text: /**
   * Copyright 2017 Google Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  import { clone, forEach } from '@firebase/util';
  /**
   * Returns the delta from the previous call to get stats.
   *
   * @param collection_ The collection to "listen" to.
   * @constructor
   */
  var StatsListener = /** @class */ (function () {
      function StatsListener(collection_) {
          this.collection_ = collection_;
          this.last_ = null;
      }
      StatsListener.prototype.get = function () {
          var newStats = this.collection_.get();
          var delta = clone(newStats);
          if (this.last_) {
              forEach(this.last_, function (stat, value) {
                  delta[stat] = delta[stat] - value;
              });
          }
          this.last_ = newStats;
          return delta;
      };
      return StatsListener;
  }());
  export { StatsListener };
  
  //# sourceMappingURL=StatsListener.js.map
  