GenerateModuleCpp: Replace string replace with string templates

Summary:
## Benefits:
- Improved Readability
- Improved type-safety with templates

Changelog: [Internal]

Differential Revision: D24386276

fbshipit-source-id: d5913122221960c06c5256af10ace1d2f7a60b49

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

@@ -24,32 +24,60 @@ const {unwrapNullable} = require('../../parsers/flow/modules/utils');
 
 type FilesOutput = Map<string, string>;
 
-const propertyHeaderTemplate =
-  'static jsi::Value __hostFunction_::_HASTE_MODULE_NAME_::CxxSpecJSI_::_PROPERTY_NAME_::(jsi::Runtime &rt, TurboModule &turboModule, const jsi::Value* args, size_t count) {';
+const HostFunctionTemplate = ({
+  hasteModuleName,
+  methodName,
+  isVoid,
+  args,
+}: $ReadOnly<{
+  hasteModuleName: string,
+  methodName: string,
+  isVoid: boolean,
+  args: Array<string>,
+}>) => {
+  const methodCallArgs = ['rt', ...args].join(', ');
+  const methodCall = `static_cast<${hasteModuleName}CxxSpecJSI *>(&turboModule)->${methodName}(${methodCallArgs});`;
 
-const propertyCastTemplate =
-  'static_cast<::_HASTE_MODULE_NAME_::CxxSpecJSI *>(&turboModule)->::_PROPERTY_NAME_::(rt::_ARGS_::);';
-
-const nonvoidPropertyTemplate = `${propertyHeaderTemplate}
-  return ${propertyCastTemplate}
-}`.trim();
-
-const voidPropertyTemplate = `${propertyHeaderTemplate}
-  ${propertyCastTemplate}
-  return jsi::Value::undefined();
+  return `static jsi::Value __hostFunction_${hasteModuleName}CxxSpecJSI_${methodName}(jsi::Runtime &rt, TurboModule &turboModule, const jsi::Value* args, size_t count) {${
+    isVoid ? `\n  ${methodCall}` : ''
+  }
+  return ${isVoid ? 'jsi::Value::undefined();' : methodCall}
 }`;
+};
 
-const proprertyDefTemplate =
-  '  methodMap_["::_PROPERTY_NAME_::"] = MethodMetadata {::_ARGS_COUNT_::, __hostFunction_::_HASTE_MODULE_NAME_::CxxSpecJSI_::_PROPERTY_NAME_::};';
+const ModuleTemplate = ({
+  hasteModuleName,
+  hostFunctions,
+  moduleName,
+  methods,
+}: $ReadOnly<{|
+  hasteModuleName: string,
+  hostFunctions: $ReadOnlyArray<string>,
+  moduleName: string,
+  methods: $ReadOnlyArray<
+    $ReadOnly<{|methodName: string, paramCount: number|}>,
+  >,
+|}>) => {
+  return `${hostFunctions.join('\n')}
 
-const moduleTemplate = `::_MODULE_PROPERTIES_::
+${hasteModuleName}CxxSpecJSI::${hasteModuleName}CxxSpecJSI(std::shared_ptr<CallInvoker> jsInvoker)
+  : TurboModule("${moduleName}", jsInvoker) {
+${methods
+  .map(({methodName, paramCount}) => {
+    return `  methodMap_["${methodName}"] = MethodMetadata {${paramCount}, __hostFunction_${hasteModuleName}CxxSpecJSI_${methodName}};`;
+  })
+  .join('\n')}
+}`;
+};
 
-::_HASTE_MODULE_NAME_::CxxSpecJSI::::_HASTE_MODULE_NAME_::CxxSpecJSI(std::shared_ptr<CallInvoker> jsInvoker)
-  : TurboModule("::_NATIVE_MODULE_NAME_::", jsInvoker) {
-::_PROPERTIES_MAP_::
-}`.trim();
-
-const template = `/**
+const FileTemplate = ({
+  libraryName,
+  modules,
+}: $ReadOnly<{
+  libraryName: string,
+  modules: string,
+}>) => {
+  return `/**
  * ${'C'}opyright (c) Facebook, Inc. and its affiliates.
  *
  * This source code is licensed under the MIT license found in the
@@ -58,19 +86,20 @@ const template = `/**
  * ${'@'}generated by codegen project: GenerateModuleH.js
  */
 
-#include <react/modules/::_LIBRARY_NAME_::/NativeModules.h>
+#include <react/modules/${libraryName}/NativeModules.h>
 
 namespace facebook {
 namespace react {
 
-::_MODULES_::
+${modules}
 
 
 } // namespace react
 } // namespace facebook
 `;
+};
 
-function traverseArg(
+function serializeArg(
   arg: NativeModuleMethodParamSchema,
   index: number,
   resolveAlias: AliasResolver,
@@ -127,7 +156,8 @@ function traverseArg(
   }
 }
 
-function traverseProperty(
+function serializePropertyIntoHostFunction(
+  hasteModuleName: string,
   property: NativeModulePropertySchema,
   resolveAlias: AliasResolver,
 ): string {
@@ -136,16 +166,17 @@ function traverseProperty(
   ] = unwrapNullable<NativeModuleFunctionTypeAnnotation>(
     property.typeAnnotation,
   );
-  const propertyTemplate =
-    propertyTypeAnnotation.returnTypeAnnotation.type === 'VoidTypeAnnotation'
-      ? voidPropertyTemplate
-      : nonvoidPropertyTemplate;
-  const traversedArgs = propertyTypeAnnotation.params
-    .map((p, i) => traverseArg(p, i, resolveAlias))
-    .join(', ');
-  return propertyTemplate
-    .replace(/::_PROPERTY_NAME_::/g, property.name)
-    .replace(/::_ARGS_::/g, traversedArgs === '' ? '' : ', ' + traversedArgs);
+  const isVoid =
+    propertyTypeAnnotation.returnTypeAnnotation.type === 'VoidTypeAnnotation';
+
+  return HostFunctionTemplate({
+    hasteModuleName,
+    methodName: property.name,
+    isVoid,
+    args: propertyTypeAnnotation.params.map((p, i) =>
+      serializeArg(p, i, resolveAlias),
+    ),
+  });
 }
 
 module.exports = {
@@ -157,7 +188,7 @@ module.exports = {
     const nativeModules = getModules(schema);
 
     const modules = Object.keys(nativeModules)
-      .map(hasteModuleName => {
+      .map((hasteModuleName: string) => {
         const nativeModule = nativeModules[hasteModuleName];
         const {
           aliases,
@@ -165,39 +196,37 @@ module.exports = {
           moduleNames,
         } = nativeModule;
         const resolveAlias = createAliasResolver(aliases);
-        const traversedProperties = properties
-          .map(property => traverseProperty(property, resolveAlias))
-          .join('\n');
-        return (
-          moduleTemplate
-            .replace(/::_MODULE_PROPERTIES_::/g, traversedProperties)
-            // TODO: What happens when there are more than one NativeModule requires?
-            .replace('::_NATIVE_MODULE_NAME_::', moduleNames[0])
-            .replace(
-              '::_PROPERTIES_MAP_::',
-              properties
-                .map(
-                  ({
-                    name: propertyName,
-                    typeAnnotation: nullableTypeAnnotation,
-                  }) => {
-                    const [{params}] = unwrapNullable(nullableTypeAnnotation);
-                    return proprertyDefTemplate
-                      .replace(/::_PROPERTY_NAME_::/g, propertyName)
-                      .replace(/::_ARGS_COUNT_::/g, params.length.toString());
-                  },
-                )
-                .join('\n'),
-            )
-            .replace(/::_HASTE_MODULE_NAME_::/g, hasteModuleName)
+        const hostFunctions = properties.map(property =>
+          serializePropertyIntoHostFunction(
+            hasteModuleName,
+            property,
+            resolveAlias,
+          ),
         );
+
+        return ModuleTemplate({
+          hasteModuleName,
+          hostFunctions,
+          // TODO: What happens when there are more than one NativeModule requires?
+          moduleName: moduleNames[0],
+          methods: properties.map(
+            ({name: propertyName, typeAnnotation: nullableTypeAnnotation}) => {
+              const [{params}] = unwrapNullable(nullableTypeAnnotation);
+              return {
+                methodName: propertyName,
+                paramCount: params.length,
+              };
+            },
+          ),
+        });
       })
       .join('\n');
 
     const fileName = 'NativeModules.cpp';
-    const replacedTemplate = template
-      .replace(/::_MODULES_::/g, modules)
-      .replace(/::_LIBRARY_NAME_::/g, libraryName);
+    const replacedTemplate = FileTemplate({
+      modules,
+      libraryName,
+    });
     return new Map([[fileName, replacedTemplate]]);
   },
 };