Add basic traverseGenerator

Need to allow changing order

src/traverse.ts

@@ -1,5 +1,5 @@
 // import { isNodeSimple } from './utils';
-import {FiberNode} from './mocked-types';
+import { FiberNode } from "./mocked-types";
 
 function traverse(node: FiberNode, fn: (node: FiberNode) => any) {
   fn.call(null, node);
@@ -10,6 +10,25 @@ function traverse(node: FiberNode, fn: (node: FiberNode) => any) {
   if (node.sibling !== null) {
     traverse(node.sibling, fn);
   }
-};
+}
 
-export default traverse;
+function* traverseGenerator(
+  node: FiberNode
+  // {
+  //   order = "pre"
+  // }: { order: "in" | "pre" | "post" }
+): IterableIterator<FiberNode> {
+  const { skipChild, skipSibling } = yield node;
+
+  if (!skipChild && node.child !== null) {
+    const nextNode = node.child;
+    yield* traverseGenerator(nextNode);
+  }
+
+  if (!skipSibling && node.sibling !== null) {
+    const nextNode = node.sibling;
+    yield* traverseGenerator(nextNode);
+  }
+}
+
+export { traverse, traverseGenerator };