content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.
   */
  
  package accord.api;
  
  import accord.primitives.Ranges;
  import accord.primitives.Timestamp;
  import accord.primitives.TxnId;
  import accord.utils.Invariants;
  
  /**
   * The result of some (potentially partial) {@link Read} from some {@link DataStore}
   */
  public interface Data
  {
      Data NOOP_DATA = new Data()
      {
          @Override
          public Data merge(Data data)
          {
              Invariants.require(data == null || data == NOOP_DATA, "Can't mix no op Data with other implementations of Data");
              return NOOP_DATA;
          }
  
          @Override
          public Data without(Ranges ranges)
          {
              return this;
          }
  
          @Override
          public boolean validateReply(TxnId txnId, Timestamp executeAt, boolean futureReadPossible)
          {
              return true;
          }
      };
  
      /**
       * Combine the contents of the parameter with this object and return the resultant object.
       * This method may modify the current object and return itself.
       */
      Data merge(Data data);
      Data without(Ranges ranges);
  
      /**
       * Optionally perform some validity checks prior to sending this object as a read reply
       */
      default boolean validateReply(TxnId txnId, Timestamp executeAt, boolean futureReadPossible)
      {
          Invariants.require(!futureReadPossible);
          return true;
      }
  }
  