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- // 26.1.2 Reflect.construct(target, argumentsList [, newTarget])
- var $export = require('./_export');
- var create = require('./_object-create');
- var aFunction = require('./_a-function');
- var anObject = require('./_an-object');
- var isObject = require('./_is-object');
- var fails = require('./_fails');
- var bind = require('./_bind');
- var 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() { /* empty */ }
- return !(rConstruct(function () { /* empty */ }, [], F) instanceof F);
- });
- var ARGS_BUG = !fails(function () {
- rConstruct(function () { /* empty */ });
- });
- $export($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;
- var instance = create(isObject(proto) ? proto : Object.prototype);
- var result = Function.apply.call(Target, instance, args);
- return isObject(result) ? result : instance;
- }
- });
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