protected function computeValue($expr)
	{
		$properties = [
			'exprIsChar'         => self::IS_CHAR,
			'exprIsQuantifiable' => self::IS_QUANTIFIABLE
		];
		$value = (1 + count($this->meta)) * -pow(2, count($properties));
		foreach ($properties as $methodName => $bitValue)
		{
			if ($this->$methodName($expr))
			{
				$value |= $bitValue;
			}
		}

		return $value;
	}