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- // 26.1.2 Reflect.construct(target, argumentsList [, newTarget])
- var $export = require('./_export')
- , create = require('./_object-create')
- , aFunction = require('./_a-function')
- , anObject = require('./_an-object')
- , isObject = require('./_is-object')
- , fails = require('./_fails')
- , bind = require('./_bind')
- , rConstruct = (require('./_global').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(){}
- return !(rConstruct(function(){}, [], F) instanceof F);
- });
- var ARGS_BUG = !fails(function(){
- rConstruct(function(){});
- });
- $export($export.S + $export.F * (NEW_TARGET_BUG || ARGS_BUG), 'Reflect', {
- construct: function construct(Target, args /*, newTarget*/){
- aFunction(Target);
- anObject(args);
- var newTarget = arguments.length < 3 ? Target : aFunction(arguments[2]);
- if(ARGS_BUG && !NEW_TARGET_BUG)return rConstruct(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];
- $args.push.apply($args, args);
- return new (bind.apply(Target, $args));
- }
- // with altered newTarget, not support built-in constructors
- var proto = newTarget.prototype
- , instance = create(isObject(proto) ? proto : Object.prototype)
- , result = Function.apply.call(Target, instance, args);
- return isObject(result) ? result : instance;
- }
- });
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