Enhance caching mechanism by adding future promise to cached function and updating maps retrieval logic to use it

src/components/stores/cached.ts

@@ -17,20 +17,30 @@
  *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-import {readonly, writable} from "svelte/store";
+import { readonly, writable } from "svelte/store";
 
-import type {Readable, Subscriber, Unsubscriber} from "svelte/store";
+import type { Readable, Subscriber, Unsubscriber } from "svelte/store";
 
 export interface Cached<T> extends Readable<T> {
     reload: () => void;
+    future: Promise<T>;
 }
 
 export function cached<T>(normal: T, init: () => Promise<T>): Cached<T> {
     const store = writable<T>(normal);
+    const future = new Promise<T>((resolve) => {
+        let f = true;
+        store.subscribe((value) => {
+            if (f) {
+                f = false;
+                resolve(value);
+            }
+        });
+    });
     let first = true;
 
     const reload = () => {
-        init().then(data => {
+        init().then((data) => {
             store.set(data);
         });
     };
@@ -45,6 +55,7 @@ export function cached<T>(normal: T, init: () => Promise<T>): Cached<T> {
             return store.subscribe(run, invalidate);
         },
         reload,
+        future,
     };
 }
 
@@ -58,7 +69,7 @@ export function cachedFamily<T, K>(normal: K, init: (arg0: T) => Promise<K>): (a
             let first = true;
 
             const reload = () => {
-                init(arg).then(data => {
+                init(arg).then((data) => {
                     store.set(data);
                 });
             };