Hi Rémi,
Yes, this was something I was hoping to get into the preview, but I wasn't sure
where that conversion should end up.
There are a few different places where it might go:
Gatherer.of(Collector)
Gatherers.collect(Collector)
Collector.asGatherer()
Collectors.gather(Collector)
I wasn't really convinced where it should go, and I was hesitant to making any
changes to existing public interfaces as a "nice to have", so I opted to leave
it out for now.
I think people would prefer to see it on Collector as a default method, but as
I said before, making changes to Collector wasn't something I was ready to
prioritize for the (first) JEP.
Cheers,
√
Viktor Klang
Software Architect, Java Platform Group
Oracle
________________________________
From: core-libs-dev <core-libs-dev-r...@openjdk.org> on behalf of Remi Forax
<fo...@univ-mlv.fr>
Sent: Wednesday, 17 January 2024 17:08
To: core-libs-dev <core-libs-...@openjdk.java.net>
Subject: Seing a Collector as a Gatherer
Hello,
I may have overlook that, but it seems there is no method to see a Collector as
a Gatherer.
A Gatherer is more general than a Collector and a Gatherer with a greedy
integrator that does not call Downstream.push in the intergator and only once
is the finisher is basicaly a Collector.
In code:
<E, A, T> Gatherer<E, A, T> asGatherer(Collector<? super E, A, ? extends T>
collector) {
var supplier = collector.supplier();
var accumulator = collector.accumulator();
var combiner = collector.combiner();
var finisher = collector.finisher();
return Gatherer.of(supplier,
Gatherer.Integrator.ofGreedy((state, element, _) -> {
accumulator.accept(state, element);
return true;
}),
combiner,
(state, downstream) -> downstream.push(finisher.apply(state)));
}
This is eaxctly how Gatherer.fold() works.
Is there a reason why such method does not exist ?
regards,
Rémi
