text: 'use strict';
  var defineProperty = require('../internals/object-define-property').f;
  var create = require('../internals/object-create');
  var redefineAll = require('../internals/redefine-all');
  var bind = require('../internals/function-bind-context');
  var anInstance = require('../internals/an-instance');
  var iterate = require('../internals/iterate');
  var defineIterator = require('../internals/define-iterator');
  var setSpecies = require('../internals/set-species');
  var DESCRIPTORS = require('../internals/descriptors');
  var fastKey = require('../internals/internal-metadata').fastKey;
  var InternalStateModule = require('../internals/internal-state');
  
  var setInternalState = InternalStateModule.set;
  var internalStateGetterFor = InternalStateModule.getterFor;
  
  module.exports = {
    getConstructor: function (wrapper, CONSTRUCTOR_NAME, IS_MAP, ADDER) {
      var C = wrapper(function (that, iterable) {
        anInstance(that, C, CONSTRUCTOR_NAME);
        setInternalState(that, {
          type: CONSTRUCTOR_NAME,
          index: create(null),
          first: undefined,
          last: undefined,
          size: 0
        });
        if (!DESCRIPTORS) that.size = 0;
        if (iterable != undefined) iterate(iterable, that[ADDER], { that: that, AS_ENTRIES: IS_MAP });
      });
  
      var getInternalState = internalStateGetterFor(CONSTRUCTOR_NAME);
  
      var define = function (that, key, value) {
        var state = getInternalState(that);
        var entry = getEntry(that, key);
        var previous, index;
        // change existing entry
        if (entry) {
          entry.value = value;
        // create new entry
        } else {
          state.last = entry = {
            index: index = fastKey(key, true),
            key: key,
            value: value,
            previous: previous = state.last,
            next: undefined,
            removed: false
          };
          if (!state.first) state.first = entry;
          if (previous) previous.next = entry;
          if (DESCRIPTORS) state.size++;
          else that.size++;
          // add to index
          if (index !== 'F') state.index[index] = entry;
        } return that;
      };
  
      var getEntry = function (that, key) {
        var state = getInternalState(that);
        // fast case
        var index = fastKey(key);
        var entry;
        if (index !== 'F') return state.index[index];
        // frozen object case
        for (entry = state.first; entry; entry = entry.next) {
          if (entry.key == key) return entry;
        }
      };
  
      redefineAll(C.prototype, {
        // `{ Map, Set }.prototype.clear()` methods
        // https://tc39.es/ecma262/#sec-map.prototype.clear
        // https://tc39.es/ecma262/#sec-set.prototype.clear
        clear: function clear() {
          var that = this;
          var state = getInternalState(that);
          var data = state.index;
          var entry = state.first;
          while (entry) {
            entry.removed = true;
            if (entry.previous) entry.previous = entry.previous.next = undefined;
            delete data[entry.index];
            entry = entry.next;
          }
          state.first = state.last = undefined;
          if (DESCRIPTORS) state.size = 0;
          else that.size = 0;
        },
        // `{ Map, Set }.prototype.delete(key)` methods
        // https://tc39.es/ecma262/#sec-map.prototype.delete
        // https://tc39.es/ecma262/#sec-set.prototype.delete
        'delete': function (key) {
          var that = this;
          var state = getInternalState(that);
          var entry = getEntry(that, key);
          if (entry) {
            var next = entry.next;
            var prev = entry.previous;
            delete state.index[entry.index];
            entry.removed = true;
            if (prev) prev.next = next;
            if (next) next.previous = prev;
            if (state.first == entry) state.first = next;
            if (state.last == entry) state.last = prev;
            if (DESCRIPTORS) state.size--;
            else that.size--;
          } return !!entry;
        },
        // `{ Map, Set }.prototype.forEach(callbackfn, thisArg = undefined)` methods
        // https://tc39.es/ecma262/#sec-map.prototype.foreach
        // https://tc39.es/ecma262/#sec-set.prototype.foreach
        forEach: function forEach(callbackfn /* , that = undefined */) {
          var state = getInternalState(this);
          var boundFunction = bind(callbackfn, arguments.length > 1 ? arguments[1] : undefined);
          var entry;
          while (entry = entry ? entry.next : state.first) {
            boundFunction(entry.value, entry.key, this);
            // revert to the last existing entry
            while (entry && entry.removed) entry = entry.previous;
          }
        },
        // `{ Map, Set}.prototype.has(key)` methods
        // https://tc39.es/ecma262/#sec-map.prototype.has
        // https://tc39.es/ecma262/#sec-set.prototype.has
        has: function has(key) {
          return !!getEntry(this, key);
        }
      });
  
      redefineAll(C.prototype, IS_MAP ? {
        // `Map.prototype.get(key)` method
        // https://tc39.es/ecma262/#sec-map.prototype.get
        get: function get(key) {
          var entry = getEntry(this, key);
          return entry && entry.value;
        },
        // `Map.prototype.set(key, value)` method
        // https://tc39.es/ecma262/#sec-map.prototype.set
        set: function set(key, value) {
          return define(this, key === 0 ? 0 : key, value);
        }
      } : {
        // `Set.prototype.add(value)` method
        // https://tc39.es/ecma262/#sec-set.prototype.add
        add: function add(value) {
          return define(this, value = value === 0 ? 0 : value, value);
        }
      });
      if (DESCRIPTORS) defineProperty(C.prototype, 'size', {
        get: function () {
          return getInternalState(this).size;
        }
      });
      return C;
    },
    setStrong: function (C, CONSTRUCTOR_NAME, IS_MAP) {
      var ITERATOR_NAME = CONSTRUCTOR_NAME + ' Iterator';
      var getInternalCollectionState = internalStateGetterFor(CONSTRUCTOR_NAME);
      var getInternalIteratorState = internalStateGetterFor(ITERATOR_NAME);
      // `{ Map, Set }.prototype.{ keys, values, entries, @@iterator }()` methods
      // https://tc39.es/ecma262/#sec-map.prototype.entries
      // https://tc39.es/ecma262/#sec-map.prototype.keys
      // https://tc39.es/ecma262/#sec-map.prototype.values
      // https://tc39.es/ecma262/#sec-map.prototype-@@iterator
      // https://tc39.es/ecma262/#sec-set.prototype.entries
      // https://tc39.es/ecma262/#sec-set.prototype.keys
      // https://tc39.es/ecma262/#sec-set.prototype.values
      // https://tc39.es/ecma262/#sec-set.prototype-@@iterator
      defineIterator(C, CONSTRUCTOR_NAME, function (iterated, kind) {
        setInternalState(this, {
          type: ITERATOR_NAME,
          target: iterated,
          state: getInternalCollectionState(iterated),
          kind: kind,
          last: undefined
        });
      }, function () {
        var state = getInternalIteratorState(this);
        var kind = state.kind;
        var entry = state.last;
        // revert to the last existing entry
        while (entry && entry.removed) entry = entry.previous;
        // get next entry
        if (!state.target || !(state.last = entry = entry ? entry.next : state.state.first)) {
          // or finish the iteration
          state.target = undefined;
          return { value: undefined, done: true };
        }
        // return step by kind
        if (kind == 'keys') return { value: entry.key, done: false };
        if (kind == 'values') return { value: entry.value, done: false };
        return { value: [entry.key, entry.value], done: false };
      }, IS_MAP ? 'entries' : 'values', !IS_MAP, true);
  
      // `{ Map, Set }.prototype[@@species]` accessors
      // https://tc39.es/ecma262/#sec-get-map-@@species
      // https://tc39.es/ecma262/#sec-get-set-@@species
      setSpecies(CONSTRUCTOR_NAME);
    }
  };
  