internal-state.js

var NATIVE_WEAK_MAP = require('../internals/weak-map-basic-detection');
var global = require('../internals/global');
var isObject = require('../internals/is-object');
var createNonEnumerableProperty = require('../internals/create-non-enumerable-property');
var hasOwn = require('../internals/has-own-property');
var shared = require('../internals/shared-store');
var sharedKey = require('../internals/shared-key');
var hiddenKeys = require('../internals/hidden-keys');

var OBJECT_ALREADY_INITIALIZED = 'Object already initialized';
var TypeError = global.TypeError;
var WeakMap = global.WeakMap;
var set, get, has;

var enforce = function (it) {
  return has(it) ? get(it) : set(it, {});
};

var getterFor = function (TYPE) {
  return function (it) {
    var state;
    if (!isObject(it) || (state = get(it)).type !== TYPE) {
      throw TypeError('Incompatible receiver, ' + TYPE + ' required');
    } return state;
  };
};

if (NATIVE_WEAK_MAP || shared.state) {
  var store = shared.state || (shared.state = new WeakMap());
  /* eslint-disable no-self-assign -- prototype methods protection */
  store.get = store.get;
  store.has = store.has;
  store.set = store.set;
  /* eslint-enable no-self-assign -- prototype methods protection */
  set = function (it, metadata) {
    if (store.has(it)) throw TypeError(OBJECT_ALREADY_INITIALIZED);
    metadata.facade = it;
    store.set(it, metadata);
    return metadata;
  };
  get = function (it) {
    return store.get(it) || {};
  };
  has = function (it) {
    return store.has(it);
  };
} else {
  var STATE = sharedKey('state');
  hiddenKeys[STATE] = true;
  set = function (it, metadata) {
    if (hasOwn(it, STATE)) throw TypeError(OBJECT_ALREADY_INITIALIZED);
    metadata.facade = it;
    createNonEnumerableProperty(it, STATE, metadata);
    return metadata;
  };
  get = function (it) {
    return hasOwn(it, STATE) ? it[STATE] : {};
  };
  has = function (it) {
    return hasOwn(it, STATE);
  };
}

module.exports = {
  set: set,
  get: get,
  has: has,
  enforce: enforce,
  getterFor: getterFor
};