rx-player
Version:
Canal+ HTML5 Video Player
56 lines (55 loc) • 2.52 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.default = createCancellablePromise;
/**
* Returns a Promise linked to a `CancellationSignal`, which will reject the
* corresponding `CancellationError` if that signal emits before the wanted
* task finishes (either on success or on error).
*
* The given callback mimicks the Promise interface with the added possibility
* of returning a callback which will be called when and if the task is
* cancelled before being either resolved or rejected.
* In that case, that logic will be called just before the Promise is rejected
* with the corresponding `CancellationError`.
* The point of this callback is to implement aborting logic, such as for
* example aborting a request.
*
* @param {Object} cancellationSignal - The `CancellationSignal` the returned
* Promise will be linked to.
* @param {Function} cb - The function implementing the cancellable Promise. Its
* arguments follow Promise's semantics but it can also return a function which
* will be called when and if `cancellationSignal` emits before either arguments
* are called.
* @returns {Promise} - The created Promise, which will resolve when and if the
* first argument to `cb` is called first and reject either if the second
* argument to `cb` is called first or if the given `CancellationSignal` emits
* before either of the two previous conditions.
*/
function createCancellablePromise(cancellationSignal, cb) {
var abortingLogic;
return new Promise(function (res, rej) {
if (cancellationSignal.cancellationError !== null) {
// If the signal was already triggered before, do not even call `cb`
return rej(cancellationSignal.cancellationError);
}
var hasUnregistered = false;
abortingLogic = cb(function onCancellablePromiseSuccess(val) {
cancellationSignal.deregister(onCancellablePromiseCancellation);
hasUnregistered = true;
res(val);
}, function onCancellablePromiseFailure(err) {
cancellationSignal.deregister(onCancellablePromiseCancellation);
hasUnregistered = true;
rej(err);
});
if (!hasUnregistered) {
cancellationSignal.register(onCancellablePromiseCancellation);
}
function onCancellablePromiseCancellation(error) {
if (abortingLogic !== undefined) {
abortingLogic();
}
rej(error);
}
});
}