Summary:
This adds `bridging::toJs` and `bridging::fromJs` functions that will safely cast to and from JSI values and C++ types. This is extensible by specializing `Bridging<T>` with `toJs` and/or `fromJs` static methods. There are specializations for most common C++ and JSI types along with tests for those.
C++ functions and lambdas will effortlessly bridge into JS, and bridging JS functions back into C++ require you to choose `SyncCallback<R(Args...)>` or `AsyncCallback<Args...>` types. The sync version allows for having a return value and is strictly not movable to prevent accidentally moving onto another thread. The async version will move its args onto the JS thread and safely call the callback there, but hence always has a `void` return value.
For promises, you can construct a `AsyncPromise<T>` that has `resolve` and `reject` methods that can be called from any thread, and will bridge into JS as a regular `Promise`.
Changelog:
[General][Added] - New bridging API for JSI <-> C++
Reviewed By: christophpurrer
Differential Revision: D34607143
fbshipit-source-id: d832ac24cf84b4c1672a7b544d82e324d5fca3ef
Scott Kyle