1 /*
   2  * Copyright (c) 2006, 2013, 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.tree.*;
  29 
  30 /**
  31  * A TreeVisitor 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  * @author Jonathan Gibbons
  39  * @since 1.6
  40  */
  41 @jdk.Exported
  42 public class TreePathScanner<R, P> extends TreeScanner<R, P> {
  43 
  44     /**
  45      * Scan a tree from a position identified by a TreePath.
  46      */
  47     public R scan(TreePath path, P p) {
  48         this.path = path;
  49         try {
  50             return path.getLeaf().accept(this, p);
  51         } finally {
  52             this.path = null;
  53         }
  54     }
  55 
  56     /**
  57      * Scan a single node.
  58      * The current path is updated for the duration of the scan.
  59      */
  60     @Override
  61     public R scan(Tree tree, P p) {
  62         if (tree == null)
  63             return null;
  64 
  65         TreePath prev = path;
  66         path = new TreePath(path, tree);
  67         try {
  68             return tree.accept(this, p);
  69         } finally {
  70             path = prev;
  71         }
  72     }
  73 
  74     /**
  75      * Get the current path for the node, as built up by the currently
  76      * active set of scan calls.
  77      */
  78     public TreePath getCurrentPath() {
  79         return path;
  80     }
  81 
  82     private TreePath path;
  83 }