1// 26.1.2 Reflect.construct(target, argumentsList [, newTarget])
2var $export = require('./_export');
3var create = require('./_object-create');
4var aFunction = require('./_a-function');
5var anObject = require('./_an-object');
6var isObject = require('./_is-object');
7var fails = require('./_fails');
8var bind = require('./_bind');
9var rConstruct = (require('./_global').Reflect || {}).construct;
10
11// MS Edge supports only 2 arguments and argumentsList argument is optional
12// FF Nightly sets third argument as `new.target`, but does not create `this` from it
13var NEW_TARGET_BUG = fails(function () {
14  function F() { /* empty */ }
15  return !(rConstruct(function () { /* empty */ }, [], F) instanceof F);
16});
17var ARGS_BUG = !fails(function () {
18  rConstruct(function () { /* empty */ });
19});
20
21$export($export.S + $export.F * (NEW_TARGET_BUG || ARGS_BUG), 'Reflect', {
22  construct: function construct(Target, args /* , newTarget */) {
23    aFunction(Target);
24    anObject(args);
25    var newTarget = arguments.length < 3 ? Target : aFunction(arguments[2]);
26    if (ARGS_BUG && !NEW_TARGET_BUG) return rConstruct(Target, args, newTarget);
27    if (Target == newTarget) {
28      // w/o altered newTarget, optimization for 0-4 arguments
29      switch (args.length) {
30        case 0: return new Target();
31        case 1: return new Target(args[0]);
32        case 2: return new Target(args[0], args[1]);
33        case 3: return new Target(args[0], args[1], args[2]);
34        case 4: return new Target(args[0], args[1], args[2], args[3]);
35      }
36      // w/o altered newTarget, lot of arguments case
37      var $args = [null];
38      $args.push.apply($args, args);
39      return new (bind.apply(Target, $args))();
40    }
41    // with altered newTarget, not support built-in constructors
42    var proto = newTarget.prototype;
43    var instance = create(isObject(proto) ? proto : Object.prototype);
44    var result = Function.apply.call(Target, instance, args);
45    return isObject(result) ? result : instance;
46  }
47});
48