protected function getPassthroughCapture()
	{
		$passthrough = 0;
		foreach ($this->references['inText'] as $key)
		{
			if (!$this->isCatchAll($this->captures[$key]['expr']))
			{
				// Ignore if it's not a catch-all expression such as .*?
				continue;
			}
			if ($passthrough)
			{
				// Abort if there's more than 1 possible passthrough
				$passthrough = 0;
				break;
			}
			$passthrough = (int) $key;
		}

		return $passthrough;
	}