add loading progress support and new indicator

src/torqueScript/progress.ts

@@ -0,0 +1,75 @@
+export type ProgressEventType = "update";
+export type ProgressListener = () => void;
+
+export interface ProgressTracker {
+  /** Total items discovered so far (increases as dependencies are found) */
+  readonly total: number;
+  /** Items completed */
+  readonly loaded: number;
+  /** Currently loading item path, if any */
+  readonly current: string | null;
+  /** Progress as a ratio from 0 to 1 (or 0 if total is 0) */
+  readonly progress: number;
+  /** Subscribe to progress updates */
+  on(event: ProgressEventType, listener: ProgressListener): void;
+  /** Unsubscribe from progress updates */
+  off(event: ProgressEventType, listener: ProgressListener): void;
+}
+
+export interface ProgressTrackerInternal extends ProgressTracker {
+  /** Increment total count when a new item is discovered */
+  addItem(path: string): void;
+  /** Mark an item as completed */
+  completeItem(): void;
+  /** Set the currently loading item */
+  setCurrent(path: string | null): void;
+}
+
+export function createProgressTracker(): ProgressTrackerInternal {
+  const listeners = new Set<ProgressListener>();
+
+  let total = 0;
+  let loaded = 0;
+  let current: string | null = null;
+
+  function notify(): void {
+    for (const listener of listeners) {
+      listener();
+    }
+  }
+
+  return {
+    get total() {
+      return total;
+    },
+    get loaded() {
+      return loaded;
+    },
+    get current() {
+      return current;
+    },
+    get progress() {
+      return total === 0 ? 0 : loaded / total;
+    },
+    on(_event: ProgressEventType, listener: ProgressListener) {
+      listeners.add(listener);
+    },
+    off(_event: ProgressEventType, listener: ProgressListener) {
+      listeners.delete(listener);
+    },
+    addItem(path: string) {
+      total++;
+      current = path;
+      notify();
+    },
+    completeItem() {
+      loaded++;
+      current = null;
+      notify();
+    },
+    setCurrent(path: string | null) {
+      current = path;
+      notify();
+    },
+  };
+}