I love to geek out on this sort of stuff. Data Structures for Text Sequences by Charles Crowley [1] is a great read. I would also recommend checking out the Vis editor [2]. It's an interesting Vi like editor that uses the piece chain as its data structure and supports Sam's structural regular expressions.

[1] https://www.cs.unm.edu/~crowley/papers/sds.pdf

[2] https://github.com/martanne/vis