Refactor weak-node-api generator

packages/weak-node-api/.gitignore

@@ -2,6 +2,7 @@
 # Everything in weak-node-api is generated, except for the configurations
 # Generated and built via `npm run bootstrap`
 /build/
+/build-tests/
 /*.xcframework
 /*.android.node
 /generated/weak_node_api.cpp

packages/weak-node-api/package.json

@@ -33,6 +33,9 @@
     "build-weak-node-api:apple": "node --run build-weak-node-api -- --apple",
     "build-weak-node-api:all": "node --run build-weak-node-api -- --android --apple",
     "test": "tsx --test --test-reporter=@reporters/github --test-reporter-destination=stdout --test-reporter=spec --test-reporter-destination=stdout src/node/**/*.test.ts src/node/*.test.ts",
+    "test:configure": "cmake -S . -B build-tests -DBUILD_TESTS=ON",
+    "test:build": "cmake --build build-tests",
+    "test:run": "ctest --test-dir build-tests --output-on-failure",
     "bootstrap": "node --run prepare-weak-node-api && node --run build-weak-node-api",
     "prerelease": "node --run prepare-weak-node-api && node --run build-weak-node-api:all"
   },

packages/weak-node-api/scripts/generate-weak-node-api.ts

@@ -9,92 +9,114 @@ import {
 
 export const OUTPUT_PATH = path.join(import.meta.dirname, "../generated");
 
+type GenerateFileOptions = {
+  functions: FunctionDecl[];
+  fileName: string;
+  generator: (functions: FunctionDecl[]) => string;
+};
+
+async function generateFile({
+  functions,
+  fileName,
+  generator,
+}: GenerateFileOptions) {
+  const output = generator(functions);
+  const outputPath = path.join(OUTPUT_PATH, fileName);
+  await fs.promises.writeFile(outputPath, output, "utf-8");
+  cp.spawnSync("clang-format", ["-i", outputPath], { stdio: "inherit" });
+}
+
+async function run() {
+  await fs.promises.mkdir(OUTPUT_PATH, { recursive: true });
+
+  const functions = getNodeApiFunctions();
+  await generateFile({
+    functions,
+    fileName: "weak_node_api.hpp",
+    generator: generateHeader,
+  });
+  await generateFile({
+    functions,
+    fileName: "weak_node_api.cpp",
+    generator: generateSource,
+  });
+}
+
+export function generateFunctionDecl({
+  returnType,
+  name,
+  argumentTypes,
+}: FunctionDecl) {
+  return `${returnType} (*${name})(${argumentTypes.join(", ")});`;
+}
+
 /**
  * Generates source code for a version script for the given Node API version.
  */
 export function generateHeader(functions: FunctionDecl[]) {
-  return [
-    "// This file is generated by react-native-node-api",
-    "#include <node_api.h>", // Node-API
-    "#include <stdio.h>", // fprintf()
-    "#include <stdlib.h>", // abort()
-    "",
+  return `
+    // This file is generated by react-native-node-api
+    #include <node_api.h> // Node-API
+    #include <stdio.h> // fprintf()
+    #include <stdlib.h> // abort()
+
     // Ideally we would have just used NAPI_NO_RETURN, but
     // __declspec(noreturn) (when building with Microsoft Visual C++) cannot be used on members of a struct
     // TODO: If we targeted C++23 we could use std::unreachable()
-    "#if defined(__GNUC__)",
-    "#define WEAK_NODE_API_UNREACHABLE __builtin_unreachable();",
-    "#else",
-    "#define WEAK_NODE_API_UNREACHABLE __assume(0);",
-    "#endif",
-    "",
+
+    #if defined(__GNUC__)
+    #define WEAK_NODE_API_UNREACHABLE __builtin_unreachable();
+    #else
+    #define WEAK_NODE_API_UNREACHABLE __assume(0);
+    #endif
+
     // Generate the struct of function pointers
-    "struct WeakNodeApiHost {",
-    ...functions.map(({ returnType, name, argumentTypes }) =>
-      [
-        returnType,
-        // Signature
-        `(*${name})(${argumentTypes.join(", ")});`,
-      ].join(" "),
-    ),
-    "};",
-    "typedef void(*InjectHostFunction)(const WeakNodeApiHost&);",
-    `extern "C" void inject_weak_node_api_host(const WeakNodeApiHost& host);`,
-  ].join("\n");
+    struct WeakNodeApiHost {
+      ${functions.map(generateFunctionDecl).join("\n")}
+    };
+    typedef void(*InjectHostFunction)(const WeakNodeApiHost&);
+    extern "C" void inject_weak_node_api_host(const WeakNodeApiHost& host);
+  `;
+}
+
+function generateFunctionImpl({
+  returnType,
+  name,
+  argumentTypes,
+  noReturn,
+}: FunctionDecl) {
+  return `
+    extern "C" ${returnType} ${name}(
+      ${argumentTypes.map((type, index) => `${type} arg${index}`).join(", ")}
+    ) {
+      if (g_host.${name} == nullptr) {
+        fprintf(stderr, "Node-API function '${name}' called before it was injected!\\n");
+        abort();
+      }
+      ${returnType === "void" ? "" : "return "} g_host.${name}(
+        ${argumentTypes.map((_, index) => `arg${index}`).join(", ")}
+      );
+      ${noReturn ? "WEAK_NODE_API_UNREACHABLE" : ""}
+    };
+  `;
 }
 
 /**
  * Generates source code for a version script for the given Node API version.
  */
 export function generateSource(functions: FunctionDecl[]) {
-  return [
-    "// This file is generated by react-native-node-api",
-    `#include "weak_node_api.hpp"`, // Generated header
-    // Generate the struct of function pointers
-    "WeakNodeApiHost g_host;",
-    "void inject_weak_node_api_host(const WeakNodeApiHost& host) {",
-    "  g_host = host;",
-    "};",
-    ``,
-    // Generate function calling into the host
-    ...functions.flatMap(({ returnType, name, argumentTypes, noReturn }) => {
-      return [
-        'extern "C"',
-        returnType,
-        name,
-        "(",
-        argumentTypes.map((type, index) => `${type} arg${index}`).join(", "),
-        ") {",
-        `if (g_host.${name} == nullptr) {`,
-        `  fprintf(stderr, "Node-API function '${name}' called before it was injected!\\n");`,
-        "  abort();",
-        "}",
-        returnType === "void" ? "" : "return ",
-        `g_host.${name}`,
-        "(",
-        argumentTypes.map((_, index) => `arg${index}`).join(", "),
-        ");",
-        noReturn ? "WEAK_NODE_API_UNREACHABLE" : "",
-        "};",
-      ].join(" ");
-    }),
-  ].join("\n");
-}
+  return `
+    // This file is generated by react-native-node-api
+    #include "weak_node_api.hpp" // Generated header
 
-async function run() {
-  await fs.promises.mkdir(OUTPUT_PATH, { recursive: true });
-
-  const nodeApiFunctions = getNodeApiFunctions();
-
-  const header = generateHeader(nodeApiFunctions);
-  const headerPath = path.join(OUTPUT_PATH, "weak_node_api.hpp");
-  await fs.promises.writeFile(headerPath, header, "utf-8");
-  cp.spawnSync("clang-format", ["-i", headerPath], { stdio: "inherit" });
-
-  const source = generateSource(nodeApiFunctions);
-  const sourcePath = path.join(OUTPUT_PATH, "weak_node_api.cpp");
-  await fs.promises.writeFile(sourcePath, source, "utf-8");
-  cp.spawnSync("clang-format", ["-i", sourcePath], { stdio: "inherit" });
+    WeakNodeApiHost g_host;
+    void inject_weak_node_api_host(const WeakNodeApiHost& host) {
+      g_host = host;
+    };
+
+    // Generate function calling into the host
+    ${functions.map(generateFunctionImpl).join("\n")}
+  `;
 }
 
 run().catch((err) => {