Add codegen for C++ TurboModule automatic type conversions

Summary:
This adds the *option* for C++ TurboModules to use a `*CxxSpec<T>` base class that extends the existing (and unchanged) corresponding `*CxxSpecJSI` base class with code-generated methods that use `bridging::calFromJs` to safely convert types between JSI and C++. If a type conversion cannot be made, then it will fail to compile.

Changelog:
[General][Added] - Automatic type conversions for C++ TurboModules

Reviewed By: christophpurrer

Differential Revision: D34780512

fbshipit-source-id: 58b34533c40652db8e3aea43804ceb73bcbe97a5

ReactCommon/react/bridging/Class.h

@@ -52,4 +52,14 @@ T callFromJs(
   }
 }
 
+template <typename R, typename... Args>
+constexpr size_t getParameterCount(R (*)(Args...)) {
+  return sizeof...(Args);
+}
+
+template <typename C, typename R, typename... Args>
+constexpr size_t getParameterCount(R (C::*)(Args...)) {
+  return sizeof...(Args);
+}
+
 } // namespace facebook::react::bridging

packages/react-native-codegen/src/generators/modules/GenerateModuleH.js

@@ -15,6 +15,7 @@ import type {
   SchemaType,
   NativeModuleTypeAnnotation,
   NativeModuleFunctionTypeAnnotation,
+  NativeModulePropertyShape,
 } from '../../CodegenSchema';
 
 import type {AliasResolver} from './Utils';
@@ -27,21 +28,58 @@ type FilesOutput = Map<string, string>;
 const ModuleClassDeclarationTemplate = ({
   hasteModuleName,
   moduleProperties,
-}: $ReadOnly<{hasteModuleName: string, moduleProperties: string}>) => {
+}: $ReadOnly<{hasteModuleName: string, moduleProperties: string[]}>) => {
   return `class JSI_EXPORT ${hasteModuleName}CxxSpecJSI : public TurboModule {
 protected:
   ${hasteModuleName}CxxSpecJSI(std::shared_ptr<CallInvoker> jsInvoker);
 
 public:
-  ${indent(moduleProperties, 2)}
+  ${indent(moduleProperties.join('\n'), 2)}
 
 };`;
 };
 
+const ModuleSpecClassDeclarationTemplate = ({
+  hasteModuleName,
+  moduleName,
+  moduleProperties,
+}: $ReadOnly<{
+  hasteModuleName: string,
+  moduleName: string,
+  moduleProperties: string[],
+}>) => {
+  return `template <typename T>
+class JSI_EXPORT ${hasteModuleName}CxxSpec : public TurboModule {
+public:
+  jsi::Value get(jsi::Runtime &rt, const jsi::PropNameID &propName) override {
+    return delegate_.get(rt, propName);
+  }
+
+protected:
+  ${hasteModuleName}CxxSpec(std::shared_ptr<CallInvoker> jsInvoker)
+    : TurboModule("${moduleName}", jsInvoker),
+      delegate_(static_cast<T*>(this), jsInvoker) {}
+
+private:
+  class Delegate : public ${hasteModuleName}CxxSpecJSI {
+  public:
+    Delegate(T *instance, std::shared_ptr<CallInvoker> jsInvoker) :
+      ${hasteModuleName}CxxSpecJSI(std::move(jsInvoker)), instance_(instance) {}
+
+    ${indent(moduleProperties.join('\n'), 4)}
+
+  private:
+    T *instance_;
+  };
+
+  Delegate delegate_;
+};`;
+};
+
 const FileTemplate = ({
   modules,
 }: $ReadOnly<{
-  modules: string,
+  modules: string[],
 }>) => {
   return `/**
  * This code was generated by [react-native-codegen](https://www.npmjs.com/package/react-native-codegen).
@@ -55,11 +93,12 @@ const FileTemplate = ({
 #pragma once
 
 #include <ReactCommon/TurboModule.h>
+#include <react/bridging/Bridging.h>
 
 namespace facebook {
 namespace react {
 
-${modules}
+${modules.join('\n\n')}
 
 } // namespace react
 } // namespace facebook
@@ -118,8 +157,52 @@ function translatePrimitiveJSTypeToCpp(
   }
 }
 
-const propertyTemplate =
-  'virtual ::_RETURN_VALUE_:: ::_PROPERTY_NAME_::(jsi::Runtime &rt::_ARGS_::) = 0;';
+function translatePropertyToCpp(
+  prop: NativeModulePropertyShape,
+  resolveAlias: AliasResolver,
+  abstract: boolean = false,
+) {
+  const [propTypeAnnotation] =
+    unwrapNullable<NativeModuleFunctionTypeAnnotation>(prop.typeAnnotation);
+
+  const params = propTypeAnnotation.params.map(
+    param => `std::move(${param.name})`,
+  );
+
+  const paramTypes = propTypeAnnotation.params.map(param => {
+    const translatedParam = translatePrimitiveJSTypeToCpp(
+      param.typeAnnotation,
+      typeName =>
+        `Unsupported type for param "${param.name}" in ${prop.name}. Found: ${typeName}`,
+      resolveAlias,
+    );
+    return `${translatedParam} ${param.name}`;
+  });
+
+  const returnType = translatePrimitiveJSTypeToCpp(
+    propTypeAnnotation.returnTypeAnnotation,
+    typeName => `Unsupported return type for ${prop.name}. Found: ${typeName}`,
+    resolveAlias,
+  );
+
+  // The first param will always be the runtime reference.
+  paramTypes.unshift('jsi::Runtime &rt');
+
+  const method = `${returnType} ${prop.name}(${paramTypes.join(', ')})`;
+
+  if (abstract) {
+    return `virtual ${method} = 0;`;
+  }
+
+  return `${method} override {
+  static_assert(
+      bridging::getParameterCount(&T::${prop.name}) == ${paramTypes.length},
+      "Expected ${prop.name}(...) to have ${paramTypes.length} parameters");
+
+  return bridging::callFromJs<${returnType}>(
+      rt, &T::${prop.name}, jsInvoker_, ${['instance_', ...params].join(', ')});
+}`;
+}
 
 module.exports = {
   generate(
@@ -130,55 +213,30 @@ module.exports = {
   ): FilesOutput {
     const nativeModules = getModules(schema);
 
-    const modules = Object.keys(nativeModules)
-      .map(hasteModuleName => {
-        const {
-          aliases,
-          spec: {properties},
-        } = nativeModules[hasteModuleName];
-        const resolveAlias = createAliasResolver(aliases);
-
-        const traversedProperties = properties
-          .map(prop => {
-            const [propTypeAnnotation] =
-              unwrapNullable<NativeModuleFunctionTypeAnnotation>(
-                prop.typeAnnotation,
-              );
-            const traversedArgs = propTypeAnnotation.params
-              .map(param => {
-                const translatedParam = translatePrimitiveJSTypeToCpp(
-                  param.typeAnnotation,
-                  typeName =>
-                    `Unsupported type for param "${param.name}" in ${prop.name}. Found: ${typeName}`,
-                  resolveAlias,
-                );
-                return `${translatedParam} ${param.name}`;
-              })
-              .join(', ');
-            return propertyTemplate
-              .replace('::_PROPERTY_NAME_::', prop.name)
-              .replace(
-                '::_RETURN_VALUE_::',
-                translatePrimitiveJSTypeToCpp(
-                  propTypeAnnotation.returnTypeAnnotation,
-                  typeName =>
-                    `Unsupported return type for ${prop.name}. Found: ${typeName}`,
-                  resolveAlias,
-                ),
-              )
-              .replace(
-                '::_ARGS_::',
-                traversedArgs === '' ? '' : ', ' + traversedArgs,
-              );
-          })
-          .join('\n');
-
-        return ModuleClassDeclarationTemplate({
+    const modules = Object.keys(nativeModules).flatMap(hasteModuleName => {
+      const {
+        aliases,
+        spec: {properties},
+        moduleNames: [moduleName],
+      } = nativeModules[hasteModuleName];
+      const resolveAlias = createAliasResolver(aliases);
+
+      return [
+        ModuleClassDeclarationTemplate({
+          hasteModuleName,
+          moduleProperties: properties.map(prop =>
+            translatePropertyToCpp(prop, resolveAlias, true),
+          ),
+        }),
+        ModuleSpecClassDeclarationTemplate({
           hasteModuleName,
-          moduleProperties: traversedProperties,
-        });
-      })
-      .join('\n');
+          moduleName,
+          moduleProperties: properties.map(prop =>
+            translatePropertyToCpp(prop, resolveAlias),
+          ),
+        }),
+      ];
+    });
 
     const fileName = `${libraryName}JSI.h`;
     const replacedTemplate = FileTemplate({modules});