node_modules/core-js/modules/library/_collection.js

'use strict';
var global = require('./_global');
var $export = require('./_export');
var meta = require('./_meta');
var fails = require('./_fails');
var hide = require('./_hide');
var redefineAll = require('./_redefine-all');
var forOf = require('./_for-of');
var anInstance = require('./_an-instance');
var isObject = require('./_is-object');
var setToStringTag = require('./_set-to-string-tag');
var dP = require('./_object-dp').f;
var each = require('./_array-methods')(0);
var DESCRIPTORS = require('./_descriptors');

module.exports = function (NAME, wrapper, methods, common, IS_MAP, IS_WEAK) {
  var Base = global[NAME];
  var C = Base;
  var ADDER = IS_MAP ? 'set' : 'add';
  var proto = C && C.prototype;
  var O = {};
  if (!DESCRIPTORS || typeof C != 'function' || !(IS_WEAK || proto.forEach && !fails(function () {
    new C().entries().next();
  }))) {
    // create collection constructor
    C = common.getConstructor(wrapper, NAME, IS_MAP, ADDER);
    redefineAll(C.prototype, methods);
    meta.NEED = true;
  } else {
    C = wrapper(function (target, iterable) {
      anInstance(target, C, NAME, '_c');
      target._c = new Base();
      if (iterable != undefined) forOf(iterable, IS_MAP, target[ADDER], target);
    });
    each('add,clear,delete,forEach,get,has,set,keys,values,entries,toJSON'.split(','), function (KEY) {
      var IS_ADDER = KEY == 'add' || KEY == 'set';
      if (KEY in proto && !(IS_WEAK && KEY == 'clear')) hide(C.prototype, KEY, function (a, b) {
        anInstance(this, C, KEY);
        if (!IS_ADDER && IS_WEAK && !isObject(a)) return KEY == 'get' ? undefined : false;
        var result = this._c[KEY](a === 0 ? 0 : a, b);
        return IS_ADDER ? this : result;
      });
    });
    IS_WEAK || dP(C.prototype, 'size', {
      get: function () {
        return this._c.size;
      }
    });
  }

  setToStringTag(C, NAME);

  O[NAME] = C;
  $export($export.G + $export.W + $export.F, O);

  if (!IS_WEAK) common.setStrong(C, NAME, IS_MAP);

  return C;
};