/**
  * Score specified document
  *
  * @param integer $docId
  * @param ZSearch $reader
  * @return float
  */
 public function score($docId, $reader)
 {
     if ($this->_docVector === null) {
         if (extension_loaded('bitset')) {
             $this->_docVector = bitset_from_array($reader->termDocs($this->_term));
         } else {
             $this->_docVector = array_flip($reader->termDocs($this->_term));
         }
         $this->_termPositions = $reader->termPositions($this->_term);
         $this->_initWeight($reader);
     }
     $match = extension_loaded('bitset') ? bitset_in($this->_docVector, $docId) : isset($this->_docVector[$docId]);
     if ($this->_sign && $match) {
         return $reader->getSimilarity()->tf(count($this->_termPositions[$docId])) * $this->_weight->getValue() * $reader->norm($docId, $this->_term->field);
     } else {
         return 0;
     }
 }
 /**
  * Calculate result vector
  *
  * @param ZSearch $reader
  */
 private function _calculateResult($reader)
 {
     if (extension_loaded('bitset')) {
         foreach ($this->_terms as $termId => $term) {
             if ($this->_resVector === null) {
                 $this->_resVector = bitset_from_array($reader->termDocs($term));
             } else {
                 $this->_resVector = bitset_intersection($this->_resVector, bitset_from_array($reader->termDocs($term)));
             }
             $this->_termsPositions[$termId] = $reader->termPositions($term);
         }
     } else {
         foreach ($this->_terms as $termId => $term) {
             if ($this->_resVector === null) {
                 $this->_resVector = array_flip($reader->termDocs($term));
             } else {
                 $termDocs = array_flip($reader->termDocs($term));
                 foreach ($this->_resVector as $key => $value) {
                     if (!isset($termDocs[$key])) {
                         unset($this->_resVector[$key]);
                     }
                 }
             }
             $this->_termsPositions[$termId] = $reader->termPositions($term);
         }
     }
 }
 /**
  * Calculate result vector for non Conjunction query
  * (like '+something -another')
  *
  * @param ZSearch $reader
  */
 private function _calculateNonConjunctionResult($reader)
 {
     if (extension_loaded('bitset')) {
         $required = null;
         $neither = bitset_empty();
         $prohibited = bitset_empty();
         foreach ($this->_terms as $termId => $term) {
             $termDocs = bitset_from_array($reader->termDocs($term));
             if ($this->_signs[$termId] === true) {
                 // required
                 if ($required !== null) {
                     $required = bitset_intersection($required, $termDocs);
                 } else {
                     $required = $termDocs;
                 }
             } elseif ($this->_signs[$termId] === false) {
                 // prohibited
                 $prohibited = bitset_union($prohibited, $termDocs);
             } else {
                 // neither required, nor prohibited
                 $neither = bitset_union($neither, $termDocs);
             }
             $this->_termsPositions[$termId] = $reader->termPositions($term);
         }
         if ($required === null) {
             $required = $neither;
         }
         $this->_resVector = bitset_intersection($required, bitset_invert($prohibited, $reader->count()));
     } else {
         $required = null;
         $neither = array();
         $prohibited = array();
         foreach ($this->_terms as $termId => $term) {
             $termDocs = array_flip($reader->termDocs($term));
             if ($this->_signs[$termId] === true) {
                 // required
                 if ($required !== null) {
                     // substitute for bitset_intersection
                     foreach ($required as $key => $value) {
                         if (!isset($termDocs[$key])) {
                             unset($required[$key]);
                         }
                     }
                 } else {
                     $required = $termDocs;
                 }
             } elseif ($this->_signs[$termId] === false) {
                 // prohibited
                 // substitute for bitset_union
                 foreach ($termDocs as $key => $value) {
                     $prohibited[$key] = $value;
                 }
             } else {
                 // neither required, nor prohibited
                 // substitute for bitset_union
                 foreach ($termDocs as $key => $value) {
                     $neither[$key] = $value;
                 }
             }
             $this->_termsPositions[$termId] = $reader->termPositions($term);
         }
         if ($required === null) {
             $required = $neither;
         }
         foreach ($required as $key => $value) {
             if (isset($prohibited[$key])) {
                 unset($required[$key]);
             }
         }
         $this->_resVector = $required;
     }
 }