/**
    * 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 org.apache.hadoop.hbase.types;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.hbase.util.Order;
  import org.apache.hadoop.hbase.util.PositionedByteRange;
  
  /**
   * The {@code Union} family of {@link DataType}s encode one of a fixed
   * set of {@code Object}s. They provide convenience methods which handle
   * type casting on your behalf.
   */
  @SuppressWarnings("unchecked")
  @InterfaceAudience.Public
  @InterfaceStability.Evolving
  public abstract class Union2<A, B> implements DataType<Object> {
  
    protected final DataType<A> typeA;
    protected final DataType<B> typeB;
  
    /**
     * Create an instance of {@code Union2} over the set of specified
     * types.
     */
    public Union2(DataType<A> typeA, DataType<B> typeB) {
      this.typeA = typeA;
      this.typeB = typeB;
    }
  
    @Override
    public boolean isOrderPreserving() {
      return typeA.isOrderPreserving() && typeB.isOrderPreserving();
    }
  
    @Override
    public Order getOrder() { return null; }
  
    @Override
    public boolean isNullable() {
      return typeA.isNullable() && typeB.isNullable();
    }
  
    @Override
    public boolean isSkippable() {
      return typeA.isSkippable() && typeB.isSkippable();
    }
  
    @Override
    public Class<Object> encodedClass() {
      throw new UnsupportedOperationException(
        "Union types do not expose a definitive encoded class.");
    }
  
    /**
     * Read an instance of the first type parameter from buffer {@code src}.
     */
    public A decodeA(PositionedByteRange src) {
      return (A) decode(src);
    }
  
    /**
     * Read an instance of the second type parameter from buffer {@code src}.
     */
    public B decodeB(PositionedByteRange src) {
      return (B) decode(src);
    }
  }