includes/api/ApiQueryBase.php

   1 <?php
   2 /**
   3  *
   4  *
   5  * Created on Sep 7, 2006
   6  *
   7  * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License along
  20  * with this program; if not, write to the Free Software Foundation, Inc.,
  21  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  22  * http://www.gnu.org/copyleft/gpl.html
  23  *
  24  * @file
  25  */
  26
  27 /**
  28  * This is a base class for all Query modules.
  29  * It provides some common functionality such as constructing various SQL
  30  * queries.
  31  *
  32  * @ingroup API
  33  */
  34 abstract class ApiQueryBase extends ApiBase {
  35
  36         private $mQueryModule, $mDb, $tables, $where, $fields, $options, $join_conds;
  37
  38         /**
  39          * @param $query ApiBase
  40          * @param $moduleName string
  41          * @param $paramPrefix string
  42          */
  43         public function __construct( ApiBase $query, $moduleName, $paramPrefix = '' ) {
  44                 parent::__construct( $query->getMain(), $moduleName, $paramPrefix );
  45                 $this->mQueryModule = $query;
  46                 $this->mDb = null;
  47                 $this->resetQueryParams();
  48         }
  49
  50         /**
  51          * Get the cache mode for the data generated by this module. Override
  52          * this in the module subclass. For possible return values and other
  53          * details about cache modes, see ApiMain::setCacheMode()
  54          *
  55          * Public caching will only be allowed if *all* the modules that supply
  56          * data for a given request return a cache mode of public.
  57          *
  58          * @param $params
  59          * @return string
  60          */
  61         public function getCacheMode( $params ) {
  62                 return 'private';
  63         }
  64
  65         /**
  66          * Blank the internal arrays with query parameters
  67          */
  68         protected function resetQueryParams() {
  69                 $this->tables = array();
  70                 $this->where = array();
  71                 $this->fields = array();
  72                 $this->options = array();
  73                 $this->join_conds = array();
  74         }
  75
  76         /**
  77          * Add a set of tables to the internal array
  78          * @param $tables mixed Table name or array of table names
  79          * @param $alias mixed Table alias, or null for no alias. Cannot be
  80          *  used with multiple tables
  81          */
  82         protected function addTables( $tables, $alias = null ) {
  83                 if ( is_array( $tables ) ) {
  84                         if ( !is_null( $alias ) ) {
  85                                 ApiBase::dieDebug( __METHOD__, 'Multiple table aliases not supported' );
  86                         }
  87                         $this->tables = array_merge( $this->tables, $tables );
  88                 } else {
  89                         if ( !is_null( $alias ) ) {
  90                                 $this->tables[$alias] = $tables;
  91                         } else {
  92                                 $this->tables[] = $tables;
  93                         }
  94                 }
  95         }
  96
  97         /**
  98          * Add a set of JOIN conditions to the internal array
  99          *
 100          * JOIN conditions are formatted as array( tablename => array(jointype,
 101          * conditions) e.g. array('page' => array('LEFT JOIN',
 102          * 'page_id=rev_page')) . conditions may be a string or an
 103          * addWhere()-style array
 104          * @param $join_conds array JOIN conditions
 105          */
 106         protected function addJoinConds( $join_conds ) {
 107                 if ( !is_array( $join_conds ) ) {
 108                         ApiBase::dieDebug( __METHOD__, 'Join conditions have to be arrays' );
 109                 }
 110                 $this->join_conds = array_merge( $this->join_conds, $join_conds );
 111         }
 112
 113         /**
 114          * Add a set of fields to select to the internal array
 115          * @param array|string $value Field name or array of field names
 116          */
 117         protected function addFields( $value ) {
 118                 if ( is_array( $value ) ) {
 119                         $this->fields = array_merge( $this->fields, $value );
 120                 } else {
 121                         $this->fields[] = $value;
 122                 }
 123         }
 124
 125         /**
 126          * Same as addFields(), but add the fields only if a condition is met
 127          * @param array|string $value See addFields()
 128          * @param bool $condition If false, do nothing
 129          * @return bool $condition
 130          */
 131         protected function addFieldsIf( $value, $condition ) {
 132                 if ( $condition ) {
 133                         $this->addFields( $value );
 134
 135                         return true;
 136                 }
 137
 138                 return false;
 139         }
 140
 141         /**
 142          * Add a set of WHERE clauses to the internal array.
 143          * Clauses can be formatted as 'foo=bar' or array('foo' => 'bar'),
 144          * the latter only works if the value is a constant (i.e. not another field)
 145          *
 146          * If $value is an empty array, this function does nothing.
 147          *
 148          * For example, array('foo=bar', 'baz' => 3, 'bla' => 'foo') translates
 149          * to "foo=bar AND baz='3' AND bla='foo'"
 150          * @param $value mixed String or array
 151          */
 152         protected function addWhere( $value ) {
 153                 if ( is_array( $value ) ) {
 154                         // Sanity check: don't insert empty arrays,
 155                         // Database::makeList() chokes on them
 156                         if ( count( $value ) ) {
 157                                 $this->where = array_merge( $this->where, $value );
 158                         }
 159                 } else {
 160                         $this->where[] = $value;
 161                 }
 162         }
 163
 164         /**
 165          * Same as addWhere(), but add the WHERE clauses only if a condition is met
 166          * @param $value mixed See addWhere()
 167          * @param bool $condition If false, do nothing
 168          * @return bool $condition
 169          */
 170         protected function addWhereIf( $value, $condition ) {
 171                 if ( $condition ) {
 172                         $this->addWhere( $value );
 173
 174                         return true;
 175                 }
 176
 177                 return false;
 178         }
 179
 180         /**
 181          * Equivalent to addWhere(array($field => $value))
 182          * @param string $field Field name
 183          * @param string $value Value; ignored if null or empty array;
 184          */
 185         protected function addWhereFld( $field, $value ) {
 186                 // Use count() to its full documented capabilities to simultaneously
 187                 // test for null, empty array or empty countable object
 188                 if ( count( $value ) ) {
 189                         $this->where[$field] = $value;
 190                 }
 191         }
 192
 193         /**
 194          * Add a WHERE clause corresponding to a range, and an ORDER BY
 195          * clause to sort in the right direction
 196          * @param string $field Field name
 197          * @param string $dir If 'newer', sort in ascending order, otherwise
 198          *  sort in descending order
 199          * @param string $start Value to start the list at. If $dir == 'newer'
 200          *  this is the lower boundary, otherwise it's the upper boundary
 201          * @param string $end Value to end the list at. If $dir == 'newer' this
 202          *  is the upper boundary, otherwise it's the lower boundary
 203          * @param bool $sort If false, don't add an ORDER BY clause
 204          */
 205         protected function addWhereRange( $field, $dir, $start, $end, $sort = true ) {
 206                 $isDirNewer = ( $dir === 'newer' );
 207                 $after = ( $isDirNewer ? '>=' : '<=' );
 208                 $before = ( $isDirNewer ? '<=' : '>=' );
 209                 $db = $this->getDB();
 210
 211                 if ( !is_null( $start ) ) {
 212                         $this->addWhere( $field . $after . $db->addQuotes( $start ) );
 213                 }
 214
 215                 if ( !is_null( $end ) ) {
 216                         $this->addWhere( $field . $before . $db->addQuotes( $end ) );
 217                 }
 218
 219                 if ( $sort ) {
 220                         $order = $field . ( $isDirNewer ? '' : ' DESC' );
 221                         // Append ORDER BY
 222                         $optionOrderBy = isset( $this->options['ORDER BY'] )
 223                                 ? (array)$this->options['ORDER BY']
 224                                 : array();
 225                         $optionOrderBy[] = $order;
 226                         $this->addOption( 'ORDER BY', $optionOrderBy );
 227                 }
 228         }
 229
 230         /**
 231          * Add a WHERE clause corresponding to a range, similar to addWhereRange,
 232          * but converts $start and $end to database timestamps.
 233          * @see addWhereRange
 234          * @param $field
 235          * @param $dir
 236          * @param $start
 237          * @param $end
 238          * @param $sort bool
 239          */
 240         protected function addTimestampWhereRange( $field, $dir, $start, $end, $sort = true ) {
 241                 $db = $this->getDb();
 242                 $this->addWhereRange( $field, $dir,
 243                         $db->timestampOrNull( $start ), $db->timestampOrNull( $end ), $sort );
 244         }
 245
 246         /**
 247          * Add an option such as LIMIT or USE INDEX. If an option was set
 248          * before, the old value will be overwritten
 249          * @param string $name Option name
 250          * @param string $value Option value
 251          */
 252         protected function addOption( $name, $value = null ) {
 253                 if ( is_null( $value ) ) {
 254                         $this->options[] = $name;
 255                 } else {
 256                         $this->options[$name] = $value;
 257                 }
 258         }
 259
 260         /**
 261          * Execute a SELECT query based on the values in the internal arrays
 262          * @param string $method Function the query should be attributed to.
 263          *  You should usually use __METHOD__ here
 264          * @param array $extraQuery Query data to add but not store in the object
 265          *  Format is array(
 266          *    'tables' => ...,
 267          *    'fields' => ...,
 268          *    'where' => ...,
 269          *    'options' => ...,
 270          *    'join_conds' => ...
 271          *  )
 272          * @return ResultWrapper
 273          */
 274         protected function select( $method, $extraQuery = array() ) {
 275
 276                 $tables = array_merge(
 277                         $this->tables,
 278                         isset( $extraQuery['tables'] ) ? (array)$extraQuery['tables'] : array()
 279                 );
 280                 $fields = array_merge(
 281                         $this->fields,
 282                         isset( $extraQuery['fields'] ) ? (array)$extraQuery['fields'] : array()
 283                 );
 284                 $where = array_merge(
 285                         $this->where,
 286                         isset( $extraQuery['where'] ) ? (array)$extraQuery['where'] : array()
 287                 );
 288                 $options = array_merge(
 289                         $this->options,
 290                         isset( $extraQuery['options'] ) ? (array)$extraQuery['options'] : array()
 291                 );
 292                 $join_conds = array_merge(
 293                         $this->join_conds,
 294                         isset( $extraQuery['join_conds'] ) ? (array)$extraQuery['join_conds'] : array()
 295                 );
 296
 297                 // getDB has its own profileDBIn/Out calls
 298                 $db = $this->getDB();
 299
 300                 $this->profileDBIn();
 301                 $res = $db->select( $tables, $fields, $where, $method, $options, $join_conds );
 302                 $this->profileDBOut();
 303
 304                 return $res;
 305         }
 306
 307         /**
 308          * Estimate the row count for the SELECT query that would be run if we
 309          * called select() right now, and check if it's acceptable.
 310          * @return bool true if acceptable, false otherwise
 311          */
 312         protected function checkRowCount() {
 313                 $db = $this->getDB();
 314                 $this->profileDBIn();
 315                 $rowcount = $db->estimateRowCount(
 316                         $this->tables,
 317                         $this->fields,
 318                         $this->where,
 319                         __METHOD__,
 320                         $this->options
 321                 );
 322                 $this->profileDBOut();
 323
 324                 global $wgAPIMaxDBRows;
 325                 if ( $rowcount > $wgAPIMaxDBRows ) {
 326                         return false;
 327                 }
 328
 329                 return true;
 330         }
 331
 332         /**
 333          * Add information (title and namespace) about a Title object to a
 334          * result array
 335          * @param array $arr Result array à la ApiResult
 336          * @param $title Title
 337          * @param string $prefix Module prefix
 338          */
 339         public static function addTitleInfo( &$arr, $title, $prefix = '' ) {
 340                 $arr[$prefix . 'ns'] = intval( $title->getNamespace() );
 341                 $arr[$prefix . 'title'] = $title->getPrefixedText();
 342         }
 343
 344         /**
 345          * Override this method to request extra fields from the pageSet
 346          * using $pageSet->requestField('fieldName')
 347          * @param $pageSet ApiPageSet
 348          */
 349         public function requestExtraData( $pageSet ) {
 350         }
 351
 352         /**
 353          * Get the main Query module
 354          * @return ApiQuery
 355          */
 356         public function getQuery() {
 357                 return $this->mQueryModule;
 358         }
 359
 360         /**
 361          * Add a sub-element under the page element with the given page ID
 362          * @param int $pageId Page ID
 363          * @param array $data Data array à la ApiResult
 364          * @return bool Whether the element fit in the result
 365          */
 366         protected function addPageSubItems( $pageId, $data ) {
 367                 $result = $this->getResult();
 368                 $result->setIndexedTagName( $data, $this->getModulePrefix() );
 369
 370                 return $result->addValue( array( 'query', 'pages', intval( $pageId ) ),
 371                         $this->getModuleName(),
 372                         $data );
 373         }
 374
 375         /**
 376          * Same as addPageSubItems(), but one element of $data at a time
 377          * @param int $pageId Page ID
 378          * @param array $item Data array à la ApiResult
 379          * @param string $elemname XML element name. If null, getModuleName()
 380          *  is used
 381          * @return bool Whether the element fit in the result
 382          */
 383         protected function addPageSubItem( $pageId, $item, $elemname = null ) {
 384                 if ( is_null( $elemname ) ) {
 385                         $elemname = $this->getModulePrefix();
 386                 }
 387                 $result = $this->getResult();
 388                 $fit = $result->addValue( array( 'query', 'pages', $pageId,
 389                         $this->getModuleName() ), null, $item );
 390                 if ( !$fit ) {
 391                         return false;
 392                 }
 393                 $result->setIndexedTagName_internal( array( 'query', 'pages', $pageId,
 394                         $this->getModuleName() ), $elemname );
 395
 396                 return true;
 397         }
 398
 399         /**
 400          * Set a query-continue value
 401          * @param string $paramName Parameter name
 402          * @param string $paramValue Parameter value
 403          */
 404         protected function setContinueEnumParameter( $paramName, $paramValue ) {
 405                 $paramName = $this->encodeParamName( $paramName );
 406                 $msg = array( $paramName => $paramValue );
 407                 $result = $this->getResult();
 408                 $result->disableSizeCheck();
 409                 $result->addValue( 'query-continue', $this->getModuleName(), $msg, ApiResult::ADD_ON_TOP );
 410                 $result->enableSizeCheck();
 411         }
 412
 413         /**
 414          * Get the Query database connection (read-only)
 415          * @return DatabaseBase
 416          */
 417         protected function getDB() {
 418                 if ( is_null( $this->mDb ) ) {
 419                         $this->mDb = $this->getQuery()->getDB();
 420                 }
 421
 422                 return $this->mDb;
 423         }
 424
 425         /**
 426          * Selects the query database connection with the given name.
 427          * See ApiQuery::getNamedDB() for more information
 428          * @param string $name Name to assign to the database connection
 429          * @param int $db One of the DB_* constants
 430          * @param array $groups Query groups
 431          * @return DatabaseBase
 432          */
 433         public function selectNamedDB( $name, $db, $groups ) {
 434                 $this->mDb = $this->getQuery()->getNamedDB( $name, $db, $groups );
 435         }
 436
 437         /**
 438          * Get the PageSet object to work on
 439          * @return ApiPageSet
 440          */
 441         protected function getPageSet() {
 442                 return $this->getQuery()->getPageSet();
 443         }
 444
 445         /**
 446          * Convert a title to a DB key
 447          * @param string $title Page title with spaces
 448          * @return string Page title with underscores
 449          */
 450         public function titleToKey( $title ) {
 451                 // Don't throw an error if we got an empty string
 452                 if ( trim( $title ) == '' ) {
 453                         return '';
 454                 }
 455                 $t = Title::newFromText( $title );
 456                 if ( !$t ) {
 457                         $this->dieUsageMsg( array( 'invalidtitle', $title ) );
 458                 }
 459
 460                 return $t->getPrefixedDBkey();
 461         }
 462
 463         /**
 464          * The inverse of titleToKey()
 465          * @param string $key Page title with underscores
 466          * @return string Page title with spaces
 467          */
 468         public function keyToTitle( $key ) {
 469                 // Don't throw an error if we got an empty string
 470                 if ( trim( $key ) == '' ) {
 471                         return '';
 472                 }
 473                 $t = Title::newFromDBkey( $key );
 474                 // This really shouldn't happen but we gotta check anyway
 475                 if ( !$t ) {
 476                         $this->dieUsageMsg( array( 'invalidtitle', $key ) );
 477                 }
 478
 479                 return $t->getPrefixedText();
 480         }
 481
 482         /**
 483          * An alternative to titleToKey() that doesn't trim trailing spaces, and
 484          * does not mangle the input if starts with something that looks like a
 485          * namespace. It is advisable to pass the namespace parameter in order to
 486          * handle per-namespace capitalization settings.
 487          * @param string $titlePart Title part with spaces
 488          * @param $defaultNamespace int Namespace to assume
 489          * @return string Title part with underscores
 490          */
 491         public function titlePartToKey( $titlePart, $defaultNamespace = NS_MAIN ) {
 492                 $t = Title::makeTitleSafe( $defaultNamespace, $titlePart . 'x' );
 493                 if ( !$t ) {
 494                         $this->dieUsageMsg( array( 'invalidtitle', $titlePart ) );
 495                 }
 496                 if ( $defaultNamespace != $t->getNamespace() || $t->isExternal() ) {
 497                         // This can happen in two cases. First, if you call titlePartToKey with a title part
 498                         // that looks like a namespace, but with $defaultNamespace = NS_MAIN. It would be very
 499                         // difficult to handle such a case. Such cases cannot exist and are therefore treated
 500                         // as invalid user input. The second case is when somebody specifies a title interwiki
 501                         // prefix.
 502                         $this->dieUsageMsg( array( 'invalidtitle', $titlePart ) );
 503                 }
 504                 return substr( $t->getDbKey(), 0, -1 );
 505         }
 506
 507         /**
 508          * An alternative to keyToTitle() that doesn't trim trailing spaces
 509          * @param string $keyPart Key part with spaces
 510          * @return string Key part with underscores
 511          */
 512         public function keyPartToTitle( $keyPart ) {
 513                 return substr( $this->keyToTitle( $keyPart . 'x' ), 0, -1 );
 514         }
 515
 516         /**
 517          * Gets the personalised direction parameter description
 518          *
 519          * @param string $p ModulePrefix
 520          * @param string $extraDirText Any extra text to be appended on the description
 521          * @return array
 522          */
 523         public function getDirectionDescription( $p = '', $extraDirText = '' ) {
 524                 return array(
 525                         "In which direction to enumerate{$extraDirText}",
 526                         " newer          - List oldest first. Note: {$p}start has to be before {$p}end.",
 527                         " older          - List newest first (default). Note: {$p}start has to be later than {$p}end.",
 528                 );
 529         }
 530
 531         /**
 532          * @param $query String
 533          * @param $protocol String
 534          * @return null|string
 535          */
 536         public function prepareUrlQuerySearchString( $query = null, $protocol = null ) {
 537                 $db = $this->getDb();
 538                 if ( !is_null( $query ) || $query != '' ) {
 539                         if ( is_null( $protocol ) ) {
 540                                 $protocol = 'http://';
 541                         }
 542
 543                         $likeQuery = LinkFilter::makeLikeArray( $query, $protocol );
 544                         if ( !$likeQuery ) {
 545                                 $this->dieUsage( 'Invalid query', 'bad_query' );
 546                         }
 547
 548                         $likeQuery = LinkFilter::keepOneWildcard( $likeQuery );
 549
 550                         return 'el_index ' . $db->buildLike( $likeQuery );
 551                 } elseif ( !is_null( $protocol ) ) {
 552                         return 'el_index ' . $db->buildLike( "$protocol", $db->anyString() );
 553                 }
 554
 555                 return null;
 556         }
 557
 558         /**
 559          * Filters hidden users (where the user doesn't have the right to view them)
 560          * Also adds relevant block information
 561          *
 562          * @param bool $showBlockInfo
 563          * @return void
 564          */
 565         public function showHiddenUsersAddBlockInfo( $showBlockInfo ) {
 566                 $this->addTables( 'ipblocks' );
 567                 $this->addJoinConds( array(
 568                         'ipblocks' => array( 'LEFT JOIN', 'ipb_user=user_id' ),
 569                 ) );
 570
 571                 $this->addFields( 'ipb_deleted' );
 572
 573                 if ( $showBlockInfo ) {
 574                         $this->addFields( array( 'ipb_id', 'ipb_by', 'ipb_by_text', 'ipb_reason', 'ipb_expiry' ) );
 575                 }
 576
 577                 // Don't show hidden names
 578                 if ( !$this->getUser()->isAllowed( 'hideuser' ) ) {
 579                         $this->addWhere( 'ipb_deleted = 0 OR ipb_deleted IS NULL' );
 580                 }
 581         }
 582
 583         /**
 584          * @param $hash string
 585          * @return bool
 586          */
 587         public function validateSha1Hash( $hash ) {
 588                 return preg_match( '/^[a-f0-9]{40}$/', $hash );
 589         }
 590
 591         /**
 592          * @param $hash string
 593          * @return bool
 594          */
 595         public function validateSha1Base36Hash( $hash ) {
 596                 return preg_match( '/^[a-z0-9]{31}$/', $hash );
 597         }
 598
 599         /**
 600          * @return array
 601          */
 602         public function getPossibleErrors() {
 603                 $errors = parent::getPossibleErrors();
 604                 $errors = array_merge( $errors, array(
 605                         array( 'invalidtitle', 'title' ),
 606                         array( 'invalidtitle', 'key' ),
 607                 ) );
 608
 609                 return $errors;
 610         }
 611
 612         /**
 613          * Check whether the current user has permission to view revision-deleted
 614          * fields.
 615          * @return bool
 616          */
 617         public function userCanSeeRevDel() {
 618                 return $this->getUser()->isAllowedAny( 'deletedhistory', 'deletedtext', 'suppressrevision' );
 619         }
 620 }
 621
 622 /**
 623  * @ingroup API
 624  */
 625 abstract class ApiQueryGeneratorBase extends ApiQueryBase {
 626
 627         private $mGeneratorPageSet = null;
 628
 629         /**
 630          * Switch this module to generator mode. By default, generator mode is
 631          * switched off and the module acts like a normal query module.
 632          * @since 1.21 requires pageset parameter
 633          * @param $generatorPageSet ApiPageSet object that the module will get
 634          *        by calling getPageSet() when in generator mode.
 635          */
 636         public function setGeneratorMode( ApiPageSet $generatorPageSet ) {
 637                 if ( $generatorPageSet === null ) {
 638                         ApiBase::dieDebug( __METHOD__, 'Required parameter missing - $generatorPageSet' );
 639                 }
 640                 $this->mGeneratorPageSet = $generatorPageSet;
 641         }
 642
 643         /**
 644          * Get the PageSet object to work on.
 645          * If this module is generator, the pageSet object is different from other module's
 646          * @return ApiPageSet
 647          */
 648         protected function getPageSet() {
 649                 if ( $this->mGeneratorPageSet !== null ) {
 650                         return $this->mGeneratorPageSet;
 651                 }
 652
 653                 return parent::getPageSet();
 654         }
 655
 656         /**
 657          * Overrides base class to prepend 'g' to every generator parameter
 658          * @param string $paramName Parameter name
 659          * @return string Prefixed parameter name
 660          */
 661         public function encodeParamName( $paramName ) {
 662                 if ( $this->mGeneratorPageSet !== null ) {
 663                         return 'g' . parent::encodeParamName( $paramName );
 664                 } else {
 665                         return parent::encodeParamName( $paramName );
 666                 }
 667         }
 668
 669         /**
 670          * Overrides base in case of generator & smart continue to
 671          * notify ApiQueryMain instead of adding them to the result right away.
 672          * @param string $paramName Parameter name
 673          * @param string $paramValue Parameter value
 674          */
 675         protected function setContinueEnumParameter( $paramName, $paramValue ) {
 676                 // If this is a generator and query->setGeneratorContinue() returns false, treat as before
 677                 if ( $this->mGeneratorPageSet === null
 678                         || !$this->getQuery()->setGeneratorContinue( $this, $paramName, $paramValue )
 679                 ) {
 680                         parent::setContinueEnumParameter( $paramName, $paramValue );
 681                 }
 682         }
 683
 684         /**
 685          * Execute this module as a generator
 686          * @param $resultPageSet ApiPageSet: All output should be appended to
 687          *  this object
 688          */
 689         abstract public function executeGenerator( $resultPageSet );
 690 }