protected function parseQuotePairs($regexp, $leftQuote, $rightQuote)
	{
		preg_match_all($regexp, $this->text, $matches, PREG_OFFSET_CAPTURE);
		foreach ($matches[0] as $m)
		{
			$left  = $this->addTag($m[1], 1, $leftQuote);
			$right = $this->addTag($m[1] + strlen($m[0]) - 1, 1, $rightQuote);

			// Cascade left tag's invalidation to the right so that if we skip the left quote,
			// the right quote remains untouched
			$left->cascadeInvalidationTo($right);
		}
	}