iwmlib/3rdparty/systemjs/babel-helpers/asyncGenerator.js
2019-03-21 09:57:27 +01:00

112 lines
2.3 KiB
JavaScript
Executable File

export default (function () {
function AwaitValue(value) {
this.value = value;
}
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;
if (value instanceof AwaitValue) {
Promise.resolve(value.value).then(function (arg) {
resume("next", arg);
}, function (arg) {
resume("throw", arg);
});
} else {
settle(result.done ? "return" : "normal", result.value);
}
} 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);
};
return {
wrap: function (fn) {
return function () {
return new AsyncGenerator(fn.apply(this, arguments));
};
},
await: function (value) {
return new AwaitValue(value);
}
};
})();