1 /*
2 * Copyright (c) 2005, 2010, 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.element.*;
29 import static javax.lang.model.element.ElementKind.*;
30 import javax.annotation.processing.SupportedSourceVersion;
31 import static javax.lang.model.SourceVersion.*;
32 import javax.lang.model.SourceVersion;
33
34
35 /**
36 * A visitor of program elements based on their {@linkplain
37 * ElementKind kind} with default behavior appropriate for the {@link
38 * SourceVersion#RELEASE_6 RELEASE_6} source version. For {@linkplain
39 * Element elements} <tt><i>XYZ</i></tt> that may have more than one
40 * kind, the <tt>visit<i>XYZ</i></tt> methods in this class delegate
41 * to the <tt>visit<i>XYZKind</i></tt> method corresponding to the
42 * first argument's kind. The <tt>visit<i>XYZKind</i></tt> methods
43 * call {@link #defaultAction defaultAction}, passing their arguments
44 * to {@code defaultAction}'s corresponding parameters.
45 *
46 * <p> Methods in this class may be overridden subject to their
47 * general contract. Note that annotating methods in concrete
48 * subclasses with {@link java.lang.Override @Override} will help
49 * ensure that methods are overridden as intended.
50 *
51 * <p> <b>WARNING:</b> The {@code ElementVisitor} interface
52 * implemented by this class may have methods added to it or the
53 * {@code ElementKind} {@code enum} used in this case may have
54 * constants added to it in the future to accommodate new, currently
55 * unknown, language structures added to future versions of the
56 * Java™ programming language. Therefore, methods whose names
57 * begin with {@code "visit"} may be added to this class in the
58 * future; to avoid incompatibilities, classes which extend this class
59 * should not declare any instance methods with names beginning with
60 * {@code "visit"}.
61 *
62 * <p>When such a new visit method is added, the default
63 * implementation in this class will be to call the {@link
64 * #visitUnknown visitUnknown} method. A new abstract element kind
65 * visitor class will also be introduced to correspond to the new
66 * language level; this visitor will have different default behavior
67 * for the visit method in question. When the new visitor is
68 * introduced, all or portions of this visitor may be deprecated.
69 *
70 * @param <R> the return type of this visitor's methods. Use {@link
71 * Void} for visitors that do not need to return results.
72 * @param <P> the type of the additional parameter to this visitor's
73 * methods. Use {@code Void} for visitors that do not need an
74 * additional parameter.
75 *
76 * @author Joseph D. Darcy
77 * @author Scott Seligman
78 * @author Peter von der Ahé
79 *
80 * @see ElementKindVisitor7
81 * @since 1.6
82 */
83 @SupportedSourceVersion(RELEASE_6)
84 public class ElementKindVisitor6<R, P>
85 extends SimpleElementVisitor6<R, P> {
86 /**
87 * Constructor for concrete subclasses; uses {@code null} for the
88 * default value.
89 */
90 protected ElementKindVisitor6() {
91 super(null);
92 }
93
94 /**
95 * Constructor for concrete subclasses; uses the argument for the
96 * default value.
97 *
98 * @param defaultValue the value to assign to {@link #DEFAULT_VALUE}
99 */
100 protected ElementKindVisitor6(R defaultValue) {
101 super(defaultValue);
102 }
103
104 /**
105 * {@inheritDoc}
106 *
107 * The element argument has kind {@code PACKAGE}.
108 *
109 * @param e {@inheritDoc}
110 * @param p {@inheritDoc}
111 * @return {@inheritDoc}
112 */
113 @Override
114 public R visitPackage(PackageElement e, P p) {
115 assert e.getKind() == PACKAGE: "Bad kind on PackageElement";
116 return defaultAction(e, p);
117 }
118
119 /**
120 * Visits a type element, dispatching to the visit method for the
121 * specific {@linkplain ElementKind kind} of type, {@code
122 * ANNOTATION_TYPE}, {@code CLASS}, {@code ENUM}, or {@code
123 * INTERFACE}.
124 *
125 * @param e {@inheritDoc}
126 * @param p {@inheritDoc}
127 * @return the result of the kind-specific visit method
128 */
129 @Override
130 public R visitType(TypeElement e, P p) {
131 ElementKind k = e.getKind();
132 switch(k) {
133 case ANNOTATION_TYPE:
134 return visitTypeAsAnnotationType(e, p);
135
136 case CLASS:
137 return visitTypeAsClass(e, p);
138
139 case ENUM:
140 return visitTypeAsEnum(e, p);
141
142 case INTERFACE:
143 return visitTypeAsInterface(e, p);
144
145 default:
146 throw new AssertionError("Bad kind " + k + " for TypeElement" + e);
147 }
148 }
149
150 /**
151 * Visits an {@code ANNOTATION_TYPE} type element by calling
152 * {@code defaultAction}.
153 *
154 * @param e the element to visit
155 * @param p a visitor-specified parameter
156 * @return the result of {@code defaultAction}
157 */
158 public R visitTypeAsAnnotationType(TypeElement e, P p) {
159 return defaultAction(e, p);
160 }
161
162 /**
163 * Visits a {@code CLASS} type element by calling {@code
164 * defaultAction}.
165 *
166 * @param e the element to visit
167 * @param p a visitor-specified parameter
168 * @return the result of {@code defaultAction}
169 */
170 public R visitTypeAsClass(TypeElement e, P p) {
171 return defaultAction(e, p);
172 }
173
174 /**
175 * Visits an {@code ENUM} type element by calling {@code
176 * defaultAction}.
177 *
178 * @param e the element to visit
179 * @param p a visitor-specified parameter
180 * @return the result of {@code defaultAction}
181 */
182 public R visitTypeAsEnum(TypeElement e, P p) {
183 return defaultAction(e, p);
184 }
185
186 /**
187 * Visits an {@code INTERFACE} type element by calling {@code
188 * defaultAction}.
189 *.
190 * @param e the element to visit
191 * @param p a visitor-specified parameter
192 * @return the result of {@code defaultAction}
193 */
194 public R visitTypeAsInterface(TypeElement e, P p) {
195 return defaultAction(e, p);
196 }
197
198 /**
199 * Visits a variable element, dispatching to the visit method for
200 * the specific {@linkplain ElementKind kind} of variable, {@code
201 * ENUM_CONSTANT}, {@code EXCEPTION_PARAMETER}, {@code FIELD},
202 * {@code LOCAL_VARIABLE}, or {@code PARAMETER}.
203 * @param e {@inheritDoc}
204 * @param p {@inheritDoc}
205 * @return the result of the kind-specific visit method
206 */
207 @Override
208 public R visitVariable(VariableElement e, P p) {
209 ElementKind k = e.getKind();
210 switch(k) {
211 case ENUM_CONSTANT:
212 return visitVariableAsEnumConstant(e, p);
213
214 case EXCEPTION_PARAMETER:
215 return visitVariableAsExceptionParameter(e, p);
216
217 case FIELD:
218 return visitVariableAsField(e, p);
219
220 case LOCAL_VARIABLE:
221 return visitVariableAsLocalVariable(e, p);
222
223 case PARAMETER:
224 return visitVariableAsParameter(e, p);
225
226 default:
227 throw new AssertionError("Bad kind " + k + " for VariableElement" + e);
228 }
229
230 }
231
232 /**
233 * Visits an {@code ENUM_CONSTANT} variable element by calling
234 * {@code defaultAction}.
235 *
236 * @param e the element to visit
237 * @param p a visitor-specified parameter
238 * @return the result of {@code defaultAction}
239 */
240 public R visitVariableAsEnumConstant(VariableElement e, P p) {
241 return defaultAction(e, p);
242 }
243
244 /**
245 * Visits an {@code EXCEPTION_PARAMETER} variable element by calling
246 * {@code defaultAction}.
247 *
248 * @param e the element to visit
249 * @param p a visitor-specified parameter
250 * @return the result of {@code defaultAction}
251 */
252 public R visitVariableAsExceptionParameter(VariableElement e, P p) {
253 return defaultAction(e, p);
254 }
255
256 /**
257 * Visits a {@code FIELD} variable element by calling
258 * {@code defaultAction}.
259 *
260 * @param e the element to visit
261 * @param p a visitor-specified parameter
262 * @return the result of {@code defaultAction}
263 */
264 public R visitVariableAsField(VariableElement e, P p) {
265 return defaultAction(e, p);
266 }
267
268 /**
269 * Visits a {@code LOCAL_VARIABLE} variable element by calling
270 * {@code defaultAction}.
271 *
272 * @param e the element to visit
273 * @param p a visitor-specified parameter
274 * @return the result of {@code defaultAction}
275 */
276 public R visitVariableAsLocalVariable(VariableElement e, P p) {
277 return defaultAction(e, p);
278 }
279
280 /**
281 * Visits a {@code PARAMETER} variable element by calling
282 * {@code defaultAction}.
283 *
284 * @param e the element to visit
285 * @param p a visitor-specified parameter
286 * @return the result of {@code defaultAction}
287 */
288 public R visitVariableAsParameter(VariableElement e, P p) {
289 return defaultAction(e, p);
290 }
291
292 /**
293 * Visits an executable element, dispatching to the visit method
294 * for the specific {@linkplain ElementKind kind} of executable,
295 * {@code CONSTRUCTOR}, {@code INSTANCE_INIT}, {@code METHOD}, or
296 * {@code STATIC_INIT}.
297 *
298 * @param e {@inheritDoc}
299 * @param p {@inheritDoc}
300 * @return the result of the kind-specific visit method
301 */
302 @Override
303 public R visitExecutable(ExecutableElement e, P p) {
304 ElementKind k = e.getKind();
305 switch(k) {
306 case CONSTRUCTOR:
307 return visitExecutableAsConstructor(e, p);
308
309 case INSTANCE_INIT:
310 return visitExecutableAsInstanceInit(e, p);
311
312 case METHOD:
313 return visitExecutableAsMethod(e, p);
314
315 case STATIC_INIT:
316 return visitExecutableAsStaticInit(e, p);
317
318 default:
319 throw new AssertionError("Bad kind " + k + " for ExecutableElement" + e);
320 }
321 }
322
323 /**
324 * Visits a {@code CONSTRUCTOR} executable element by calling
325 * {@code defaultAction}.
326 *
327 * @param e the element to visit
328 * @param p a visitor-specified parameter
329 * @return the result of {@code defaultAction}
330 */
331 public R visitExecutableAsConstructor(ExecutableElement e, P p) {
332 return defaultAction(e, p);
333 }
334
335 /**
336 * Visits an {@code INSTANCE_INIT} executable element by calling
337 * {@code defaultAction}.
338 *
339 * @param e the element to visit
340 * @param p a visitor-specified parameter
341 * @return the result of {@code defaultAction}
342 */
343 public R visitExecutableAsInstanceInit(ExecutableElement e, P p) {
344 return defaultAction(e, p);
345 }
346
347 /**
348 * Visits a {@code METHOD} executable element by calling
349 * {@code defaultAction}.
350 *
351 * @param e the element to visit
352 * @param p a visitor-specified parameter
353 * @return the result of {@code defaultAction}
354 */
355 public R visitExecutableAsMethod(ExecutableElement e, P p) {
356 return defaultAction(e, p);
357 }
358
359 /**
360 * Visits a {@code STATIC_INIT} executable element by calling
361 * {@code defaultAction}.
362 *
363 * @param e the element to visit
364 * @param p a visitor-specified parameter
365 * @return the result of {@code defaultAction}
366 */
367 public R visitExecutableAsStaticInit(ExecutableElement e, P p) {
368 return defaultAction(e, p);
369 }
370
371
372 /**
373 * {@inheritDoc}
374 *
375 * The element argument has kind {@code TYPE_PARAMETER}.
376 *
377 * @param e {@inheritDoc}
378 * @param p {@inheritDoc}
379 * @return {@inheritDoc}
380 */
381 @Override
382 public R visitTypeParameter(TypeParameterElement e, P p) {
383 assert e.getKind() == TYPE_PARAMETER: "Bad kind on TypeParameterElement";
384 return defaultAction(e, p);
385 }
386 }