function reset($pos = null, $l = 100) {
		if (!is_null ($pos)) {
			fseek ($this->file, $pos);
		}

		$this->buffer = $l > 0 ? fread($this->file, $l) : '';
		$this->offset = 0;
		$this->length = strlen($this->buffer);
		$this->stack = array();
	}