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.api.core.type.codec;
  
  import com.datastax.oss.driver.api.core.ProtocolVersion;
  import com.datastax.oss.driver.api.core.type.DataType;
  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.nio.ByteBuffer;
  import java.util.Objects;
  
  /**
   * A {@link TypeCodec} that maps instances of {@code InnerT}, a driver supported Java type, to
   * instances of a target {@code OuterT} Java type.
   *
   * <p>This codec can be used to provide support for Java types that are not natively handled by the
   * driver, as long as there is a conversion path to and from another supported Java type.
   *
   * @param <InnerT> The "inner" Java type; must be a driver supported Java type (that is, there must
   *     exist a codec registered for it).
   * @param <OuterT> The "outer", or target Java type; this codec will handle the mapping to and from
   *     {@code InnerT} and {@code OuterT}.
   * @see <a
   *     href="https://docs.datastax.com/en/developer/java-driver/latest/manual/core/custom_codecs/">driver
   *     documentation on custom codecs</a>
   * @see <a
   *     href="https://docs.datastax.com/en/developer/java-driver/latest/manual/core/#cql-to-java-type-mapping">
   *     driver supported Java types</a>
   */
  public abstract class MappingCodec<InnerT, OuterT> implements TypeCodec<OuterT> {
  
    protected final TypeCodec<InnerT> innerCodec;
    protected final GenericType<OuterT> outerJavaType;
  
    /**
     * Creates a new mapping codec providing support for {@code OuterT} based on an existing codec for
     * {@code InnerT}.
     *
     * @param innerCodec The inner codec to use to handle instances of InnerT; must not be null.
     * @param outerJavaType The outer Java type; must not be null.
     */
    protected MappingCodec(
        @NonNull TypeCodec<InnerT> innerCodec, @NonNull GenericType<OuterT> outerJavaType) {
      this.innerCodec = Objects.requireNonNull(innerCodec, "innerCodec cannot be null");
      this.outerJavaType = Objects.requireNonNull(outerJavaType, "outerJavaType cannot be null");
    }
  
    /** @return The type of {@code OuterT}. */
    @NonNull
    @Override
    public GenericType<OuterT> getJavaType() {
      return outerJavaType;
    }
  
    /** @return The type of {@code InnerT}. */
    public GenericType<InnerT> getInnerJavaType() {
      return innerCodec.getJavaType();
    }
  
    @NonNull
    @Override
    public DataType getCqlType() {
      return innerCodec.getCqlType();
    }
  
    @Override
    public ByteBuffer encode(OuterT value, @NonNull ProtocolVersion protocolVersion) {
      return innerCodec.encode(outerToInner(value), protocolVersion);
    }
  
    @Override
    public OuterT decode(ByteBuffer bytes, @NonNull ProtocolVersion protocolVersion) {
      return innerToOuter(innerCodec.decode(bytes, protocolVersion));
    }
  
    @NonNull
    @Override
    public String format(OuterT value) {
      return innerCodec.format(outerToInner(value));
    }
  
    @Override
    public OuterT parse(String value) {
      return innerToOuter(innerCodec.parse(value));
    }
  
    /**
     * Converts from an instance of the inner Java type to an instance of the outer Java type. Used
     * when deserializing or parsing.
     *
     * @param value The value to convert; may be null.
     * @return The converted value; may be null.
     */
    @Nullable
    protected abstract OuterT innerToOuter(@Nullable InnerT value);
  
    /**
     * Converts from an instance of the outer Java type to an instance of the inner Java type. Used
     * when serializing or formatting.
     *
     * @param value The value to convert; may be null.
     * @return The converted value; may be null.
     */
    @Nullable
    protected abstract InnerT outerToInner(@Nullable OuterT value);
  }
  