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 org.apache.kafka.streams.state.internals;
  
  import java.util.Objects;
  
  /**
   * This class is used in combination of {@link TimestampedKeyAndJoinSide}. The {@link TimestampedKeyAndJoinSide} class
   * combines a key with a boolean value that specifies if the key is found in the left side of a
   * join or on the right side. This {@link LeftOrRightValue} object contains either the V1 value,
   * which is found in the left topic, or V2 value if it is found in the right topic.
   */
  public class LeftOrRightValue<V1, V2> {
      private final V1 leftValue;
      private final V2 rightValue;
  
      private LeftOrRightValue(final V1 leftValue, final V2 rightValue) {
          if (leftValue != null && rightValue != null) {
              throw new IllegalArgumentException("Only one value cannot be null");
          } else if (leftValue == null && rightValue == null) {
              throw new NullPointerException("Only one value can be null");
          }
  
          this.leftValue = leftValue;
          this.rightValue = rightValue;
      }
  
      /**
       * Create a new {@link LeftOrRightValue} instance with the V1 value as {@code leftValue} and
       * V2 value as null.
       *
       * @param leftValue the left V1 value
       * @param <V1>      the type of the value
       * @return a new {@link LeftOrRightValue} instance
       */
      public static <V1, V2> LeftOrRightValue<V1, V2> makeLeftValue(final V1 leftValue) {
          return new LeftOrRightValue<>(leftValue, null);
      }
  
      /**
       * Create a new {@link LeftOrRightValue} instance with the V2 value as {@code rightValue} and
       * V1 value as null.
       *
       * @param rightValue the right V2 value
       * @param <V2>       the type of the value
       * @return a new {@link LeftOrRightValue} instance
       */
      public static <V1, V2> LeftOrRightValue<V1, V2> makeRightValue(final V2 rightValue) {
          return new LeftOrRightValue<>(null, rightValue);
      }
  
      public V1 leftValue() {
          return leftValue;
      }
  
      public V2 rightValue() {
          return rightValue;
      }
  
      @Override
      public String toString() {
          return "<"
              + ((leftValue != null) ? "left," + leftValue : "right," + rightValue)
              + ">";
      }
  
      @Override
      public boolean equals(final Object o) {
          if (this == o) {
              return true;
          }
          if (o == null || getClass() != o.getClass()) {
              return false;
          }
          final LeftOrRightValue<?, ?> that = (LeftOrRightValue<?, ?>) o;
          return Objects.equals(leftValue, that.leftValue) &&
              Objects.equals(rightValue, that.rightValue);
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(leftValue, rightValue);
      }
  }
  