WASM Demo

[ashu26jha]

This Pull Request is intended to shift our WASM demo from using create_compiled to dynamically load locales whenever request from a front end. It achieves falling task:

1. Created a DataProviderManager which forks locales on the go

2. Added fallback with config

3. It prints the fallback locale, also printing trying possibilties

   • Instead of logging in the console, we display onto the frontend if. It could a better user experence. This needs approval.

Fixes #2769

Also we could also discuss the possiblity of adding DataGen in our FFI declarations, I could only find it for Dart, not for C++ and JavaScript. I could work on this, if this is what dev wants. This could be useful reduce application's binary size, for eg.

1. Retrieve user's system locale.
2. Generate the data dynamically for that locale only.

[sffc]

Thanks for looking into this!

[sffc]

Issue: enable_locale_fallback_with should take a ICU4XLocaleFallbacker, not a ICU4XLocaleFallbackerWithConfig. I think TypeScript should catch this

[ashu26jha]

Actually I wanted to display the fallbacked locale. ICU4XLocaleFallbackerWithConfig gives an iterator which helps to get the fallback, not sure how to achieve this using ICU4XLocaleFallbacker.

Also it doesn't through an error 😕

[robertbastian]

The resolved locale is returned in DataResponseMetdata.locale (None if it's the request locale).

[robertbastian]

(oh this is not Rust, ignore my comment).

[ashu26jha]

Just to test the new fallbacker instead of ICU4XLocaleFallbackerWithConfig. I tried to write this function, but couldn't create the formatter:

let enProvider = await createDataProviderFromBlob('dist/en.postcard');
let unProvider = await createDataProviderFromBlob('dist/und.postcard');
let fallbacker = ICU4XLocaleFallbacker.create(unProvider);
enProvider.enable_locale_fallback_with(fallbacker);
const locale = result(() => ICU4XLocale.create_from_string("bn"));
const groupingStrategy = ICU4XFixedDecimalGroupingStrategy.Auto;
const formatter = result(() => ICU4XFixedDecimalFormatter.create_with_grouping_strategy(
    enProvider,
    unwrap(locale),
    groupingStrategy
));

Also @robertbastian for caching we could possible generate a hash of gen.sh, If this hash is not changed no need to generate files again. This way we will avoid repeated use of datagen.

[ashu26jha]

Tried this with dist/und.postcard, with no help. Will fix this in consecutive commits**

[ashu26jha]

Added changes suggested by @sffc & @robertbastian except the fallbacker. I have added a sample code of how I am planning to integrate. Is this the correct way to integrate fallbacker?

[sffc]

ICU4X WG discussion:

• @robertbastian - For splitting locales, this seems reasonable. However, ideally we could also split functionality, but that might result in more duplication.
• @robertbastian - The data provider manager that is being implemented might better live in the FFI crate. We could upstream it later. Might need callbacks.

Conclusion: yes, merge this PR after comments have been resolved.