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.map.fromdocs;
  
  import net.openhft.chronicle.bytes.Bytes;
  import net.openhft.chronicle.core.io.IORuntimeException;
  import net.openhft.chronicle.core.util.ReadResolvable;
  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 java.util.ArrayList;
  import java.util.List;
  
  public final class PointListSizedMarshaller
          implements SizedReader<List<Point>>, SizedWriter<List<Point>>,
          ReadResolvable<PointListSizedMarshaller> {
  
      static final PointListSizedMarshaller INSTANCE = new PointListSizedMarshaller();
      /**
       * A point takes 16 bytes in serialized form: 8 bytes for both x and y value
       */
      private static final long ELEMENT_SIZE = 16;
  
      private PointListSizedMarshaller() {
      }
  
      @Override
      public long size(@NotNull List<Point> toWrite) {
          return toWrite.size() * ELEMENT_SIZE;
      }
  
      @Override
      public void write(Bytes out, long size, @NotNull List<Point> toWrite) {
          toWrite.forEach(point -> {
              out.writeDouble(point.x);
              out.writeDouble(point.y);
          });
      }
  
      @NotNull
      @Override
      public List<Point> read(@NotNull Bytes in, long size, List<Point> using) {
          if (size % ELEMENT_SIZE != 0) {
              throw new IORuntimeException("Bytes size should be a multiple of " + ELEMENT_SIZE +
                      ", " + size + " read");
          }
          long listSizeAsLong = size / ELEMENT_SIZE;
          if (listSizeAsLong > Integer.MAX_VALUE) {
              throw new IORuntimeException("List size couldn't be more than " + Integer.MAX_VALUE +
                      ", " + listSizeAsLong + " read");
          }
          int listSize = (int) listSizeAsLong;
          if (using == null) {
              using = new ArrayList<>(listSize);
              for (int i = 0; i < listSize; i++) {
                  using.add(null);
              }
          } else if (using.size() < listSize) {
              while (using.size() < listSize) {
                  using.add(null);
              }
          } else if (using.size() > listSize) {
              using.subList(listSize, using.size()).clear();
          }
          for (int i = 0; i < listSize; i++) {
              Point point = using.get(i);
              if (point == null)
                  using.set(i, point = new Point());
              point.x = in.readDouble();
              point.y = in.readDouble();
          }
          return using;
      }
  
      @Override
      public void writeMarshallable(@NotNull WireOut wireOut) {
          // no fields to write
      }
  
      @Override
      public void readMarshallable(@NotNull WireIn wireIn) {
          // no fields to read
      }
  
      @NotNull
      @Override
      public PointListSizedMarshaller readResolve() {
          return INSTANCE;
      }
  }