FYI I got rid of this line, now I just don't add the quotes in the first place, unless the caller requests it. Performance didn't actually change, but it looks smarter. Thanks again for the review though.

30% performance improvement after removing the `yield return`, and readability is probably better too.

I will add a micro benchmark to see if the `yield return` is slowing things down, compared to just calling _sb.Add() inside Read*(). I will also see if it looks cleaner that way. To be honest, the `yield return` is currently in there just because I thought it's "cool".

The unit tests have an emoji test (which uses a surrogate pair). I thought I would have to use Runes, but it's not necessary. https://github.com/kjpgit/SmallestCSVParser/blob/master/Smal...

Thanks... I didn't think that would compile on .net 6, but it does!

You can probably shorten it to

    column[1..]

and it compiles down to a Substring call, and ranges are part of C# 8, so they exist since .NET Core 3.1. But even if the syntax is newer (e.g. collection expressions in C# 12) you can often also use features on older target frameworks if they don't require additional runtime support (and even that can often be retrofitted internally).

That's different. It includes the last character.