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- 'use strict';
- var $ = require('../internals/export');
- var getBuiltIn = require('../internals/get-built-in');
- var apply = require('../internals/function-apply');
- var bind = require('../internals/function-bind');
- var aConstructor = require('../internals/a-constructor');
- var anObject = require('../internals/an-object');
- var isObject = require('../internals/is-object');
- var create = require('../internals/object-create');
- var fails = require('../internals/fails');
-
- var nativeConstruct = getBuiltIn('Reflect', 'construct');
- var ObjectPrototype = Object.prototype;
- var push = [].push;
-
- // `Reflect.construct` method
- // https://tc39.es/ecma262/#sec-reflect.construct
- // MS Edge supports only 2 arguments and argumentsList argument is optional
- // FF Nightly sets third argument as `new.target`, but does not create `this` from it
- var NEW_TARGET_BUG = fails(function () {
- function F() { /* empty */ }
- return !(nativeConstruct(function () { /* empty */ }, [], F) instanceof F);
- });
-
- var ARGS_BUG = !fails(function () {
- nativeConstruct(function () { /* empty */ });
- });
-
- var FORCED = NEW_TARGET_BUG || ARGS_BUG;
-
- $({ target: 'Reflect', stat: true, forced: FORCED, sham: FORCED }, {
- construct: function construct(Target, args /* , newTarget */) {
- aConstructor(Target);
- anObject(args);
- var newTarget = arguments.length < 3 ? Target : aConstructor(arguments[2]);
- if (ARGS_BUG && !NEW_TARGET_BUG) return nativeConstruct(Target, args, newTarget);
- if (Target === newTarget) {
- // w/o altered newTarget, optimization for 0-4 arguments
- switch (args.length) {
- case 0: return new Target();
- case 1: return new Target(args[0]);
- case 2: return new Target(args[0], args[1]);
- case 3: return new Target(args[0], args[1], args[2]);
- case 4: return new Target(args[0], args[1], args[2], args[3]);
- }
- // w/o altered newTarget, lot of arguments case
- var $args = [null];
- apply(push, $args, args);
- return new (apply(bind, Target, $args))();
- }
- // with altered newTarget, not support built-in constructors
- var proto = newTarget.prototype;
- var instance = create(isObject(proto) ? proto : ObjectPrototype);
- var result = apply(Target, instance, args);
- return isObject(result) ? result : instance;
- }
- });
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