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