Bump to v4.0.0.

internal/stringToPath.js

@@ -0,0 +1,24 @@
+import toString from '../toString';
+
+/** Used to match property names within property paths. */
+var rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\\]|\\.)*?)\2)\]/g;
+
+/** Used to match backslashes in property paths. */
+var reEscapeChar = /\\(\\)?/g;
+
+/**
+ * Converts `string` to a property path array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the property path array.
+ */
+function stringToPath(string) {
+  var result = [];
+  toString(string).replace(rePropName, function(match, number, quote, string) {
+    result.push(quote ? string.replace(reEscapeChar, '$1') : (number || match));
+  });
+  return result;
+}
+
+export default stringToPath;