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'use strict';
class CancelError extends Error {
constructor(reason) {
super(reason || 'Promise was canceled');
this.name = 'CancelError';
}
get isCanceled() {
return true;
}
}
class PCancelable {
static fn(userFn) {
return (...args) => {
return new PCancelable((resolve, reject, onCancel) => {
args.push(onCancel);
userFn(...args).then(resolve, reject);
});
};
}
constructor(executor) {
this._cancelHandlers = [];
this._isPending = true;
this._isCanceled = false;
this._rejectOnCancel = true;
this._promise = new Promise((resolve, reject) => {
this._reject = reject;
const onResolve = value => {
this._isPending = false;
resolve(value);
};
const onReject = error => {
this._isPending = false;
reject(error);
};
const onCancel = handler => {
this._cancelHandlers.push(handler);
};
Object.defineProperties(onCancel, {
shouldReject: {
get: () => this._rejectOnCancel,
set: bool => {
this._rejectOnCancel = bool;
}
}
});
return executor(onResolve, onReject, onCancel);
});
}
then(onFulfilled, onRejected) {
return this._promise.then(onFulfilled, onRejected);
}
catch(onRejected) {
return this._promise.catch(onRejected);
}
finally(onFinally) {
return this._promise.finally(onFinally);
}
cancel(reason) {
if (!this._isPending || this._isCanceled) {
return;
}
if (this._cancelHandlers.length > 0) {
try {
for (const handler of this._cancelHandlers) {
handler();
}
} catch (error) {
this._reject(error);
}
}
this._isCanceled = true;
if (this._rejectOnCancel) {
this._reject(new CancelError(reason));
}
}
get isCanceled() {
return this._isCanceled;
}
}
Object.setPrototypeOf(PCancelable.prototype, Promise.prototype);
module.exports = PCancelable;
module.exports.default = PCancelable;
module.exports.CancelError = CancelError;
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