tools: move eslint from tools to tools/node_modules

This is required because we need to add the babel-eslint dependency
and it has to be able to resolve "eslint".
babel-eslint is required to support future ES features such as async
iterators and import.meta.

Refs: https://github.com/nodejs/node/pull/17755
PR-URL: https://github.com/nodejs/node/pull/17820
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>

1 files changed, 45 insertions, 0 deletions

diff --git a/tools/node_modules/eslint/lib/util/traverser.js b/tools/node_modules/eslint/lib/util/traverser.js
new file mode 100644
index 0000000000..fc070186b3
--- /dev/null
+++ b/tools/node_modules/eslint/lib/util/traverser.js
@@ -0,0 +1,45 @@
+/**
+ * @fileoverview Wrapper around estraverse
+ * @author Nicholas C. Zakas
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const estraverse = require("estraverse");
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const KEY_BLACKLIST = new Set([
+    "parent",
+    "leadingComments",
+    "trailingComments"
+]);
+
+/**
+ * Wrapper around an estraverse controller that ensures the correct keys
+ * are visited.
+ * @constructor
+ */
+class Traverser extends estraverse.Controller {
+    traverse(node, visitor) {
+        visitor.fallback = Traverser.getKeys;
+        return super.traverse(node, visitor);
+    }
+
+    /**
+     * Calculates the keys to use for traversal.
+     * @param {ASTNode} node The node to read keys from.
+     * @returns {string[]} An array of keys to visit on the node.
+     * @private
+     */
+    static getKeys(node) {
+        return Object.keys(node).filter(key => !KEY_BLACKLIST.has(key));
+    }
+}
+
+module.exports = Traverser;