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.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}, {@code PARAMETER}, or {@code RESOURCE_VARIABLE}.
203 *
204 * @param e {@inheritDoc}
205 * @param p {@inheritDoc}
206 * @return the result of the kind-specific visit method
207 */
208 @Override
209 public R visitVariable(VariableElement e, P p) {
210 ElementKind k = e.getKind();
211 switch(k) {
212 case ENUM_CONSTANT:
213 return visitVariableAsEnumConstant(e, p);
214
215 case EXCEPTION_PARAMETER:
216 return visitVariableAsExceptionParameter(e, p);
217
218 case FIELD:
219 return visitVariableAsField(e, p);
220
221 case LOCAL_VARIABLE:
222 return visitVariableAsLocalVariable(e, p);
223
224 case PARAMETER:
225 return visitVariableAsParameter(e, p);
226
227 case RESOURCE_VARIABLE:
228 return visitVariableAsResourceVariable(e, p);
229
230 default:
231 throw new AssertionError("Bad kind " + k + " for VariableElement" + e);
232 }
233 }
234
235 /**
236 * Visits an {@code ENUM_CONSTANT} variable element by calling
237 * {@code defaultAction}.
238 *
239 * @param e the element to visit
240 * @param p a visitor-specified parameter
241 * @return the result of {@code defaultAction}
242 */
243 public R visitVariableAsEnumConstant(VariableElement e, P p) {
244 return defaultAction(e, p);
245 }
246
247 /**
248 * Visits an {@code EXCEPTION_PARAMETER} variable element by calling
249 * {@code defaultAction}.
250 *
251 * @param e the element to visit
252 * @param p a visitor-specified parameter
253 * @return the result of {@code defaultAction}
254 */
255 public R visitVariableAsExceptionParameter(VariableElement e, P p) {
256 return defaultAction(e, p);
257 }
258
259 /**
260 * Visits a {@code FIELD} variable element by calling
261 * {@code defaultAction}.
262 *
263 * @param e the element to visit
264 * @param p a visitor-specified parameter
265 * @return the result of {@code defaultAction}
266 */
267 public R visitVariableAsField(VariableElement e, P p) {
268 return defaultAction(e, p);
269 }
270
271 /**
272 * Visits a {@code LOCAL_VARIABLE} variable element by calling
273 * {@code defaultAction}.
274 *
275 * @param e the element to visit
276 * @param p a visitor-specified parameter
277 * @return the result of {@code defaultAction}
278 */
279 public R visitVariableAsLocalVariable(VariableElement e, P p) {
280 return defaultAction(e, p);
281 }
282
283 /**
284 * Visits a {@code PARAMETER} variable element by calling
285 * {@code defaultAction}.
286 *
287 * @param e the element to visit
288 * @param p a visitor-specified parameter
289 * @return the result of {@code defaultAction}
290 */
291 public R visitVariableAsParameter(VariableElement e, P p) {
292 return defaultAction(e, p);
293 }
294
295 /**
296 * Visits a {@code RESOURCE_VARIABLE} variable element by calling
297 * {@code visitUnknown}.
298 *
299 * @param e the element to visit
300 * @param p a visitor-specified parameter
301 * @return the result of {@code visitUnknown}
302 *
303 * @since 1.7
304 */
305 public R visitVariableAsResourceVariable(VariableElement e, P p) {
306 return visitUnknown(e, p);
307 }
308
309 /**
310 * Visits an executable element, dispatching to the visit method
311 * for the specific {@linkplain ElementKind kind} of executable,
312 * {@code CONSTRUCTOR}, {@code INSTANCE_INIT}, {@code METHOD}, or
313 * {@code STATIC_INIT}.
314 *
315 * @param e {@inheritDoc}
316 * @param p {@inheritDoc}
317 * @return the result of the kind-specific visit method
318 */
319 @Override
320 public R visitExecutable(ExecutableElement e, P p) {
321 ElementKind k = e.getKind();
322 switch(k) {
323 case CONSTRUCTOR:
324 return visitExecutableAsConstructor(e, p);
325
326 case INSTANCE_INIT:
327 return visitExecutableAsInstanceInit(e, p);
328
329 case METHOD:
330 return visitExecutableAsMethod(e, p);
331
332 case STATIC_INIT:
333 return visitExecutableAsStaticInit(e, p);
334
335 default:
336 throw new AssertionError("Bad kind " + k + " for ExecutableElement" + e);
337 }
338 }
339
340 /**
341 * Visits a {@code CONSTRUCTOR} executable element by calling
342 * {@code defaultAction}.
343 *
344 * @param e the element to visit
345 * @param p a visitor-specified parameter
346 * @return the result of {@code defaultAction}
347 */
348 public R visitExecutableAsConstructor(ExecutableElement e, P p) {
349 return defaultAction(e, p);
350 }
351
352 /**
353 * Visits an {@code INSTANCE_INIT} executable element by calling
354 * {@code defaultAction}.
355 *
356 * @param e the element to visit
357 * @param p a visitor-specified parameter
358 * @return the result of {@code defaultAction}
359 */
360 public R visitExecutableAsInstanceInit(ExecutableElement e, P p) {
361 return defaultAction(e, p);
362 }
363
364 /**
365 * Visits a {@code METHOD} executable element by calling
366 * {@code defaultAction}.
367 *
368 * @param e the element to visit
369 * @param p a visitor-specified parameter
370 * @return the result of {@code defaultAction}
371 */
372 public R visitExecutableAsMethod(ExecutableElement e, P p) {
373 return defaultAction(e, p);
374 }
375
376 /**
377 * Visits a {@code STATIC_INIT} executable element by calling
378 * {@code defaultAction}.
379 *
380 * @param e the element to visit
381 * @param p a visitor-specified parameter
382 * @return the result of {@code defaultAction}
383 */
384 public R visitExecutableAsStaticInit(ExecutableElement e, P p) {
385 return defaultAction(e, p);
386 }
387
388
389 /**
390 * {@inheritDoc}
391 *
392 * The element argument has kind {@code TYPE_PARAMETER}.
393 *
394 * @param e {@inheritDoc}
395 * @param p {@inheritDoc}
396 * @return {@inheritDoc}
397 */
398 @Override
399 public R visitTypeParameter(TypeParameterElement e, P p) {
400 assert e.getKind() == TYPE_PARAMETER: "Bad kind on TypeParameterElement";
401 return defaultAction(e, p);
402 }
403 }