1 /*
2 * Copyright (c) 2005, 2019, 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 com.sun.source.util;
27
28 import com.sun.source.tree.*;
29
30 /**
31 * A simple visitor for tree nodes.
32 *
33 * @param <R> the return type of this visitor's methods. Use {@link
34 * Void} for visitors that do not need to return results.
35 * @param <P> the type of the additional parameter to this visitor's
36 * methods. Use {@code Void} for visitors that do not need an
37 * additional parameter.
38 *
39 * @author Peter von der Ahé
40 * @since 1.6
41 */
42 public class SimpleTreeVisitor <R,P> implements TreeVisitor<R,P> {
43 /**
44 * The default value, returned by the {@link #defaultAction default action}.
45 */
46 protected final R DEFAULT_VALUE;
47
48 /**
49 * Creates a visitor, with a DEFAULT_VALUE of {@code null}.
50 */
51 protected SimpleTreeVisitor() {
52 DEFAULT_VALUE = null;
53 }
54
55 /**
56 * Creates a visitor, with a specified DEFAULT_VALUE.
57 * @param defaultValue the default value to be returned by the default action.
58 */
59 protected SimpleTreeVisitor(R defaultValue) {
60 DEFAULT_VALUE = defaultValue;
61 }
62
63 /**
64 * The default action, used by all visit methods that are not overridden.
65 * @param node the node being visited
66 * @param p the parameter value passed to the visit method
67 * @return the result value to be returned from the visit method
68 */
69 protected R defaultAction(Tree node, P p) {
70 return DEFAULT_VALUE;
71 }
72
73 /**
74 * Invokes the appropriate visit method specific to the type of the node.
75 * @param node the node on which to dispatch
76 * @param p a parameter to be passed to the appropriate visit method
77 * @return the value returns from the appropriate visit method
78 */
79 public final R visit(Tree node, P p) {
80 return (node == null) ? null : node.accept(this, p);
81 }
82
83 /**
84 * Invokes the appropriate visit method on each of a sequence of nodes.
85 * @param nodes the nodes on which to dispatch
86 * @param p a parameter value to be passed to each appropriate visit method
87 * @return the value return from the last of the visit methods, or null
88 * if none were called.
89 */
90 public final R visit(Iterable<? extends Tree> nodes, P p) {
91 R r = null;
92 if (nodes != null)
93 for (Tree node : nodes)
94 r = visit(node, p);
95 return r;
96 }
97
98 /**
99 * {@inheritDoc} This implementation calls {@code defaultAction}.
100 *
101 * @param node {@inheritDoc}
102 * @param p {@inheritDoc}
103 * @return the result of {@code defaultAction}
104 */
105 @Override
106 public R visitCompilationUnit(CompilationUnitTree node, P p) {
107 return defaultAction(node, p);
108 }
109
110 /**
111 * {@inheritDoc} This implementation calls {@code defaultAction}.
112 *
113 * @param node {@inheritDoc}
114 * @param p {@inheritDoc}
115 * @return the result of {@code defaultAction}
116 */
117 @Override
118 public R visitPackage(PackageTree node, P p) {
119 return defaultAction(node, p);
120 }
121
122 /**
123 * {@inheritDoc} This implementation calls {@code defaultAction}.
124 *
125 * @param node {@inheritDoc}
126 * @param p {@inheritDoc}
127 * @return the result of {@code defaultAction}
128 */
129 @Override
130 public R visitImport(ImportTree node, P p) {
131 return defaultAction(node, p);
132 }
133
134 /**
135 * {@inheritDoc} This implementation calls {@code defaultAction}.
136 *
137 * @param node {@inheritDoc}
138 * @param p {@inheritDoc}
139 * @return the result of {@code defaultAction}
140 */
141 @Override
142 public R visitClass(ClassTree node, P p) {
143 return defaultAction(node, p);
144 }
145
146 /**
147 * {@inheritDoc} This implementation calls {@code defaultAction}.
148 *
149 * @param node {@inheritDoc}
150 * @param p {@inheritDoc}
151 * @return the result of {@code defaultAction}
152 */
153 @Override
154 public R visitMethod(MethodTree node, P p) {
155 return defaultAction(node, p);
156 }
157
158 /**
159 * {@inheritDoc} This implementation calls {@code defaultAction}.
160 *
161 * @param node {@inheritDoc}
162 * @param p {@inheritDoc}
163 * @return the result of {@code defaultAction}
164 */
165 @Override
166 public R visitVariable(VariableTree node, P p) {
167 return defaultAction(node, p);
168 }
169
170 /**
171 * {@inheritDoc} This implementation calls {@code defaultAction}.
172 *
173 * @param node {@inheritDoc}
174 * @param p {@inheritDoc}
175 * @return the result of {@code defaultAction}
176 */
177 @Override
178 public R visitEmptyStatement(EmptyStatementTree node, P p) {
179 return defaultAction(node, p);
180 }
181
182 /**
183 * {@inheritDoc} This implementation calls {@code defaultAction}.
184 *
185 * @param node {@inheritDoc}
186 * @param p {@inheritDoc}
187 * @return the result of {@code defaultAction}
188 */
189 @Override
190 public R visitBlock(BlockTree node, P p) {
191 return defaultAction(node, p);
192 }
193
194 /**
195 * {@inheritDoc} This implementation calls {@code defaultAction}.
196 *
197 * @param node {@inheritDoc}
198 * @param p {@inheritDoc}
199 * @return the result of {@code defaultAction}
200 */
201 @Override
202 public R visitDoWhileLoop(DoWhileLoopTree node, P p) {
203 return defaultAction(node, p);
204 }
205
206 /**
207 * {@inheritDoc} This implementation calls {@code defaultAction}.
208 *
209 * @param node {@inheritDoc}
210 * @param p {@inheritDoc}
211 * @return the result of {@code defaultAction}
212 */
213 @Override
214 public R visitWhileLoop(WhileLoopTree node, P p) {
215 return defaultAction(node, p);
216 }
217
218 /**
219 * {@inheritDoc} This implementation calls {@code defaultAction}.
220 *
221 * @param node {@inheritDoc}
222 * @param p {@inheritDoc}
223 * @return the result of {@code defaultAction}
224 */
225 @Override
226 public R visitForLoop(ForLoopTree node, P p) {
227 return defaultAction(node, p);
228 }
229
230 /**
231 * {@inheritDoc} This implementation calls {@code defaultAction}.
232 *
233 * @param node {@inheritDoc}
234 * @param p {@inheritDoc}
235 * @return the result of {@code defaultAction}
236 */
237 @Override
238 public R visitEnhancedForLoop(EnhancedForLoopTree node, P p) {
239 return defaultAction(node, p);
240 }
241
242 /**
243 * {@inheritDoc} This implementation calls {@code defaultAction}.
244 *
245 * @param node {@inheritDoc}
246 * @param p {@inheritDoc}
247 * @return the result of {@code defaultAction}
248 */
249 @Override
250 public R visitLabeledStatement(LabeledStatementTree node, P p) {
251 return defaultAction(node, p);
252 }
253
254 /**
255 * {@inheritDoc} This implementation calls {@code defaultAction}.
256 *
257 * @param node {@inheritDoc}
258 * @param p {@inheritDoc}
259 * @return the result of {@code defaultAction}
260 */
261 @Override
262 public R visitSwitch(SwitchTree node, P p) {
263 return defaultAction(node, p);
264 }
265
266 /**
267 * {@inheritDoc} This implementation calls {@code defaultAction}.
268 *
269 * @param node {@inheritDoc}
270 * @param p {@inheritDoc}
271 * @return the result of {@code defaultAction}
272 *
273 * @deprecated
274 * This method is modeling switch expressions,
275 * which are part of a preview feature and may be removed
276 * if the preview feature is removed.
277 */
278 @Override
279 @Deprecated(forRemoval=true, since="12")
280 @SuppressWarnings("removal")
281 public R visitSwitchExpression(SwitchExpressionTree node, P p) {
282 return defaultAction(node, p);
283 }
284
285 /**
286 * {@inheritDoc} This implementation calls {@code defaultAction}.
287 *
288 * @param node {@inheritDoc}
289 * @param p {@inheritDoc}
290 * @return the result of {@code defaultAction}
291 */
292 @Override
293 public R visitCase(CaseTree node, P p) {
294 return defaultAction(node, p);
295 }
296
297 /**
298 * {@inheritDoc} This implementation calls {@code defaultAction}.
299 *
300 * @param node {@inheritDoc}
301 * @param p {@inheritDoc}
302 * @return the result of {@code defaultAction}
303 */
304 @Override
305 public R visitSynchronized(SynchronizedTree node, P p) {
306 return defaultAction(node, p);
307 }
308
309 /**
310 * {@inheritDoc} This implementation calls {@code defaultAction}.
311 *
312 * @param node {@inheritDoc}
313 * @param p {@inheritDoc}
314 * @return the result of {@code defaultAction}
315 */
316 @Override
317 public R visitTry(TryTree node, P p) {
318 return defaultAction(node, p);
319 }
320
321 /**
322 * {@inheritDoc} This implementation calls {@code defaultAction}.
323 *
324 * @param node {@inheritDoc}
325 * @param p {@inheritDoc}
326 * @return the result of {@code defaultAction}
327 */
328 @Override
329 public R visitCatch(CatchTree node, P p) {
330 return defaultAction(node, p);
331 }
332
333 /**
334 * {@inheritDoc} This implementation calls {@code defaultAction}.
335 *
336 * @param node {@inheritDoc}
337 * @param p {@inheritDoc}
338 * @return the result of {@code defaultAction}
339 */
340 @Override
341 public R visitConditionalExpression(ConditionalExpressionTree node, P p) {
342 return defaultAction(node, p);
343 }
344
345 /**
346 * {@inheritDoc} This implementation calls {@code defaultAction}.
347 *
348 * @param node {@inheritDoc}
349 * @param p {@inheritDoc}
350 * @return the result of {@code defaultAction}
351 */
352 @Override
353 public R visitIf(IfTree node, P p) {
354 return defaultAction(node, p);
355 }
356
357 /**
358 * {@inheritDoc} This implementation calls {@code defaultAction}.
359 *
360 * @param node {@inheritDoc}
361 * @param p {@inheritDoc}
362 * @return the result of {@code defaultAction}
363 */
364 @Override
365 public R visitExpressionStatement(ExpressionStatementTree node, P p) {
366 return defaultAction(node, p);
367 }
368
369 /**
370 * {@inheritDoc} This implementation calls {@code defaultAction}.
371 *
372 * @param node {@inheritDoc}
373 * @param p {@inheritDoc}
374 * @return the result of {@code defaultAction}
375 */
376 @Override
377 public R visitBreak(BreakTree node, P p) {
378 return defaultAction(node, p);
379 }
380
381 /**
382 * {@inheritDoc} This implementation calls {@code defaultAction}.
383 *
384 * @param node {@inheritDoc}
385 * @param p {@inheritDoc}
386 * @return the result of {@code defaultAction}
387 */
388 @Override
389 public R visitContinue(ContinueTree node, P p) {
390 return defaultAction(node, p);
391 }
392
393 /**
394 * {@inheritDoc} This implementation calls {@code defaultAction}.
395 *
396 * @param node {@inheritDoc}
397 * @param p {@inheritDoc}
398 * @return the result of {@code defaultAction}
399 */
400 @Override
401 public R visitReturn(ReturnTree node, P p) {
402 return defaultAction(node, p);
403 }
404
405 /**
406 * {@inheritDoc} This implementation calls {@code defaultAction}.
407 *
408 * @param node {@inheritDoc}
409 * @param p {@inheritDoc}
410 * @return the result of {@code defaultAction}
411 */
412 @Override
413 public R visitThrow(ThrowTree node, P p) {
414 return defaultAction(node, p);
415 }
416
417 /**
418 * {@inheritDoc} This implementation calls {@code defaultAction}.
419 *
420 * @param node {@inheritDoc}
421 * @param p {@inheritDoc}
422 * @return the result of {@code defaultAction}
423 */
424 @Override
425 public R visitAssert(AssertTree node, P p) {
426 return defaultAction(node, p);
427 }
428
429 /**
430 * {@inheritDoc} This implementation calls {@code defaultAction}.
431 *
432 * @param node {@inheritDoc}
433 * @param p {@inheritDoc}
434 * @return the result of {@code defaultAction}
435 */
436 @Override
437 public R visitMethodInvocation(MethodInvocationTree node, P p) {
438 return defaultAction(node, p);
439 }
440
441 /**
442 * {@inheritDoc} This implementation calls {@code defaultAction}.
443 *
444 * @param node {@inheritDoc}
445 * @param p {@inheritDoc}
446 * @return the result of {@code defaultAction}
447 */
448 @Override
449 public R visitNewClass(NewClassTree node, P p) {
450 return defaultAction(node, p);
451 }
452
453 /**
454 * {@inheritDoc} This implementation calls {@code defaultAction}.
455 *
456 * @param node {@inheritDoc}
457 * @param p {@inheritDoc}
458 * @return the result of {@code defaultAction}
459 */
460 @Override
461 public R visitNewArray(NewArrayTree node, P p) {
462 return defaultAction(node, p);
463 }
464
465 /**
466 * {@inheritDoc} This implementation calls {@code defaultAction}.
467 *
468 * @param node {@inheritDoc}
469 * @param p {@inheritDoc}
470 * @return the result of {@code defaultAction}
471 */
472 @Override
473 public R visitLambdaExpression(LambdaExpressionTree node, P p) {
474 return defaultAction(node, p);
475 }
476
477 /**
478 * {@inheritDoc} This implementation calls {@code defaultAction}.
479 *
480 * @param node {@inheritDoc}
481 * @param p {@inheritDoc}
482 * @return the result of {@code defaultAction}
483 */
484 @Override
485 public R visitParenthesized(ParenthesizedTree node, P p) {
486 return defaultAction(node, p);
487 }
488
489 /**
490 * {@inheritDoc} This implementation calls {@code defaultAction}.
491 *
492 * @param node {@inheritDoc}
493 * @param p {@inheritDoc}
494 * @return the result of {@code defaultAction}
495 */
496 @Override
497 public R visitAssignment(AssignmentTree node, P p) {
498 return defaultAction(node, p);
499 }
500
501 /**
502 * {@inheritDoc} This implementation calls {@code defaultAction}.
503 *
504 * @param node {@inheritDoc}
505 * @param p {@inheritDoc}
506 * @return the result of {@code defaultAction}
507 */
508 @Override
509 public R visitCompoundAssignment(CompoundAssignmentTree node, P p) {
510 return defaultAction(node, p);
511 }
512
513 /**
514 * {@inheritDoc} This implementation calls {@code defaultAction}.
515 *
516 * @param node {@inheritDoc}
517 * @param p {@inheritDoc}
518 * @return the result of {@code defaultAction}
519 */
520 @Override
521 public R visitUnary(UnaryTree node, P p) {
522 return defaultAction(node, p);
523 }
524
525 /**
526 * {@inheritDoc} This implementation calls {@code defaultAction}.
527 *
528 * @param node {@inheritDoc}
529 * @param p {@inheritDoc}
530 * @return the result of {@code defaultAction}
531 */
532 @Override
533 public R visitBinary(BinaryTree node, P p) {
534 return defaultAction(node, p);
535 }
536
537 /**
538 * {@inheritDoc} This implementation calls {@code defaultAction}.
539 *
540 * @param node {@inheritDoc}
541 * @param p {@inheritDoc}
542 * @return the result of {@code defaultAction}
543 */
544 @Override
545 public R visitTypeCast(TypeCastTree node, P p) {
546 return defaultAction(node, p);
547 }
548
549 /**
550 * {@inheritDoc} This implementation calls {@code defaultAction}.
551 *
552 * @param node {@inheritDoc}
553 * @param p {@inheritDoc}
554 * @return the result of {@code defaultAction}
555 */
556 @Override
557 public R visitInstanceOf(InstanceOfTree node, P p) {
558 return defaultAction(node, p);
559 }
560
561 /**
562 * {@inheritDoc} This implementation calls {@code defaultAction}.
563 *
564 * @param node {@inheritDoc}
565 * @param p {@inheritDoc}
566 * @return the result of {@code defaultAction}
567 */
568 @Override
569 public R visitArrayAccess(ArrayAccessTree node, P p) {
570 return defaultAction(node, p);
571 }
572
573 /**
574 * {@inheritDoc} This implementation calls {@code defaultAction}.
575 *
576 * @param node {@inheritDoc}
577 * @param p {@inheritDoc}
578 * @return the result of {@code defaultAction}
579 */
580 @Override
581 public R visitMemberSelect(MemberSelectTree node, P p) {
582 return defaultAction(node, p);
583 }
584
585 /**
586 * {@inheritDoc} This implementation calls {@code defaultAction}.
587 *
588 * @param node {@inheritDoc}
589 * @param p {@inheritDoc}
590 * @return the result of {@code defaultAction}
591 */
592 @Override
593 public R visitMemberReference(MemberReferenceTree node, P p) {
594 return defaultAction(node, p);
595 }
596
597 /**
598 * {@inheritDoc} This implementation calls {@code defaultAction}.
599 *
600 * @param node {@inheritDoc}
601 * @param p {@inheritDoc}
602 * @return the result of {@code defaultAction}
603 */
604 @Override
605 public R visitIdentifier(IdentifierTree node, P p) {
606 return defaultAction(node, p);
607 }
608
609 /**
610 * {@inheritDoc} This implementation calls {@code defaultAction}.
611 *
612 * @param node {@inheritDoc}
613 * @param p {@inheritDoc}
614 * @return the result of {@code defaultAction}
615 */
616 @Override
617 public R visitLiteral(LiteralTree node, P p) {
618 return defaultAction(node, p);
619 }
620
621 /**
622 * {@inheritDoc} This implementation calls {@code defaultAction}.
623 *
624 * @param node {@inheritDoc}
625 * @param p {@inheritDoc}
626 * @return the result of {@code defaultAction}
627 */
628 @Override
629 public R visitPrimitiveType(PrimitiveTypeTree node, P p) {
630 return defaultAction(node, p);
631 }
632
633 /**
634 * {@inheritDoc} This implementation calls {@code defaultAction}.
635 *
636 * @param node {@inheritDoc}
637 * @param p {@inheritDoc}
638 * @return the result of {@code defaultAction}
639 */
640 @Override
641 public R visitArrayType(ArrayTypeTree node, P p) {
642 return defaultAction(node, p);
643 }
644
645 /**
646 * {@inheritDoc} This implementation calls {@code defaultAction}.
647 *
648 * @param node {@inheritDoc}
649 * @param p {@inheritDoc}
650 * @return the result of {@code defaultAction}
651 */
652 @Override
653 public R visitParameterizedType(ParameterizedTypeTree node, P p) {
654 return defaultAction(node, p);
655 }
656
657 /**
658 * {@inheritDoc} This implementation calls {@code defaultAction}.
659 *
660 * @param node {@inheritDoc}
661 * @param p {@inheritDoc}
662 * @return the result of {@code defaultAction}
663 */
664 @Override
665 public R visitUnionType(UnionTypeTree node, P p) {
666 return defaultAction(node, p);
667 }
668
669 /**
670 * {@inheritDoc} This implementation calls {@code defaultAction}.
671 *
672 * @param node {@inheritDoc}
673 * @param p {@inheritDoc}
674 * @return the result of {@code defaultAction}
675 */
676 @Override
677 public R visitIntersectionType(IntersectionTypeTree node, P p) {
678 return defaultAction(node, p);
679 }
680
681 /**
682 * {@inheritDoc} This implementation calls {@code defaultAction}.
683 *
684 * @param node {@inheritDoc}
685 * @param p {@inheritDoc}
686 * @return the result of {@code defaultAction}
687 */
688 @Override
689 public R visitTypeParameter(TypeParameterTree node, P p) {
690 return defaultAction(node, p);
691 }
692
693 /**
694 * {@inheritDoc} This implementation calls {@code defaultAction}.
695 *
696 * @param node {@inheritDoc}
697 * @param p {@inheritDoc}
698 * @return the result of {@code defaultAction}
699 */
700 @Override
701 public R visitWildcard(WildcardTree node, P p) {
702 return defaultAction(node, p);
703 }
704
705 /**
706 * {@inheritDoc} This implementation calls {@code defaultAction}.
707 *
708 * @param node {@inheritDoc}
709 * @param p {@inheritDoc}
710 * @return the result of {@code defaultAction}
711 */
712 @Override
713 public R visitModifiers(ModifiersTree node, P p) {
714 return defaultAction(node, p);
715 }
716
717 /**
718 * {@inheritDoc} This implementation calls {@code defaultAction}.
719 *
720 * @param node {@inheritDoc}
721 * @param p {@inheritDoc}
722 * @return the result of {@code defaultAction}
723 */
724 @Override
725 public R visitAnnotation(AnnotationTree node, P p) {
726 return defaultAction(node, p);
727 }
728
729 /**
730 * {@inheritDoc} This implementation calls {@code defaultAction}.
731 *
732 * @param node {@inheritDoc}
733 * @param p {@inheritDoc}
734 * @return the result of {@code defaultAction}
735 */
736 @Override
737 public R visitAnnotatedType(AnnotatedTypeTree node, P p) {
738 return defaultAction(node, p);
739 }
740
741 public R visitModule(ModuleTree node, P p) {
742 return defaultAction(node, p);
743 }
744
745 @Override
746 public R visitExports(ExportsTree node, P p) {
747 return defaultAction(node, p);
748 }
749
750 @Override
751 public R visitOpens(OpensTree node, P p) {
752 return defaultAction(node, p);
753 }
754
755 @Override
756 public R visitProvides(ProvidesTree node, P p) {
757 return defaultAction(node, p);
758 }
759
760 @Override
761 public R visitRequires(RequiresTree node, P p) {
762 return defaultAction(node, p);
763 }
764
765 @Override
766 public R visitUses(UsesTree node, P p) {
767 return defaultAction(node, p);
768 }
769
770 public R visitErroneous(ErroneousTree node, P p) {
771 return defaultAction(node, p);
772 }
773
774 /**
775 * {@inheritDoc} This implementation calls {@code defaultAction}.
776 *
777 * @param node {@inheritDoc}
778 * @param p {@inheritDoc}
779 * @return the result of {@code defaultAction}
780 */
781 @Override
782 public R visitOther(Tree node, P p) {
783 return defaultAction(node, p);
784 }
785
786 /**
787 * {@inheritDoc} This implementation calls {@code defaultAction}.
788 *
789 * @param node {@inheritDoc}
790 * @param p {@inheritDoc}
791 * @return the result of {@code defaultAction}
792 */
793 @Override
794 @Deprecated(forRemoval=true, since="13")
795 @SuppressWarnings("removal")
796 public R visitYield(YieldTree node, P p) {
797 return defaultAction(node, p);
798 }
799 }