rollup-plugin-babel/dist/rollup-plugin-babel.es6.js

Seamless integration between Rollup and Babel.

import { join, dirname } from 'path';
import { transform, buildExternalHelpers } from 'babel-core';
import { createFilter } from 'rollup-pluginutils';
import classes from 'babel-plugin-transform-es2015-classes';

var INLINE = {};
var RUNTIME = {};
var BUNDLED = {};

var preflightCheckResults = {};

function preflightCheck(options, dir) {
	if (!preflightCheckResults[dir]) {
		var helpers = undefined;

		options = assign({}, options);
		options.filename = join(dir, 'x.js');

		if (!options.plugins) options.plugins = [];
		options.plugins.push(classes);

		var check = transform('export default class Foo {}', options).code;

		if (! ~check.indexOf('export default') && ! ~check.indexOf('export { Foo as default }')) throw new Error('It looks like your Babel configuration specifies a module transformer. Please disable it. If you\'re using the "es2015" preset, consider using "es2015-rollup" instead. See https://github.com/rollup/rollup-plugin-babel#configuring-babel for more information');

		if (~check.indexOf('import _classCallCheck from "babel-runtime')) helpers = RUNTIME;else if (~check.indexOf('function _classCallCheck')) helpers = INLINE;else if (~check.indexOf('babelHelpers')) helpers = BUNDLED;else {
			throw new Error('An unexpected situation arose. Please raise an issue at https://github.com/rollup/rollup-plugin-babel/issues. Thanks!');
		}

		preflightCheckResults[dir] = helpers;
	}

	return preflightCheckResults[dir];
}

function assign(target, source) {
	Object.keys(source).forEach(function (key) {
		target[key] = source[key];
	});
	return target;
}

var warned = {};
function warnOnce(msg) {
	if (warned[msg]) return;
	warned[msg] = true;
	console.warn(msg);
}

function babel(options) {
	options = assign({}, options || {});
	var bundledHelpers = {};
	var inlineHelpers = {};

	var filter = createFilter(options.include, options.exclude);
	delete options.include;
	delete options.exclude;

	if (options.sourceMap !== false) options.sourceMaps = true;
	if (options.sourceMaps !== false) options.sourceMaps = true;
	delete options.sourceMap;

	var runtimeHelpers = options.runtimeHelpers;
	delete options.runtimeHelpers;

	var externalHelpers;
	if (options.externalHelpers) externalHelpers = true;
	delete options.externalHelpers;

	return {
		transform: function transform$$(code, id) {
			if (!filter(id)) return null;

			var helpers = preflightCheck(options, dirname(id));
			var localOpts = assign({ filename: id }, options);

			var transformed = transform(code, localOpts);
			var usedHelpers = transformed.metadata.usedHelpers;

			if (usedHelpers.length) {
				if (helpers === BUNDLED) {
					usedHelpers.forEach(function (helper) {
						bundledHelpers[helper] = true;
					});
				} else if (helpers === RUNTIME && !runtimeHelpers) {
					throw new Error('Runtime helpers are not enabled. Either exclude the transform-runtime Babel plugin or pass the `runtimeHelpers: true` option. See https://github.com/rollup/rollup-plugin-babel#configuring-babel for more information');
				} else {
					usedHelpers.forEach(function (helper) {
						if (inlineHelpers[helper]) {
							warnOnce('The \'' + helper + '\' Babel helper is used more than once in your code. It\'s strongly recommended that you use the "external-helpers" plugin or the "es2015-rollup" preset. See https://github.com/rollup/rollup-plugin-babel#configuring-babel for more information');
						}

						inlineHelpers[helper] = true;
					});
				}
			}

			return {
				code: transformed.code,
				map: transformed.map
			};
		},
		intro: function intro() {
			if (externalHelpers) return '';
			var helpers = Object.keys(bundledHelpers);
			if (!helpers.length) return '';

			return buildExternalHelpers(helpers, 'var').trim() + '\n';
		}
	};
}

export default babel;