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.facets.object.navchild;
  
  import java.util.Optional;
  import java.util.stream.Stream;
  
  import org.apache.causeway.applib.graph.tree.TreeAdapter;
  import org.apache.causeway.core.metamodel.specloader.SpecificationLoader;
  
  public record ObjectTreeAdapter(SpecificationLoader specLoader)
  implements
      TreeAdapter<Object> {
  
      @Override
      public int childCountOf(final Object node) {
          return treeNodeFacet(node)
              .map(treeNodeFacet->treeNodeFacet.childCountOf(node))
              .orElse(0);
      }
      @Override
      public Stream<Object> childrenOf(final Object node) {
          return treeNodeFacet(node)
              .map(treeNodeFacet->treeNodeFacet.childrenOf(node))
              .orElseGet(Stream::empty);
      }
  
      // -- HELPER
  
      private <T> Optional<NavigableSubtreeFacet> treeNodeFacet(final T node) {
          return specLoader().loadSpecification(node.getClass())
                  .lookupFacet(NavigableSubtreeFacet.class);
      }
  
  }