includes/Pager.php

   1 <?php
   2 /**
   3  * Efficient paging for SQL queries.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Pager
  22  */
  23
  24 /**
  25  * @defgroup Pager Pager
  26  */
  27
  28 /**
  29  * Basic pager interface.
  30  * @ingroup Pager
  31  */
  32 interface Pager {
  33         function getNavigationBar();
  34         function getBody();
  35 }
  36
  37 /**
  38  * IndexPager is an efficient pager which uses a (roughly unique) index in the
  39  * data set to implement paging, rather than a "LIMIT offset,limit" clause.
  40  * In MySQL, such a limit/offset clause requires counting through the
  41  * specified number of offset rows to find the desired data, which can be
  42  * expensive for large offsets.
  43  *
  44  * ReverseChronologicalPager is a child class of the abstract IndexPager, and
  45  * contains  some formatting and display code which is specific to the use of
  46  * timestamps as  indexes. Here is a synopsis of its operation:
  47  *
  48  *    * The query is specified by the offset, limit and direction (dir)
  49  *      parameters, in addition to any subclass-specific parameters.
  50  *    * The offset is the non-inclusive start of the DB query. A row with an
  51  *      index value equal to the offset will never be shown.
  52  *    * The query may either be done backwards, where the rows are returned by
  53  *      the database in the opposite order to which they are displayed to the
  54  *      user, or forwards. This is specified by the "dir" parameter, dir=prev
  55  *      means backwards, anything else means forwards. The offset value
  56  *      specifies the start of the database result set, which may be either
  57  *      the start or end of the displayed data set. This allows "previous"
  58  *      links to be implemented without knowledge of the index value at the
  59  *      start of the previous page.
  60  *    * An additional row beyond the user-specified limit is always requested.
  61  *      This allows us to tell whether we should display a "next" link in the
  62  *      case of forwards mode, or a "previous" link in the case of backwards
  63  *      mode. Determining whether to display the other link (the one for the
  64  *      page before the start of the database result set) can be done
  65  *      heuristically by examining the offset.
  66  *
  67  *    * An empty offset indicates that the offset condition should be omitted
  68  *      from the query. This naturally produces either the first page or the
  69  *      last page depending on the dir parameter.
  70  *
  71  *  Subclassing the pager to implement concrete functionality should be fairly
  72  *  simple, please see the examples in HistoryPage.php and
  73  *  SpecialBlockList.php. You just need to override formatRow(),
  74  *  getQueryInfo() and getIndexField(). Don't forget to call the parent
  75  *  constructor if you override it.
  76  *
  77  * @ingroup Pager
  78  */
  79 abstract class IndexPager extends ContextSource implements Pager {
  80         public $mRequest;
  81         public $mLimitsShown = array( 20, 50, 100, 250, 500 );
  82         public $mDefaultLimit = 50;
  83         public $mOffset, $mLimit;
  84         public $mQueryDone = false;
  85         public $mDb;
  86         public $mPastTheEndRow;
  87
  88         /**
  89          * The index to actually be used for ordering. This is a single column,
  90          * for one ordering, even if multiple orderings are supported.
  91          */
  92         protected $mIndexField;
  93         /**
  94          * An array of secondary columns to order by. These fields are not part of the offset.
  95          * This is a column list for one ordering, even if multiple orderings are supported.
  96          */
  97         protected $mExtraSortFields;
  98         /** For pages that support multiple types of ordering, which one to use.
  99          */
 100         protected $mOrderType;
 101         /**
 102          * $mDefaultDirection gives the direction to use when sorting results:
 103          * false for ascending, true for descending.  If $mIsBackwards is set, we
 104          * start from the opposite end, but we still sort the page itself according
 105          * to $mDefaultDirection.  E.g., if $mDefaultDirection is false but we're
 106          * going backwards, we'll display the last page of results, but the last
 107          * result will be at the bottom, not the top.
 108          *
 109          * Like $mIndexField, $mDefaultDirection will be a single value even if the
 110          * class supports multiple default directions for different order types.
 111          */
 112         public $mDefaultDirection;
 113         public $mIsBackwards;
 114
 115         /** True if the current result set is the first one */
 116         public $mIsFirst;
 117         public $mIsLast;
 118
 119         protected $mLastShown, $mFirstShown, $mPastTheEndIndex, $mDefaultQuery, $mNavigationBar;
 120
 121         /**
 122          * Whether to include the offset in the query
 123          */
 124         protected $mIncludeOffset = false;
 125
 126         /**
 127          * Result object for the query. Warning: seek before use.
 128          *
 129          * @var ResultWrapper
 130          */
 131         public $mResult;
 132
 133         public function __construct( IContextSource $context = null ) {
 134                 if ( $context ) {
 135                         $this->setContext( $context );
 136                 }
 137
 138                 $this->mRequest = $this->getRequest();
 139
 140                 # NB: the offset is quoted, not validated. It is treated as an
 141                 # arbitrary string to support the widest variety of index types. Be
 142                 # careful outputting it into HTML!
 143                 $this->mOffset = $this->mRequest->getText( 'offset' );
 144
 145                 # Use consistent behavior for the limit options
 146                 $this->mDefaultLimit = $this->getUser()->getIntOption( 'rclimit' );
 147                 if ( !$this->mLimit ) {
 148                         // Don't override if a subclass calls $this->setLimit() in its constructor.
 149                         list( $this->mLimit, /* $offset */ ) = $this->mRequest->getLimitOffset();
 150                 }
 151
 152                 $this->mIsBackwards = ( $this->mRequest->getVal( 'dir' ) == 'prev' );
 153                 $this->mDb = wfGetDB( DB_SLAVE );
 154
 155                 $index = $this->getIndexField(); // column to sort on
 156                 $extraSort = $this->getExtraSortFields(); // extra columns to sort on for query planning
 157                 $order = $this->mRequest->getVal( 'order' );
 158                 if ( is_array( $index ) && isset( $index[$order] ) ) {
 159                         $this->mOrderType = $order;
 160                         $this->mIndexField = $index[$order];
 161                         $this->mExtraSortFields = isset( $extraSort[$order] )
 162                                 ? (array)$extraSort[$order]
 163                                 : array();
 164                 } elseif ( is_array( $index ) ) {
 165                         # First element is the default
 166                         reset( $index );
 167                         list( $this->mOrderType, $this->mIndexField ) = each( $index );
 168                         $this->mExtraSortFields = isset( $extraSort[$this->mOrderType] )
 169                                 ? (array)$extraSort[$this->mOrderType]
 170                                 : array();
 171                 } else {
 172                         # $index is not an array
 173                         $this->mOrderType = null;
 174                         $this->mIndexField = $index;
 175                         $this->mExtraSortFields = (array)$extraSort;
 176                 }
 177
 178                 if ( !isset( $this->mDefaultDirection ) ) {
 179                         $dir = $this->getDefaultDirections();
 180                         $this->mDefaultDirection = is_array( $dir )
 181                                 ? $dir[$this->mOrderType]
 182                                 : $dir;
 183                 }
 184         }
 185
 186         /**
 187          * Get the Database object in use
 188          *
 189          * @return DatabaseBase
 190          */
 191         public function getDatabase() {
 192                 return $this->mDb;
 193         }
 194
 195         /**
 196          * Do the query, using information from the object context. This function
 197          * has been kept minimal to make it overridable if necessary, to allow for
 198          * result sets formed from multiple DB queries.
 199          */
 200         public function doQuery() {
 201                 # Use the child class name for profiling
 202                 $fname = __METHOD__ . ' (' . get_class( $this ) . ')';
 203                 wfProfileIn( $fname );
 204
 205                 $descending = ( $this->mIsBackwards == $this->mDefaultDirection );
 206                 # Plus an extra row so that we can tell the "next" link should be shown
 207                 $queryLimit = $this->mLimit + 1;
 208
 209                 if ( $this->mOffset == '' ) {
 210                         $isFirst = true;
 211                 } else {
 212                         // If there's an offset, we may or may not be at the first entry.
 213                         // The only way to tell is to run the query in the opposite
 214                         // direction see if we get a row.
 215                         $oldIncludeOffset = $this->mIncludeOffset;
 216                         $this->mIncludeOffset = !$this->mIncludeOffset;
 217                         $isFirst = !$this->reallyDoQuery( $this->mOffset, 1, !$descending )->numRows();
 218                         $this->mIncludeOffset = $oldIncludeOffset;
 219                 }
 220
 221                 $this->mResult = $this->reallyDoQuery(
 222                         $this->mOffset,
 223                         $queryLimit,
 224                         $descending
 225                 );
 226
 227                 $this->extractResultInfo( $isFirst, $queryLimit, $this->mResult );
 228                 $this->mQueryDone = true;
 229
 230                 $this->preprocessResults( $this->mResult );
 231                 $this->mResult->rewind(); // Paranoia
 232
 233                 wfProfileOut( $fname );
 234         }
 235
 236         /**
 237          * @return ResultWrapper The result wrapper.
 238          */
 239         function getResult() {
 240                 return $this->mResult;
 241         }
 242
 243         /**
 244          * Set the offset from an other source than the request
 245          *
 246          * @param $offset Int|String
 247          */
 248         function setOffset( $offset ) {
 249                 $this->mOffset = $offset;
 250         }
 251         /**
 252          * Set the limit from an other source than the request
 253          *
 254          * Verifies limit is between 1 and 5000
 255          *
 256          * @param $limit Int|String
 257          */
 258         function setLimit( $limit ) {
 259                 $limit = (int) $limit;
 260                 // WebRequest::getLimitOffset() puts a cap of 5000, so do same here.
 261                 if ( $limit > 5000 ) {
 262                         $limit = 5000;
 263                 }
 264                 if ( $limit > 0 ) {
 265                         $this->mLimit = $limit;
 266                 }
 267         }
 268
 269         /**
 270          * Set whether a row matching exactly the offset should be also included
 271          * in the result or not. By default this is not the case, but when the
 272          * offset is user-supplied this might be wanted.
 273          *
 274          * @param $include bool
 275          */
 276         public function setIncludeOffset( $include ) {
 277                 $this->mIncludeOffset = $include;
 278         }
 279
 280         /**
 281          * Extract some useful data from the result object for use by
 282          * the navigation bar, put it into $this
 283          *
 284          * @param $isFirst bool: False if there are rows before those fetched (i.e.
 285          *     if a "previous" link would make sense)
 286          * @param $limit Integer: exact query limit
 287          * @param $res ResultWrapper
 288          */
 289         function extractResultInfo( $isFirst, $limit, ResultWrapper $res ) {
 290                 $numRows = $res->numRows();
 291                 if ( $numRows ) {
 292                         # Remove any table prefix from index field
 293                         $parts = explode( '.', $this->mIndexField );
 294                         $indexColumn = end( $parts );
 295
 296                         $row = $res->fetchRow();
 297                         $firstIndex = $row[$indexColumn];
 298
 299                         # Discard the extra result row if there is one
 300                         if ( $numRows > $this->mLimit && $numRows > 1 ) {
 301                                 $res->seek( $numRows - 1 );
 302                                 $this->mPastTheEndRow = $res->fetchObject();
 303                                 $this->mPastTheEndIndex = $this->mPastTheEndRow->$indexColumn;
 304                                 $res->seek( $numRows - 2 );
 305                                 $row = $res->fetchRow();
 306                                 $lastIndex = $row[$indexColumn];
 307                         } else {
 308                                 $this->mPastTheEndRow = null;
 309                                 # Setting indexes to an empty string means that they will be
 310                                 # omitted if they would otherwise appear in URLs. It just so
 311                                 # happens that this  is the right thing to do in the standard
 312                                 # UI, in all the relevant cases.
 313                                 $this->mPastTheEndIndex = '';
 314                                 $res->seek( $numRows - 1 );
 315                                 $row = $res->fetchRow();
 316                                 $lastIndex = $row[$indexColumn];
 317                         }
 318                 } else {
 319                         $firstIndex = '';
 320                         $lastIndex = '';
 321                         $this->mPastTheEndRow = null;
 322                         $this->mPastTheEndIndex = '';
 323                 }
 324
 325                 if ( $this->mIsBackwards ) {
 326                         $this->mIsFirst = ( $numRows < $limit );
 327                         $this->mIsLast = $isFirst;
 328                         $this->mLastShown = $firstIndex;
 329                         $this->mFirstShown = $lastIndex;
 330                 } else {
 331                         $this->mIsFirst = $isFirst;
 332                         $this->mIsLast = ( $numRows < $limit );
 333                         $this->mLastShown = $lastIndex;
 334                         $this->mFirstShown = $firstIndex;
 335                 }
 336         }
 337
 338         /**
 339          * Get some text to go in brackets in the "function name" part of the SQL comment
 340          *
 341          * @return String
 342          */
 343         function getSqlComment() {
 344                 return get_class( $this );
 345         }
 346
 347         /**
 348          * Do a query with specified parameters, rather than using the object
 349          * context
 350          *
 351          * @param string $offset index offset, inclusive
 352          * @param $limit Integer: exact query limit
 353          * @param $descending Boolean: query direction, false for ascending, true for descending
 354          * @return ResultWrapper
 355          */
 356         public function reallyDoQuery( $offset, $limit, $descending ) {
 357                 list( $tables, $fields, $conds, $fname, $options, $join_conds ) = $this->buildQueryInfo( $offset, $limit, $descending );
 358                 return $this->mDb->select( $tables, $fields, $conds, $fname, $options, $join_conds );
 359         }
 360
 361         /**
 362          * Build variables to use by the database wrapper.
 363          *
 364          * @param string $offset index offset, inclusive
 365          * @param $limit Integer: exact query limit
 366          * @param $descending Boolean: query direction, false for ascending, true for descending
 367          * @return array
 368          */
 369         protected function buildQueryInfo( $offset, $limit, $descending ) {
 370                 $fname = __METHOD__ . ' (' . $this->getSqlComment() . ')';
 371                 $info = $this->getQueryInfo();
 372                 $tables = $info['tables'];
 373                 $fields = $info['fields'];
 374                 $conds = isset( $info['conds'] ) ? $info['conds'] : array();
 375                 $options = isset( $info['options'] ) ? $info['options'] : array();
 376                 $join_conds = isset( $info['join_conds'] ) ? $info['join_conds'] : array();
 377                 $sortColumns = array_merge( array( $this->mIndexField ), $this->mExtraSortFields );
 378                 if ( $descending ) {
 379                         $options['ORDER BY'] = $sortColumns;
 380                         $operator = $this->mIncludeOffset ? '>=' : '>';
 381                 } else {
 382                         $orderBy = array();
 383                         foreach ( $sortColumns as $col ) {
 384                                 $orderBy[] = $col . ' DESC';
 385                         }
 386                         $options['ORDER BY'] = $orderBy;
 387                         $operator = $this->mIncludeOffset ? '<=' : '<';
 388                 }
 389                 if ( $offset != '' ) {
 390                         $conds[] = $this->mIndexField . $operator . $this->mDb->addQuotes( $offset );
 391                 }
 392                 $options['LIMIT'] = intval( $limit );
 393                 return array( $tables, $fields, $conds, $fname, $options, $join_conds );
 394         }
 395
 396         /**
 397          * Pre-process results; useful for performing batch existence checks, etc.
 398          *
 399          * @param $result ResultWrapper
 400          */
 401         protected function preprocessResults( $result ) {}
 402
 403         /**
 404          * Get the formatted result list. Calls getStartBody(), formatRow() and
 405          * getEndBody(), concatenates the results and returns them.
 406          *
 407          * @return String
 408          */
 409         public function getBody() {
 410                 if ( !$this->mQueryDone ) {
 411                         $this->doQuery();
 412                 }
 413
 414                 if ( $this->mResult->numRows() ) {
 415                         # Do any special query batches before display
 416                         $this->doBatchLookups();
 417                 }
 418
 419                 # Don't use any extra rows returned by the query
 420                 $numRows = min( $this->mResult->numRows(), $this->mLimit );
 421
 422                 $s = $this->getStartBody();
 423                 if ( $numRows ) {
 424                         if ( $this->mIsBackwards ) {
 425                                 for ( $i = $numRows - 1; $i >= 0; $i-- ) {
 426                                         $this->mResult->seek( $i );
 427                                         $row = $this->mResult->fetchObject();
 428                                         $s .= $this->formatRow( $row );
 429                                 }
 430                         } else {
 431                                 $this->mResult->seek( 0 );
 432                                 for ( $i = 0; $i < $numRows; $i++ ) {
 433                                         $row = $this->mResult->fetchObject();
 434                                         $s .= $this->formatRow( $row );
 435                                 }
 436                         }
 437                 } else {
 438                         $s .= $this->getEmptyBody();
 439                 }
 440                 $s .= $this->getEndBody();
 441                 return $s;
 442         }
 443
 444         /**
 445          * Make a self-link
 446          *
 447          * @param string $text text displayed on the link
 448          * @param array $query associative array of parameter to be in the query string
 449          * @param string $type value of the "rel" attribute
 450          *
 451          * @return String: HTML fragment
 452          */
 453         function makeLink( $text, array $query = null, $type = null ) {
 454                 if ( $query === null ) {
 455                         return $text;
 456                 }
 457
 458                 $attrs = array();
 459                 if ( in_array( $type, array( 'first', 'prev', 'next', 'last' ) ) ) {
 460                         # HTML5 rel attributes
 461                         $attrs['rel'] = $type;
 462                 }
 463
 464                 if ( $type ) {
 465                         $attrs['class'] = "mw-{$type}link";
 466                 }
 467
 468                 return Linker::linkKnown(
 469                         $this->getTitle(),
 470                         $text,
 471                         $attrs,
 472                         $query + $this->getDefaultQuery()
 473                 );
 474         }
 475
 476         /**
 477          * Called from getBody(), before getStartBody() is called and
 478          * after doQuery() was called. This will be called only if there
 479          * are rows in the result set.
 480          *
 481          * @return void
 482          */
 483         protected function doBatchLookups() {}
 484
 485         /**
 486          * Hook into getBody(), allows text to be inserted at the start. This
 487          * will be called even if there are no rows in the result set.
 488          *
 489          * @return String
 490          */
 491         protected function getStartBody() {
 492                 return '';
 493         }
 494
 495         /**
 496          * Hook into getBody() for the end of the list
 497          *
 498          * @return String
 499          */
 500         protected function getEndBody() {
 501                 return '';
 502         }
 503
 504         /**
 505          * Hook into getBody(), for the bit between the start and the
 506          * end when there are no rows
 507          *
 508          * @return String
 509          */
 510         protected function getEmptyBody() {
 511                 return '';
 512         }
 513
 514         /**
 515          * Get an array of query parameters that should be put into self-links.
 516          * By default, all parameters passed in the URL are used, except for a
 517          * short blacklist.
 518          *
 519          * @return array Associative array
 520          */
 521         function getDefaultQuery() {
 522                 if ( !isset( $this->mDefaultQuery ) ) {
 523                         $this->mDefaultQuery = $this->getRequest()->getQueryValues();
 524                         unset( $this->mDefaultQuery['title'] );
 525                         unset( $this->mDefaultQuery['dir'] );
 526                         unset( $this->mDefaultQuery['offset'] );
 527                         unset( $this->mDefaultQuery['limit'] );
 528                         unset( $this->mDefaultQuery['order'] );
 529                         unset( $this->mDefaultQuery['month'] );
 530                         unset( $this->mDefaultQuery['year'] );
 531                 }
 532                 return $this->mDefaultQuery;
 533         }
 534
 535         /**
 536          * Get the number of rows in the result set
 537          *
 538          * @return Integer
 539          */
 540         function getNumRows() {
 541                 if ( !$this->mQueryDone ) {
 542                         $this->doQuery();
 543                 }
 544                 return $this->mResult->numRows();
 545         }
 546
 547         /**
 548          * Get a URL query array for the prev, next, first and last links.
 549          *
 550          * @return Array
 551          */
 552         function getPagingQueries() {
 553                 if ( !$this->mQueryDone ) {
 554                         $this->doQuery();
 555                 }
 556
 557                 # Don't announce the limit everywhere if it's the default
 558                 $urlLimit = $this->mLimit == $this->mDefaultLimit ? null : $this->mLimit;
 559
 560                 if ( $this->mIsFirst ) {
 561                         $prev = false;
 562                         $first = false;
 563                 } else {
 564                         $prev = array(
 565                                 'dir' => 'prev',
 566                                 'offset' => $this->mFirstShown,
 567                                 'limit' => $urlLimit
 568                         );
 569                         $first = array( 'limit' => $urlLimit );
 570                 }
 571                 if ( $this->mIsLast ) {
 572                         $next = false;
 573                         $last = false;
 574                 } else {
 575                         $next = array( 'offset' => $this->mLastShown, 'limit' => $urlLimit );
 576                         $last = array( 'dir' => 'prev', 'limit' => $urlLimit );
 577                 }
 578                 return array(
 579                         'prev' => $prev,
 580                         'next' => $next,
 581                         'first' => $first,
 582                         'last' => $last
 583                 );
 584         }
 585
 586         /**
 587          * Returns whether to show the "navigation bar"
 588          *
 589          * @return Boolean
 590          */
 591         function isNavigationBarShown() {
 592                 if ( !$this->mQueryDone ) {
 593                         $this->doQuery();
 594                 }
 595                 // Hide navigation by default if there is nothing to page
 596                 return !( $this->mIsFirst && $this->mIsLast );
 597         }
 598
 599         /**
 600          * Get paging links. If a link is disabled, the item from $disabledTexts
 601          * will be used. If there is no such item, the unlinked text from
 602          * $linkTexts will be used. Both $linkTexts and $disabledTexts are arrays
 603          * of HTML.
 604          *
 605          * @param $linkTexts Array
 606          * @param $disabledTexts Array
 607          * @return Array
 608          */
 609         function getPagingLinks( $linkTexts, $disabledTexts = array() ) {
 610                 $queries = $this->getPagingQueries();
 611                 $links = array();
 612
 613                 foreach ( $queries as $type => $query ) {
 614                         if ( $query !== false ) {
 615                                 $links[$type] = $this->makeLink(
 616                                         $linkTexts[$type],
 617                                         $queries[$type],
 618                                         $type
 619                                 );
 620                         } elseif ( isset( $disabledTexts[$type] ) ) {
 621                                 $links[$type] = $disabledTexts[$type];
 622                         } else {
 623                                 $links[$type] = $linkTexts[$type];
 624                         }
 625                 }
 626
 627                 return $links;
 628         }
 629
 630         function getLimitLinks() {
 631                 $links = array();
 632                 if ( $this->mIsBackwards ) {
 633                         $offset = $this->mPastTheEndIndex;
 634                 } else {
 635                         $offset = $this->mOffset;
 636                 }
 637                 foreach ( $this->mLimitsShown as $limit ) {
 638                         $links[] = $this->makeLink(
 639                                 $this->getLanguage()->formatNum( $limit ),
 640                                 array( 'offset' => $offset, 'limit' => $limit ),
 641                                 'num'
 642                         );
 643                 }
 644                 return $links;
 645         }
 646
 647         /**
 648          * Abstract formatting function. This should return an HTML string
 649          * representing the result row $row. Rows will be concatenated and
 650          * returned by getBody()
 651          *
 652          * @param $row Object: database row
 653          * @return String
 654          */
 655         abstract function formatRow( $row );
 656
 657         /**
 658          * This function should be overridden to provide all parameters
 659          * needed for the main paged query. It returns an associative
 660          * array with the following elements:
 661          *    tables => Table(s) for passing to Database::select()
 662          *    fields => Field(s) for passing to Database::select(), may be *
 663          *    conds => WHERE conditions
 664          *    options => option array
 665          *    join_conds => JOIN conditions
 666          *
 667          * @return Array
 668          */
 669         abstract function getQueryInfo();
 670
 671         /**
 672          * This function should be overridden to return the name of the index fi-
 673          * eld.  If the pager supports multiple orders, it may return an array of
 674          * 'querykey' => 'indexfield' pairs, so that a request with &count=querykey
 675          * will use indexfield to sort.  In this case, the first returned key is
 676          * the default.
 677          *
 678          * Needless to say, it's really not a good idea to use a non-unique index
 679          * for this!  That won't page right.
 680          *
 681          * @return string|Array
 682          */
 683         abstract function getIndexField();
 684
 685         /**
 686          * This function should be overridden to return the names of secondary columns
 687          * to order by in addition to the column in getIndexField(). These fields will
 688          * not be used in the pager offset or in any links for users.
 689          *
 690          * If getIndexField() returns an array of 'querykey' => 'indexfield' pairs then
 691          * this must return a corresponding array of 'querykey' => array( fields...) pairs
 692          * in order for a request with &count=querykey to use array( fields...) to sort.
 693          *
 694          * This is useful for pagers that GROUP BY a unique column (say page_id)
 695          * and ORDER BY another (say page_len). Using GROUP BY and ORDER BY both on
 696          * page_len,page_id avoids temp tables (given a page_len index). This would
 697          * also work if page_id was non-unique but we had a page_len,page_id index.
 698          *
 699          * @return Array
 700          */
 701         protected function getExtraSortFields() {
 702                 return array();
 703         }
 704
 705         /**
 706          * Return the default sorting direction: false for ascending, true for
 707          * descending.  You can also have an associative array of ordertype => dir,
 708          * if multiple order types are supported.  In this case getIndexField()
 709          * must return an array, and the keys of that must exactly match the keys
 710          * of this.
 711          *
 712          * For backward compatibility, this method's return value will be ignored
 713          * if $this->mDefaultDirection is already set when the constructor is
 714          * called, for instance if it's statically initialized.  In that case the
 715          * value of that variable (which must be a boolean) will be used.
 716          *
 717          * Note that despite its name, this does not return the value of the
 718          * $this->mDefaultDirection member variable.  That's the default for this
 719          * particular instantiation, which is a single value.  This is the set of
 720          * all defaults for the class.
 721          *
 722          * @return Boolean
 723          */
 724         protected function getDefaultDirections() {
 725                 return false;
 726         }
 727 }
 728
 729 /**
 730  * IndexPager with an alphabetic list and a formatted navigation bar
 731  * @ingroup Pager
 732  */
 733 abstract class AlphabeticPager extends IndexPager {
 734
 735         /**
 736          * Shamelessly stolen bits from ReverseChronologicalPager,
 737          * didn't want to do class magic as may be still revamped
 738          *
 739          * @return String HTML
 740          */
 741         function getNavigationBar() {
 742                 if ( !$this->isNavigationBarShown() ) {
 743                         return '';
 744                 }
 745
 746                 if ( isset( $this->mNavigationBar ) ) {
 747                         return $this->mNavigationBar;
 748                 }
 749
 750                 $linkTexts = array(
 751                         'prev' => $this->msg( 'prevn' )->numParams( $this->mLimit )->escaped(),
 752                         'next' => $this->msg( 'nextn' )->numParams( $this->mLimit )->escaped(),
 753                         'first' => $this->msg( 'page_first' )->escaped(),
 754                         'last' => $this->msg( 'page_last' )->escaped()
 755                 );
 756
 757                 $lang = $this->getLanguage();
 758
 759                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 760                 $limitLinks = $this->getLimitLinks();
 761                 $limits = $lang->pipeList( $limitLinks );
 762
 763                 $this->mNavigationBar = $this->msg( 'parentheses' )->rawParams(
 764                         $lang->pipeList( array( $pagingLinks['first'],
 765                         $pagingLinks['last'] ) ) )->escaped() . " " .
 766                         $this->msg( 'viewprevnext' )->rawParams( $pagingLinks['prev'],
 767                                 $pagingLinks['next'], $limits )->escaped();
 768
 769                 if ( !is_array( $this->getIndexField() ) ) {
 770                         # Early return to avoid undue nesting
 771                         return $this->mNavigationBar;
 772                 }
 773
 774                 $extra = '';
 775                 $first = true;
 776                 $msgs = $this->getOrderTypeMessages();
 777                 foreach ( array_keys( $msgs ) as $order ) {
 778                         if ( $first ) {
 779                                 $first = false;
 780                         } else {
 781                                 $extra .= $this->msg( 'pipe-separator' )->escaped();
 782                         }
 783
 784                         if ( $order == $this->mOrderType ) {
 785                                 $extra .= $this->msg( $msgs[$order] )->escaped();
 786                         } else {
 787                                 $extra .= $this->makeLink(
 788                                         $this->msg( $msgs[$order] )->escaped(),
 789                                         array( 'order' => $order )
 790                                 );
 791                         }
 792                 }
 793
 794                 if ( $extra !== '' ) {
 795                         $extra = ' ' . $this->msg( 'parentheses' )->rawParams( $extra )->escaped();
 796                         $this->mNavigationBar .= $extra;
 797                 }
 798
 799                 return $this->mNavigationBar;
 800         }
 801
 802         /**
 803          * If this supports multiple order type messages, give the message key for
 804          * enabling each one in getNavigationBar.  The return type is an associative
 805          * array whose keys must exactly match the keys of the array returned
 806          * by getIndexField(), and whose values are message keys.
 807          *
 808          * @return Array
 809          */
 810         protected function getOrderTypeMessages() {
 811                 return null;
 812         }
 813 }
 814
 815 /**
 816  * IndexPager with a formatted navigation bar
 817  * @ingroup Pager
 818  */
 819 abstract class ReverseChronologicalPager extends IndexPager {
 820         public $mDefaultDirection = true;
 821         public $mYear;
 822         public $mMonth;
 823
 824         function getNavigationBar() {
 825                 if ( !$this->isNavigationBarShown() ) {
 826                         return '';
 827                 }
 828
 829                 if ( isset( $this->mNavigationBar ) ) {
 830                         return $this->mNavigationBar;
 831                 }
 832
 833                 $linkTexts = array(
 834                         'prev' => $this->msg( 'pager-newer-n' )->numParams( $this->mLimit )->escaped(),
 835                         'next' => $this->msg( 'pager-older-n' )->numParams( $this->mLimit )->escaped(),
 836                         'first' => $this->msg( 'histlast' )->escaped(),
 837                         'last' => $this->msg( 'histfirst' )->escaped()
 838                 );
 839
 840                 $pagingLinks = $this->getPagingLinks( $linkTexts );
 841                 $limitLinks = $this->getLimitLinks();
 842                 $limits = $this->getLanguage()->pipeList( $limitLinks );
 843                 $firstLastLinks = $this->msg( 'parentheses' )->rawParams( "{$pagingLinks['first']}" .
 844                         $this->msg( 'pipe-separator' )->escaped() .
 845                         "{$pagingLinks['last']}" )->escaped();
 846
 847                 $this->mNavigationBar = $firstLastLinks . ' ' .
 848                         $this->msg( 'viewprevnext' )->rawParams(
 849                                 $pagingLinks['prev'], $pagingLinks['next'], $limits )->escaped();
 850
 851                 return $this->mNavigationBar;
 852         }
 853
 854         function getDateCond( $year, $month ) {
 855                 $year = intval( $year );
 856                 $month = intval( $month );
 857
 858                 // Basic validity checks
 859                 $this->mYear = $year > 0 ? $year : false;
 860                 $this->mMonth = ( $month > 0 && $month < 13 ) ? $month : false;
 861
 862                 // Given an optional year and month, we need to generate a timestamp
 863                 // to use as "WHERE rev_timestamp <= result"
 864                 // Examples: year = 2006 equals < 20070101 (+000000)
 865                 // year=2005, month=1    equals < 20050201
 866                 // year=2005, month=12   equals < 20060101
 867                 if ( !$this->mYear && !$this->mMonth ) {
 868                         return;
 869                 }
 870
 871                 if ( $this->mYear ) {
 872                         $year = $this->mYear;
 873                 } else {
 874                         // If no year given, assume the current one
 875                         $year = gmdate( 'Y' );
 876                         // If this month hasn't happened yet this year, go back to last year's month
 877                         if ( $this->mMonth > gmdate( 'n' ) ) {
 878                                 $year--;
 879                         }
 880                 }
 881
 882                 if ( $this->mMonth ) {
 883                         $month = $this->mMonth + 1;
 884                         // For December, we want January 1 of the next year
 885                         if ( $month > 12 ) {
 886                                 $month = 1;
 887                                 $year++;
 888                         }
 889                 } else {
 890                         // No month implies we want up to the end of the year in question
 891                         $month = 1;
 892                         $year++;
 893                 }
 894
 895                 // Y2K38 bug
 896                 if ( $year > 2032 ) {
 897                         $year = 2032;
 898                 }
 899
 900                 $ymd = (int)sprintf( "%04d%02d01", $year, $month );
 901
 902                 if ( $ymd > 20320101 ) {
 903                         $ymd = 20320101;
 904                 }
 905
 906                 $this->mOffset = $this->mDb->timestamp( "${ymd}000000" );
 907         }
 908 }
 909
 910 /**
 911  * Table-based display with a user-selectable sort order
 912  * @ingroup Pager
 913  */
 914 abstract class TablePager extends IndexPager {
 915         var $mSort;
 916         var $mCurrentRow;
 917
 918         public function __construct( IContextSource $context = null ) {
 919                 if ( $context ) {
 920                         $this->setContext( $context );
 921                 }
 922
 923                 $this->mSort = $this->getRequest()->getText( 'sort' );
 924                 if ( !array_key_exists( $this->mSort, $this->getFieldNames() )
 925                         || !$this->isFieldSortable( $this->mSort )
 926                 ) {
 927                         $this->mSort = $this->getDefaultSort();
 928                 }
 929                 if ( $this->getRequest()->getBool( 'asc' ) ) {
 930                         $this->mDefaultDirection = false;
 931                 } elseif ( $this->getRequest()->getBool( 'desc' ) ) {
 932                         $this->mDefaultDirection = true;
 933                 } /* Else leave it at whatever the class default is */
 934
 935                 parent::__construct();
 936         }
 937
 938         /**
 939          * @protected
 940          * @return string
 941          */
 942         function getStartBody() {
 943                 global $wgStylePath;
 944                 $sortClass = $this->getSortHeaderClass();
 945
 946                 $s = '';
 947                 $fields = $this->getFieldNames();
 948
 949                 # Make table header
 950                 foreach ( $fields as $field => $name ) {
 951                         if ( strval( $name ) == '' ) {
 952                                 $s .= Html::rawElement( 'th', array(), '&#160;' ) . "\n";
 953                         } elseif ( $this->isFieldSortable( $field ) ) {
 954                                 $query = array( 'sort' => $field, 'limit' => $this->mLimit );
 955                                 if ( $field == $this->mSort ) {
 956                                         # This is the sorted column
 957                                         # Prepare a link that goes in the other sort order
 958                                         if ( $this->mDefaultDirection ) {
 959                                                 # Descending
 960                                                 $image = 'Arr_d.png';
 961                                                 $query['asc'] = '1';
 962                                                 $query['desc'] = '';
 963                                                 $alt = $this->msg( 'descending_abbrev' )->escaped();
 964                                         } else {
 965                                                 # Ascending
 966                                                 $image = 'Arr_u.png';
 967                                                 $query['asc'] = '';
 968                                                 $query['desc'] = '1';
 969                                                 $alt = $this->msg( 'ascending_abbrev' )->escaped();
 970                                         }
 971                                         $image = "$wgStylePath/common/images/$image";
 972                                         $link = $this->makeLink(
 973                                                 Html::element( 'img', array( 'width' => 12, 'height' => 12,
 974                                                         'alt' => $alt, 'src' => $image ) ) . htmlspecialchars( $name ), $query );
 975                                         $s .= Html::rawElement( 'th', array( 'class' => $sortClass ), $link ) . "\n";
 976                                 } else {
 977                                         $s .= Html::rawElement( 'th', array(),
 978                                                 $this->makeLink( htmlspecialchars( $name ), $query ) ) . "\n";
 979                                 }
 980                         } else {
 981                                 $s .= Html::element( 'th', array(), $name ) . "\n";
 982                         }
 983                 }
 984
 985                 $tableClass = $this->getTableClass();
 986                 $ret = Html::openElement( 'table', array( 'style' => 'border:1px;', 'class' => "mw-datatable $tableClass" ) );
 987                 $ret .= Html::rawElement( 'thead', array(), Html::rawElement( 'tr', array(), "\n" . $s . "\n" ) );
 988                 $ret .= Html::openElement( 'tbody' ) . "\n";
 989
 990                 return $ret;
 991         }
 992
 993         /**
 994          * @protected
 995          * @return string
 996          */
 997         function getEndBody() {
 998                 return "</tbody></table>\n";
 999         }
1000
1001         /**
1002          * @protected
1003          * @return string
1004          */
1005         function getEmptyBody() {
1006                 $colspan = count( $this->getFieldNames() );
1007                 $msgEmpty = $this->msg( 'table_pager_empty' )->text();
1008                 return Html::rawElement( 'tr', array(),
1009                         Html::element( 'td', array( 'colspan' => $colspan ), $msgEmpty ) );
1010         }
1011
1012         /**
1013          * @protected
1014          * @param stdClass $row
1015          * @return String HTML
1016          */
1017         function formatRow( $row ) {
1018                 $this->mCurrentRow = $row; // In case formatValue etc need to know
1019                 $s = Html::openElement( 'tr', $this->getRowAttrs( $row ) ) . "\n";
1020                 $fieldNames = $this->getFieldNames();
1021
1022                 foreach ( $fieldNames as $field => $name ) {
1023                         $value = isset( $row->$field ) ? $row->$field : null;
1024                         $formatted = strval( $this->formatValue( $field, $value ) );
1025
1026                         if ( $formatted == '' ) {
1027                                 $formatted = '&#160;';
1028                         }
1029
1030                         $s .= Html::rawElement( 'td', $this->getCellAttrs( $field, $value ), $formatted ) . "\n";
1031                 }
1032
1033                 $s .= Html::closeElement( 'tr' ) . "\n";
1034
1035                 return $s;
1036         }
1037
1038         /**
1039          * Get a class name to be applied to the given row.
1040          *
1041          * @protected
1042          *
1043          * @param $row Object: the database result row
1044          * @return String
1045          */
1046         function getRowClass( $row ) {
1047                 return '';
1048         }
1049
1050         /**
1051          * Get attributes to be applied to the given row.
1052          *
1053          * @protected
1054          *
1055          * @param $row Object: the database result row
1056          * @return Array of attribute => value
1057          */
1058         function getRowAttrs( $row ) {
1059                 $class = $this->getRowClass( $row );
1060                 if ( $class === '' ) {
1061                         // Return an empty array to avoid clutter in HTML like class=""
1062                         return array();
1063                 } else {
1064                         return array( 'class' => $this->getRowClass( $row ) );
1065                 }
1066         }
1067
1068         /**
1069          * Get any extra attributes to be applied to the given cell. Don't
1070          * take this as an excuse to hardcode styles; use classes and
1071          * CSS instead.  Row context is available in $this->mCurrentRow
1072          *
1073          * @protected
1074          *
1075          * @param string $field The column
1076          * @param string $value The cell contents
1077          * @return Array of attr => value
1078          */
1079         function getCellAttrs( $field, $value ) {
1080                 return array( 'class' => 'TablePager_col_' . $field );
1081         }
1082
1083         /**
1084          * @protected
1085          * @return string
1086          */
1087         function getIndexField() {
1088                 return $this->mSort;
1089         }
1090
1091         /**
1092          * @protected
1093          * @return string
1094          */
1095         function getTableClass() {
1096                 return 'TablePager';
1097         }
1098
1099         /**
1100          * @protected
1101          * @return string
1102          */
1103         function getNavClass() {
1104                 return 'TablePager_nav';
1105         }
1106
1107         /**
1108          * @protected
1109          * @return string
1110          */
1111         function getSortHeaderClass() {
1112                 return 'TablePager_sort';
1113         }
1114
1115         /**
1116          * A navigation bar with images
1117          * @return String HTML
1118          */
1119         public function getNavigationBar() {
1120                 global $wgStylePath;
1121
1122                 if ( !$this->isNavigationBarShown() ) {
1123                         return '';
1124                 }
1125
1126                 $path = "$wgStylePath/common/images";
1127                 $labels = array(
1128                         'first' => 'table_pager_first',
1129                         'prev' => 'table_pager_prev',
1130                         'next' => 'table_pager_next',
1131                         'last' => 'table_pager_last',
1132                 );
1133                 $images = array(
1134                         'first' => 'arrow_first_25.png',
1135                         'prev' => 'arrow_left_25.png',
1136                         'next' => 'arrow_right_25.png',
1137                         'last' => 'arrow_last_25.png',
1138                 );
1139                 $disabledImages = array(
1140                         'first' => 'arrow_disabled_first_25.png',
1141                         'prev' => 'arrow_disabled_left_25.png',
1142                         'next' => 'arrow_disabled_right_25.png',
1143                         'last' => 'arrow_disabled_last_25.png',
1144                 );
1145                 if ( $this->getLanguage()->isRTL() ) {
1146                         $keys = array_keys( $labels );
1147                         $images = array_combine( $keys, array_reverse( $images ) );
1148                         $disabledImages = array_combine( $keys, array_reverse( $disabledImages ) );
1149                 }
1150
1151                 $linkTexts = array();
1152                 $disabledTexts = array();
1153                 foreach ( $labels as $type => $label ) {
1154                         $msgLabel = $this->msg( $label )->escaped();
1155                         $linkTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$images[$type]}",
1156                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1157                         $disabledTexts[$type] = Html::element( 'img', array( 'src' => "$path/{$disabledImages[$type]}",
1158                                 'alt' => $msgLabel ) ) . "<br />$msgLabel";
1159                 }
1160                 $links = $this->getPagingLinks( $linkTexts, $disabledTexts );
1161
1162                 $s = Html::openElement( 'table', array( 'class' => $this->getNavClass() ) );
1163                 $s .= Html::openElement( 'tr' ) . "\n";
1164                 $width = 100 / count( $links ) . '%';
1165                 foreach ( $labels as $type => $label ) {
1166                         $s .= Html::rawElement( 'td', array( 'style' => "width:$width;" ), $links[$type] ) . "\n";
1167                 }
1168                 $s .= Html::closeElement( 'tr' ) . Html::closeElement( 'table' ) . "\n";
1169                 return $s;
1170         }
1171
1172         /**
1173          * Get a "<select>" element which has options for each of the allowed limits
1174          *
1175          * @return String: HTML fragment
1176          */
1177         public function getLimitSelect() {
1178                 $select = new XmlSelect( 'limit', false, $this->mLimit );
1179                 $select->addOptions( $this->getLimitSelectList() );
1180                 return $select->getHTML();
1181         }
1182
1183         /**
1184          * Get a list of items to show in a "<select>" element of limits.
1185          * This can be passed directly to XmlSelect::addOptions().
1186          *
1187          * @since 1.22
1188          * @return array
1189          */
1190         public function getLimitSelectList() {
1191                 # Add the current limit from the query string
1192                 # to avoid that the limit is lost after clicking Go next time
1193                 if ( !in_array( $this->mLimit, $this->mLimitsShown ) ) {
1194                         $this->mLimitsShown[] = $this->mLimit;
1195                         sort( $this->mLimitsShown );
1196                 }
1197                 $ret = array();
1198                 foreach ( $this->mLimitsShown as $key => $value ) {
1199                         # The pair is either $index => $limit, in which case the $value
1200                         # will be numeric, or $limit => $text, in which case the $value
1201                         # will be a string.
1202                         if ( is_int( $value ) ) {
1203                                 $limit = $value;
1204                                 $text = $this->getLanguage()->formatNum( $limit );
1205                         } else {
1206                                 $limit = $key;
1207                                 $text = $value;
1208                         }
1209                         $ret[$text] = $limit;
1210                 }
1211                 return $ret;
1212         }
1213
1214         /**
1215          * Get \<input type="hidden"\> elements for use in a method="get" form.
1216          * Resubmits all defined elements of the query string, except for a
1217          * blacklist, passed in the $blacklist parameter.
1218          *
1219          * @param array $blacklist parameters from the request query which should not be resubmitted
1220          * @return String: HTML fragment
1221          */
1222         function getHiddenFields( $blacklist = array() ) {
1223                 $blacklist = (array)$blacklist;
1224                 $query = $this->getRequest()->getQueryValues();
1225                 foreach ( $blacklist as $name ) {
1226                         unset( $query[$name] );
1227                 }
1228                 $s = '';
1229                 foreach ( $query as $name => $value ) {
1230                         $s .= Html::hidden( $name, $value ) . "\n";
1231                 }
1232                 return $s;
1233         }
1234
1235         /**
1236          * Get a form containing a limit selection dropdown
1237          *
1238          * @return String: HTML fragment
1239          */
1240         function getLimitForm() {
1241                 global $wgScript;
1242
1243                 return Html::rawElement(
1244                         'form',
1245                         array(
1246                                 'method' => 'get',
1247                                 'action' => $wgScript
1248                         ),
1249                         "\n" . $this->getLimitDropdown()
1250                 ) . "\n";
1251         }
1252
1253         /**
1254          * Gets a limit selection dropdown
1255          *
1256          * @return string
1257          */
1258         function getLimitDropdown() {
1259                 # Make the select with some explanatory text
1260                 $msgSubmit = $this->msg( 'table_pager_limit_submit' )->escaped();
1261
1262                 return $this->msg( 'table_pager_limit' )
1263                         ->rawParams( $this->getLimitSelect() )->escaped() .
1264                         "\n<input type=\"submit\" value=\"$msgSubmit\"/>\n" .
1265                         $this->getHiddenFields( array( 'limit' ) );
1266         }
1267
1268         /**
1269          * Return true if the named field should be sortable by the UI, false
1270          * otherwise
1271          *
1272          * @param $field String
1273          */
1274         abstract function isFieldSortable( $field );
1275
1276         /**
1277          * Format a table cell. The return value should be HTML, but use an empty
1278          * string not &#160; for empty cells. Do not include the <td> and </td>.
1279          *
1280          * The current result row is available as $this->mCurrentRow, in case you
1281          * need more context.
1282          *
1283          * @protected
1284          *
1285          * @param string $name the database field name
1286          * @param string $value the value retrieved from the database
1287          */
1288         abstract function formatValue( $name, $value );
1289
1290         /**
1291          * The database field name used as a default sort order.
1292          *
1293          * @protected
1294          *
1295          * @return string
1296          */
1297         abstract function getDefaultSort();
1298
1299         /**
1300          * An array mapping database field names to a textual description of the
1301          * field name, for use in the table header. The description should be plain
1302          * text, it will be HTML-escaped later.
1303          *
1304          * @return Array
1305          */
1306         abstract function getFieldNames();
1307 }