es.weak-map.js

'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;
    }
  });
}