Hierarchical data behaviours

[kirkbushell]

One thing that I've wanted to build for a while is a behaviour to support hierarchical data structures, think node trees and their like.

There are multiple potential data models to support hierarchical data structures, such as Adjacency Lists, Path enumeration, Nested sets and Closure tables. My goal here is to support each one of these data models, because each model has both pros and cons, and I believe it's up to the developer which solution suits them best.

I'd love to get some early feedback here based on what you'd prefer to use, and I'll start with those behaviours and if others are interested, they could also contribute to this work.