async/await 语法糖

/**
 * 将 async/await 转为 generator 以 Promise 形式使用，可以在过程中随时打断/等待
 * function build(appPath, config) {
		return awaiter(this, undefined, undefined, function* () {
			const mode = config.mode
			const newConfig = yield chain_1.makeConfig(config)
			const webpackChain = build_conf_1.default(appPath, mode, newConfig)
			yield customizeChain(
				webpackChain,
				newConfig.modifyWebpackChain,
				newConfig.webpackChain
			)
		}
	}
 */
const awaiter = function (thisArg, _arguments, P, generator) {
	function adopt(value) {
		return value instanceof P
			? value
			: new P(function (resolve) {
					resolve(value)
				})
	}
	return new (P || (P = Promise))(function (resolve, reject) {
		function fulfilled(value) {
			try {
				step(generator.next(value))
			} catch (e) {
				reject(e)
			}
		}
		function rejected(value) {
			try {
				step(generator['throw'](value))
			} catch (e) {
				reject(e)
			}
		}
		function step(result) {
			result.done
				? resolve(result.value)
				: adopt(result.value).then(fulfilled, rejected)
		}
		step((generator = generator.apply(thisArg, _arguments || [])).next())
	})
}