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.type.*;
30
31 import static javax.lang.model.SourceVersion.*;
32
33 /**
34 * A skeletal visitor of types with default behavior appropriate for
35 * the {@link javax.lang.model.SourceVersion#RELEASE_6 RELEASE_6}
36 * source version.
37 *
38 * @apiNote
39 * <p id=note_for_subclasses><strong>WARNING:</strong> The {@code
40 * TypeVisitor} interface implemented by this class may have methods
41 * added to it in the future to accommodate new, currently unknown,
42 * language structures added to future versions of the Java
43 * programming language. Therefore, methods whose names begin with
44 * {@code "visit"} may be added to this class in the future; to avoid
45 * incompatibilities, classes and subclasses which extend this class
46 * should not declare any instance methods with names beginning with
47 * {@code "visit"}.
48 *
49 * <p>When such a new visit method is added, the default
50 * implementation in this class will be to directly or indirectly call
51 * the {@link #visitUnknown visitUnknown} method. A new abstract type
52 * visitor class will also be introduced to correspond to the new
53 * language level; this visitor will have different default behavior
54 * for the visit method in question. When a new visitor is
55 * introduced, portions of this visitor class may be deprecated,
56 * including its constructors.
57 *
58 * @param <R> the return type of this visitor's methods. Use {@link
59 * Void} for visitors that do not need to return results.
60 * @param <P> the type of the additional parameter to this visitor's
61 * methods. Use {@code Void} for visitors that do not need an
62 * additional parameter.
63 *
64 * @author Joseph D. Darcy
65 * @author Scott Seligman
66 * @author Peter von der Ahé
67 *
68 * @see AbstractTypeVisitor7
69 * @see AbstractTypeVisitor8
70 * @see AbstractTypeVisitor9
71 * @see AbstractTypeVisitor14
72 * @since 1.6
73 */
74 @SupportedSourceVersion(RELEASE_6)
75 public abstract class AbstractTypeVisitor6<R, P> implements TypeVisitor<R, P> {
76 /**
77 * Constructor for concrete subclasses to call.
78 * @deprecated Release 6 is obsolete; update to a visitor for a newer
79 * release level.
80 */
81 @Deprecated(since="9")
82 protected AbstractTypeVisitor6() {}
83
84 /**
85 * Visits any type mirror as if by passing itself to that type
86 * mirror's {@link TypeMirror#accept accept} method. The
87 * invocation {@code v.visit(t, p)} is equivalent to {@code
88 * t.accept(v, p)}.
89 *
90 * @param t the type to visit
91 * @param p a visitor-specified parameter
92 * @return a visitor-specified result
93 */
94 public final R visit(TypeMirror t, P p) {
95 return t.accept(this, p);
96 }
97
98 /**
99 * Visits any type mirror as if by passing itself to that type
100 * mirror's {@link TypeMirror#accept accept} method and passing
101 * {@code null} for the additional parameter. The invocation
102 * {@code v.visit(t)} is equivalent to {@code t.accept(v, null)}.
103 *
104 * @param t the type to visit
105 * @return a visitor-specified result
106 */
107 public final R visit(TypeMirror t) {
108 return t.accept(this, null);
109 }
110
111 /**
112 * {@inheritDoc}
113 *
114 * @implSpec Visits a {@code UnionType} element by calling {@code
115 * visitUnknown}.
116 *
117 * @param t {@inheritDoc}
118 * @param p {@inheritDoc}
119 * @return the result of {@code visitUnknown}
120 *
121 * @since 1.7
122 */
123 public R visitUnion(UnionType t, P p) {
124 return visitUnknown(t, p);
125 }
126
127 /**
128 * {@inheritDoc}
129 *
130 * @implSpec Visits an {@code IntersectionType} element by calling {@code
131 * visitUnknown}.
132 *
133 * @param t {@inheritDoc}
134 * @param p {@inheritDoc}
135 * @return the result of {@code visitUnknown}
136 *
137 * @since 1.8
138 */
139 @Override
140 public R visitIntersection(IntersectionType t, P p) {
141 return visitUnknown(t, p);
142 }
143
144 /**
145 * {@inheritDoc}
146 *
147 * @implSpec The default implementation of this method in {@code
148 * AbstractTypeVisitor6} will always throw {@code
149 * new UnknownTypeException(t, p)}. This behavior is not required of a
150 * subclass.
151 *
152 * @param t {@inheritDoc}
153 * @param p {@inheritDoc}
154 * @return a visitor-specified result
155 * @throws UnknownTypeException
156 * a visitor implementation may optionally throw this exception
157 */
158 @Override
159 public R visitUnknown(TypeMirror t, P p) {
160 throw new UnknownTypeException(t, p);
161 }
162 }