refactor(linter/plugins): introduce methods for deep cloning JSON values

apps/oxlint/src-js/plugins/json.ts

@@ -62,3 +62,48 @@ export function deepFreezeJsonArray(arr: JsonValue[]): undefined {
   }
   Object.freeze(arr);
 }
+
+/**
+ * Deep clone a JSON value, recursively cloning all nested objects and arrays.
+ * @param value - The value to deep clone
+ * @returns Cloned value
+ */
+export function deepCloneJsonValue(value: JsonValue): JsonValue {
+  if (value === null || typeof value !== "object") return value;
+
+  if (Array.isArray(value)) return deepCloneJsonArray(value);
+  return deepCloneJsonObject(value);
+}
+
+/**
+ * Deep clone a JSON object, recursively cloning all nested objects and arrays.
+ * @param obj - The object to deep clone
+ * @returns Cloned object
+ */
+export function deepCloneJsonObject(obj: JsonObject): JsonObject {
+  // Circular references are not possible in JSON, so no need to handle them here.
+  // Symbol properties are not possible in JSON, so no need to handle them here.
+  // All properties are enumerable own properties, so can use simple `for..in` loop.
+  // Clone `obj` into `cloned` first, so then don't have to handle if object has a key called `__proto__`.
+  const cloned = { ...obj };
+  for (const key in obj) {
+    const value = obj[key];
+    if (typeof value !== "object" || value === null) continue;
+    cloned[key] = Array.isArray(value) ? deepCloneJsonArray(value) : deepCloneJsonObject(value);
+  }
+  return cloned;
+}
+
+/**
+ * Deep clone a JSON array, recursively cloning all nested objects and arrays.
+ * @param arr - The array to deep clone
+ * @returns Cloned array
+ */
+export function deepCloneJsonArray(arr: JsonValue[]): JsonValue[] {
+  // Circular references are not possible in JSON, so no need to handle them here
+  const cloned = [];
+  for (let i = 0, len = arr.length; i !== len; i++) {
+    cloned.push(deepCloneJsonValue(arr[i]));
+  }
+  return cloned;
+}