get feature highlighting working both ways

From the editor to the viewer and from the viewer to the editor

src/useStore.ts

@@ -0,0 +1,32 @@
+import create from 'zustand'
+import {addLineHighlight, EditorView} from './editor/highlightextension'
+
+export type Range = [number, number]
+
+interface StoreState {
+    editorView: EditorView | null,
+    setEditorView: (editorView: EditorView) => void,
+    highlightRange: [number, number],
+    setHighlightRange: (range: Range) => void,
+    selectionRange: [number, number],
+    setSelectionRange: (range: Range) => void,
+}
+
+export const useStore = create<StoreState>()((set, get) => ({
+    editorView: null,
+    setEditorView: (editorView) => {
+        set({editorView})
+    },
+    highlightRange: [0, 0],
+    setHighlightRange: (highlightRange) => {
+        set({ highlightRange })
+        const editorView = get().editorView
+        if (editorView) {
+            editorView.dispatch({ effects: addLineHighlight.of(highlightRange) });
+        }
+    },
+    selectionRange: [0, 0],
+    setSelectionRange: (selectionRange) => {
+        set({ selectionRange })
+    },
+}))