one shot queries

[levnach]

Hi there!
It looks like some queries are 'one shot' queries. They are not reusable. For example the following test passes.
test('ienum', () => { function* foo() { yield 0 } const e = from(foo()) expect(e.count()).toBe(1) expect(e.count()).toBe(0) })
Please notice that the first call to e.count() returns 1 as the second returns 0!
Is it by design?

[arogozine]

I think that makes sense. You can only go forward with an iteration. So the first count iterates through all the values, giving nothing to iterate over for the second call to count.

In the next release (see dev branch) you should be able to do the following,

function* foo() { yield 0 }
const e2 = from(foo)
console.log(e2.count())
console.log(e2.count())

[levnach]

Sorry, your comment is not clear for me. Do you expect to get 1 at the second printout?
I noticed that you used foo without (). Do you expect output 1 in both cases? It would be great.

[arogozine]

No to the first question. The iterator given by foo() can only move forward. So the first count() iterates through all the elements and gives the correct number but the second count() has nothing to iterate over so the number is 0. The library does not cache anything.

Yes to the second question. With the upcoming release - you can pass in the generator function itself - not the iterator given by the function - thus each count() calls foo() resulting in both being 1

Currently if you want to go from a generator, I'd suggest converting to an array [...foo()]

[arogozine]

I did a quick release that should allow passing in generator functions - like from(foo)

[levnach]

It seems working, thanks!