add bidnings to TextEncoder/TextDecoder

[cometkim]

• TextEncoder
• TextDecoder

Both are available on browsers, Node.js, and Deno.

In most cases, it is used without arguments

// UTF-8 encoding/decoding

let e = TextEncoder.make()

e->TextEncoder.encoding // "utf-8"
let bin = e->TextEncoder.encode("Hello, World!")

let d = TextDecoder.make()
d->TextDecoder.decode(bin) // "Hello, World!"

I added some additional bindings to support the full specification.

[TheSpyder]

Looks like a good start! Since this is creating a new type rather than reusing something from ReScript, feel free to use the records-as-objects capability of ReScript instead of @get methods:

type t = pri {
  encoding: string,
  fatal: bool,
  ignoreBOM: bool
}

Then your code can look like this:

let e = TextEncoder.make()
e.encoding // "utf-8"

[cometkim]

Thanks, @TheSpyder

TIL a binding pattern!

[TheSpyder]

Haha yeah it's not obvious but a really nice ergonomic way to do bindings.

So, two more things before we can merge:

• Add something to the test folder. These files aren't tests we run, they just validate that the correct JS is generated (the JS is checked in to help with this).
• Changelog entry

[cometkim]

There is also TextDecoderStream API in the web, which depends on ReadableStream and WritableStream interface.

Since the WritableStream binding is still empty, I leave it to do.

[TheSpyder]

Apologies for not picking up on the other thing that needs changing when I reviewed last week.

[TheSpyder]

While I appreciate the sentiment to make the bindings more usable, we want these bindings to be zero-cost as much as possible. In this case ReScript 10 should have a new feature that makes makeDecoderOptions unnecessary, but it will be easier to switch to the upcoming style if the exported API takes a decoderOptions.

Please remove the private wrappers and export the more difficult to use way for now; here and below.

Suggested change

	%%private(
	@new external _makeWithOptions: (string, decoderOptions) => t = "TextDecoder"
	@obj
	external makeDecoderOptions: (
	~fatal: option<bool>=?,
	~ignoreBOM: option<bool>=?,
	unit,
	) => decoderOptions = ""
	)
	@new external make: unit => t = "TextDecoder"
	let makeWithOptions = (~encoding="utf-8", ~fatal=?, ~ignoreBOM=?, ()) =>
	_makeWithOptions(encoding, makeDecoderOptions(~fatal, ~ignoreBOM, ()))
	@obj
	external makeDecoderOptions: (
	~fatal: option<bool>=?,
	~ignoreBOM: option<bool>=?,
	unit,
	) => decoderOptions = ""
	@new external make: unit => t = "TextDecoder"
	@new external makeWithOptions: (string, decoderOptions) => t = "TextDecoder"

[spocke]

You could still have a name argument for the encoding helps people to know that that parameter is supposed to be:
@new external makeWithOptions: (~encoding: string, decoderOptions) => t = "TextDecoder"