esm: experimental wasm modules

lib/internal/modules/cjs/loader.js

@@ -643,7 +643,7 @@ Module.prototype.load = function(filename) {
         url,
         new ModuleJob(ESMLoader, url, async () => {
           return createDynamicModule(
-            ['default'], url, (reflect) => {
+            [], ['default'], url, (reflect) => {
               reflect.exports.default.set(exports);
             });
         })

lib/internal/modules/esm/create_dynamic_module.js

@@ -1,14 +1,18 @@
 'use strict';
 
-const { ArrayPrototype } = primordials;
+const { ArrayPrototype, JSON, Object } = primordials;
 
 const debug = require('internal/util/debuglog').debuglog('esm');
 
-const createDynamicModule = (exports, url = '', evaluate) => {
+const createDynamicModule = (imports, exports, url = '', evaluate) => {
   debug('creating ESM facade for %s with exports: %j', url, exports);
   const names = ArrayPrototype.map(exports, (name) => `${name}`);
 
   const source = `
+${ArrayPrototype.join(ArrayPrototype.map(imports, (impt, index) =>
+    `import * as $import_${index} from ${JSON.stringify(impt)};
+import.meta.imports[${JSON.stringify(impt)}] = $import_${index};`), '\n')
+}
 ${ArrayPrototype.join(ArrayPrototype.map(names, (name) =>
     `let $${name};
 export { $${name} as ${name} };
@@ -22,19 +26,21 @@ import.meta.done();
 `;
   const { ModuleWrap, callbackMap } = internalBinding('module_wrap');
   const m = new ModuleWrap(source, `${url}`);
-  m.link(() => 0);
-  m.instantiate();
 
   const readyfns = new Set();
   const reflect = {
-    namespace: m.namespace(),
-    exports: {},
+    exports: Object.create(null),
     onReady: (cb) => { readyfns.add(cb); },
   };
 
+  if (imports.length)
+    reflect.imports = Object.create(null);
+
   callbackMap.set(m, {
     initializeImportMeta: (meta, wrap) => {
       meta.exports = reflect.exports;
+      if (reflect.imports)
+        meta.imports = reflect.imports;
       meta.done = () => {
         evaluate(reflect);
         reflect.onReady = (cb) => cb(reflect);

lib/internal/modules/esm/default_resolve.js

@@ -10,7 +10,7 @@ const preserveSymlinks = getOptionValue('--preserve-symlinks');
 const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
 const experimentalJsonModules = getOptionValue('--experimental-json-modules');
 const typeFlag = getOptionValue('--input-type');
-
+const experimentalWasmModules = getOptionValue('--experimental-wasm-modules');
 const { resolve: moduleWrapResolve,
         getPackageType } = internalBinding('module_wrap');
 const { pathToFileURL, fileURLToPath } = require('internal/url');
@@ -44,6 +44,15 @@ const legacyExtensionFormatMap = {
   '.node': 'commonjs'
 };
 
+if (experimentalWasmModules) {
+  Object.assign(extensionFormatMap, {
+    '.wasm': 'wasm'
+  });
+  Object.assign(legacyExtensionFormatMap, {
+    '.wasm': 'wasm'
+  });
+}
+
 if (experimentalJsonModules) {
   // This is a total hack
   Object.assign(extensionFormatMap, {

lib/internal/modules/esm/loader.js

@@ -153,7 +153,7 @@ class Loader {
       loaderInstance = async (url) => {
         debug(`Translating dynamic ${url}`);
         const { exports, execute } = await this._dynamicInstantiate(url);
-        return createDynamicModule(exports, url, (reflect) => {
+        return createDynamicModule([], exports, url, (reflect) => {
           debug(`Loading dynamic ${url}`);
           execute(reflect.exports);
         });

lib/internal/modules/esm/translators.js

@@ -1,9 +1,12 @@
 'use strict';
 
+/* global WebAssembly */
+
 const {
+  JSON,
+  Object,
   SafeMap,
-  StringPrototype,
-  JSON
+  StringPrototype
 } = primordials;
 
 const { NativeModule } = require('internal/bootstrap/loaders');
@@ -72,11 +75,11 @@ translators.set('commonjs', async function commonjsStrategy(url, isMain) {
   ];
   if (module && module.loaded) {
     const exports = module.exports;
-    return createDynamicModule(['default'], url, (reflect) => {
+    return createDynamicModule([], ['default'], url, (reflect) => {
       reflect.exports.default.set(exports);
     });
   }
-  return createDynamicModule(['default'], url, () => {
+  return createDynamicModule([], ['default'], url, () => {
     debug(`Loading CJSModule ${url}`);
     // We don't care about the return val of _load here because Module#load
     // will handle it for us by checking the loader registry and filling the
@@ -97,7 +100,7 @@ translators.set('builtin', async function builtinStrategy(url) {
   }
   module.compileForPublicLoader(true);
   return createDynamicModule(
-    [...module.exportKeys, 'default'], url, (reflect) => {
+    [], [...module.exportKeys, 'default'], url, (reflect) => {
       debug(`Loading BuiltinModule ${url}`);
       module.reflect = reflect;
       for (const key of module.exportKeys)
@@ -116,7 +119,7 @@ translators.set('json', async function jsonStrategy(url) {
   let module = CJSModule._cache[modulePath];
   if (module && module.loaded) {
     const exports = module.exports;
-    return createDynamicModule(['default'], url, (reflect) => {
+    return createDynamicModule([], ['default'], url, (reflect) => {
       reflect.exports.default.set(exports);
     });
   }
@@ -136,8 +139,32 @@ translators.set('json', async function jsonStrategy(url) {
     throw err;
   }
   CJSModule._cache[modulePath] = module;
-  return createDynamicModule(['default'], url, (reflect) => {
+  return createDynamicModule([], ['default'], url, (reflect) => {
     debug(`Parsing JSONModule ${url}`);
     reflect.exports.default.set(module.exports);
   });
 });
+
+// Strategy for loading a wasm module
+translators.set('wasm', async function(url) {
+  const pathname = fileURLToPath(url);
+  const buffer = await readFileAsync(pathname);
+  debug(`Translating WASMModule ${url}`);
+  let compiled;
+  try {
+    compiled = await WebAssembly.compile(buffer);
+  } catch (err) {
+    err.message = pathname + ': ' + err.message;
+    throw err;
+  }
+
+  const imports =
+      WebAssembly.Module.imports(compiled).map(({ module }) => module);
+  const exports = WebAssembly.Module.exports(compiled).map(({ name }) => name);
+
+  return createDynamicModule(imports, exports, url, (reflect) => {
+    const { exports } = new WebAssembly.Instance(compiled, reflect.imports);
+    for (const expt of Object.keys(exports))
+      reflect.exports[expt].set(exports[expt]);
+  });
+});

src/node_options.cc

@@ -269,6 +269,10 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
             "experimental ES Module support and caching modules",
             &EnvironmentOptions::experimental_modules,
             kAllowedInEnvironment);
+  AddOption("--experimental-wasm-modules",
+            "experimental ES Module support for webassembly modules",
+            &EnvironmentOptions::experimental_wasm_modules,
+            kAllowedInEnvironment);
   AddOption("--experimental-policy",
             "use the specified file as a "
             "security policy",

src/node_options.h

@@ -94,6 +94,7 @@ class EnvironmentOptions : public Options {
   bool experimental_json_modules = false;
   bool experimental_modules = false;
   std::string es_module_specifier_resolution;
+  bool experimental_wasm_modules = false;
   std::string module_type;
   std::string experimental_policy;
   bool experimental_repl_await = false;

test/es-module/test-esm-wasm.mjs

@@ -0,0 +1,9 @@
+// Flags: --experimental-modules --experimental-wasm-modules
+/* eslint-disable node-core/required-modules */
+import { add, addImported } from '../fixtures/es-modules/simple.wasm';
+import { strictEqual } from 'assert';
+
+strictEqual(add(10, 20), 30);
+
+strictEqual(addImported(0), 42);
+strictEqual(addImported(1), 43);

test/fixtures/es-modules/wasm-dep.mjs

@@ -0,0 +1,3 @@
+export function jsFn () {
+  return 42;
+}