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.graph.tree;
  
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  import org.jspecify.annotations.Nullable;
  
  class TreeNode_iteratorHierarchyUp<T> implements Iterator<TreeNode<T>> {
  
      private TreeNode<T> next;
  
      TreeNode_iteratorHierarchyUp(TreeNode<T> treeNode) {
          next = treeNode;
      }
  
      @Override
      public boolean hasNext() {
          return next!=null;
      }
  
      @Override
      public TreeNode<T> next() {
          if(next==null) {
              throw new NoSuchElementException("Iterator has run out of elements.");
          }
          final TreeNode<T> result = next;
          next = fetchNext(next);
          return result;
      }
  
      // -- HELPER
  
      private @Nullable TreeNode<T> fetchNext(TreeNode<T> current) {
          return current.lookupParent().orElse(null);
      }
  
  }
  