001    /*
002     * Copyright 2004 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.mirror.util;
027    
028    /**
029     * Utilities to create specialized <tt>DeclarationVisitor</tt> instances.
030     *
031     * @author Joseph D. Darcy
032     * @author Scott Seligman
033     * @since 1.5
034     */
035    public class DeclarationVisitors {
036        private DeclarationVisitors(){} // do not instantiate.
037    
038        /**
039         * A visitor that has no side effects and keeps no state.
040         */
041        public static final DeclarationVisitor NO_OP = new SimpleDeclarationVisitor();
042    
043        /**
044         * Return a <tt>DeclarationVisitor</tt> that will scan the
045         * declaration structure, visiting declarations contained in
046         * another declaration.  For example, when visiting a class, the
047         * fields, methods, constructors, etc. of the class are also
048         * visited.  The order in which the contained declarations are scanned is
049         * not specified.
050         *
051         * <p>The <tt>pre</tt> and <tt>post</tt>
052         * <tt>DeclarationVisitor</tt> parameters specify,
053         * respectively, the processing the scanner will do before or
054         * after visiting the contained declarations.  If only one of pre
055         * and post processing is needed, use {@link
056         * DeclarationVisitors#NO_OP DeclarationVisitors.NO_OP} for the
057         * other parameter.
058         *
059         * @param pre visitor representing processing to do before
060         * visiting contained declarations.
061         *
062         * @param post visitor representing processing to do after
063         * visiting contained declarations.
064         */
065        public static DeclarationVisitor getDeclarationScanner(DeclarationVisitor pre,
066                                                               DeclarationVisitor post) {
067            return new DeclarationScanner(pre, post);
068        }
069    
070        /**
071         * Return a <tt>DeclarationVisitor</tt> that will scan the
072         * declaration structure, visiting declarations contained in
073         * another declaration in source code order.  For example, when
074         * visiting a class, the fields, methods, constructors, etc. of
075         * the class are also visited.  The order in which the contained
076         * declarations are visited is as close to source code order as
077         * possible; declaration mirrors created from class files instead
078         * of source code will not have source position information.
079         *
080         * <p>The <tt>pre</tt> and <tt>post</tt>
081         * <tt>DeclarationVisitor</tt> parameters specify,
082         * respectively, the processing the scanner will do before or
083         * after visiting the contained declarations.  If only one of pre
084         * and post processing is needed, use {@link
085         * DeclarationVisitors#NO_OP DeclarationVisitors.NO_OP} for the other parameter.
086         *
087         * @param pre visitor representing processing to do before
088         * visiting contained declarations.
089         *
090         * @param post visitor representing processing to do after
091         * visiting contained declarations.
092         */
093        public static DeclarationVisitor getSourceOrderDeclarationScanner(DeclarationVisitor pre,
094                                                                          DeclarationVisitor post) {
095            return new SourceOrderDeclScanner(pre, post);
096        }
097    }