Add __generator helper

src/index.js

@@ -143,7 +143,7 @@ export default function typescript ( options ) {
 			return {
 				// Always append an import for the helpers.
 				code: transformed.outputText +
-					`\nimport { __assign, __awaiter, __extends, __decorate, __metadata, __param } from '${helpersId}';`,
+					`\nimport { __assign, __awaiter, __extends, __decorate, __generator, __metadata, __param } from '${helpersId}';`,
 
 				// Rollup expects `map` to be an object so we must parse the string
 				map: transformed.sourceMapText ? JSON.parse(transformed.sourceMapText) : null

src/typescript-helpers.js

@@ -39,3 +39,31 @@ export function __awaiter(thisArg, _arguments, P, generator) {
         step((generator = generator.apply(thisArg, _arguments)).next());
     });
 }
+
+export function __generator(thisArg, body) {
+    var _ = { label: 0, sent: function () { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t;
+    return { next: verb(0), "throw": verb(1), "return": verb(2) };
+    function verb(n) { return function (v) { return step([n, v]); }; }
+    function step(op) {
+        if (f) throw new TypeError("Generator is already executing.");
+        while (_) try {
+            if (f = 1, y && (t = y[op[0] & 2 ? "return" : op[0] ? "throw" : "next"]) && !(t = t.call(y, op[1])).done) return t;
+            if (y = 0, t) op = [0, t.value];
+            switch (op[0]) {
+                case 0: case 1: t = op; break;
+                case 4: _.label++; return { value: op[1], done: false };
+                case 5: _.label++; y = op[1]; op = [0]; continue;
+                case 7: op = _.ops.pop(); _.trys.pop(); continue;
+                default:
+                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
+                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
+                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
+                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
+                    if (t[2]) _.ops.pop();
+                    _.trys.pop(); continue;
+            }
+            op = body.call(thisArg, _);
+        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
+        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
+    }
+}