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 org.osgl.$;
  import org.osgl.util.C;
  
  import java.util.ArrayList;
  import java.util.List;
  
  public class FilteredTreeNode implements TreeNode {
      private C.List<TreeNode> path;
      private TreeNodeFilter filter;
      private TreeNode theNode;
  
      public FilteredTreeNode(TreeNode root, TreeNodeFilter filter) {
          this(C.<TreeNode>list(), root, filter);
      }
  
      public FilteredTreeNode(List<TreeNode> path, TreeNode theNode, TreeNodeFilter filter) {
          this.theNode = $.requireNotNull(theNode);
          this.filter = $.requireNotNull(filter);
          this.path = C.list($.requireNotNull(path));
      }
  
      @Override
      public String id() {
          return theNode.id();
      }
  
      @Override
      public String label() {
          return theNode.label();
      }
  
      @Override
      public List<TreeNode> children() {
          List<TreeNode> filteredChildren = new ArrayList<>();
          C.List<TreeNode> pathToKid = path.append(theNode);
          for (TreeNode kid : theNode.children()) {
              if (hasAppliedChild(pathToKid, kid)) {
                  filteredChildren.add(new FilteredTreeNode(pathToKid, kid, filter));
              }
          }
          return filteredChildren;
      }
  
      private boolean applied(C.List<TreeNode> path, TreeNode theNode) {
          return filter.apply(path, theNode);
      }
  
      private boolean hasAppliedChild(C.List<TreeNode> path, TreeNode theNode) {
          if (applied(path, theNode)) {
              return true;
          }
          List<TreeNode> children = theNode.children();
          C.List<TreeNode> pathToKid = path.append(theNode);
          for (TreeNode kid : children) {
              if (hasAppliedChild(pathToKid, kid)) {
                  return true;
              }
          }
          return false;
      }
  }
  