001    /*
002     * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
003     * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004     *
005     * This code is free software; you can redistribute it and/or modify it
006     * under the terms of the GNU General Public License version 2 only, as
007     * published by the Free Software Foundation.  Sun designates this
008     * particular file as subject to the "Classpath" exception as provided
009     * by Sun in the LICENSE file that accompanied this code.
010     *
011     * This code is distributed in the hope that it will be useful, but WITHOUT
012     * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013     * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
014     * version 2 for more details (a copy is included in the LICENSE file that
015     * accompanied this code).
016     *
017     * You should have received a copy of the GNU General Public License version
018     * 2 along with this work; if not, write to the Free Software Foundation,
019     * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020     *
021     * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022     * CA 95054 USA or visit www.sun.com if you need additional information or
023     * have any questions.
024     */
025    
026    package com.sun.source.util;
027    
028    import com.sun.source.tree.*;
029    
030    /**
031     * A TreeVisitor that visits all the child tree nodes, and provides
032     * support for maintaining a path for the parent nodes.
033     * To visit nodes of a particular type, just override the
034     * corresponding visitorXYZ method.
035     * Inside your method, call super.visitXYZ to visit descendant
036     * nodes.
037     *
038     * @author Jonathan Gibbons
039     * @since 1.6
040     */
041    public class TreePathScanner<R, P> extends TreeScanner<R, P> {
042    
043        /**
044         * Scan a tree from a position identified by a TreePath.
045         */
046        public R scan(TreePath path, P p) {
047            this.path = path;
048            try {
049                return path.getLeaf().accept(this, p);
050            } finally {
051                this.path = null;
052            }
053        }
054    
055        /**
056         * Scan a single node.
057         * The current path is updated for the duration of the scan.
058         */
059        @Override
060        public R scan(Tree tree, P p) {
061            if (tree == null)
062                return null;
063    
064            TreePath prev = path;
065            path = new TreePath(path, tree);
066            try {
067                return tree.accept(this, p);
068            } finally {
069                path = prev;
070            }
071        }
072    
073        /**
074         * Get the current path for the node, as built up by the currently
075         * active set of scan calls.
076         */
077        public TreePath getCurrentPath() {
078            return path;
079        }
080    
081        private TreePath path;
082    }