Using rustfmt programmatically

[kardeiz]

Unless I am missing something, there isn't a super nice way to use rustfmt programmatically—

For example, I have a project where I am generating some repetitive Rust code with syn and quote in build.rs. The output is missing newlines, etc., so it is desirable to run the code through rustfmt.

Currently I am writing the generated string to a file and then using rustfmt::format_input to format and overwrite that file. This works, and is really not so bad, I was mostly just surprised to find that there was no function like fn(config: Config, input: &str) -> String.

Is there some reason not to support this simple case? Or am I missing something?

[nrc]

You should be able to pass format_input an Input::Text(String), but it looks like this does not quite work since it relies on stdin.

There are a few technical problems here, but I have to fix them for IDE support too, so hopefully we'll have something soon.

[kardeiz]

Right, I tried the Input::Text(String) first, but couldn't get it to work. Thanks for the reply!

[nrc]

You could look at how the RLS calls Rustfmt as an example of how to do this.

[aep]

does it work now? i cant figure out how to get the actual output when using Input::Text(String)

[nrc]

@aep it does. Look at the code around https://github.com/rust-lang-nursery/rls/blob/master/src/actions/requests.rs#L769 for an example.

[bcmyers]

I'm not sure if this is the intended way of doing things, but I was able to cobble together some Rust code that does this (in large part thanks to nrc's link above). Here's the code. It (the function) takes a String representation of a rust module and returns a rustfmt formatted String representation of the same module. As already mentioned, though, I'm not at all sure if I'm doing this correctly. It would be nice if there were a well-documented official API for this use-case. In any case, posting here so that if someone else stumbles across this issue via a Google search (as I did), they'll have a simple example to go off of.

[SOF3]

@nrc' link broke. Use a canonical link instead: https://github.com/rust-lang/rls/blob/66c78983717c998c29e876777782d74a1e96e983/src/actions/requests.rs#L769