1  var createCtor = require('./_createCtor'),
 2      root = require('./_root');
 3  
 4  /** Used to compose bitmasks for function metadata. */
 5  var WRAP_BIND_FLAG = 1;
 6  
 7  /**
 8   * Creates a function that wraps `func` to invoke it with the optional `this`
 9   * binding of `thisArg`.
10   *
11   * @private
12   * @param {Function} func The function to wrap.
13   * @param {number} bitmask The bitmask flags. See `createWrap` for more details.
14   * @param {*} [thisArg] The `this` binding of `func`.
15   * @returns {Function} Returns the new wrapped function.
16   */
17  function createBind(func, bitmask, thisArg) {
18    var isBind = bitmask & WRAP_BIND_FLAG,
19        Ctor = createCtor(func);
20  
21    function wrapper() {
22      var fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
23      return fn.apply(isBind ? thisArg : this, arguments);
24    }
25    return wrapper;
26  }
27  
28  module.exports = createBind;