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.element;
27
28
29 import java.util.List;
30
31 import javax.lang.model.type.TypeMirror;
32
33
34 /**
35 * A visitor of the values of annotation type elements, using a
36 * variant of the visitor design pattern. Unlike a standard visitor
37 * which dispatches based on the concrete type of a member of a type
38 * hierarchy, this visitor dispatches based on the type of data
39 * stored; there are no distinct subclasses for storing, for example,
40 * {@code boolean} values versus {@code int} values. Classes
41 * implementing this interface are used to operate on a value when the
42 * type of that value is unknown at compile time. When a visitor is
43 * passed to a value's {@link AnnotationValue#accept accept} method,
44 * the <tt>visit<i>XYZ</i></tt> method applicable to that value is
45 * invoked.
46 *
47 * <p> Classes implementing this interface may or may not throw a
48 * {@code NullPointerException} if the additional parameter {@code p}
49 * is {@code null}; see documentation of the implementing class for
50 * details.
51 *
52 * <p> <b>WARNING:</b> It is possible that methods will be added to
53 * this interface to accommodate new, currently unknown, language
54 * structures added to future versions of the Java™ programming
55 * language. Therefore, visitor classes directly implementing this
56 * interface may be source incompatible with future versions of the
57 * platform. To avoid this source incompatibility, visitor
58 * implementations are encouraged to instead extend the appropriate
59 * abstract visitor class that implements this interface. However, an
60 * API should generally use this visitor interface as the type for
61 * parameters, return type, etc. rather than one of the abstract
62 * classes.
63 *
64 * @param <R> the return type of this visitor's methods
65 * @param <P> the type of the additional parameter to this visitor's methods.
66 * @author Joseph D. Darcy
67 * @author Scott Seligman
68 * @author Peter von der Ahé
69 * @since 1.6
70 */
71 public interface AnnotationValueVisitor<R, P> {
72 /**
73 * Visits an annotation value.
74 * @param av the value to visit
75 * @param p a visitor-specified parameter
76 * @return a visitor-specified result
77 */
78 R visit(AnnotationValue av, P p);
79
80 /**
81 * A convenience method equivalent to {@code v.visit(av, null)}.
82 * @param av the value to visit
83 * @return a visitor-specified result
84 */
85 R visit(AnnotationValue av);
86
87 /**
88 * Visits a {@code boolean} value in an annotation.
89 * @param b the value being visited
90 * @param p a visitor-specified parameter
91 * @return the result of the visit
92 */
93 R visitBoolean(boolean b, P p);
94
95 /**
96 * Visits a {@code byte} value in an annotation.
97 * @param b the value being visited
98 * @param p a visitor-specified parameter
99 * @return the result of the visit
100 */
101 R visitByte(byte b, P p);
102
103 /**
104 * Visits a {@code char} value in an annotation.
105 * @param c the value being visited
106 * @param p a visitor-specified parameter
107 * @return the result of the visit
108 */
109 R visitChar(char c, P p);
110
111 /**
112 * Visits a {@code double} value in an annotation.
113 * @param d the value being visited
114 * @param p a visitor-specified parameter
115 * @return the result of the visit
116 */
117 R visitDouble(double d, P p);
118
119 /**
120 * Visits a {@code float} value in an annotation.
121 * @param f the value being visited
122 * @param p a visitor-specified parameter
123 * @return the result of the visit
124 */
125 R visitFloat(float f, P p);
126
127 /**
128 * Visits an {@code int} value in an annotation.
129 * @param i the value being visited
130 * @param p a visitor-specified parameter
131 * @return the result of the visit
132 */
133 R visitInt(int i, P p);
134
135 /**
136 * Visits a {@code long} value in an annotation.
137 * @param i the value being visited
138 * @param p a visitor-specified parameter
139 * @return the result of the visit
140 */
141 R visitLong(long i, P p);
142
143 /**
144 * Visits a {@code short} value in an annotation.
145 * @param s the value being visited
146 * @param p a visitor-specified parameter
147 * @return the result of the visit
148 */
149 R visitShort(short s, P p);
150
151 /**
152 * Visits a string value in an annotation.
153 * @param s the value being visited
154 * @param p a visitor-specified parameter
155 * @return the result of the visit
156 */
157 R visitString(String s, P p);
158
159 /**
160 * Visits a type value in an annotation.
161 * @param t the value being visited
162 * @param p a visitor-specified parameter
163 * @return the result of the visit
164 */
165 R visitType(TypeMirror t, P p);
166
167 /**
168 * Visits an {@code enum} value in an annotation.
169 * @param c the value being visited
170 * @param p a visitor-specified parameter
171 * @return the result of the visit
172 */
173 R visitEnumConstant(VariableElement c, P p);
174
175 /**
176 * Visits an annotation value in an annotation.
177 * @param a the value being visited
178 * @param p a visitor-specified parameter
179 * @return the result of the visit
180 */
181 R visitAnnotation(AnnotationMirror a, P p);
182
183 /**
184 * Visits an array value in an annotation.
185 * @param vals the value being visited
186 * @param p a visitor-specified parameter
187 * @return the result of the visit
188 */
189 R visitArray(List<? extends AnnotationValue> vals, P p);
190
191 /**
192 * Visits an unknown kind of annotation value.
193 * This can occur if the language evolves and new kinds
194 * of value can be stored in an annotation.
195 * @param av the unknown value being visited
196 * @param p a visitor-specified parameter
197 * @return the result of the visit
198 * @throws UnknownAnnotationValueException
199 * a visitor implementation may optionally throw this exception
200 */
201 R visitUnknown(AnnotationValue av, P p);
202 }