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47 lines
1.9 KiB
47 lines
1.9 KiB
// 26.1.2 Reflect.construct(target, argumentsList [, newTarget]) |
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var $export = require('./_export'); |
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var create = require('./_object-create'); |
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var aFunction = require('./_a-function'); |
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var anObject = require('./_an-object'); |
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var isObject = require('./_is-object'); |
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var fails = require('./_fails'); |
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var bind = require('./_bind'); |
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var rConstruct = (require('./_global').Reflect || {}).construct; |
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// MS Edge supports only 2 arguments and argumentsList argument is optional |
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// FF Nightly sets third argument as `new.target`, but does not create `this` from it |
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var NEW_TARGET_BUG = fails(function () { |
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function F() { /* empty */ } |
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return !(rConstruct(function () { /* empty */ }, [], F) instanceof F); |
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}); |
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var ARGS_BUG = !fails(function () { |
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rConstruct(function () { /* empty */ }); |
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}); |
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$export($export.S + $export.F * (NEW_TARGET_BUG || ARGS_BUG), 'Reflect', { |
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construct: function construct(Target, args /* , newTarget */) { |
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aFunction(Target); |
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anObject(args); |
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var newTarget = arguments.length < 3 ? Target : aFunction(arguments[2]); |
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if (ARGS_BUG && !NEW_TARGET_BUG) return rConstruct(Target, args, newTarget); |
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if (Target == newTarget) { |
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// w/o altered newTarget, optimization for 0-4 arguments |
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switch (args.length) { |
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case 0: return new Target(); |
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case 1: return new Target(args[0]); |
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case 2: return new Target(args[0], args[1]); |
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case 3: return new Target(args[0], args[1], args[2]); |
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case 4: return new Target(args[0], args[1], args[2], args[3]); |
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} |
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// w/o altered newTarget, lot of arguments case |
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var $args = [null]; |
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$args.push.apply($args, args); |
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return new (bind.apply(Target, $args))(); |
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} |
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// with altered newTarget, not support built-in constructors |
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var proto = newTarget.prototype; |
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var instance = create(isObject(proto) ? proto : Object.prototype); |
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var result = Function.apply.call(Target, instance, args); |
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return isObject(result) ? result : instance; |
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} |
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});
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