Regex: Workaround for PHP's look-behind fixed-length assert limitation
问题 I'm trying to understand more about look-around asserts and I found this thread, where their solution is supposed to work in some engines but not PHP's, because of PHP's requiring the look-behind assert to be fixed-length. What I want is to make the same scenario work in PHP or at least know if it's possible at all. I tried to reduce the regex rules explanation, so it's not the same as in the thread I mention above, but it follows the same principle. Need to match a string built in three