mine/node_modules/core-js/modules/es.weak-map.constructor.js

'use strict';
var FREEZING = require('../internals/freezing');
var global = require('../internals/global');
var uncurryThis = require('../internals/function-uncurry-this');
var defineBuiltIns = require('../internals/define-built-ins');
var InternalMetadataModule = require('../internals/internal-metadata');
var collection = require('../internals/collection');
var collectionWeak = require('../internals/collection-weak');
var isObject = require('../internals/is-object');
var enforceInternalState = require('../internals/internal-state').enforce;
var fails = require('../internals/fails');
var NATIVE_WEAK_MAP = require('../internals/weak-map-basic-detection');

var $Object = Object;
// eslint-disable-next-line es/no-array-isarray -- safe
var isArray = Array.isArray;
// eslint-disable-next-line es/no-object-isextensible -- safe
var isExtensible = $Object.isExtensible;
// eslint-disable-next-line es/no-object-isfrozen -- safe
var isFrozen = $Object.isFrozen;
// eslint-disable-next-line es/no-object-issealed -- safe
var isSealed = $Object.isSealed;
// eslint-disable-next-line es/no-object-freeze -- safe
var freeze = $Object.freeze;
// eslint-disable-next-line es/no-object-seal -- safe
var seal = $Object.seal;

var FROZEN = {};
var SEALED = {};
var IS_IE11 = !global.ActiveXObject && 'ActiveXObject' in global;
var InternalWeakMap;

var wrapper = function (init) {
  return function WeakMap() {
    return init(this, arguments.length ? arguments[0] : undefined);
  };
};

// `WeakMap` constructor
// https://tc39.es/ecma262/#sec-weakmap-constructor
var $WeakMap = collection('WeakMap', wrapper, collectionWeak);
var WeakMapPrototype = $WeakMap.prototype;
var nativeSet = uncurryThis(WeakMapPrototype.set);

// Chakra Edge bug: adding frozen arrays to WeakMap unfreeze them
var hasMSEdgeFreezingBug = function () {
  return FREEZING && fails(function () {
    var frozenArray = freeze([]);
    nativeSet(new $WeakMap(), frozenArray, 1);
    return !isFrozen(frozenArray);
  });
};

// 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) if (IS_IE11) {
  InternalWeakMap = collectionWeak.getConstructor(wrapper, 'WeakMap', true);
  InternalMetadataModule.enable();
  var nativeDelete = uncurryThis(WeakMapPrototype['delete']);
  var nativeHas = uncurryThis(WeakMapPrototype.has);
  var nativeGet = uncurryThis(WeakMapPrototype.get);
  defineBuiltIns(WeakMapPrototype, {
    'delete': function (key) {
      if (isObject(key) && !isExtensible(key)) {
        var state = enforceInternalState(this);
        if (!state.frozen) state.frozen = new InternalWeakMap();
        return nativeDelete(this, key) || state.frozen['delete'](key);
      } return nativeDelete(this, key);
    },
    has: function has(key) {
      if (isObject(key) && !isExtensible(key)) {
        var state = enforceInternalState(this);
        if (!state.frozen) state.frozen = new InternalWeakMap();
        return nativeHas(this, key) || state.frozen.has(key);
      } return nativeHas(this, key);
    },
    get: function get(key) {
      if (isObject(key) && !isExtensible(key)) {
        var state = enforceInternalState(this);
        if (!state.frozen) state.frozen = new InternalWeakMap();
        return nativeHas(this, key) ? nativeGet(this, key) : state.frozen.get(key);
      } return nativeGet(this, key);
    },
    set: function set(key, value) {
      if (isObject(key) && !isExtensible(key)) {
        var state = enforceInternalState(this);
        if (!state.frozen) state.frozen = new InternalWeakMap();
        nativeHas(this, key) ? nativeSet(this, key, value) : state.frozen.set(key, value);
      } else nativeSet(this, key, value);
      return this;
    }
  });
// Chakra Edge frozen keys fix
} else if (hasMSEdgeFreezingBug()) {
  defineBuiltIns(WeakMapPrototype, {
    set: function set(key, value) {
      var arrayIntegrityLevel;
      if (isArray(key)) {
        if (isFrozen(key)) arrayIntegrityLevel = FROZEN;
        else if (isSealed(key)) arrayIntegrityLevel = SEALED;
      }
      nativeSet(this, key, value);
      if (arrayIntegrityLevel === FROZEN) freeze(key);
      if (arrayIntegrityLevel === SEALED) seal(key);
      return this;
    }
  });
}