001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.types;
019
020import org.apache.hadoop.hbase.util.Order;
021import org.apache.hadoop.hbase.util.PositionedByteRange;
022import org.apache.yetus.audience.InterfaceAudience;
023
024/**
025 * The {@code Union} family of {@link DataType}s encode one of a fixed
026 * set of {@code Object}s. They provide convenience methods which handle
027 * type casting on your behalf.
028 */
029@SuppressWarnings("unchecked")
030@InterfaceAudience.Public
031public abstract class Union2<A, B> implements DataType<Object> {
032
033  protected final DataType<A> typeA;
034  protected final DataType<B> typeB;
035
036  /**
037   * Create an instance of {@code Union2} over the set of specified
038   * types.
039   */
040  public Union2(DataType<A> typeA, DataType<B> typeB) {
041    this.typeA = typeA;
042    this.typeB = typeB;
043  }
044
045  @Override
046  public boolean isOrderPreserving() {
047    return typeA.isOrderPreserving() && typeB.isOrderPreserving();
048  }
049
050  @Override
051  public Order getOrder() {
052    return null;
053  }
054
055  @Override
056  public boolean isNullable() {
057    return typeA.isNullable() && typeB.isNullable();
058  }
059
060  @Override
061  public boolean isSkippable() {
062    return typeA.isSkippable() && typeB.isSkippable();
063  }
064
065  @Override
066  public Class<Object> encodedClass() {
067    throw new UnsupportedOperationException(
068      "Union types do not expose a definitive encoded class.");
069  }
070
071  /**
072   * Read an instance of the first type parameter from buffer {@code src}.
073   */
074  public A decodeA(PositionedByteRange src) {
075    return (A) decode(src);
076  }
077
078  /**
079   * Read an instance of the second type parameter from buffer {@code src}.
080   */
081  public B decodeB(PositionedByteRange src) {
082    return (B) decode(src);
083  }
084}