refactor the whole damn thing

src/Util/structReferences.js

@@ -0,0 +1,30 @@
+import YArray from '../Type/YArray'
+import YMap from '../Type/YMap'
+import YText from '../Type/YText'
+import YXml from '../Type/YXml'
+
+import ItemJSON from '../Struct/ItemJSON'
+import ItemString from '../Struct/ItemString'
+
+const structs = new Map()
+const references = new Map()
+
+function addStruct (reference, structConstructor) {
+  structs.set(reference, structConstructor)
+  references.set(structConstructor, reference)
+}
+
+export function getStruct (reference) {
+  return structs.get(reference)
+}
+
+export function getReference (typeConstructor) {
+  return references.get(typeConstructor)
+}
+
+addStruct(0, YArray)
+addStruct(1, YMap)
+addStruct(2, YText)
+addStruct(3, YXml)
+addStruct(4, ItemJSON)
+addStruct(5, ItemString)