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 com.datastax.oss.driver.internal.core.type.codec.extras;
  
  import com.datastax.oss.driver.api.core.type.codec.MappingCodec;
  import com.datastax.oss.driver.api.core.type.codec.TypeCodec;
  import com.datastax.oss.driver.api.core.type.reflect.GenericType;
  import edu.umd.cs.findbugs.annotations.NonNull;
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.util.Collection;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  import net.jcip.annotations.Immutable;
  
  /**
   * A codec that wraps other codecs around {@link Optional} instances.
   *
   * @param <T> The wrapped Java type.
   */
  @Immutable
  public class OptionalCodec<T> extends MappingCodec<T, Optional<T>> {
  
    public OptionalCodec(@NonNull TypeCodec<T> innerCodec) {
      super(
          Objects.requireNonNull(innerCodec, "innerCodec must not be null"),
          GenericType.optionalOf(innerCodec.getJavaType()));
    }
  
    @Override
    public boolean accepts(@NonNull Object value) {
      Objects.requireNonNull(value);
      if (value instanceof Optional) {
        Optional<?> optional = (Optional<?>) value;
        return optional.map(innerCodec::accepts).orElse(true);
      }
      return false;
    }
  
    @Nullable
    @Override
    protected Optional<T> innerToOuter(@Nullable T value) {
      return Optional.ofNullable(isAbsent(value) ? null : value);
    }
  
    @Nullable
    @Override
    protected T outerToInner(@Nullable Optional<T> value) {
      return value != null && value.isPresent() ? value.get() : null;
    }
  
    protected boolean isAbsent(@Nullable T value) {
      return value == null
          || (value instanceof Collection && ((Collection<?>) value).isEmpty())
          || (value instanceof Map && ((Map<?, ?>) value).isEmpty());
    }
  }
  