content: package act.cli.tree;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * Licensed 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.
   * #L%
   */
  
  import act.cli.view.CliView;
  
  import java.util.List;
  
  /**
   * Defines an abstract tree node that can be printed
   * using {@link CliView#TREE Tree view}
   */
  public interface TreeNode {
  
      /**
       * Returns {@code id} of this node.
       * <p>
       *     The {@code id} of a node can be used to identify a
       *     node in a certain context In other words children
       *     nodes of the same parent node cannot share a same id
       * </p>
       * @return the node id
       */
      String id();
  
      /**
       * Returns the label on the current tree node
       * @return the label string
       */
      String label();
  
      /**
       * Returns a list of child tree node
       * @return the children list
       */
      List<TreeNode> children();
  }
  