Prevent stack overflow in cyclical graphs

Summary: Logview reported "Error: Maximum call stack size exceeded" for "getElementLeaves". Apparently, there was a cycle in the graph that caused it. The new implementation should ignore cycles.

Reviewed By: lblasa

Differential Revision: D43976359

fbshipit-source-id: bb5218a3b29706146501241492ee079773d5abc3

desktop/plugins/public/layout/Inspector.tsx

@@ -341,20 +341,29 @@ export default class Inspector extends Component<Props, State> {
   }
 
   getElementLeaves(tree: ElementSelectorNode): Array<ElementID> {
-    return tree
+    if (!tree) {
-      ? Object.entries(tree).reduce(
+      return [];
-          (
+    }
-            currLeafNode: Array<ElementID>,
+    const leavesSet = new Set<ElementID>();
-            [id, children]: [ElementID, ElementSelectorNode],
+
-          ): Array<ElementID> =>
+    const treeIteratorStack: [ElementID, ElementSelectorNode][] = [
-            currLeafNode.concat(
+      ...Object.entries(tree),
-              Object.keys(children).length > 0
+    ];
-                ? this.getElementLeaves(children)
+    while (treeIteratorStack.length) {
-                : [id],
+      const [id, children] = treeIteratorStack.pop()!;
-            ),
+
-          [],
+      if (leavesSet.has(id)) {
-        )
+        continue;
-      : [];
+      }
+
+      if (Object.keys(children).length) {
+        treeIteratorStack.push(...Object.entries(children));
+      } else {
+        leavesSet.add(id);
+      }
+    }
+
+    return [...leavesSet];
   }
 
   /// Return path from given tree structure and id if id is not null; otherwise return any path