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.core.metamodel.spec;
  
  import org.apache.causeway.commons.collections.Can;
  
  public interface Hierarchical {
  
      /**
       * Returns true if the <tt>subclasses()</tt> method will return an array of
       * one or more elements (ie, not an empty array).
       */
      boolean hasSubclasses();
  
      /**
       * Get the set of specifications for all the interfaces that the class
       * represented by this specification implements.
       */
      Can<ObjectSpecification> interfaces();
  
      /**
       * Whether <code>this</code> specification represents the same specification,
       * or a subclass of the specified <code>other</code> specification.
       * <p>
       * <tt>subSpec.isOfType(superSpec)</tt> is equivalent to
       * {@link Class#isAssignableFrom(Class) Java's}
       * <tt>superType.isAssignableFrom(subType)</tt>.
       * @return whether <code>this</code> is <b>instanceof</b> <code>other</code>
       */
      boolean isOfType(ObjectSpecification other);
  
      /**
       * Same as {@link #isOfType(ObjectSpecification)}, except treating wrapper/primitive the same.
       */
      boolean isOfTypeResolvePrimitive(ObjectSpecification other);
  
      public static enum Depth {
          DIRECT,
          TRANSITIVE
      }
  
      /**
       * Get the set of specifications for the subclasses of the class
       * represented by this specification
       */
      Can<ObjectSpecification> subclasses(Depth depth);
  
      /**
       * Get the specification for this specification's class's superclass.
       */
      ObjectSpecification superclass();
  
      default boolean isTypeHierarchyRoot() {
          return superclass()==null;
      }
  
  }
  