1 /*
   2  * Copyright (c) 2006, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.source.util;
  27 
  28 import com.sun.source.doctree.DocTree;
  29 
  30 /**
  31  * A DocTreeVisitor that visits all the child tree nodes, and provides
  32  * support for maintaining a path for the parent nodes.
  33  * To visit nodes of a particular type, just override the
  34  * corresponding visitorXYZ method.
  35  * Inside your method, call super.visitXYZ to visit descendant
  36  * nodes.
  37  *
  38  * @since 1.8
  39  */
  40 @jdk.Exported
  41 public class DocTreePathScanner<R, P> extends DocTreeScanner<R, P> {
  42     /**
  43      * Scans a tree from a position identified by a tree path.
  44      * @param path the path
  45      * @param p a value to be passed to visitor methods
  46      * @return the result returned from the main visitor method
  47      */
  48     public R scan(DocTreePath path, P p) {
  49         this.path = path;
  50         try {
  51             return path.getLeaf().accept(this, p);
  52         } finally {
  53             this.path = null;
  54         }
  55     }
  56 
  57     /**
  58      * Scans a single node.
  59      * The current path is updated for the duration of the scan.
  60      * @param tree the tree to be scanned
  61      * @param p a value to be passed to visitor methods
  62      * @return the result returned from the main visitor method
  63      */
  64     @Override
  65     public R scan(DocTree tree, P p) {
  66         if (tree == null)
  67             return null;
  68 
  69         DocTreePath prev = path;
  70         path = new DocTreePath(path, tree);
  71         try {
  72             return tree.accept(this, p);
  73         } finally {
  74             path = prev;
  75         }
  76     }
  77 
  78     /**
  79      * Returns the current path for the node, as built up by the currently
  80      * active set of scan calls.
  81      * @return the current path
  82      */
  83     public DocTreePath getCurrentPath() {
  84         return path;
  85     }
  86 
  87     private DocTreePath path;
  88 }