typescript-eslint · JamesHenry · Jun 20, 2019 · Jun 19, 2019 · Jun 20, 2019
diff --git a/packages/parser/src/parser.ts b/packages/parser/src/parser.ts
@@ -1,12 +1,12 @@
+import { TSESLint } from '@typescript-eslint/experimental-utils';
 import {
   AST_NODE_TYPES,
   parseAndGenerateServices,
-  TSESTreeOptions,
   ParserServices,
+  TSESTreeOptions,
 } from '@typescript-eslint/typescript-estree';
-import { TSESLint } from '@typescript-eslint/experimental-utils';
-import traverser from 'eslint/lib/util/traverser';
 import { analyzeScope } from './analyze-scope';
+import { simpleTraverse } from './simple-traverse';
 import { visitorKeys } from './visitor-keys';
 
 type ParserOptions = TSESLint.ParserOptions;
@@ -87,7 +87,7 @@ export function parseForESLint(
   const { ast, services } = parseAndGenerateServices(code, parserOptions);
   ast.sourceType = options.sourceType;
 
-  traverser.traverse(ast, {
+  simpleTraverse(ast, {
     enter(node) {
       switch (node.type) {
         // Function#body cannot be null in ESTree spec.

diff --git a/packages/parser/src/simple-traverse.ts b/packages/parser/src/simple-traverse.ts
@@ -0,0 +1,58 @@
+import { TSESTree } from '@typescript-eslint/typescript-estree';
+import { visitorKeys } from './visitor-keys';
+
+function isValidNode(x: any): x is TSESTree.Node {
+  return x !== null && typeof x === 'object' && typeof x.type === 'string';
+}
+
+function getVisitorKeysForNode(
+  allVisitorKeys: typeof visitorKeys,
+  node: TSESTree.Node,
+): readonly string[] {
+  const keys = allVisitorKeys[node.type];
+  return keys || [];
+}
+
+interface SimpleTraverseOptions {
+  enter: (node: TSESTree.Node, parent: TSESTree.Node | undefined) => void;
+}
+
+class SimpleTraverser {
+  private allVisitorKeys = visitorKeys;
+  private enter: SimpleTraverseOptions['enter'];
+
+  constructor({ enter }: SimpleTraverseOptions) {
+    this.enter = enter;
+  }
+
+  traverse(node: unknown, parent: TSESTree.Node | undefined) {
+    if (!isValidNode(node)) {
+      return;
+    }
+    this.enter(node, parent);
+
+    const keys = getVisitorKeysForNode(this.allVisitorKeys, node);
+    if (keys.length < 1) {
+      return;
+    }
+
+    for (const key of keys) {
+      const childOrChildren = node[key as keyof typeof node];
+
+      if (Array.isArray(childOrChildren)) {
+        for (const child of childOrChildren) {
+          this.traverse(child, node);
+        }
+      } else {
+        this.traverse(childOrChildren, node);
+      }
+    }
+  }
+}
+
+export function simpleTraverse(
+  startingNode: TSESTree.Node,
+  options: SimpleTraverseOptions,
+) {
+  new SimpleTraverser(options).traverse(startingNode, undefined);
+}
diff --git a/packages/parser/tsconfig.build.json b/packages/parser/tsconfig.build.json
@@ -4,5 +4,5 @@
     "declaration": true,
     "outDir": "./dist"
   },
-  "include": ["src", "typings"]
+  "include": ["src"]
 }
diff --git a/packages/parser/tsconfig.json b/packages/parser/tsconfig.json
@@ -1,5 +1,5 @@
 {
   "extends": "./tsconfig.build.json",
-  "include": ["src", "typings", "tests", "tools"],
+  "include": ["src", "tests", "tools"],
   "exclude": ["tests/fixtures"]
 }
diff --git a/packages/parser/typings/eslint.d.ts b/packages/parser/typings/eslint.d.ts