/**
  * Parse a query string given in SMW's query language to create
  * an SMWQuery. Parameters are given as key-value-pairs in the
  * given array. The parameter $context defines in what context the
  * query is used, which affects ceretain general settings.
  * An object of type SMWQuery is returned.
  *
  * The format string is used to specify the output format if already
  * known. Otherwise it will be determined from the parameters when
  * needed. This parameter is just for optimisation in a common case.
  *
  * @param string $queryString
  * @param array $params These need to be the result of a list fed to getProcessedParams
  * @param $context
  * @param string $format
  * @param array $extraPrintouts
  *
  * @return SMWQuery
  */
 public static function createQuery($queryString, array $params, $context = self::INLINE_QUERY, $format = '', array $extraPrintouts = array())
 {
     global $smwgQDefaultNamespaces, $smwgQFeatures, $smwgQConceptFeatures;
     // parse query:
     $queryfeatures = $context == self::CONCEPT_DESC ? $smwgQConceptFeatures : $smwgQFeatures;
     $qp = new SMWQueryParser($queryfeatures);
     $qp->setDefaultNamespaces($smwgQDefaultNamespaces);
     $desc = $qp->getQueryDescription($queryString);
     if ($format === '' || is_null($format)) {
         $format = $params['format']->getValue();
     }
     if ($format == 'count') {
         $querymode = SMWQuery::MODE_COUNT;
     } elseif ($format == 'debug') {
         $querymode = SMWQuery::MODE_DEBUG;
     } else {
         $printer = self::getResultPrinter($format, $context);
         $querymode = $printer->getQueryMode($context);
     }
     $query = new SMWQuery($desc, $context != self::SPECIAL_PAGE, $context == self::CONCEPT_DESC);
     $query->setQueryString($queryString);
     $query->setExtraPrintouts($extraPrintouts);
     $query->setMainLabel($params['mainlabel']->getValue());
     $query->addErrors($qp->getErrors());
     // keep parsing errors for later output
     $query->setQuerySource($params['source']->getValue());
     // set mode, limit, and offset:
     $query->querymode = $querymode;
     if (array_key_exists('offset', $params) && is_int($params['offset']->getValue() + 0)) {
         $query->setOffset(max(0, trim($params['offset']->getValue()) + 0));
     }
     if ($query->querymode == SMWQuery::MODE_COUNT) {
         // largest possible limit for "count", even inline
         global $smwgQMaxLimit;
         $query->setOffset(0);
         $query->setLimit($smwgQMaxLimit, false);
     } else {
         if (array_key_exists('limit', $params) && is_int(trim($params['limit']->getValue()) + 0)) {
             $query->setLimit(max(0, trim($params['limit']->getValue()) + 0));
             if (trim($params['limit']->getValue()) + 0 < 0) {
                 // limit < 0: always show further results link only
                 $query->querymode = SMWQuery::MODE_NONE;
             }
         } else {
             global $smwgQDefaultLimit;
             $query->setLimit($smwgQDefaultLimit);
         }
     }
     $defaultSort = $format === 'rss' ? 'DESC' : 'ASC';
     $sort = self::getSortKeys($params['sort']->getValue(), $params['order']->getValue(), $defaultSort);
     $query->sortkeys = $sort['keys'];
     $query->addErrors($sort['errors']);
     $query->sort = count($query->sortkeys) > 0;
     // TODO: Why would we do this here?
     return $query;
 }