001 /*
002 * Copyright 2005-2006 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 javax.lang.model.util;
027
028 import javax.lang.model.type.*;
029
030 /**
031 * A skeletal visitor of types with default behavior appropriate for
032 * the version 6 language level.
033 *
034 * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
035 * by this class may have methods added to it in the future to
036 * accommodate new, currently unknown, language structures added to
037 * future versions of the Java™ programming language.
038 * Therefore, methods whose names begin with {@code "visit"} may be
039 * added to this class in the future; to avoid incompatibilities,
040 * classes which extend this class should not declare any instance
041 * methods with names beginning with {@code "visit"}.
042 *
043 * <p>When such a new visit method is added, the default
044 * implementation in this class will be to call the {@link
045 * #visitUnknown visitUnknown} method. A new abstract type visitor
046 * class will also be introduced to correspond to the new language
047 * level; this visitor will have different default behavior for the
048 * visit method in question. When the new visitor is introduced, all
049 * or portions of this visitor may be deprecated.
050 *
051 * @param <R> the return type of this visitor's methods. Use {@link
052 * Void} for visitors that do not need to return results.
053 * @param <P> the type of the additional parameter to this visitor's
054 * methods. Use {@code Void} for visitors that do not need an
055 * additional parameter.
056 *
057 * @author Joseph D. Darcy
058 * @author Scott Seligman
059 * @author Peter von der Ahé
060 * @version 1.10 07/05/05
061 * @since 1.6
062 */
063 public abstract class AbstractTypeVisitor6<R, P> implements
064 TypeVisitor<R, P> {
065 /**
066 * Constructor for concrete subclasses to call.
067 */
068 protected AbstractTypeVisitor6() {
069 }
070
071 /**
072 * Visits any type mirror as if by passing itself to that type
073 * mirror's {@link TypeMirror#accept accept} method. The
074 * invocation {@code v.visit(t, p)} is equivalent to {@code
075 * t.accept(v, p)}.
076 *
077 * @param t the type to visit
078 * @param p a visitor-specified parameter
079 * @return a visitor-specified result
080 */
081 public final R visit(TypeMirror t, P p) {
082 return t.accept(this , p);
083 }
084
085 /**
086 * Visits any type mirror as if by passing itself to that type
087 * mirror's {@link TypeMirror#accept accept} method and passing
088 * {@code null} for the additional parameter. The invocation
089 * {@code v.visit(t)} is equivalent to {@code t.accept(v, null)}.
090 *
091 * @param t the type to visit
092 * @return a visitor-specified result
093 */
094 public final R visit(TypeMirror t) {
095 return t.accept(this , null);
096 }
097
098 /**
099 * {@inheritDoc}
100 *
101 * <p> The default implementation of this method in {@code
102 * AbstractTypeVisitor6} will always throw {@code
103 * UnknownTypeException}. This behavior is not required of a
104 * subclass.
105 *
106 * @param t the type to visit
107 * @return a visitor-specified result
108 * @throws UnknownTypeException
109 * a visitor implementation may optionally throw this exception
110 */
111 public R visitUnknown(TypeMirror t, P p) {
112 throw new UnknownTypeException(t, p);
113 }
114 }
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