Initial import with skill sheet working

node_modules/eslint-visitor-keys/lib/index.js

@@ -0,0 +1,67 @@
+/**
+ * @author Toru Nagashima <https://github.com/mysticatea>
+ * See LICENSE file in root directory for full license.
+ */
+import KEYS from "./visitor-keys.js";
+
+/**
+ * @typedef {import('./visitor-keys.js').VisitorKeys} VisitorKeys
+ */
+
+// List to ignore keys.
+const KEY_BLACKLIST = new Set([
+    "parent",
+    "leadingComments",
+    "trailingComments"
+]);
+
+/**
+ * Check whether a given key should be used or not.
+ * @param {string} key The key to check.
+ * @returns {boolean} `true` if the key should be used.
+ */
+function filterKey(key) {
+    return !KEY_BLACKLIST.has(key) && key[0] !== "_";
+}
+
+
+/* eslint-disable jsdoc/valid-types -- doesn't allow `readonly`.
+   TODO: remove eslint-disable when https://github.com/jsdoc-type-pratt-parser/jsdoc-type-pratt-parser/issues/164 is fixed
+*/
+/**
+ * Get visitor keys of a given node.
+ * @param {Object} node The AST node to get keys.
+ * @returns {readonly string[]} Visitor keys of the node.
+ */
+export function getKeys(node) {
+    return Object.keys(node).filter(filterKey);
+}
+/* eslint-enable jsdoc/valid-types -- doesn't allow `readonly` */
+
+/**
+ * Make the union set with `KEYS` and given keys.
+ * @param {VisitorKeys} additionalKeys The additional keys.
+ * @returns {VisitorKeys} The union set.
+ */
+export function unionWith(additionalKeys) {
+    const retv = /** @type {{ [type: string]: ReadonlyArray<string> }} */
+        (Object.assign({}, KEYS));
+
+    for (const type of Object.keys(additionalKeys)) {
+        if (Object.hasOwn(retv, type)) {
+            const keys = new Set(additionalKeys[type]);
+
+            for (const key of retv[type]) {
+                keys.add(key);
+            }
+
+            retv[type] = Object.freeze(Array.from(keys));
+        } else {
+            retv[type] = Object.freeze(Array.from(additionalKeys[type]));
+        }
+    }
+
+    return Object.freeze(retv);
+}
+
+export { KEYS };