itertools: Added bfs iterator

src/utils/itertools.ts

@@ -22,6 +22,34 @@ export function * MakeIterator(root: IContainerModel): Generator<IContainerModel
   }
 }
 
+export interface ContainerAndDepth {
+  container: IContainerModel
+  depth: number
+}
+/**
+ * Returns a Generator iterating of over the children depth-first
+ */
+export function * MakeBFSIterator(root: IContainerModel): Generator<ContainerAndDepth, void, unknown> {
+  const queue: IContainerModel[] = [root];
+  let depth = 0;
+  while (queue.length > 0) {
+    let levelSize = queue.length;
+    while (levelSize-- !== 0) {
+      const container = queue.shift() as IContainerModel;
+      yield {
+        container,
+        depth
+      };
+
+      for (let i = container.children.length - 1; i >= 0; i--) {
+        const child = container.children[i];
+        queue.push(child);
+      }
+    }
+    depth++;
+  }
+}
+
 /**
  * Returns the depth of the container
  * @returns The depth of the container