DocTreePathScanner.java revision 3170:dc017a37aac5 
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
26package com.sun.source.util;
27
28import 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
41public 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}
89