foo,bar,"quux
zap",bang
Is there any situation where csv fields can contain literal newline characters? (ascii value 10.)
Will post code fairly soon. There aren't any tricks. I just implemented slice as well.
Also, when you're ready, I would like to be able to run and inspect the code myself. :-)
Certainly!
EDIT: Ah, user error. CSVs can indeed contain literal newlines, and XSV handles that. I'll switch it to parse doublequoted strings and add some tests.
One simplification: if a line contains N commas, where N matches the number of columns minus one, then there's no need to parse it for count, slice, etc.
I would definitely be curious to know why your program is taking 184ms though. That isn't startup time, is it?
It's actually the time it takes to load in a C function to swap big-endian uint64 to little-endian.
Counting is interesting, because you don't have to implement unescaping to do it, but any robust csv parser will do it. So if you write two different versions of a csv parser, one for normal reading and one just for counting, then the one for counting can go faster and you'll avoid the need to amortize allocation. It's a nice trick though! However, I was using `xsv count` as a proxy for CSV parsing. So if you're just going to not do actual CSV parsing, then your solution is much less interesting. :-)
> I would definitely be curious to know why your program is taking 184ms though. That isn't startup time, is it?
> It's actually the time it takes to load in a C function to swap big-endian uint64 to little-endian.
Holy moly. Really? Do you know why it takes so long? That's a showstopper...
EDIT: I'm actually not sure what's going on with the startup time, since it's usually fast. I have quite a few windows open, which might be affecting results. (xsv count is suddenly taking ~70ms for simple data, so I think a reboot is in order.)
To clarify, I was mainly just excited to share some WIP. There's still a lot of work left to do to cross the finish line.
Also, counting records with an index isn't particular interesting, since it's just reading 8 bytes from the index file. I would definitely be curious to know why your program is taking 184ms though. That isn't startup time, is it?
In your comment above, you compared your CSV parser to `xsv stats --everything`, but `xsv stats` does a lot more than just CSV parsing. If you want to test how fast xsv takes to parse CSV, then `xsv count` without an index is the way to do it. `xsv` only takes 19ms on my machine to parse nfl_all_plays_small.csv, which is basically within process overhead time.
Also, when you're ready, I would like to be able to run and inspect the code myself. :-)
I warned you above: the key challenge you're going to face is creating a robust CSV parser, and using that to implement every command, including `count`. If that isn't a requirement, then basically all comparisons are unfortunately completely moot.