Trees of varying depths

[justinbmeyer]

I'm not sure can-key-tree should take this on, but it would be helpful in some places for KeyTree to support in some way trees of varying depths. This issue explores one idea.

Lets say I had a structure similar to the DependencyRecord type in can-observation-recorder:

var dependencyRecord = {
  keyDependencies: Map{
    [person]: Set["first", "last"]
  },
  valueDependencies: Set[ageCompute]
}

I would like to easily be able to add and remove values to this tree, especially the keyDependencies Map with the familiar tree.add() api:

dependencyRecord.add(["keyDependencies", person, "first"])
dependencyRecord.add(["valueDependencies", ageCompute])

One way might be to support creating a tree of trees, where the nodes can be determined by their parent key:

dependencyRecord = new KeyTree([{
  keyDependencies: KeyTree.extend([Map, Set]),
  valueDependencies: KeyTree.extend([Map, Set])
}])

Then:

dependencyRecord.add(["keyDependencies", [person, "first"] ]);
dependencyRecord.add(["valueDependencies", [ageCompute] ]);

For something like https://github.com/canjs/can-reflect-mutate-dependencies

mutateStore = new KeyTree([ WeakMap, {
  mutateDependenciesForKey: KeyTree.extend([ Map, DependencyRecord ])
  mutateDependenciesForValue: DependencyRecord
}])

// john.on("born", function(){ fred.age = 0; })

mutateStore.add(
  [ fred, "mutateDependenciesForKey",
    [ "age", 
      ["keyDependencies", 
        [john, "born"]
      ]
    ]
  ])