Thu, 31 Aug 2017 15:17:03 +0800
merge
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 */
26 package com.sun.source.util;
28 import com.sun.source.tree.*;
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> {
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 }
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;
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 }
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 }
82 private TreePath path;
83 }