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.causeway.applib.util;
  
  import java.util.List;
  import java.util.Objects;
  import java.util.function.Function;
  
  import org.apache.causeway.commons.internal.base._Casts;
  import org.apache.causeway.commons.internal.collections._Lists;
  
  /**
   * Fluent Object Equality Composition.
   *
   * @param <T>
   * @since 2.0 {@index}
   */
  public class Equality<T> {
  
      public static <T> Equality<T> checkEquals(Function<? super T, ?> getter) {
          Objects.requireNonNull(getter);
          return new Equality<>(getter);
      }
  
      private final List<Function<? super T, ?>> getters = _Lists.newArrayList();
  
      private Equality(Function<? super T, ?> getter) {
          getters.add(getter);
      }
  
      public Equality<T> thenCheckEquals(Function<? super T, ?> getter){
          Objects.requireNonNull(getter);
          getters.add(getter);
          return this;
      }
  
      public boolean equals(T target, Object other){
          if(target==null && other==null) {
              return true;
          }
          if(target==null || other==null) {
              return false;
          }
          if(target.getClass() != other.getClass()) {
              return false;
          }
          final T o = _Casts.uncheckedCast(other);
  
          for(Function<? super T, ?> getter : getters) {
              if(!Objects.equals(getter.apply(target), getter.apply(o)))
                  return false;
          }
  
          return true;
      }
  
  }
  