source: node_modules/core-js-pure/internals/collection.js

'use strict';
var $ = require('../internals/export');
var global = require('../internals/global');
var InternalMetadataModule = require('../internals/internal-metadata');
var fails = require('../internals/fails');
var createNonEnumerableProperty = require('../internals/create-non-enumerable-property');
var iterate = require('../internals/iterate');
var anInstance = require('../internals/an-instance');
var isCallable = require('../internals/is-callable');
var isObject = require('../internals/is-object');
var isNullOrUndefined = require('../internals/is-null-or-undefined');
var setToStringTag = require('../internals/set-to-string-tag');
var defineProperty = require('../internals/object-define-property').f;
var forEach = require('../internals/array-iteration').forEach;
var DESCRIPTORS = require('../internals/descriptors');
var InternalStateModule = require('../internals/internal-state');

var setInternalState = InternalStateModule.set;
var internalStateGetterFor = InternalStateModule.getterFor;

module.exports = function (CONSTRUCTOR_NAME, wrapper, common) {
  var IS_MAP = CONSTRUCTOR_NAME.indexOf('Map') !== -1;
  var IS_WEAK = CONSTRUCTOR_NAME.indexOf('Weak') !== -1;
  var ADDER = IS_MAP ? 'set' : 'add';
  var NativeConstructor = global[CONSTRUCTOR_NAME];
  var NativePrototype = NativeConstructor && NativeConstructor.prototype;
  var exported = {};
  var Constructor;

  if (!DESCRIPTORS || !isCallable(NativeConstructor)
    || !(IS_WEAK || NativePrototype.forEach && !fails(function () { new NativeConstructor().entries().next(); }))
  ) {
    // create collection constructor
    Constructor = common.getConstructor(wrapper, CONSTRUCTOR_NAME, IS_MAP, ADDER);
    InternalMetadataModule.enable();
  } else {
    Constructor = wrapper(function (target, iterable) {
      setInternalState(anInstance(target, Prototype), {
        type: CONSTRUCTOR_NAME,
        collection: new NativeConstructor()
      });
      if (!isNullOrUndefined(iterable)) iterate(iterable, target[ADDER], { that: target, AS_ENTRIES: IS_MAP });
    });

    var Prototype = Constructor.prototype;

    var getInternalState = internalStateGetterFor(CONSTRUCTOR_NAME);

    forEach(['add', 'clear', 'delete', 'forEach', 'get', 'has', 'set', 'keys', 'values', 'entries'], function (KEY) {
      var IS_ADDER = KEY === 'add' || KEY === 'set';
      if (KEY in NativePrototype && !(IS_WEAK && KEY === 'clear')) {
        createNonEnumerableProperty(Prototype, KEY, function (a, b) {
          var collection = getInternalState(this).collection;
          if (!IS_ADDER && IS_WEAK && !isObject(a)) return KEY === 'get' ? undefined : false;
          var result = collection[KEY](a === 0 ? 0 : a, b);
          return IS_ADDER ? this : result;
        });
      }
    });

    IS_WEAK || defineProperty(Prototype, 'size', {
      configurable: true,
      get: function () {
        return getInternalState(this).collection.size;
      }
    });
  }

  setToStringTag(Constructor, CONSTRUCTOR_NAME, false, true);

  exported[CONSTRUCTOR_NAME] = Constructor;
  $({ global: true, forced: true }, exported);

  if (!IS_WEAK) common.setStrong(Constructor, CONSTRUCTOR_NAME, IS_MAP);

  return Constructor;
};