1  var baseRest = require('./_baseRest'),
 2      createWrap = require('./_createWrap'),
 3      getHolder = require('./_getHolder'),
 4      replaceHolders = require('./_replaceHolders');
 5  
 6  /** Used to compose bitmasks for function metadata. */
 7  var WRAP_BIND_FLAG = 1,
 8      WRAP_BIND_KEY_FLAG = 2,
 9      WRAP_PARTIAL_FLAG = 32;
10  
11  /**
12   * Creates a function that invokes the method at `object[key]` with `partials`
13   * prepended to the arguments it receives.
14   *
15   * This method differs from `_.bind` by allowing bound functions to reference
16   * methods that may be redefined or don't yet exist. See
17   * [Peter Michaux's article](http://peter.michaux.ca/articles/lazy-function-definition-pattern)
18   * for more details.
19   *
20   * The `_.bindKey.placeholder` value, which defaults to `_` in monolithic
21   * builds, may be used as a placeholder for partially applied arguments.
22   *
23   * @static
24   * @memberOf _
25   * @since 0.10.0
26   * @category Function
27   * @param {Object} object The object to invoke the method on.
28   * @param {string} key The key of the method.
29   * @param {...*} [partials] The arguments to be partially applied.
30   * @returns {Function} Returns the new bound function.
31   * @example
32   *
33   * var object = {
34   *   'user': 'fred',
35   *   'greet': function(greeting, punctuation) {
36   *     return greeting + ' ' + this.user + punctuation;
37   *   }
38   * };
39   *
40   * var bound = _.bindKey(object, 'greet', 'hi');
41   * bound('!');
42   * // => 'hi fred!'
43   *
44   * object.greet = function(greeting, punctuation) {
45   *   return greeting + 'ya ' + this.user + punctuation;
46   * };
47   *
48   * bound('!');
49   * // => 'hiya fred!'
50   *
51   * // Bound with placeholders.
52   * var bound = _.bindKey(object, 'greet', _, '!');
53   * bound('hi');
54   * // => 'hiya fred!'
55   */
56  var bindKey = baseRest(function(object, key, partials) {
57    var bitmask = WRAP_BIND_FLAG | WRAP_BIND_KEY_FLAG;
58    if (partials.length) {
59      var holders = replaceHolders(partials, getHolder(bindKey));
60      bitmask |= WRAP_PARTIAL_FLAG;
61    }
62    return createWrap(key, bitmask, object, partials, holders);
63  });
64  
65  // Assign default placeholders.
66  bindKey.placeholder = {};
67  
68  module.exports = bindKey;