boa: create a new DSL to generate JavaScript native extension

[yorkie]

As we have discussed at #172, to support boa is able to work on multiple platforms includes: N-API, WASM, Rust-based native extension for Deno.

@yjjnls has created a great project: https://github.com/yjjnls/napi-emscripten, which uses emscripten APIs as the DSL to generate N-API-based add-ons.

Boa is heavily based on N-API and it's mainly working for Node.js, therefore we are going to propose creating a N-API based DSL which could generate N-API, WASM, Deno extension and more.

Just feel free to comment anything if something wrong :)

[rickyes]

Perhaps we could also use Emscripten APIs to generate WASM, as napi-emscripten does.

[yorkie]

napi-emscripten seems using Emscripten API to generate the N-API.

[yorkie]

Or we can just compile CPython to .wasm and call it in JavaScript.

[rickyes]

IMO it works, given that WASM will be supported by more platforms in the future.

[yorkie]

But we need to maintain the wasm-backend for boa/lib/*, how do you think about this implementation?

[rickyes]

Maybe we need to maintain the various versions of boa/lib/*, which does not look too good.

[yorkie]

Hmm, wasm-backend is for reducing the maintenance of that works IMHO.

[rickyes]

I have some ideas and don't know if they'll work:

1. compile Boa NAPI-addon as .wasm
2. write DSL, generate extensions for each platforms based on existing boa/lib/* code

[yorkie]

I'm -1 on the first one, that's really to implement because the N-API and WASM have some differences especially like Node.js Buffer, and write a DSL to generate extensions for platforms have the same implementation issue.

Why not try to maintain both the 2 backends(napi, wasm), that we can cover all possible issues one by one :)