1  var apply = require('./_apply'),
 2      createCtor = require('./_createCtor'),
 3      root = require('./_root');
 4  
 5  /** Used to compose bitmasks for function metadata. */
 6  var WRAP_BIND_FLAG = 1;
 7  
 8  /**
 9   * Creates a function that wraps `func` to invoke it with the `this` binding
10   * of `thisArg` and `partials` prepended to the arguments it receives.
11   *
12   * @private
13   * @param {Function} func The function to wrap.
14   * @param {number} bitmask The bitmask flags. See `createWrap` for more details.
15   * @param {*} thisArg The `this` binding of `func`.
16   * @param {Array} partials The arguments to prepend to those provided to
17   *  the new function.
18   * @returns {Function} Returns the new wrapped function.
19   */
20  function createPartial(func, bitmask, thisArg, partials) {
21    var isBind = bitmask & WRAP_BIND_FLAG,
22        Ctor = createCtor(func);
23  
24    function wrapper() {
25      var argsIndex = -1,
26          argsLength = arguments.length,
27          leftIndex = -1,
28          leftLength = partials.length,
29          args = Array(leftLength + argsLength),
30          fn = (this && this !== root && this instanceof wrapper) ? Ctor : func;
31  
32      while (++leftIndex < leftLength) {
33        args[leftIndex] = partials[leftIndex];
34      }
35      while (argsLength--) {
36        args[leftIndex++] = arguments[++argsIndex];
37      }
38      return apply(fn, isBind ? thisArg : this, args);
39    }
40    return wrapper;
41  }
42  
43  module.exports = createPartial;