An O(n^2) parser is not fine for the mere reason that I don't know how one would make such a mess of the job in the first place.

A simple recursive-descent parser is easy to write by hand and runs in linear time.

> A simple recursive-descent parser is easy to write by hand and runs in linear time.

Recursive descenrs parsers are not linear.

They are generally O(n^2) and can even can go exponential with some grammars if written naively.

It can be pretty easy to do adverserival attacks on most naive descent parser and bring it to its knees.

Packrat parser [^1] are linear, but they are by no means "trivial 200 lines" type of parsers.

[^1]: https://arxiv.org/abs/cs/0603077

Recursive descent isnt guaranteed linear time

In the face of backtracking the time depends on the complexity of the grammar, since it's basically a brute force search through all the rules.

I think the point was that even if you managed to make a O(n*2) parser it will ve fast enough for human entered problems.