1var apply = require('./_apply'),
2    createCtor = require('./_createCtor'),
3    root = require('./_root');
4
5/** Used to compose bitmasks for function metadata. */
6var 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 */
20function 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
43module.exports = createPartial;
44