Design Cancellable Function — LeetCode 2650 Python Solution

The problem

Sometimes you have a long running task, and you may wish to cancel it before it completes. To help with this goal, write a function cancellable that accepts a generator object and returns an array of two values: a cancel function and a promise.

Example

function* tasks() {
  const val = yield new Promise(resolve => resolve(2 + 2));
  yield new Promise(resolve => setTimeout(resolve, 100));
  return val + 1; // calculation shouldn't be done.
}
const [cancel, promise] = cancellable(tasks());
setTimeout(cancel, 50);
promise.catch(console.log); // logs "Cancelled" at t=50ms

Complexity

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