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