Summary:
NativeModules are instantiated by the bridge. If they choose, they can capture the bridge instance that instantiated them. From within the NativeModule, the bridge can then be used to lookup other NativeModules. TurboModules have no way to do such a lookup.
Both NativeModules and TurboModules need to be able to query for one another. Therefore, we have four cases:
1. NativeModule accesses NativeModule.
2. NativeModule accesses TurboModule.
3. TurboModule accesses NativeModule.
4. TurboModule accesses TurboModule.
In summary, this solution extends the bridge to support querying TurboModules. It also introduces a `RCTTurboModuleLookupDelegate` protocol, which, implemented by `RCTTurboModuleManager`, supports querying TurboModules:
```
protocol RCTTurboModuleLookupDelegate <NSObject>
- (id)moduleForName:(NSString *)moduleName;
- (id)moduleForName:(NSString *)moduleName warnOnLookupFailure:(BOOL)warnOnLookupFailure;
- (BOOL)moduleIsInitialized:(NSString *)moduleName
end
```
If TurboModules want to query other TurboModules, then they need to implement this protocol and synthesize `turboModuleLookupDelegate`:
```
protocol RCTTurboModuleWithLookupCapabilities
property (nonatomic, weak) id<RCTTurboModuleLookupDelegate> turboModuleLookupDelegate;
end
```
NativeModules will continue to use `RCTBridge` to access other NativeModules. Nothing needs to change.
When we attach the bridge to `RCTTurboModuleManager`, we also attach `RCTTurboModuleManager` to the bridge as a `RCTTurboModuleLookupDelegate`. This allows the bridge to query TurboModules, which enables our NativeModules to transparently (i.e: without any NativeModule code modification) query TurboModules.
In an ideal world, all modules would be TurboModules. Until then, we're going to require that TurboModules use the bridge to query for NativeModules or TurboModules.
`RCTTurboModuleManager` keeps a map of all TurboModules that we instantiated. We simply search in this map and return the TurboModule.
This setup allows us to switch NativeModules to TurboModules without compromising their ability to use the bridge to search for other NativeModules (and TurboModules). When we write new TurboModules, we can have them use `RCTTurboModuleLookupDelegate` to do access other TurboModules. Eventually, after we migrate all NativeModules to TurboModules, we can migrate all old callsites to use `RCTTurboModuleLookupDelegate`.
Reviewed By: fkgozali
Differential Revision: D13553186
fbshipit-source-id: 4d0488eef081332c8b70782e1337eccf10717dae
0ceefb40d5