--- /dev/null
+'use strict';
+var each = require('./_array-methods')(0)
+ , redefine = require('./_redefine')
+ , meta = require('./_meta')
+ , assign = require('./_object-assign')
+ , weak = require('./_collection-weak')
+ , isObject = require('./_is-object')
+ , getWeak = meta.getWeak
+ , isExtensible = Object.isExtensible
+ , uncaughtFrozenStore = weak.ufstore
+ , tmp = {}
+ , InternalMap;
+
+var wrapper = function(get){
+ return function WeakMap(){
+ return get(this, arguments.length > 0 ? arguments[0] : undefined);
+ };
+};
+
+var methods = {
+ // 23.3.3.3 WeakMap.prototype.get(key)
+ get: function get(key){
+ if(isObject(key)){
+ var data = getWeak(key);
+ if(data === true)return uncaughtFrozenStore(this).get(key);
+ return data ? data[this._i] : undefined;
+ }
+ },
+ // 23.3.3.5 WeakMap.prototype.set(key, value)
+ set: function set(key, value){
+ return weak.def(this, key, value);
+ }
+};
+
+// 23.3 WeakMap Objects
+var $WeakMap = module.exports = require('./_collection')('WeakMap', wrapper, methods, weak, true, true);
+
+// IE11 WeakMap frozen keys fix
+if(new $WeakMap().set((Object.freeze || Object)(tmp), 7).get(tmp) != 7){
+ InternalMap = weak.getConstructor(wrapper);
+ assign(InternalMap.prototype, methods);
+ meta.NEED = true;
+ each(['delete', 'has', 'get', 'set'], function(key){
+ var proto = $WeakMap.prototype
+ , method = proto[key];
+ redefine(proto, key, function(a, b){
+ // store frozen objects on internal weakmap shim
+ if(isObject(a) && !isExtensible(a)){
+ if(!this._f)this._f = new InternalMap;
+ var result = this._f[key](a, b);
+ return key == 'set' ? this : result;
+ // store all the rest on native weakmap
+ } return method.call(this, a, b);
+ });
+ });
+}
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