Thoughts on Path Fragments - microbean/microbean-settings GitHub Wiki

Maybe a Path as currently defined is too flexible and hence too complicated.

The complexity comes from having qualifiers at every node in the path. How do you apply matching algorithms to them in an additive fashion? I'm not smart enough to do that.

Let's separate the notion of qualifiers from paths for a moment.

What if instead we have PathFragments and Accessors?

Let's say a PathFragment is a List of Accessors terminating in a Type. An Accessor at its simplest is a name. An Accessor can also have parameters (a List<Class<?>>) and corresponding arguments of the appropriate type (a List<?>). So an Accessor can represent a kind of "typeless" "getter method" invocation or array access.

So a PathFragment is never absolute. It just represents, e.g. getDrivetrain/getEngine/getCylinders:List<Cylinder>. Note that getDrivetrain is not "anchored" with Car.

Or we could allow it to have a source, intermediate and target type, all optional (except for the target), separated by accessors.

So that would let you say :Car/getDrivetrain/getEngine:Engine/getCylinders:List<Cylinder>.

Then you could join them: getDailyDriver:Car + :Car/getDrivetrain/getEngine:Engine/getCylinders:List<Cylinder> = getDailyDriver:Car/getDrivetrain/getEngine:Engine/getCylinders:List<Cylinder>. Since the intermediate type is optional, you can now build arbitrary path fragments.

Then a full Path is a PathFragment with a source type of :RootType and no accessors or target type, plus another PathFragment with no source type, an optional list of accessors and a target type.

Now you can match Provider path fragments against "rooted" context paths (you'll always be looking for "ends with").