Yes, FYI that's the exact thing we've been discussing :) 2011/7/29 Niels Hoogeveen <pd_aficion...@hotmail.com>
> > Great, I would much rather see this become part of the core API than have > this as part of the Enhanced API. > To make things work correctly, one important change to core is needed: The > Node interface needs to extends Traverser (the interface in > org.neo4j.graphdb.traversal, not the one in org.neo4j.graphdb). > This is actually not a big deal. There Traverser interface supports three > methods: > Iterator<path> iterator() [return 1 path with 1 element in the path, being > the node itself]Iterable<Node> nodes() [return an iterable over the node > itself]Iterable<Relationship> relationships() [return an empty iterable] > With that addition, it's not all too difficult to enhance the current > implementation of Traverser. It only adds one more iteration level over the > current implementation. Instead of having one start node, we now have > multiple start paths. When returning values from the Traverser, the start > paths and the result paths need to be concatenated. > In the new scenario, all "old" traverse() methods can remain the same, > since Node becomes a Traverser, so those methods are just special cases > where Iterable<Path> consists of 1 path, with just 1 element. > Niels > > Date: Fri, 29 Jul 2011 18:36:28 +0200 > > From: matt...@neotechnology.com > > To: user@lists.neo4j.org > > Subject: Re: [Neo4j] Composable traversals > > > > There have been thoughts a long while to make something like this with > the > > traversal framework, but time has never been allocated to evolve it. I'm > > adding stuff to the framework in a side track and will surely add some > > aspect of composable traversers also. > > > > 2011/7/29 Niels Hoogeveen <pd_aficion...@hotmail.com> > > > > > > > > I'd like to take a stab at implementing traversals in the Enhanced API. > One > > > of the things I'd like to do, is to make traversals composable. > > > > > > Right now a Traverser is created by either calling the traverse method > on > > > Node, or to call the traverse(Node) method on TraversalDescription. > > > > > > This makes traversals inherently non-composable, so we can't define a > > > single traversal that returns the parents of all our friends. > > > > > > To make Traversers composable we need a function: > > > > > > Traverser traverse(Traverser, TraversalDescription) > > > > > > My take on it is to make Element (which is a superinterface of Node) > into a > > > Traverser. > > > > > > Traverser is basically another name for Iterable<Path>. > > > > > > Every Node (or more generally every Element) can be seen as an > > > Iterabe<Path>, returning a single Path, which contains a single > > > path-element, the Node/Element itself. > > > > > > Composing traversals would entail the concatenation of the paths > returned > > > with the paths supplied, so when we ask for the parents of all our > friends, > > > the returned paths would take the form: > > > > > > Node --FRIEND--> Node --> PARENT --> Node > > > > > > Niels > > > > > > _______________________________________________ > > > Neo4j mailing list > > > User@lists.neo4j.org > > > https://lists.neo4j.org/mailman/listinfo/user > > > > > > > > > > > -- > > Mattias Persson, [matt...@neotechnology.com] > > Hacker, Neo Technology > > www.neotechnology.com > > _______________________________________________ > > Neo4j mailing list > > User@lists.neo4j.org > > https://lists.neo4j.org/mailman/listinfo/user > > _______________________________________________ > Neo4j mailing list > User@lists.neo4j.org > https://lists.neo4j.org/mailman/listinfo/user > -- Mattias Persson, [matt...@neotechnology.com] Hacker, Neo Technology www.neotechnology.com _______________________________________________ Neo4j mailing list User@lists.neo4j.org https://lists.neo4j.org/mailman/listinfo/user
