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 public class DocTreePathScanner<R, P> extends DocTreeScanner<R, P> {
  41     /**
  42      * Constructs a {@code DocTreePathScanner}.
  43      */
  44     public DocTreePathScanner() {}
  45 
  46     /**
  47      * Scans a tree from a position identified by a tree path.
  48      * @param path the path
  49      * @param p a value to be passed to visitor methods
  50      * @return the result returned from the main visitor method
  51      */
  52     public R scan(DocTreePath path, P p) {
  53         this.path = path;
  54         try {
  55             return path.getLeaf().accept(this, p);
  56         } finally {
  57             this.path = null;
  58         }
  59     }
  60 
  61     /**
  62      * Scans a single node.
  63      * The current path is updated for the duration of the scan.
  64      * @param tree the tree to be scanned
  65      * @param p a value to be passed to visitor methods
  66      * @return the result returned from the main visitor method
  67      */
  68     @Override
  69     public R scan(DocTree tree, P p) {
  70         if (tree == null)
  71             return null;
  72 
  73         DocTreePath prev = path;
  74         path = new DocTreePath(path, tree);
  75         try {
  76             return tree.accept(this, p);
  77         } finally {
  78             path = prev;
  79         }
  80     }
  81 
  82     /**
  83      * Returns the current path for the node, as built up by the currently
  84      * active set of scan calls.
  85      * @return the current path
  86      */
  87     public DocTreePath getCurrentPath() {
  88         return path;
  89     }
  90 
  91     private DocTreePath path;
  92 }