You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
56 lines
2.2 KiB
56 lines
2.2 KiB
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; |
|
} |
|
});
|
|
|