I've also never seen a PCRE that actually works with such a stream, though it would be possible to construct one. For your remaining points, sure. I don't know

I've also never seen a PCRE that actually works with such a stream, though it would be possible to construct one. For your remaining points, sure. I don't know enough about text processing to know where the hard problems are. I do think that engineers sometimes overlook the possibility of having multiple data structures for multiple use cases for a single set of data, because it doesn't seem as elegant as one magical data structure that does it all.