code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * 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.
   */
  
  package net.openhft.chronicle.hash.serialization;
  
  import net.openhft.chronicle.bytes.Bytes;
  import net.openhft.chronicle.hash.ChronicleHash;
  import net.openhft.chronicle.hash.ChronicleHashBuilder;
  import net.openhft.chronicle.map.ChronicleMapBuilder;
  import net.openhft.chronicle.wire.Marshallable;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  /**
   * Deserializer of objects from bytes, pairing {@link SizedWriter}, i. e. assuming the length
   * of the serialized form isn't written in the beginning of the serialized form itself, but managed
   * by {@link ChronicleHash} implementation and passed to the reading methods.
   * <p>
   * <p>Read <a href="https://github.com/OpenHFT/Chronicle-Map/blob/ea/docs/CM_Tutorial_DataAccess.adoc">{@code
   * SizedWriter} and {@code SizedReader}</a>,
   * <a href="https://github.com/OpenHFT/Chronicle-Map/blob/ea/docs/CM_Tutorial_DataAccess.adoc">{@link DataAccess}
   * and {@code SizedReader}</a> and
   * <a href="https://github.com/OpenHFT/Chronicle-Map/blob/ea/docs/CM_Tutorial.adoc#custom-serialization-checklist">custom
   * serialization checklist</a> sections in the Chronicle Map tutorial for more information on this
   * interface, how to implement and use it properly.
   *
   * @param <T> the type of the object deserialized
   * @see SizedWriter
   * @see ChronicleHashBuilder#keyMarshallers(SizedReader, SizedWriter)
   * @see ChronicleHashBuilder#keyReaderAndDataAccess(SizedReader, DataAccess)
   * @see ChronicleMapBuilder#valueMarshallers(SizedReader, SizedWriter)
   * @see ChronicleMapBuilder#valueReaderAndDataAccess(SizedReader, DataAccess)
   */
  public interface SizedReader<T> extends Marshallable {
  
      /**
       * Reads and returns the object from {@link Bytes#readPosition()} (i. e. the current position)
       * to {@code Bytes.readPosition() + size} in the given {@code in}. Should attempt to reuse the
       * given {@code using} object, i. e. to read the deserialized data into the given object. If it
       * is possible, this objects then returned from this method. If it is impossible for any reason,
       * a new object should be created and returned. The given {@code using} object could be {@code
       * null}, in this case read() should always create a new object.
       * <p>
       * <p>This method should increment the position in the given {@code Bytes} by the given {@code
       * size}.
       *
       * @param in    the {@code Bytes} to read the object from
       * @param size  the size of the serialized form of the returned object
       * @param using the object to read the deserialized data into, could be {@code null}
       * @return the object read from the bytes, either reused or newly created
       */
      @NotNull
      T read(Bytes in, long size, @Nullable T using);
  }
  