add etag header

[ajnirp]

fixes #170

[seanmonstar]

Thanks for getting this started!

Would you be able to fill in the missing parts from the spec? You can find a link to it in the issue you referenced. Specifically, the weak indicator needs to be stores on the struct, and the value must be inside quotation marks.

[jdm]

Hooray, this will make rebasing servo/servo#4117 easier :D

[ajnirp]

Build is failing, but apparently due to files not touched by this commit :/

[reem]

Can we split this up into smaller tests?

[seanmonstar]

Don't worry if the tests fail for another reason. That's pretty normal with rustc changing a little every day.

[seanmonstar]

I'd use a match statement here:

match c {
    b'\x21' | b'\x23' ... b'\x7e' | b'\x80' ... b'\xff' => (),
    _ => return false
}

[ajnirp]

done

[seanmonstar]

Excellent! This is looking really close. Also, could you remove the println!s? If you need any for debugging, use debug!(), and set the env var RUST_LOG=hyper::header::common::etag=debug to see them.

[seanmonstar]

Could you also add a pub use self::etag::Etag up top?

[seanmonstar]

One last nit, and I think this is good to go. Also, could you squash this into a single commit? git rebase -i master.

I was trying to decide if it'd be better to have this as an enum Etag { Weak(String), Strong(String) }, or to use a struct with a weak field, as you've done. I can't decide, so the way you've done it seems fine to me.

[ajnirp]

Squashed. Also, how do I test for tags containing chars in the x80-xff range? Apparently rust doesn't allow byte literals to exceed x7f.

[seanmonstar]

Seems odd. You can do '\u0080'.

[seanmonstar]

Thanks for wrapping this up! Looks great.

[ajnirp]

Welcome, and thanks for the mentoring :)