fix(bug): fixes issue where babel helpers would force ESM variants ev…

…en though they were marked as external. Fixes #15

src/constant/constant.ts

@@ -1,3 +1,5 @@
+import {InputOptions} from "rollup";
+
 export const SOURCE_MAP_EXTENSION = ".map";
 export const TS_EXTENSION = ".ts";
 export const TSX_EXTENSION = ".tsx";
@@ -14,14 +16,10 @@ export const SOURCE_MAP_COMMENT_REGEXP = /\n\/\/# sourceMappingURL=.*/g;
 export const TSLIB_NAME = `tslib${DECLARATION_EXTENSION}`;
 export const BABEL_RUNTIME_PREFIX_1 = "@babel/runtime/";
 export const BABEL_RUNTIME_PREFIX_2 = "babel-runtime/";
+
 export const REGENERATOR_RUNTIME_NAME_1 = `${BABEL_RUNTIME_PREFIX_1}regenerator/index.js`;
 export const REGENERATOR_RUNTIME_NAME_2 = `${BABEL_RUNTIME_PREFIX_2}regenerator/index.js`;
-export const TYPEOF_BABEL_HELPER_NAME_1 = `${BABEL_RUNTIME_PREFIX_1}helpers/esm/typeof.js`;
-export const TYPEOF_BABEL_HELPER_NAME_2 = `${BABEL_RUNTIME_PREFIX_2}helpers/typeof.js`;
-export const TYPEOF_BABEL_HELPER_NAME_3 = `${BABEL_RUNTIME_PREFIX_1}helpers/esm/typeof.js`;
-export const TYPEOF_BABEL_HELPER_NAME_4 = `${BABEL_RUNTIME_PREFIX_2}helpers/typeof.js`;
-export const TYPEOF_BABEL_HELPER_NAME_5 = `${BABEL_RUNTIME_PREFIX_1}helpers/esm/instanceof.js`;
-export const TYPEOF_BABEL_HELPER_NAME_6 = `${BABEL_RUNTIME_PREFIX_2}helpers/instanceof.js`;
+export const BABEL_EXAMPLE_HELPERS = [`${BABEL_RUNTIME_PREFIX_1}helpers/esm/typeof.js`, `${BABEL_RUNTIME_PREFIX_2}helpers/esm/typeof.js`];
 
 export const BABEL_MINIFICATION_BLACKLIST_PRESET_NAMES = [];
 
@@ -66,10 +64,29 @@ export const FORCED_BABEL_YEARLY_PRESET_OPTIONS = {
 	...FORCED_BABEL_PRESET_ENV_OPTIONS
 };
 
-export const FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS = {
-	helpers: true,
-	useESModules: true,
-	regenerator: true
+export const FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS = (rollupInputOptions: InputOptions) => {
+	let forceESModules: boolean = true;
+
+	// Only apply the forceESModules option if @babel helpers aren't treated as external.
+	if (
+		BABEL_EXAMPLE_HELPERS.some(helper => {
+			if (typeof rollupInputOptions.external === "function") {
+				return rollupInputOptions.external(helper, "", true) === true;
+			} else if (Array.isArray(rollupInputOptions.external)) {
+				return rollupInputOptions.external.includes(helper);
+			} else {
+				return false;
+			}
+		})
+	) {
+		forceESModules = false;
+	}
+
+	return {
+		helpers: true,
+		regenerator: true,
+		...(forceESModules ? {forceESModules: true} : {})
+	};
 };
 
 export const MAIN_FIELDS = ["module", "es2015", "esm2015", "jsnext:main", "main"];

src/plugin/typescript-plugin.ts

@@ -9,7 +9,7 @@ import {EmitCache} from "../service/cache/emit-cache/emit-cache";
 import {emitDeclarations} from "../util/emit-declarations/emit-declarations";
 import {emitDiagnosticsThroughRollup} from "../util/diagnostic/emit-diagnostics-through-rollup";
 import {getSupportedExtensions} from "../util/get-supported-extensions/get-supported-extensions";
-import {ensureRelative, getExtension, isNonTransformableBabelHelper, isRollupPluginMultiEntry} from "../util/path/path-util";
+import {ensureRelative, getExtension, isBabelHelper, isRollupPluginMultiEntry} from "../util/path/path-util";
 import {join} from "path";
 import {ModuleResolutionHost} from "../service/module-resolution-host/module-resolution-host";
 import {takeBundledFilesNames} from "../util/take-bundled-filenames/take-bundled-filenames";
@@ -172,7 +172,8 @@ export default function typescriptRollupPlugin(pluginInputOptions: Partial<Types
 					babelConfig: pluginOptions.babelConfig,
 					forcedOptions: getForcedBabelOptions({cwd, pluginOptions, rollupInputOptions, browserslist: computedBrowserslist}),
 					defaultOptions: getDefaultBabelOptions({pluginOptions, rollupInputOptions, browserslist: computedBrowserslist}),
-					browserslist: computedBrowserslist
+					browserslist: computedBrowserslist,
+					rollupInputOptions
 				});
 				babelConfig = babelConfigResult.config;
 				babelMinifyConfig = babelConfigResult.minifyConfig;
@@ -261,7 +262,7 @@ export default function typescriptRollupPlugin(pluginInputOptions: Partial<Types
 			}
 
 			// Skip the file if it doesn't match the filter or if the helper cannot be transformed
-			if (!filter(file) || isNonTransformableBabelHelper(file)) {
+			if (!filter(file) || isBabelHelper(file)) {
 				return undefined;
 			}
 

src/util/flat/flat.ts

@@ -0,0 +1,70 @@
+// tslint:disable:array-type
+
+export declare type Flat<A> = A extends Array<infer B>
+	? B extends Array<infer C>
+		? C extends Array<infer D>
+			? D extends Array<infer E>
+				? E extends Array<infer F>
+					? F extends Array<infer G>
+						? G extends Array<infer H>
+							? H extends Array<infer I>
+								? I extends Array<infer J>
+									? J extends Array<infer K>
+										? K extends Array<infer L>
+											? L extends Array<infer M>
+												? M extends Array<infer N>
+													? M
+													: L
+												: K
+											: J
+										: I
+									: H
+								: G
+							: F
+						: E
+					: D
+				: C
+			: B
+		: A
+	: A;
+
+// tslint:disable:no-any
+
+/**
+ * Flattens the array with the given recursive depth
+ * @param {T[]} arr
+ * @returns {T[]}
+ */
+export function flat<T>(arr: T): Flat<T> {
+	const target: any[] = [];
+	if (!Array.isArray(arr)) return <Flat<T>>arr;
+
+	flattenIntoArray(target, arr, Infinity);
+	return <Flat<T>>(<any>target);
+}
+
+/**
+ * Flattens the given source array into a new array
+ * @param {T[]} target
+ * @param {T[]} source
+ * @param {number} [depth=1]
+ * @param {number} [start=0]
+ * @returns {number}
+ */
+function flattenIntoArray<T>(target: T[], source: T[], depth: number = 1, start: number = 0): number {
+	let targetIndex = start;
+	let sourceIndex = 0;
+	const sourceLength = source.length;
+	while (sourceIndex < sourceLength) {
+		const element = source[sourceIndex];
+
+		if (depth > 0 && Array.isArray(element)) {
+			targetIndex = flattenIntoArray(target, element, depth - 1, targetIndex);
+		} else {
+			target[targetIndex] = element;
+			targetIndex++;
+		}
+		sourceIndex++;
+	}
+	return targetIndex;
+}

src/util/get-babel-config/get-babel-config.ts

@@ -87,7 +87,7 @@ function configItemIsAllowedDuringNoMinification({file: {resolved}}: IBabelConfi
  * @param {IGetBabelConfigOptions} options
  * @returns {IGetBabelConfigResult}
  */
-export function getBabelConfig({babelConfig, cwd, forcedOptions = {}, defaultOptions = {}, browserslist}: IGetBabelConfigOptions): IGetBabelConfigResult {
+export function getBabelConfig({babelConfig, cwd, forcedOptions = {}, defaultOptions = {}, browserslist, rollupInputOptions}: IGetBabelConfigOptions): IGetBabelConfigResult {
 	// Load a partial Babel config based on the input options
 	const partialConfig = loadPartialConfig(
 		isBabelInputOptions(babelConfig)
@@ -156,7 +156,7 @@ export function getBabelConfig({babelConfig, cwd, forcedOptions = {}, defaultOpt
 						plugin.file.request,
 						{
 							...(plugin.options == null ? {} : plugin.options),
-							...FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS
+							...FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS(rollupInputOptions)
 						}
 					],
 					{type: "plugin", dirname: cwd}

src/util/get-babel-config/i-get-babel-config-options.ts

@@ -1,10 +1,12 @@
 import {ITypescriptPluginBabelOptions} from "../../plugin/i-typescript-plugin-options";
 import {IGetForcedBabelOptionsResult} from "../get-forced-babel-options/i-get-forced-babel-options-result";
 import {IGetDefaultBabelOptionsResult} from "../get-default-babel-options/i-get-default-babel-options-result";
+import {InputOptions} from "rollup";
 
 export interface IGetBabelConfigOptions {
 	cwd: string;
 	browserslist: string[] | undefined;
+	rollupInputOptions: InputOptions;
 	babelConfig?: ITypescriptPluginBabelOptions["babelConfig"];
 	forcedOptions?: IGetForcedBabelOptionsResult;
 	defaultOptions?: IGetDefaultBabelOptionsResult;

src/util/get-default-babel-options/get-default-babel-options.ts

@@ -8,7 +8,7 @@ import {FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS, FORCED_BABEL_PRESET_ENV_O
  * @param {IGetDefaultBabelOptionsOptions} _options
  * @returns {IGetDefaultBabelOptionsResult}
  */
-export function getDefaultBabelOptions({browserslist}: IGetDefaultBabelOptionsOptions): IGetDefaultBabelOptionsResult {
+export function getDefaultBabelOptions({browserslist, rollupInputOptions}: IGetDefaultBabelOptionsOptions): IGetDefaultBabelOptionsResult {
 	const includePresetEnv = browserslist != null;
 
 	return {
@@ -49,7 +49,7 @@ export function getDefaultBabelOptions({browserslist}: IGetDefaultBabelOptionsOp
 			[
 				"@babel/plugin-transform-runtime",
 				{
-					...FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS,
+					...FORCED_BABEL_PLUGIN_TRANSFORM_RUNTIME_OPTIONS(rollupInputOptions),
 					corejs: false
 				}
 			]

src/util/path/path-util.ts

@@ -1,23 +1,17 @@
-import {isAbsolute, join, parse, relative, extname} from "path";
+import {extname, isAbsolute, join, parse, relative} from "path";
 import {
+	BABEL_RUNTIME_PREFIX_1,
+	BABEL_RUNTIME_PREFIX_2,
 	DECLARATION_EXTENSION,
 	DECLARATION_MAP_EXTENSION,
+	DEFAULT_LIB_NAMES,
 	JS_EXTENSION,
 	JSX_EXTENSION,
 	MJS_EXTENSION,
-	TSX_EXTENSION,
+	ROLLUP_PLUGIN_MULTI_ENTRY,
 	TS_EXTENSION,
-	DEFAULT_LIB_NAMES,
 	TSLIB_NAME,
-	TYPEOF_BABEL_HELPER_NAME_1,
-	TYPEOF_BABEL_HELPER_NAME_2,
-	TYPEOF_BABEL_HELPER_NAME_3,
-	TYPEOF_BABEL_HELPER_NAME_4,
-	BABEL_RUNTIME_PREFIX_1,
-	BABEL_RUNTIME_PREFIX_2,
-	TYPEOF_BABEL_HELPER_NAME_6,
-	TYPEOF_BABEL_HELPER_NAME_5,
-	ROLLUP_PLUGIN_MULTI_ENTRY
+	TSX_EXTENSION
 } from "../../constant/constant";
 
 /**
@@ -59,28 +53,30 @@ export function isTslib(path: string): boolean {
 }
 
 /**
- * Returns true if the given path represents a Babel helper that shouldn't be transformed
+ * Returns true if the given path represents a Babel helper
+ * @param {string} path
+ * @returns {boolean}
+ */
+export function isBabelHelper(path: string): boolean {
+	return isBabelEsmHelper(path) || isBabelCjsHelper(path);
+}
+
+/**
+ * Returns true if the given path represents a Babel ESM helper
  * @param {string} path
  * @returns {boolean}
  */
-export function isNonTransformableBabelHelper(path: string): boolean {
-	return (
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_1) ||
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_2) ||
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_3) ||
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_4) ||
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_5) ||
-		path.endsWith(TYPEOF_BABEL_HELPER_NAME_6)
-	);
+export function isBabelEsmHelper(path: string): boolean {
+	return path.startsWith(`${BABEL_RUNTIME_PREFIX_1}helpers/esm`) || path.startsWith(`${BABEL_RUNTIME_PREFIX_2}helpers/esm`);
 }
 
 /**
- * Returns true if the given path represents a Babel helper
+ * Returns true if the given path represents a Babel CJS helper
  * @param {string} path
  * @returns {boolean}
  */
-export function isBabelHelper(path: string): boolean {
-	return path.startsWith(BABEL_RUNTIME_PREFIX_1) || path.startsWith(BABEL_RUNTIME_PREFIX_2);
+export function isBabelCjsHelper(path: string): boolean {
+	return !isBabelEsmHelper(path) && (path.startsWith(`${BABEL_RUNTIME_PREFIX_1}helpers`) || path.startsWith(`${BABEL_RUNTIME_PREFIX_2}helpers`));
 }
 
 /**