2650. 设计可取消函数

2650. 设计可取消函数

function cancellable<T>(
  generator: Generator<Promise<any>, T, unknown>
): [() => void, Promise<T>] {
  let cancelled = false

  const cancel = () => {
    cancelled = true
  }

  const promise = new Promise<T>(async (resolve, reject) => {
    try {
      let result = generator.next()

      while (!result.done) {
        await result.value

        if (cancelled) return reject('Cancelled')

        result = generator.next()
      }

      if (cancelled) return reject('Cancelled')

      resolve(result.value)
    } catch (err) {
      if (cancelled) return reject('Cancelled')
      reject(err)
    }
  })

  return [cancel, promise]
}