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 */
40public class DocTreePathScanner<R, P> extends DocTreeScanner<R, P> {
41    /**
42     * Scans a tree from a position identified by a tree path.
43     * @param path the path
44     * @param p a value to be passed to visitor methods
45     * @return the result returned from the main visitor method
46     */
47    public R scan(DocTreePath 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     * Scans a single node.
58     * The current path is updated for the duration of the scan.
59     * @param tree the tree to be scanned
60     * @param p a value to be passed to visitor methods
61     * @return the result returned from the main visitor method
62     */
63    @Override
64    public R scan(DocTree tree, P p) {
65        if (tree == null)
66            return null;
67
68        DocTreePath prev = path;
69        path = new DocTreePath(path, tree);
70        try {
71            return tree.accept(this, p);
72        } finally {
73            path = prev;
74        }
75    }
76
77    /**
78     * Returns the current path for the node, as built up by the currently
79     * active set of scan calls.
80     * @return the current path
81     */
82    public DocTreePath getCurrentPath() {
83        return path;
84    }
85
86    private DocTreePath path;
87}
88