( 'class' => $sortClass ), $link ) . "\n";
 993                                 } else {
 994                                         $s .= Html::rawElement( 'th', array(),
 995                                                 $this->makeLink( htmlspecialchars( $name ), $query ) ) . "\n";
 996                                 }
 997                         } else {
 998                                 $s .= Html::element( 'th', array(), $name ) . "\n";
 999                         }
1000                 }
1001
1002                 $tableClass = $this->getTableClass();
1003                 $ret = Html::openElement( 'table', array(
1004                         'style' => 'border:1px;',
1005                         'class' => "mw-datatable $tableClass" )
1006                 );
1007                 $ret .= Html::rawElement( 'thead', array(), Html::rawElement( 'tr', array(), "\n" . $s . "\n" ) );
1008                 $ret .= Html::openElement( 'tbody' ) . "\n";
1009
1010                 return $ret;
1011         }
1012
1013         /**
1014          * @protected
1015          * @return string
1016          */
1017         function getEndBody() {
1018                 return "</tbody></table>\n";
1019         }
1020
1021         /**
1022          * @protected
1023          * @return string
1024          */
1025         function getEmptyBody() {
1026                 $colspan = count( $this->getFieldNames() );
1027                 $msgEmpty = $this->msg( 'table_pager_empty' )->text();
1028                 return Html::rawElement( 'tr', array(),
1029                         Html::element( 'td', array( 'colspan' => $colspan ), $msgEmpty ) );
1030         }
1031
1032         /**
1033          * @protected
1034          * @param stdClass $row
1035          * @return string HTML
1036          */
1037         function formatRow( $row ) {
1038                 $this->mCurrentRow = $row; // In case formatValue etc need to know
1039                 $s = Html::openElement( 'tr', $this->getRowAttrs( $row ) ) . "\n";
1040                 $fieldNames = $this->getFieldNames();
1041
1042                 foreach ( $fieldNames as $field => $name ) {
1043                         $value = isset( $row->$field ) ? $row->$field : null;
1044                         $formatted = strval( $this->formatValue( $field, $value ) );
1045
1046                         if ( $formatted == '' ) {
1047                                 $formatted = '&#160;';
1048                         }
1049
1050                         $s .= Html::rawElement( 'td', $this->getCellAttrs( $field, $value ), $formatted ) . "\n";
1051                 }
1052
1053                 $s .= Html::closeElement( 'tr' ) . "\n";
1054
1055                 return $s;
1056         }
1057
1058         /**
1059          * Get a class name to be applied to the given row.
1060          *
1061          * @protected
1062          *
1063          * @param object $row The database result row
1064          * @return string
1065          */
1066         function getRowClass( $row ) {
1067                 return '';
1068         }
1069
1070         /**
1071          * Get attributes to be applied to the given row.
1072          *
1073          * @protected
1074          *
1075          * @param object $row The database result row
1076          * @return array Array of attribute => value
1077          */
1078         function getRowAttrs( $row ) {
1079                 $class = $this->getRowClass( $row );
1080                 if ( $class === '' ) {
1081                         // Return an empty array to avoid clutter in HTML like class=""
1082                         return array();
1083                 } else {
1084                         return array( 'class' => $this->getRowClass( $row ) );
1085                 }
1086         }
1087
1088         /**
1089          * Get any extra attributes to be applied to the given cell. Don't
1090          * take this as an excuse to hardcode styles; use classes and
1091          * CSS instead.  Row context is available in $this->mCurrentRow
1092          *
1093          * @protected
1094          *
1095          * @param string $field The column
1096          * @param string $value The cell contents
1097          * @return array Array of attr => value
1098          */
1099         function getCellAttrs( $field, $value ) {
1100                 return array( 'class' => 'TablePager_col_' . $field );
1101         }
1102
1103         /**
1104          * @protected
1105          * @return string
1106          */
1107         function getIndexField() {
1108                 return $this->mSort;
1109         }
1110
1111         /**
1112          * @protected
1113          * @return string
1114          */
1115         function getTableClass() {
1116                 return 'TablePager';
1117         }
1118
1119         /**
1120          * @protected
1121          * @return string
1122          */
1123         function getNavClass() {
1124                 return 'TablePager_nav';
1125         }
1126
1127         /**
1128          * @protected
1129          * @return string
1130          */
1131         function getSortHeaderClass() {
1132                 return 'TablePager_sort';
1133         }
1134
1135         /**
1136          * A navigation bar with images
1137          * @return string HTML
1138          */
1139         public function getNavigationBar() {
1140                 global $wgStylePath;
1141
1142                 if ( !$this->isNavigationBarShown() ) {
1143                         return '';
1144                 }
1145
1146                 $path = "$wgStylePath/common/images";
1147                 $labels = array(
1148                         'first' => 'table_pager_first',
1149                         'prev' => 'table_pager_prev',
1150                         'next' => 'table_pager_next',
1151                         'last' => 'table_pager_last',
1152                 );
1153                 $images = array(
1154                         'first' => 'arrow_first_25.png',
1155                         'prev' => 'arrow_left_25.png',
1156                         'next' => 'arrow_right_25.png',
1157                         'last' => 'arrow_last_25.png',
1158                 );
1159                 $disabledImages = array(
1160                         'first' => 'arrow_disabled_first_25.png',
1161                         'prev' => 'arrow_disabled_left_25.png',
1162                         'next' => 'arrow_disabled_right_25.png',
1163                         'last' => 'arrow_disabled_last_25.png',
1164                 );
1165                 if ( $this->getLanguage()->isRTL() ) {
1166                         $keys = array_keys( $labels );
1167                         $images = array_combine( $keys, array_reverse( $images ) );
1168                         $disabledImages = array_combine( $keys, array_reverse( $disabledImages ) );
1169                 }
1170
1171                 $linkTexts = array();
1172                 $disabledTexts = array();
1173                 foreach ( $labels as $type => $label ) {
1174                         $msgLabel = $this->msg( $label )->escaped();
1175                         $linkTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$images[$type]}",
1176                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1177                         $disabledTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$disabledImages[$type]}",
1178                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1179                 }
1180                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
1181
1182                 $s = Html::openElement( 'table', array( 'class' => $this->getNavClass() ) );
1183                 $s .= Html::openElement( 'tr' ) . "\n";
1184                 $width = 100 / count( $links ) . '%';
1185                 foreach ( $labels as $type => $label ) {
1186                         $s .= Html::rawElement( 'td', array( 'style' => "width:$width;" ), $links[$type] ) . "\n";
1187                 }
1188                 $s .= Html::closeElement( 'tr' ) . Html::closeElement( 'table' ) . "\n";
1189                 return $s;
1190         }
1191
1192         /**
1193          * Get a "<select>" element which has options for each of the allowed limits
1194          *
1195          * @param string $attribs Extra attributes to set
1196          * @return string HTML fragment
1197          */
1198         public function getLimitSelect( $attribs = array() ) {
1199                 $select = new XmlSelect( 'limit', false, $this->mLimit );
1200                 $select->addOptions( $this->getLimitSelectList() );
1201                 foreach ( $attribs as $name => $value ) {
1202                         $select->setAttribute( $name, $value );
1203                 }
1204                 return $select->getHTML();
1205         }
1206
1207         /**
1208          * Get a list of items to show in a "<select>" element of limits.
1209          * This can be passed directly to XmlSelect::addOptions().
1210          *
1211          * @since 1.22
1212          * @return array
1213          */
1214         public function getLimitSelectList() {
1215                 # Add the current limit from the query string
1216                 # to avoid that the limit is lost after clicking Go next time
1217                 if ( !in_array( $this->mLimit, $this->mLimitsShown ) ) {
1218                         $this->mLimitsShown[] = $this->mLimit;
1219                         sort( $this->mLimitsShown );
1220                 }
1221                 $ret = array();
1222                 foreach ( $this->mLimitsShown as $key => $value ) {
1223                         # The pair is either $index => $limit, in which case the $value
1224                         # will be numeric, or $limit => $text, in which case the $value
1225                         # will be a string.
1226                         if ( is_int( $value ) ) {
1227                                 $limit = $value;
1228                                 $text = $this->getLanguage()->formatNum( $limit );
1229                         } else {
1230                                 $limit = $key;
1231                                 $text = $value;
1232                         }
1233                         $ret[$text] = $limit;
1234                 }
1235                 return $ret;
1236         }
1237
1238         /**
1239          * Get \<input type="hidden"\> elements for use in a method="get" form.
1240          * Resubmits all defined elements of the query string, except for a
1241          * blacklist, passed in the $blacklist parameter.
1242          *
1243          * @param array $blacklist Parameters from the request query which should not be resubmitted
1244          * @return string HTML fragment
1245          */
1246         function getHiddenFields( $blacklist = array() ) {
1247                 $blacklist = (array)$blacklist;
1248                 $query = $this->getRequest()->getQueryValues();
1249                 foreach ( $blacklist as $name ) {
1250                         unset( $query[$name] );
1251                 }
1252                 $s = '';
1253                 foreach ( $query as $name => $value ) {
1254                         $s .= Html::hidden( $name, $value ) . "\n";
1255                 }
1256                 return $s;
1257         }
1258
1259         /**
1260          * Get a form containing a limit selection dropdown
1261          *
1262          * @return string HTML fragment
1263          */
1264         function getLimitForm() {
1265                 global $wgScript;
1266
1267                 return Html::rawElement(
1268                         'form',
1269                         array(
1270                                 'method' => 'get',
1271                                 'action' => $wgScript
1272                         ),
1273                         "\n" . $this->getLimitDropdown()
1274                 ) . "\n";
1275         }
1276
1277         /**
1278          * Gets a limit selection dropdown
1279          *
1280          * @return string
1281          */
1282         function getLimitDropdown() {
1283                 # Make the select with some explanatory text
1284                 $msgSubmit = $this->msg( 'table_pager_limit_submit' )->escaped();
1285
1286                 return $this->msg( 'table_pager_limit' )
1287                         ->rawParams( $this->getLimitSelect() )->escaped() .
1288                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
1289                         $this->getHiddenFields( array( 'limit' ) );
1290         }
1291
1292         /**
1293          * Return true if the named field should be sortable by the UI, false
1294          * otherwise
1295          *
1296          * @param string $field
1297          */
1298         abstract function isFieldSortable( $field );
1299
1300         /**
1301          * Format a table cell. The return value should be HTML, but use an empty
1302          * string not &#160; for empty cells. Do not include the <td> and </td>.
1303          *
1304          * The current result row is available as $this->mCurrentRow, in case you
1305          * need more context.
1306          *
1307          * @protected
1308          *
1309          * @param string $name The database field name
1310          * @param string $value The value retrieved from the database
1311          */
1312         abstract function formatValue( $name, $value );
1313
1314         /**
1315          * The database field name used as a default sort order.
1316          *
1317          * @protected
1318          *
1319          * @return string
1320          */
1321         abstract function getDefaultSort();
1322
1323         /**
1324          * An array mapping database field names to a textual description of the
1325          * field name, for use in the table header. The description should be plain
1326          * text, it will be HTML-escaped later.
1327          *
1328          * @return array
1329          */
1330         abstract function getFieldNames();
1331 }