On Mon, Jun 4, 2018 at 11:45 AM, Robert Munteanu <romb...@apache.org> wrote:
> Hi Jason, > > On Thu, 2018-05-31 at 10:39 -0400, Jason E Bailey wrote: > > https://github.com/apache/sling-org-apache-sling-api/pull/4 > > > > I've created a pull request to add a new class to the Sling API > > bundle that would allow you to create a Stream<Resource> object which > > traverses a resource tree. > > > > Additionally, the ResourceStream class has convenience methods to > > specify a predicate that identifies valid resources, a limit to the > > number of valid items that are returned and a range method. There is > > also a core feature of branch selection that allows you to customize > > the traversal so that it you can limit the branches that the > > traversal proceeds down. > > > > If you have concerns or questions, now's the time to raise it. > > Again, thanks for looking into this, I think it's a nice addition. > > There are two questions I want to raise: > > 1. API related > > We have two methods: > > - stream() > - stream(Predicate<Resource>) > > which traverse the whole tree. > > There were questions of whether this is OK or if we maybe need to > stream the children only. Could the API additions allow that? > > We can start with something like > > - stream(Predicate<Resource>, Set<TraversalOption>... ) > - stream(Predicate<Resource>) > - stream(Set<TraversalOption>...) > > where > > enum TraversalOption { > DIRECT_CHILDREN_ONLY, ALL_CHILDREN; > } > > (yes, the names are bad, just wanted to raise the question and start a > discussion) > Rather than having another parameter, what about providing a ResourceChildrenPredicate? Based on the current API it looks like you'd have to provide the current resource to make this work, but it seems like it would be very useful to have a predicate which would only allow for both direct children or children up to a particular depth. I'd see it useful to provide 2-3 different default predicates to help with common activities: ResourceChildrenPredicate - filter the stream of resources based on their child status ResourceTypePredicate - filter the stream of resource based on their resource type ValuePredicate - filter the stream of resources based on a value in the resource's ValueMap > > 2. Implementation related > > I think that the 'hasNext' method is not lazy, eagerly loading the > direct children of a resource when there are no more resources to load. > > If the resource has a large number of children we can end up taking > lots of memory, so I think we need to be more lazy with it, since the > streams framework can take advantage of that (IIRC). Is it possible to > ajust the implementation this way? > > Thanks, > > Robert >
