com.datastax.driver.extras.codecs.arrays.ObjectArrayCodec Maven / Gradle / Ivy

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Extended functionality for the Java driver.
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/*
 * Copyright DataStax, Inc.
 *
 * 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 com.datastax.driver.extras.codecs.arrays;

import com.datastax.driver.core.CodecUtils;
import com.datastax.driver.core.DataType;
import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.TypeCodec;
import com.datastax.driver.core.exceptions.InvalidTypeException;
import java.lang.reflect.Array;
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;

/**
 * Codec dealing with Java object arrays. Serialization and deserialization of elements in the array
 * is delegated to the provided element codec.
 *
 * For example, to create a codec that maps {@code list} to {@code String[]}, declare the
 * following:
 *
 * 
{@code
 * ObjectArrayCodec stringArrayCodec = new ObjectArrayCodec<>(
 *      DataType.list(DataType.varchar()),
 *      String[].class,
 *      TypeCodec.varchar());
 * }
 *
 * @param  The Java array component type this codec handles
 */
public class ObjectArrayCodec extends AbstractArrayCodec {

  protected final TypeCodec eltCodec;

  public ObjectArrayCodec(
      DataType.CollectionType cqlType, Class javaClass, TypeCodec eltCodec) {
    super(cqlType, javaClass);
    this.eltCodec = eltCodec;
  }

  @Override
  public ByteBuffer serialize(E[] value, ProtocolVersion protocolVersion) {
    if (value == null) return null;
    int i = 0;
    ByteBuffer[] bbs = new ByteBuffer[value.length];
    for (E elt : value) {
      if (elt == null) {
        throw new NullPointerException("Collection elements cannot be null");
      }
      ByteBuffer bb;
      try {
        bb = eltCodec.serialize(elt, protocolVersion);
      } catch (ClassCastException e) {
        throw new InvalidTypeException(
            String.format(
                "Invalid type for %s element, expecting %s but got %s",
                cqlType, eltCodec.getJavaType(), elt.getClass()),
            e);
      }
      bbs[i++] = bb;
    }
    return CodecUtils.pack(bbs, value.length, protocolVersion);
  }

  @Override
  public E[] deserialize(ByteBuffer bytes, ProtocolVersion protocolVersion) {
    if (bytes == null || bytes.remaining() == 0) return newInstance(0);
    try {
      ByteBuffer input = bytes.duplicate();
      int n = CodecUtils.readSize(input, protocolVersion);
      E[] array = newInstance(n);
      for (int i = 0; i < n; i++) {
        ByteBuffer databb = CodecUtils.readValue(input, protocolVersion);
        array[i] = eltCodec.deserialize(databb, protocolVersion);
      }
      return array;
    } catch (BufferUnderflowException e) {
      throw new InvalidTypeException("Not enough bytes to deserialize list");
    }
  }

  @Override
  protected void formatElement(StringBuilder output, E[] array, int index) {
    output.append(eltCodec.format(array[index]));
  }

  @Override
  protected void parseElement(String input, E[] array, int index) {
    array[index] = eltCodec.parse(input);
  }

  @Override
  @SuppressWarnings("unchecked")
  protected E[] newInstance(int size) {
    return (E[]) Array.newInstance(getJavaType().getRawType().getComponentType(), size);
  }
}