--- /dev/null
+'use strict';
+var global = require('../internals/global');
+var redefineAll = require('../internals/redefine-all');
+var InternalMetadataModule = require('../internals/internal-metadata');
+var collection = require('../internals/collection');
+var collectionWeak = require('../internals/collection-weak');
+var isObject = require('../internals/is-object');
+var enforceIternalState = require('../internals/internal-state').enforce;
+var NATIVE_WEAK_MAP = require('../internals/native-weak-map');
+
+var IS_IE11 = !global.ActiveXObject && 'ActiveXObject' in global;
+var isExtensible = Object.isExtensible;
+var InternalWeakMap;
+
+var wrapper = function (init) {
+ return function WeakMap() {
+ return init(this, arguments.length ? arguments[0] : undefined);
+ };
+};
+
+// `WeakMap` constructor
+// https://tc39.github.io/ecma262/#sec-weakmap-constructor
+var $WeakMap = module.exports = collection('WeakMap', wrapper, collectionWeak);
+
+// IE11 WeakMap frozen keys fix
+// We can't use feature detection because it crash some old IE builds
+// https://github.com/zloirock/core-js/issues/485
+if (NATIVE_WEAK_MAP && IS_IE11) {
+ InternalWeakMap = collectionWeak.getConstructor(wrapper, 'WeakMap', true);
+ InternalMetadataModule.REQUIRED = true;
+ var WeakMapPrototype = $WeakMap.prototype;
+ var nativeDelete = WeakMapPrototype['delete'];
+ var nativeHas = WeakMapPrototype.has;
+ var nativeGet = WeakMapPrototype.get;
+ var nativeSet = WeakMapPrototype.set;
+ redefineAll(WeakMapPrototype, {
+ 'delete': function (key) {
+ if (isObject(key) && !isExtensible(key)) {
+ var state = enforceIternalState(this);
+ if (!state.frozen) state.frozen = new InternalWeakMap();
+ return nativeDelete.call(this, key) || state.frozen['delete'](key);
+ } return nativeDelete.call(this, key);
+ },
+ has: function has(key) {
+ if (isObject(key) && !isExtensible(key)) {
+ var state = enforceIternalState(this);
+ if (!state.frozen) state.frozen = new InternalWeakMap();
+ return nativeHas.call(this, key) || state.frozen.has(key);
+ } return nativeHas.call(this, key);
+ },
+ get: function get(key) {
+ if (isObject(key) && !isExtensible(key)) {
+ var state = enforceIternalState(this);
+ if (!state.frozen) state.frozen = new InternalWeakMap();
+ return nativeHas.call(this, key) ? nativeGet.call(this, key) : state.frozen.get(key);
+ } return nativeGet.call(this, key);
+ },
+ set: function set(key, value) {
+ if (isObject(key) && !isExtensible(key)) {
+ var state = enforceIternalState(this);
+ if (!state.frozen) state.frozen = new InternalWeakMap();
+ nativeHas.call(this, key) ? nativeSet.call(this, key, value) : state.frozen.set(key, value);
+ } else nativeSet.call(this, key, value);
+ return this;
+ }
+ });
+}