1 /*
2 * Copyright (c) 2005, 2006, 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 version 6 language level.
33 *
34 * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
35 * by this class may have methods added to it in the future to
36 * accommodate new, currently unknown, language structures added to
37 * future versions of the Java™ programming language.
38 * Therefore, methods whose names begin with {@code "visit"} may be
39 * added to this class in the future; to avoid incompatibilities,
40 * classes which extend this class should not declare any instance
41 * methods with names beginning with {@code "visit"}.
42 *
43 * <p>When such a new visit method is added, the default
44 * implementation in this class will be to call the {@link
45 * #visitUnknown visitUnknown} method. A new abstract type visitor
46 * class will also be introduced to correspond to the new language
47 * level; this visitor will have different default behavior for the
48 * visit method in question. When the new visitor is introduced, all
49 * or portions of this visitor may be deprecated.
50 *
51 * @param <R> the return type of this visitor's methods. Use {@link
52 * Void} for visitors that do not need to return results.
53 * @param <P> the type of the additional parameter to this visitor's
54 * methods. Use {@code Void} for visitors that do not need an
55 * additional parameter.
56 *
57 * @author Joseph D. Darcy
58 * @author Scott Seligman
59 * @author Peter von der Ahé
60 * @since 1.6
61 */
62 public abstract class AbstractTypeVisitor6<R, P> implements TypeVisitor<R, P> {
63 /**
64 * Constructor for concrete subclasses to call.
65 */
66 protected AbstractTypeVisitor6() {}
67
68 /**
69 * Visits any type mirror as if by passing itself to that type
70 * mirror's {@link TypeMirror#accept accept} method. The
71 * invocation {@code v.visit(t, p)} is equivalent to {@code
72 * t.accept(v, p)}.
73 *
74 * @param t the type to visit
75 * @param p a visitor-specified parameter
76 * @return a visitor-specified result
77 */
78 public final R visit(TypeMirror t, P p) {
79 return t.accept(this, p);
80 }
81
82 /**
83 * Visits any type mirror as if by passing itself to that type
84 * mirror's {@link TypeMirror#accept accept} method and passing
85 * {@code null} for the additional parameter. The invocation
86 * {@code v.visit(t)} is equivalent to {@code t.accept(v, null)}.
87 *
88 * @param t the type to visit
89 * @return a visitor-specified result
90 */
91 public final R visit(TypeMirror t) {
92 return t.accept(this, null);
93 }
94
95 /**
96 * {@inheritDoc}
97 *
98 * <p> The default implementation of this method in {@code
99 * AbstractTypeVisitor6} will always throw {@code
100 * UnknownTypeException}. This behavior is not required of a
101 * subclass.
102 *
103 * @param t the type to visit
104 * @return a visitor-specified result
105 * @throws UnknownTypeException
106 * a visitor implementation may optionally throw this exception
107 */
108 public R visitUnknown(TypeMirror t, P p) {
109 throw new UnknownTypeException(t, p);
110 }
111 }