Implement TextEncoder.

[Ms2ger]

Spec: https://encoding.spec.whatwg.org/#interface-textencoder.

This includes enabling the relevant tests by adding

[encoding]
  skip: false

to tests/wpt/include.ini.

This may also include updating the mozjs and rust-mozjs dependencies to ensure we can work with typed arrays.

[yodalee]

Allow me try this if you permit. I'm afraid that I may take long time to complete.

[SimonSapin]

Go ahead!

This is mostly about plugging things together between JavaScript and Rust. The rust-encoding library, which we already use in Servo, implements the encodings themselves as well as the label lookup.

http://doc.servo.org/encoding/index.html

[yodalee]

There is a problem: the codegen python cannot recognize USVString in webidls, or should I leave the encode method comment out now?

[jdm]

Just use DOMString instead and leave a FIXME comment.

[yodalee]

I'm stuck at Encoding method, which should find encoding name by utfLabel. I'm not sure how to implement these function.
Using a large match seems not a good idea. Using an Hashmap as a member of TextEncoder will require runtime initialization. I found there is a compile time Rust static map, but not sure I can use it.
https://github.com/sfackler/rust-phf
Any suggestion about this?

[Ms2ger]

Is this http://doc.servo.org/encoding/types/trait.Encoding.html#method.whatwg_name?

[yodalee]

OH! my fault (: P)

[SimonSapin]

Also http://doc.servo.org/encoding/label/fn.encoding_from_whatwg_label.html

[yodalee]

The spec said the TextEncoder should throw a RangeError if input label is not a UTF type. However, the RangeError is not defined in domexception. Should I add an new exception or is there alternative exception? The description message of EncodingError seems quite suitable for this.

---

Since I saw the link in DOMException.webidl
https://dom.spec.whatwg.org/#domexception
There it says

RangeException has been removed.

Or maybe it talking about two different thing?

[Ms2ger]

Using RangeError won't work right now; throw something sensible and file a followup for now.