1  var baseIteratee = require('./_baseIteratee'),
 2      createInverter = require('./_createInverter');
 3  
 4  /** Used for built-in method references. */
 5  var objectProto = Object.prototype;
 6  
 7  /** Used to check objects for own properties. */
 8  var hasOwnProperty = objectProto.hasOwnProperty;
 9  
10  /**
11   * Used to resolve the
12   * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring)
13   * of values.
14   */
15  var nativeObjectToString = objectProto.toString;
16  
17  /**
18   * This method is like `_.invert` except that the inverted object is generated
19   * from the results of running each element of `object` thru `iteratee`. The
20   * corresponding inverted value of each inverted key is an array of keys
21   * responsible for generating the inverted value. The iteratee is invoked
22   * with one argument: (value).
23   *
24   * @static
25   * @memberOf _
26   * @since 4.1.0
27   * @category Object
28   * @param {Object} object The object to invert.
29   * @param {Function} [iteratee=_.identity] The iteratee invoked per element.
30   * @returns {Object} Returns the new inverted object.
31   * @example
32   *
33   * var object = { 'a': 1, 'b': 2, 'c': 1 };
34   *
35   * _.invertBy(object);
36   * // => { '1': ['a', 'c'], '2': ['b'] }
37   *
38   * _.invertBy(object, function(value) {
39   *   return 'group' + value;
40   * });
41   * // => { 'group1': ['a', 'c'], 'group2': ['b'] }
42   */
43  var invertBy = createInverter(function(result, value, key) {
44    if (value != null &&
45        typeof value.toString != 'function') {
46      value = nativeObjectToString.call(value);
47    }
48  
49    if (hasOwnProperty.call(result, value)) {
50      result[value].push(key);
51    } else {
52      result[value] = [key];
53    }
54  }, baseIteratee);
55  
56  module.exports = invertBy;