perf: revise traverseNode to use _skipKeysSet

packages/babel-traverse/src/index.js

@@ -1,8 +1,8 @@
-import TraversalContext from "./context";
 import * as visitors from "./visitors";
 import includes from "lodash/includes";
 import * as t from "@babel/types";
 import * as cache from "./cache";
+import { traverseNode } from "./traverse-node";
 
 export { default as NodePath } from "./path";
 export { default as Scope } from "./scope";
@@ -33,7 +33,11 @@ export default function traverse(
 
   visitors.explode(opts);
 
-  traverse.node(parent, opts, scope, state, parentPath);
+  if (!t.VISITOR_KEYS[parent.type]) {
+    return;
+  }
+
+  traverseNode(parent, opts, scope, state, parentPath, new Set());
 }
 
 traverse.visitors = visitors;
@@ -55,11 +59,14 @@ traverse.node = function(
   const keys: Array = t.VISITOR_KEYS[node.type];
   if (!keys) return;
 
-  const context = new TraversalContext(scope, opts, state, parentPath);
-  for (const key of keys) {
-    if (skipKeys && skipKeys[key]) continue;
-    if (context.visit(node, key)) return;
+  let skipKeysSet;
+  const skipKeysKeys = Object.keys(skipKeys);
+  if (skipKeysKeys.length > 0) {
+    skipKeysSet = new Set(skipKeysKeys.filter(v => skipKeys[v] === true));
+  } else {
+    skipKeysSet = new Set();
   }
+  return traverseNode(node, opts, scope, state, parentPath, skipKeysSet);
 };
 
 traverse.clearNode = function(node, opts) {

packages/babel-traverse/src/path/context.js

@@ -1,6 +1,6 @@
 // This file contains methods responsible for maintaining a TraversalContext.
 
-import traverse from "../index";
+import { traverseNode } from "../traverse-node";
 import { SHOULD_SKIP, SHOULD_STOP } from "./index";
 
 export function call(key): boolean {
@@ -74,13 +74,13 @@ export function visit(): boolean {
   }
 
   this.debug("Recursing into...");
-  traverse.node(
+  traverseNode(
     this.node,
     this.opts,
     this.scope,
     this.state,
     this,
-    this.skipKeys,
+    this._skipKeysSet,
   );
 
   this.call("exit");
@@ -93,7 +93,7 @@ export function skip() {
 }
 
 export function skipKey(key) {
-  this.skipKeys[key] = true;
+  this.skipKeys.add(key);
 }
 
 export function stop() {
@@ -117,7 +117,7 @@ export function setScope() {
 }
 
 export function setContext(context) {
-  this.skipKeys = {};
+  this._skipKeysSet.clear();
   this._traverseFlags = 0;
 
   if (context) {

packages/babel-traverse/src/traverse-node.js

@@ -0,0 +1,19 @@
+import * as t from "@babel/types";
+import TraversalContext from "./context";
+
+export function traverseNode(
+  node: Object,
+  opts: Object,
+  scope: Object,
+  state: Object,
+  parentPath: Object,
+  skipKeys: Set<string>,
+) {
+  const keys: Array = t.VISITOR_KEYS[node.type];
+
+  const context = new TraversalContext(scope, opts, state, parentPath);
+  for (const key of keys) {
+    if (skipKeys.has(key)) continue;
+    if (context.visit(node, key)) return;
+  }
+}