1 /*
2 * Copyright (c) 2005, 2020, 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
26 package javax.lang.model.util;
27
28 import javax.annotation.processing.SupportedSourceVersion;
29 import javax.lang.model.SourceVersion;
30 import javax.lang.model.element.*;
31 import static javax.lang.model.SourceVersion.*;
32
33
34 /**
35 * A skeletal visitor of program elements with default behavior
36 * appropriate for the {@link SourceVersion#RELEASE_6 RELEASE_6}
37 * source version.
38 *
39 * @apiNote
40 * <p id=note_for_subclasses><strong>WARNING:</strong> The {@code
41 * ElementVisitor} interface implemented by this class may have
42 * methods added to it in the future to accommodate new, currently
43 * unknown, language structures added to future versions of the
44 * Java programming language. Therefore, methods whose names
45 * begin with {@code "visit"} may be added to this class in the
46 * future; to avoid incompatibilities, classes and subclasses which
47 * extend this class should not declare any instance methods with
48 * names beginning with {@code "visit"}.</p>
49 *
50 * <p>When such a new visit method is added, the default
51 * implementation in this class will be to directly or indirectly call
52 * the {@link #visitUnknown visitUnknown} method. A new abstract
53 * element visitor class will also be introduced to correspond to the
54 * new language level; this visitor will have different default
55 * behavior for the visit method in question. When a new visitor is
56 * introduced, portions of this visitor class may be deprecated,
57 * including its constructors.
58 *
59 * @param <R> the return type of this visitor's methods. Use {@link
60 * Void} for visitors that do not need to return results.
61 * @param <P> the type of the additional parameter to this visitor's
62 * methods. Use {@code Void} for visitors that do not need an
63 * additional parameter.
64 *
65 * @author Joseph D. Darcy
66 * @author Scott Seligman
67 * @author Peter von der Ahé
68 *
69 * @see AbstractElementVisitor7
70 * @see AbstractElementVisitor8
71 * @see AbstractElementVisitor9
72 * @see AbstractElementVisitor14
73 * @since 1.6
74 */
75 @SupportedSourceVersion(RELEASE_6)
76 public abstract class AbstractElementVisitor6<R, P> implements ElementVisitor<R, P> {
77 /**
78 * Constructor for concrete subclasses to call.
79 * @deprecated Release 6 is obsolete; update to a visitor for a newer
80 * release level.
81 */
82 @Deprecated(since="9")
83 protected AbstractElementVisitor6(){}
84
85 /**
86 * Visits any program element as if by passing itself to that
87 * element's {@link Element#accept accept} method. The invocation
88 * {@code v.visit(elem, p)} is equivalent to {@code elem.accept(v,
89 * p)}.
90 *
91 * @param e the element to visit
92 * @param p a visitor-specified parameter
93 * @return a visitor-specified result
94 */
95 public final R visit(Element e, P p) {
96 return e.accept(this, p);
97 }
98
99 /**
100 * Visits any program element as if by passing itself to that
101 * element's {@link Element#accept accept} method and passing
102 * {@code null} for the additional parameter. The invocation
103 * {@code v.visit(elem)} is equivalent to {@code elem.accept(v,
104 * null)}.
105 *
106 * @param e the element to visit
107 * @return a visitor-specified result
108 */
109 public final R visit(Element e) {
110 return e.accept(this, null);
111 }
112
113 /**
114 * {@inheritDoc}
115 *
116 * @implSpec The default implementation of this method in
117 * {@code AbstractElementVisitor6} will always throw
118 * {@code new UnknownElementException(e, p)}.
119 * This behavior is not required of a subclass.
120 *
121 * @param e {@inheritDoc}
122 * @param p {@inheritDoc}
123 * @return {@inheritDoc}
124 * @throws UnknownElementException
125 * a visitor implementation may optionally throw this exception
126 */
127 @Override
128 public R visitUnknown(Element e, P p) {
129 throw new UnknownElementException(e, p);
130 }
131
132 /**
133 * {@inheritDoc}
134 *
135 * @implSpec Visits a {@code ModuleElement} by calling {@code
136 * visitUnknown}.
137 *
138 * @param e {@inheritDoc}
139 * @param p {@inheritDoc}
140 * @return {@inheritDoc}
141 *
142 * @since 9
143 * @spec JPMS
144 */
145 @Override
146 public R visitModule(ModuleElement e, P p) {
147 // Use implementation from interface default method
148 return ElementVisitor.super.visitModule(e, p);
149 }
150
151 /**
152 * {@inheritDoc}
153 *
154 * @implSpec Visits a {@code RecordComponentElement} by calling {@code
155 * visitUnknown}.
156 *
157 * @param e {@inheritDoc}
158 * @param p {@inheritDoc}
159 * @return {@inheritDoc}
160 *
161 * @since 14
162 */
163 @SuppressWarnings("preview")
164 @Override
165 public R visitRecordComponent(RecordComponentElement e, P p) {
166 // Use implementation from interface default method
167 return ElementVisitor.super.visitRecordComponent(e, p);
168 }
169 }