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.impl;
  
  import net.openhft.chronicle.bytes.*;
  import net.openhft.chronicle.hash.Data;
  import net.openhft.chronicle.hash.serialization.DataAccess;
  import net.openhft.chronicle.hash.serialization.SizedReader;
  import net.openhft.chronicle.hash.serialization.SizedWriter;
  import net.openhft.chronicle.wire.WireIn;
  import net.openhft.chronicle.wire.WireOut;
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  
  import java.lang.reflect.Type;
  
  import static net.openhft.chronicle.hash.serialization.StatefulCopyable.copyIfNeeded;
  import static net.openhft.chronicle.hash.serialization.impl.DefaultElasticBytes.DEFAULT_BYTES_CAPACITY;
  
  public class SizedMarshallableDataAccess<T> extends InstanceCreatingMarshaller<T>
          implements DataAccess<T>, Data<T> {
  
      // Config fields
      private SizedReader<T> sizedReader;
      private SizedWriter<? super T> sizedWriter;
  
      // Cache fields
      private transient boolean bytesInit;
      private transient Bytes bytes;
      private transient long size;
      private transient VanillaBytes targetBytes;
  
      /**
       * State field
       */
      private transient T instance;
  
      public SizedMarshallableDataAccess(
              Class<T> tClass, SizedReader<T> sizedReader, SizedWriter<? super T> sizedWriter) {
          this(tClass, sizedReader, sizedWriter, DEFAULT_BYTES_CAPACITY);
      }
  
      protected SizedMarshallableDataAccess(
              Type tClass, SizedReader<T> sizedReader, SizedWriter<? super T> sizedWriter,
              long bytesCapacity) {
          super(tClass);
          this.sizedWriter = sizedWriter;
          this.sizedReader = sizedReader;
          initTransients(bytesCapacity);
      }
  
      SizedReader<T> sizedReader() {
          return sizedReader;
      }
  
      SizedWriter<? super T> sizedWriter() {
          return sizedWriter;
      }
  
      private void initTransients(long bytesCapacity) {
          bytes = DefaultElasticBytes.allocateDefaultElasticBytes(bytesCapacity);
          targetBytes = VanillaBytes.vanillaBytes();
      }
  
      @Override
      public RandomDataInput bytes() {
          if (!bytesInit) {
              bytes.clear();
              sizedWriter.write(bytes, size, instance);
              bytesInit = true;
          }
          return bytes.bytesStore();
      }
  
      @Override
      public long offset() {
          return 0;
      }
  
      @Override
      public long size() {
          return size;
      }
  
      @Override
      public void writeTo(RandomDataOutput target, long targetOffset) {
          if (bytesInit || !(target instanceof BytesStore)) {
              target.write(targetOffset, bytes(), offset(), size);
          } else {
              targetBytes.bytesStore((BytesStore) target, targetOffset, size);
              targetBytes.writePosition(targetOffset);
              sizedWriter.write(targetBytes, size, instance);
              targetBytes.bytesStore(NoBytesStore.NO_BYTES_STORE, 0, 0);
          }
      }
  
      @Override
      public T get() {
          return instance;
      }
  
      @Override
      public T getUsing(@Nullable T using) {
          if (using == null)
              using = createInstance();
          T result = sizedReader.read(bytes, size(), using);
          bytes.readPosition(0);
          return result;
      }
  
      @Override
      public int hashCode() {
          return dataHashCode();
      }
  
      @Override
      public boolean equals(Object obj) {
          return dataEquals(obj);
      }
  
      @Override
      public String toString() {
          return get().toString();
      }
  
      @Override
      public Data<T> getData(@NotNull T instance) {
          this.instance = instance;
          this.size = sizedWriter.size(instance);
          bytesInit = false;
          return this;
      }
  
      @Override
      public void uninit() {
          instance = null;
      }
  
      @Override
      public DataAccess<T> copy() {
          return new SizedMarshallableDataAccess<>(
                  tType(), copyIfNeeded(sizedReader), copyIfNeeded(sizedWriter),
                  bytes.realCapacity());
      }
  
      @Override
      public void readMarshallable(@NotNull WireIn wireIn) {
          super.readMarshallable(wireIn);
          sizedReader = wireIn.read(() -> "sizedReader").object(SizedReader.class);
          sizedWriter = wireIn.read(() -> "sizedWriter").object(SizedWriter.class);
          initTransients(DEFAULT_BYTES_CAPACITY);
      }
  
      @Override
      public void writeMarshallable(@NotNull WireOut wireOut) {
          super.writeMarshallable(wireOut);
          wireOut.write(() -> "sizedReader").typedMarshallable(sizedReader);
          wireOut.write(() -> "sizedWriter").typedMarshallable(sizedWriter);
      }
  }
  