Class CancelablePromise

frontend/src/client/core/CancelablePromise.ts:20–126

}

export class CancelablePromise<T> implements Promise<T> {
  private _isResolved: boolean
  private _isRejected: boolean
  private _isCancelled: boolean
  readonly cancelHandlers: (() => void)[]
  readonly promise: Promise<T>
  private _resolve?: (value: T | PromiseLike<T>) => void
  private _reject?: (reason?: unknown) => void

  constructor(
    executor: (
      resolve: (value: T | PromiseLike<T>) => void,
      reject: (reason?: unknown) => void,
      onCancel: OnCancel,
    ) => void,
  ) {
    this._isResolved = false
    this._isRejected = false
    this._isCancelled = false
    this.cancelHandlers = []
    this.promise = new Promise<T>((resolve, reject) => {
      this._resolve = resolve
      this._reject = reject

      const onResolve = (value: T | PromiseLike<T>): void => {
        if (this._isResolved || this._isRejected || this._isCancelled) {
          return
        }
        this._isResolved = true
        if (this._resolve) this._resolve(value)
      }

      const onReject = (reason?: unknown): void => {
        if (this._isResolved || this._isRejected || this._isCancelled) {
          return
        }
        this._isRejected = true
        if (this._reject) this._reject(reason)
      }

      const onCancel = (cancelHandler: () => void): void => {
        if (this._isResolved || this._isRejected || this._isCancelled) {
          return
        }
        this.cancelHandlers.push(cancelHandler)
      }

      Object.defineProperty(onCancel, 'isResolved', {
        get: (): boolean => this._isResolved,
      })

      Object.defineProperty(onCancel, 'isRejected', {
        get: (): boolean => this._isRejected,
      })

      Object.defineProperty(onCancel, 'isCancelled', {
        get: (): boolean => this._isCancelled,
      })