content: package com.alibaba.fastjson.parser.deserializer;
  
  import java.io.IOException;
  import java.lang.reflect.Type;
  import java.util.Optional;
  import java.util.OptionalDouble;
  import java.util.OptionalInt;
  import java.util.OptionalLong;
  
  import com.alibaba.fastjson.JSONException;
  import com.alibaba.fastjson.parser.DefaultJSONParser;
  import com.alibaba.fastjson.parser.JSONToken;
  import com.alibaba.fastjson.serializer.JSONSerializer;
  import com.alibaba.fastjson.serializer.ObjectSerializer;
  import com.alibaba.fastjson.util.TypeUtils;
  
  public class OptionalCodec implements ObjectSerializer, ObjectDeserializer {
  
      public static OptionalCodec instance = new OptionalCodec();
  
      @SuppressWarnings("unchecked")
      public <T> T deserialze(DefaultJSONParser parser, Type type, Object fieldName) {
          
          if (type == OptionalInt.class) {
              Object obj = parser.parseObject(Integer.class);
              Integer value = TypeUtils.castToInt(obj);
              if (value == null) {
                  return (T) OptionalInt.empty();
              } else {
                  return (T) OptionalInt.of(value);
              }
          }
          
          if (type == OptionalLong.class) {
              Object obj = parser.parseObject(Long.class);
              Long value = TypeUtils.castToLong(obj);
              if (value == null) {
                  return (T) OptionalLong.empty();
              } else {
                  return (T) OptionalLong.of(value);
              }
          }
          
          if (type == OptionalDouble.class) {
              Object obj = parser.parseObject(Double.class);
              Double value = TypeUtils.castToDouble(obj);
              if (value == null) {
                  return (T) OptionalDouble.empty();
              } else {
                  return (T) OptionalDouble.of(value);
              }
          }
          
          type = TypeUtils.unwrapOptional(type);
          Object value = parser.parseObject(type);
          
          if (value == null) {
              return (T) Optional.empty();
          }
          
          return (T) Optional.of(value);
      }
  
      public int getFastMatchToken() {
          return JSONToken.LBRACE;
      }
  
      public void write(JSONSerializer serializer, Object object, Object fieldName, Type fieldType,
                        int features) throws IOException {
  
          if (object == null) {
              serializer.writeNull();
              return;
          }
  
          if (object instanceof Optional) {
              Optional<?> optional = (Optional<?>) object;
              Object value = optional.isPresent() ? optional.get() : null;
              serializer.write(value);
              return;
          }
  
          if (object instanceof OptionalDouble) {
              OptionalDouble optional = (OptionalDouble) object;
              if (optional.isPresent()) {
                  double value = optional.getAsDouble();
                  serializer.write(value);
              } else {
                  serializer.writeNull();
              }
              return;
          }
          
          if (object instanceof OptionalInt) {
              OptionalInt optional = (OptionalInt) object;
              if (optional.isPresent()) {
                  int value = optional.getAsInt();
                  serializer.out.writeInt(value);
              } else {
                  serializer.writeNull();
              }
              return;
          }
          
          if (object instanceof OptionalLong) {
              OptionalLong optional = (OptionalLong) object;
              if (optional.isPresent()) {
                  long value = optional.getAsLong();
                  serializer.out.writeLong(value);
              } else {
                  serializer.writeNull();
              }
              return;
          }
          
          throw new JSONException("not support optional : " + object.getClass());
      }
  
  }
  