Bump to v4.0.0.

internal/baseSet.js

@@ -0,0 +1,43 @@
+import assignValue from './assignValue';
+import baseToPath from './baseToPath';
+import isIndex from './isIndex';
+import isKey from './isKey';
+import isObject from '../isObject';
+
+/**
+ * The base implementation of `_.set`.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @param {Array|string} path The path of the property to set.
+ * @param {*} value The value to set.
+ * @param {Function} [customizer] The function to customize path creation.
+ * @returns {Object} Returns `object`.
+ */
+function baseSet(object, path, value, customizer) {
+  path = isKey(path, object) ? [path + ''] : baseToPath(path);
+
+  var index = -1,
+      length = path.length,
+      lastIndex = length - 1,
+      nested = object;
+
+  while (nested != null && ++index < length) {
+    var key = path[index];
+    if (isObject(nested)) {
+      var newValue = value;
+      if (index != lastIndex) {
+        var objValue = nested[key];
+        newValue = customizer ? customizer(objValue, key, nested) : undefined;
+        if (newValue === undefined) {
+          newValue = objValue == null ? (isIndex(path[index + 1]) ? [] : {}) : objValue;
+        }
+      }
+      assignValue(nested, key, newValue);
+    }
+    nested = nested[key];
+  }
+  return object;
+}
+
+export default baseSet;