/**
  * Create dicrionary, frequency and positions files and write necessary headers
  */
 public function initializeDictionaryFiles()
 {
     $this->_tisFile = $this->_directory->createFile($this->_name . '.tis');
     $this->_tisFile->writeInt((int) 0xfffffffd);
     $this->_tisFile->writeLong(0);
     $this->_tisFile->writeInt(self::$indexInterval);
     $this->_tisFile->writeInt(self::$skipInterval);
     $this->_tisFile->writeInt(self::$maxSkipLevels);
     $this->_tiiFile = $this->_directory->createFile($this->_name . '.tii');
     $this->_tiiFile->writeInt((int) 0xfffffffd);
     $this->_tiiFile->writeLong(0);
     $this->_tiiFile->writeInt(self::$indexInterval);
     $this->_tiiFile->writeInt(self::$skipInterval);
     $this->_tiiFile->writeInt(self::$maxSkipLevels);
     /** Dump dictionary header */
     $this->_tiiFile->writeVInt(0);
     // preffix length
     $this->_tiiFile->writeString('');
     // suffix
     $this->_tiiFile->writeInt((int) 0xffffffff);
     // field number
     $this->_tiiFile->writeByte((int) 0xf);
     $this->_tiiFile->writeVInt(0);
     // DocFreq
     $this->_tiiFile->writeVInt(0);
     // FreqDelta
     $this->_tiiFile->writeVInt(0);
     // ProxDelta
     $this->_tiiFile->writeVInt(24);
     // IndexDelta
     $this->_frqFile = $this->_directory->createFile($this->_name . '.frq');
     $this->_prxFile = $this->_directory->createFile($this->_name . '.prx');
     $this->_files[] = $this->_name . '.tis';
     $this->_files[] = $this->_name . '.tii';
     $this->_files[] = $this->_name . '.frq';
     $this->_files[] = $this->_name . '.prx';
     $this->_prevTerm = null;
     $this->_prevTermInfo = null;
     $this->_prevIndexTerm = null;
     $this->_prevIndexTermInfo = null;
     $this->_lastIndexPosition = 24;
     $this->_termCount = 0;
 }