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