feat(hydrated_bloc): support wasm

[LukasMirbt]

Description

The default HydratedStorage currently does not support WebAssembly compilation.

Reproduction steps:

1. Create an empty Flutter application

2. Add hydrated_bloc: ^9.1.5 to pubspec.yaml

3. Replace main.dart with:

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  HydratedBloc.storage = await HydratedStorage.build(
    storageDirectory: HydratedStorage.webStorageDirectory
  );
  runApp(App());
}

4. Run flutter run -d chrome --wasm --debug

Desired Solution

Support WebAssembly compilation with the default HydratedStorage.

Alternatives Considered

• Using a custom HydratedStorage

Additional Context

Relevant GitHub conversation about wasm support in the Hive repo: isar/hive#1291

[alexandrim0]

May be it is much easier to use hive_ce (drop in replacement which already supports wasm)?
But also it needs cut out using of dart:io.
I had an experiment and it works!

[alexandrim0]

@felangel would you move HydratedStorage class to new package to make this one independent of hive?

[felangel]

@felangel would you move HydratedStorage class to new package to make this one independent of hive?

What would be the benefit of a separate package? You can already swap out the storage.

[alexandrim0]

File hydrated_storage.dart contains both classes Storage and HydratedStorage, so it imports hive and dart:io.
That is why it wont works in wasm runtime, as wrote topic starter.

[quoc-huynh-cosee]

@felangel One benefit would be that if people don't use Hive as HydratedStorage, the license won't be listed. Currently even if a user opts not to use Hive, the license is still displayed using showLicensePage().

[felangel]

We'd still need to ship a default HydratedStorage implementation if we decouple the package from hive. Are you all suggesting that we implement a custom key/value storage instead of using hive as the default?

[alexandrim0]

hive_ce could be as default storage to resolve this issue, except dependency on dart:io.
I can not see if it is simple for you to drop it or not.

But hydrated_bloc is a core package and should not dependent on any other specific packages, IMHO.
I still vote for separate packages for any specific storage.

Thank you!