The optimization here is using incremental parsing, so that changing parse state goes from O(n) to may-as-well-be-O(1). It's probably linear with tree depth.

The optimization here is using incremental parsing, so that changing parse state goes from O(n) to may-as-well-be-O(1). It's probably linear with tree depth. Any language is fast enough to do this, certainly Go is. Naive parser combinators written in slow languages can tokenize six-figure LOC files fast enough that the user won't notice.