0.2.0 - Mid migration

web/node_modules/rollup-plugin-babel/src/preflightCheck.js

@@ -0,0 +1,66 @@
+import { transformSync } from '@babel/core';
+import { INLINE, RUNTIME, EXTERNAL } from './constants.js';
+import { addBabelPlugin } from './utils.js';
+
+const MODULE_ERROR =
+	'Rollup requires that your Babel configuration keeps ES6 module syntax intact. ' +
+	'Unfortunately it looks like your configuration specifies a module transformer ' +
+	'to replace ES6 modules with another module format. To continue you have to disable it.' +
+	'\n\n' +
+	"Most commonly it's a CommonJS transform added by @babel/preset-env - " +
+	'in such case you should disable it by adding `modules: false` option to that preset ' +
+	'(described in more detail here - https://github.com/rollup/rollup-plugin-babel#modules ).';
+
+const UNEXPECTED_ERROR =
+	'An unexpected situation arose. Please raise an issue at ' +
+	'https://github.com/rollup/rollup-plugin-babel/issues. Thanks!';
+
+function fallbackClassTransform() {
+	return {
+		visitor: {
+			ClassDeclaration(path, state) {
+				path.replaceWith(state.file.addHelper('inherits'));
+			},
+		},
+	};
+}
+
+export default function createPreflightCheck() {
+	let preflightCheckResults = {};
+
+	return (ctx, options) => {
+		const key = options.filename;
+
+		if (preflightCheckResults[key] === undefined) {
+			let helpers;
+
+			const inputCode = 'class Foo extends Bar {};\nexport default Foo;';
+			const transformed = transformSync(inputCode, options);
+
+			let check = transformed.code;
+
+			if (~check.indexOf('class ')) {
+				check = transformSync(inputCode, addBabelPlugin(options, fallbackClassTransform)).code;
+			}
+
+			if (
+				!~check.indexOf('export default') &&
+				!~check.indexOf('export default Foo') &&
+				!~check.indexOf('export { Foo as default }')
+			) {
+				ctx.error(MODULE_ERROR);
+			}
+
+			if (check.match(/\/helpers\/(esm\/)?inherits/)) helpers = RUNTIME;
+			else if (~check.indexOf('function _inherits')) helpers = INLINE;
+			else if (~check.indexOf('babelHelpers')) helpers = EXTERNAL;
+			else {
+				ctx.error(UNEXPECTED_ERROR);
+			}
+
+			preflightCheckResults[key] = helpers;
+		}
+
+		return preflightCheckResults[key];
+	};
+}