1 /*
2 * Copyright (c) 2005, 2011, 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.lang.model.type.*;
29
30 /**
31 * A skeletal visitor of types with default behavior appropriate for
32 * the {@link javax.lang.model.SourceVersion#RELEASE_6 RELEASE_6}
33 * source version.
34 *
35 * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
36 * by this class may have methods added to it in the future to
37 * accommodate new, currently unknown, language structures added to
38 * future versions of the Java™ programming language.
39 * Therefore, methods whose names begin with {@code "visit"} may be
40 * added to this class in the future; to avoid incompatibilities,
41 * classes which extend this class should not declare any instance
42 * methods with names beginning with {@code "visit"}.
43 *
44 * <p>When such a new visit method is added, the default
45 * implementation in this class will be to call the {@link
46 * #visitUnknown visitUnknown} method. A new abstract type visitor
47 * class will also be introduced to correspond to the new language
48 * level; this visitor will have different default behavior for the
49 * visit method in question. When the new visitor is introduced, all
50 * or portions of this visitor may be deprecated.
51 *
52 * @param <R> the return type of this visitor's methods. Use {@link
53 * Void} for visitors that do not need to return results.
54 * @param <P> the type of the additional parameter to this visitor's
55 * methods. Use {@code Void} for visitors that do not need an
56 * additional parameter.
57 *
58 * @author Joseph D. Darcy
59 * @author Scott Seligman
60 * @author Peter von der Ahé
61 *
62 * @see AbstractTypeVisitor7
63 * @since 1.6
64 */
65 public abstract class AbstractTypeVisitor6<R, P> implements TypeVisitor<R, P> {
66 /**
67 * Constructor for concrete subclasses to call.
68 */
69 protected AbstractTypeVisitor6() {}
70
71 /**
72 * Visits any type mirror as if by passing itself to that type
73 * mirror's {@link TypeMirror#accept accept} method. The
74 * invocation {@code v.visit(t, p)} is equivalent to {@code
75 * t.accept(v, p)}.
76 *
77 * @param t the type to visit
78 * @param p a visitor-specified parameter
79 * @return a visitor-specified result
80 */
81 public final R visit(TypeMirror t, P p) {
82 return t.accept(this, p);
83 }
84
85 /**
86 * Visits any type mirror as if by passing itself to that type
87 * mirror's {@link TypeMirror#accept accept} method and passing
88 * {@code null} for the additional parameter. The invocation
89 * {@code v.visit(t)} is equivalent to {@code t.accept(v, null)}.
90 *
91 * @param t the type to visit
92 * @return a visitor-specified result
93 */
94 public final R visit(TypeMirror t) {
95 return t.accept(this, null);
96 }
97
98 /**
99 * Visits a {@code UnionType} element by calling {@code
100 * visitUnknown}.
101
102 * @param t {@inheritDoc}
103 * @param p {@inheritDoc}
104 * @return the result of {@code visitUnknown}
105 *
106 * @since 1.7
107 */
108 public R visitUnion(UnionType t, P p) {
109 return visitUnknown(t, p);
110 }
111
112 /**
113 * {@inheritDoc}
114 *
115 * <p> The default implementation of this method in {@code
116 * AbstractTypeVisitor6} will always throw {@code
117 * UnknownTypeException}. This behavior is not required of a
118 * subclass.
119 *
120 * @param t the type to visit
121 * @return a visitor-specified result
122 * @throws UnknownTypeException
123 * a visitor implementation may optionally throw this exception
124 */
125 public R visitUnknown(TypeMirror t, P p) {
126 throw new UnknownTypeException(t, p);
127 }
128 }