Move existing generators to a separate file

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

@@ -1,3 +1,4 @@
+import assert from "node:assert/strict";
 import fs from "node:fs";
 import path from "node:path";
 import cp from "node:child_process";
@@ -7,6 +8,8 @@ import {
   getNodeApiFunctions,
 } from "../src/node-api-functions.js";
 
+import * as weakNodeApiGenerator from "./generators/weak-node-api.js";
+
 export const OUTPUT_PATH = path.join(import.meta.dirname, "../generated");
 
 type GenerateFileOptions = {
@@ -20,10 +23,18 @@ async function generateFile({
   fileName,
   generator,
 }: GenerateFileOptions) {
-  const output = generator(functions);
+  const generated = generator(functions);
+  const output = `// This file is generated - don't edit it directly\n\n${generated}`;
   const outputPath = path.join(OUTPUT_PATH, fileName);
   await fs.promises.writeFile(outputPath, output, "utf-8");
-  cp.spawnSync("clang-format", ["-i", outputPath], { stdio: "inherit" });
+  const { status, stderr = "No error output" } = cp.spawnSync(
+    "clang-format",
+    ["-i", outputPath],
+    {
+      encoding: "utf8",
+    },
+  );
+  assert.equal(status, 0, `Failed to format ${fileName}: ${stderr}`);
 }
 
 async function run() {
@@ -33,92 +44,15 @@ async function run() {
   await generateFile({
     functions,
     fileName: "weak_node_api.hpp",
-    generator: generateHeader,
+    generator: weakNodeApiGenerator.generateHeader,
   });
   await generateFile({
     functions,
     fileName: "weak_node_api.cpp",
-    generator: generateSource,
+    generator: weakNodeApiGenerator.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()
-
-    // 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
-
-    // Generate the struct of function pointers
-    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
-
-    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) => {
   console.error(err);
   process.exitCode = 1;

packages/weak-node-api/scripts/generators/shared.ts

@@ -0,0 +1,28 @@
+import type { FunctionDecl } from "../../src/node-api-functions.js";
+
+type FunctionOptions = FunctionDecl & {
+  extern?: true;
+  static?: true;
+  namespace?: string;
+  body?: string;
+  argumentNames?: string[];
+};
+
+export function generateFunction({
+  extern,
+  static: staticMember,
+  returnType,
+  namespace,
+  name,
+  argumentTypes,
+  argumentNames = [],
+  noReturn,
+  body,
+}: FunctionOptions) {
+  return `
+    ${staticMember ? "static " : ""}${extern ? 'extern "C" ' : ""}${returnType} ${namespace ? namespace + "::" : ""}${name}(
+      ${argumentTypes.map((type, index) => `${type} ` + (argumentNames[index] ?? `arg${index}`)).join(", ")}
+    ) ${body ? `{ ${body} ${noReturn ? "WEAK_NODE_API_UNREACHABLE;" : ""}\n}` : ""}
+    ;
+  `;
+}

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

@@ -0,0 +1,74 @@
+import type { FunctionDecl } from "../../src/node-api-functions.js";
+import { generateFunction } from "./shared.js";
+
+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 `
+    #pragma once
+
+    #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
+    
+    // Generate the struct of function pointers
+    struct WeakNodeApiHost {
+      ${functions.map(generateFunctionDecl).join("\n")}
+    };
+    typedef void(*InjectHostFunction)(const WeakNodeApiHost&);
+    extern "C" void inject_weak_node_api_host(const WeakNodeApiHost& host);
+  `;
+}
+
+function generateFunctionImpl(fn: FunctionDecl) {
+  const { name, returnType, argumentTypes } = fn;
+  return generateFunction({
+    ...fn,
+    extern: true,
+    body: `
+        if (g_host.${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(", ")}
+        );
+      `,
+  });
+}
+
+/**
+ * Generates source code for a version script for the given Node API version.
+ */
+export function generateSource(functions: FunctionDecl[]) {
+  return `
+    #include "weak_node_api.hpp"
+
+    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")}
+  `;
+}