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.calcite.schema.lookup;
  
  import org.checkerframework.checker.nullness.qual.NonNull;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * This class is used to hold an object including its name.
   *
   * @param <T> Element type
   */
  public class Named<T> {
    private final String name;
    private final @NonNull T entity;
  
    public Named(String name, T entity) {
      this.name = name;
      this.entity = requireNonNull(entity, "entity");
    }
  
    public final String name() {
      return name;
    }
  
    public final T entity() {
      return entity;
    }
  
    public static <T> @Nullable T entityOrNull(@Nullable Named<T> named) {
      return named == null ? null : named.entity;
    }
  
    @Override public boolean equals(final @Nullable Object o) {
      if (this == o) {
        return true;
      }
      if (o == null || getClass() != o.getClass()) {
        return false;
      }
  
      final Named<?> named = (Named<?>) o;
      return name.equals(named.name) && entity.equals(named.entity);
    }
  
    @Override public int hashCode() {
      int result = name.hashCode();
      result = 31 * result + entity.hashCode();
      return result;
    }
  }
  