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 import javax.annotation.processing.SupportedSourceVersion;
30 import javax.lang.model.SourceVersion;
31 import static javax.lang.model.SourceVersion.*;
32
33
34 /**
35 * A simple visitor of types with default behavior appropriate for the
36 * {@link SourceVersion#RELEASE_6 RELEASE_6} source version.
37 *
38 * Visit methods corresponding to {@code RELEASE_6} language
39 * constructs call {@link #defaultAction defaultAction}, passing their
40 * arguments to {@code defaultAction}'s corresponding parameters.
41 *
42 * For constructs introduced in {@code RELEASE_7} and later, {@code
43 * visitUnknown} is called instead.
44 *
45 * <p> Methods in this class may be overridden subject to their
46 * general contract. Note that annotating methods in concrete
47 * subclasses with {@link java.lang.Override @Override} will help
48 * ensure that methods are overridden as intended.
49 *
50 * <p> <b>WARNING:</b> The {@code TypeVisitor} interface implemented
51 * by this class may have methods added to it in the future to
52 * accommodate new, currently unknown, language structures added to
53 * future versions of the Java™ programming language.
54 * Therefore, methods whose names begin with {@code "visit"} may be
55 * added to this class in the future; to avoid incompatibilities,
56 * classes which extend this class should not declare any instance
57 * methods with names beginning with {@code "visit"}.
58 *
59 * <p>When such a new visit method is added, the default
60 * implementation in this class will be to call the {@link
61 * #visitUnknown visitUnknown} method. A new simple type visitor
62 * class will also be introduced to correspond to the new language
63 * level; this visitor will have different default behavior for the
64 * visit method in question. When the new visitor is introduced, all
65 * or portions of this visitor may be deprecated.
66 *
67 * @param <R> the return type of this visitor's methods. Use {@link
68 * Void} for visitors that do not need to return results.
69 * @param <P> the type of the additional parameter to this visitor's
70 * methods. Use {@code Void} for visitors that do not need an
71 * additional parameter.
72 *
73 * @author Joseph D. Darcy
74 * @author Scott Seligman
75 * @author Peter von der Ahé
76 *
77 * @see SimpleTypeVisitor7
78 * @see SimpleTypeVisitor8
79 * @since 1.6
80 */
81 @SupportedSourceVersion(RELEASE_6)
82 public class SimpleTypeVisitor6<R, P> extends AbstractTypeVisitor6<R, P> {
83 /**
84 * Default value to be returned; {@link #defaultAction
85 * defaultAction} returns this value unless the method is
86 * overridden.
87 */
88 protected final R DEFAULT_VALUE;
89
90 /**
91 * Constructor for concrete subclasses; uses {@code null} for the
92 * default value.
93 */
94 protected SimpleTypeVisitor6(){
95 DEFAULT_VALUE = null;
96 }
97
98 /**
99 * Constructor for concrete subclasses; uses the argument for the
100 * default value.
101 *
102 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
103 */
104 protected SimpleTypeVisitor6(R defaultValue){
105 DEFAULT_VALUE = defaultValue;
106 }
107
108 /**
109 * The default action for visit methods. The implementation in
110 * this class just returns {@link #DEFAULT_VALUE}; subclasses will
111 * commonly override this method.
112 */
113 protected R defaultAction(TypeMirror e, P p) {
114 return DEFAULT_VALUE;
115 }
116
117 /**
118 * {@inheritDoc} This implementation calls {@code defaultAction}.
119 *
120 * @param t {@inheritDoc}
121 * @param p {@inheritDoc}
122 * @return the result of {@code defaultAction}
123 */
124 public R visitPrimitive(PrimitiveType t, P p) {
125 return defaultAction(t, p);
126 }
127
128 /**
129 * {@inheritDoc} This implementation calls {@code defaultAction}.
130 *
131 * @param t {@inheritDoc}
132 * @param p {@inheritDoc}
133 * @return the result of {@code defaultAction}
134 */
135 public R visitNull(NullType t, P p){
136 return defaultAction(t, p);
137 }
138
139 /**
140 * {@inheritDoc} This implementation calls {@code defaultAction}.
141 *
142 * @param t {@inheritDoc}
143 * @param p {@inheritDoc}
144 * @return the result of {@code defaultAction}
145 */
146 public R visitArray(ArrayType t, P p){
147 return defaultAction(t, p);
148 }
149
150 /**
151 * {@inheritDoc} This implementation calls {@code defaultAction}.
152 *
153 * @param t {@inheritDoc}
154 * @param p {@inheritDoc}
155 * @return the result of {@code defaultAction}
156 */
157 public R visitDeclared(DeclaredType t, P p){
158 return defaultAction(t, p);
159 }
160
161 /**
162 * {@inheritDoc} This implementation calls {@code defaultAction}.
163 *
164 * @param t {@inheritDoc}
165 * @param p {@inheritDoc}
166 * @return the result of {@code defaultAction}
167 */
168 public R visitError(ErrorType t, P p){
169 return defaultAction(t, p);
170 }
171
172 /**
173 * {@inheritDoc} This implementation calls {@code defaultAction}.
174 *
175 * @param t {@inheritDoc}
176 * @param p {@inheritDoc}
177 * @return the result of {@code defaultAction}
178 */
179 public R visitTypeVariable(TypeVariable t, P p){
180 return defaultAction(t, p);
181 }
182
183 /**
184 * {@inheritDoc} This implementation calls {@code defaultAction}.
185 *
186 * @param t {@inheritDoc}
187 * @param p {@inheritDoc}
188 * @return the result of {@code defaultAction}
189 */
190 public R visitWildcard(WildcardType t, P p){
191 return defaultAction(t, p);
192 }
193
194 /**
195 * {@inheritDoc} This implementation calls {@code defaultAction}.
196 *
197 * @param t {@inheritDoc}
198 * @param p {@inheritDoc}
199 * @return the result of {@code defaultAction}
200 */
201 public R visitExecutable(ExecutableType t, P p) {
202 return defaultAction(t, p);
203 }
204
205 /**
206 * {@inheritDoc} This implementation calls {@code defaultAction}.
207 *
208 * @param t {@inheritDoc}
209 * @param p {@inheritDoc}
210 * @return the result of {@code defaultAction}
211 */
212 public R visitNoType(NoType t, P p){
213 return defaultAction(t, p);
214 }
215 }