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