import AwaitValue from "./AwaitValue"; export default function AsyncGenerator(gen) { var front, back; function send(key, arg) { return new Promise(function (resolve, reject) { var request = { key: key, arg: arg, resolve: resolve, reject: reject, next: null }; if (back) { back = back.next = request; } else { front = back = request; resume(key, arg); } }); } function resume(key, arg) { try { var result = gen[key](arg); var value = result.value; var wrappedAwait = value instanceof AwaitValue; Promise.resolve(wrappedAwait ? value.wrapped : value).then(function (arg) { if (wrappedAwait) { resume("next", arg); return; } settle(result.done ? "return" : "normal", arg); }, function (err) { resume("throw", err); }); } catch (err) { settle("throw", err); } } function settle(type, value) { switch (type) { case "return": front.resolve({ value: value, done: true }); break; case "throw": front.reject(value); break; default: front.resolve({ value: value, done: false }); break; } front = front.next; if (front) { resume(front.key, front.arg); } else { back = null; } } this._invoke = send; if (typeof gen["return"] !== "function") { this["return"] = undefined; } } if (typeof Symbol === "function" && Symbol.asyncIterator) { AsyncGenerator.prototype[Symbol.asyncIterator] = function () { return this; }; } AsyncGenerator.prototype.next = function (arg) { return this._invoke("next", arg); }; AsyncGenerator.prototype["throw"] = function (arg) { return this._invoke("throw", arg); }; AsyncGenerator.prototype["return"] = function (arg) { return this._invoke("return", arg); };