constructor(settings: StoreSettings) {
    const source = settings.source;

    this.transformLog = source.transformLog;
    this.requestQueue = source.requestQueue;
    this.syncQueue = source.syncQueue;

    const sourceCache: MemoryCache = source.cache;
    const factory = new ModelFactory(this);

    this.identityMap = new IdentityMap({ factory });

    this.source = source;
    this.cache = new Cache(source.cache, this.identityMap);

    this._listener = this.generateListener();
    sourceCache.on('patch', this._listener);
  }

 query(queryOrExpression: QueryOrExpression, options?: object, id?: string) {
   const query = buildQuery(
     queryOrExpression,
     options,
     id,
     this._sourceCache.queryBuilder
   );
   const result = this._sourceCache.query(query);
   return this._identityMap.lookupQueryResult(query, result);
 }

  retrieveRelatedRecord(identity: RecordIdentity, relationship: string) {
    const record = this._sourceCache.getRecordSync(identity);
    if (record) {
      const identity = deepGet(record, ['relationships', relationship, 'data']);
      if (!identity) {
        return null;
      }

      return this._identityMap.lookup(identity);
    }
    return null;
  }

 retrieveAttribute(identity: RecordIdentity, attribute: string) {
   const record = this._sourceCache.getRecordSync(identity);
   return deepGet(record, ['attributes', attribute]);
 }

 retrieveRecordData(type: string, id: string) {
   return this._sourceCache.getRecordSync({ type, id });
 }