'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;
|
}
|
});
|
