Generate Data-Structure of PsiFile for Annotator once before 'annotate' is called for every element

Hi!

I'm currently attempting to create a simple plugin extending the already existing JSON language. I've already got a json schema, but that's not really enough to support things like auto complete (e.g. I have a property where the value would get vaölidated based on a totally different property value somewhere different in the file).

I'm using an com.intellij.lang.annotation.Annotator, where it's obviously called for every PsiElement - but I would need to traverse the whole PsiFile to find those values which are allowed for the annotated PsiElement. That would happen for every single PsiElement, is there any possibility, like a PreAnnotateFile-Method to collect those values beforehand? Otherwise it would be quite a few .parent.parent.parent.parent…. and child searching.

Example JSON:

{
  "my-values": {
    "test1": {
       "id": "my-id1"
    },
    "test2": {
       "id": "my-id2"
    }
  },
  "my-other-things:" {
    "whatever": {
      "reference": "only my-id1 or my-id2 is allowed (and should be auto-completed)"
	}
  }
}