feat: add initSync() to initialize WASM synchronously

README.md

@@ -59,7 +59,8 @@ When using the ESM version, Wasm is supported instead:
 
 ```js
 import { parse, init } from 'cjs-module-lexer';
-// init needs to be called and waited upon
+// init() needs to be called and waited upon, or use initSync() to compile
+// Wasm blockingly and synchronously.
 await init();
 const { exports, reexports } = parse(source);
 ```

lexer.d.ts

@@ -5,3 +5,4 @@ export interface Exports {
 
 export declare function parse(source: string, name?: string): Exports;
 export declare function init(): Promise<void>;
+export declare function initSync(): void;

lexer.js

@@ -1439,4 +1439,5 @@ function isExpressionTerminator (curPos) {
 const initPromise = Promise.resolve();
 
 module.exports.init = () => initPromise;
+module.exports.initSync = () => {};
 module.exports.parse = parseCJS;

package.json

@@ -14,7 +14,8 @@
   "scripts": {
     "test-js": "mocha -b -u tdd test/*.js",
     "test-wasm": "cross-env WASM=1 mocha -b -u tdd test/*.js",
-    "test": "npm run test-wasm && npm run test-js",
+    "test-wasm-sync": "cross-env WASM_SYNC=1 mocha -b -u tdd test/*.js",
+    "test": "npm run test-wasm && npm run test-wasm-sync && npm run test-js",
     "bench": "node --expose-gc bench/index.mjs",
     "build": "node build.js ; babel dist/lexer.mjs -o dist/lexer.js ; terser dist/lexer.js -o dist/lexer.js",
     "build-wasm": "make lib/lexer.wasm && node build.js",

src/lexer.js

@@ -90,16 +90,30 @@ function copyLE (src, outBuf16) {
     outBuf16[i] = src.charCodeAt(i++);
 }
 
+function getWasmBytes() {
+  const binary = 'WASM_BINARY';  // This string will be replaced by build.js.
+  if (typeof window !== 'undefined' && typeof atob === 'function')
+    return Uint8Array.from(atob(binary), x => x.charCodeAt(0));
+  return Buffer.from(binary, 'base64');
+}
+
 let initPromise;
 export function init () {
   if (initPromise)
     return initPromise;
   return initPromise = (async () => {
-    const compiled = await WebAssembly.compile(
-      (binary => typeof window !== 'undefined' && typeof atob === 'function' ? Uint8Array.from(atob(binary), x => x.charCodeAt(0)) : Buffer.from(binary, 'base64'))
-      ('WASM_BINARY')
-    )
+    const compiled = await WebAssembly.compile(getWasmBytes());
     const { exports } = await WebAssembly.instantiate(compiled);
     wasm = exports;
   })();
 }
+
+export function initSync () {
+  if (wasm) {
+    return;
+  }
+  const compiled = new WebAssembly.Module(getWasmBytes());
+  const { exports } = new WebAssembly.Instance(compiled);
+  wasm = exports;
+  return;
+}

test/_unit.js

@@ -7,6 +7,10 @@ async function loadParser () {
     const m = await import('../dist/lexer.mjs');
     await m.init();
     parse = m.parse;
+  } else if (process.env.WASM_SYNC) {
+    const m = require('../dist/lexer.js');
+    m.initSync();
+    parse = m.parse;
   }
   else {
     parse = require('../lexer.js').parse;

test/integration.js

@@ -8,6 +8,10 @@ async function loadParser () {
     const m = await import('../dist/lexer.mjs');
     await m.init();
     parse = m.parse;
+  } else if (process.env.WASM_SYNC) {
+    const m = require('../dist/lexer.js');
+    m.initSync();
+    parse = m.parse;
   }
   else {
     parse = require('../lexer.js').parse;
@@ -31,7 +35,7 @@ suite('Samples', () => {
   const selfSource = fs.readFileSync(process.cwd() + '/lexer.js').toString();
   test('Self test', async () => {
     const { exports } = parse(selfSource);
-    assert.deepStrictEqual(exports, ['init', 'parse']);
+    assert.deepStrictEqual(exports, ['init', 'initSync', 'parse']);
   });
 
   files.forEach(({ file, code }) => {