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