public function getIndexData() {
		if ($this->index === null) {
			$currentPointer = ftell($this->file);
			fseek($this->file, 0);
			
			$count       = 0;
			$this->index = [];
			
			while (fgets($this->file) !== false) {
				$this->index[++ $count] = ftell($this->file);
			}

			fseek($this->file, $currentPointer);
		}
		
		return $this->index;
	}