public function addFieldInfo(Zend_Search_Lucene_Index_FieldInfo $fieldInfo)
    {
        if (!isset($this->_fields[$fieldInfo->name])) {
            $fieldNumber = count($this->_fields);
            $this->_fields[$fieldInfo->name] =
                                new Zend_Search_Lucene_Index_FieldInfo(
                                    $fieldInfo->name,
                                    $fieldInfo->isIndexed,
                                    $fieldNumber,
                                    $fieldInfo->storeTermVector
                                );

            return $fieldNumber;
        } else {
            $this->_fields[$fieldInfo->name]->isIndexed       |= $fieldInfo->isIndexed;
            $this->_fields[$fieldInfo->name]->storeTermVector |= $fieldInfo->storeTermVector;

            return $this->_fields[$fieldInfo->name]->number;
        }
    }