1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 the original author or authors.
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 ///////////////////////////////////////////////////////////////////////////////////////////////
19
20 package com.puppycrawl.tools.checkstyle.checks.blocks;
21
22 import java.util.Arrays;
23 import java.util.Locale;
24 import java.util.Optional;
25
26 import com.puppycrawl.tools.checkstyle.StatelessCheck;
27 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
28 import com.puppycrawl.tools.checkstyle.api.DetailAST;
29 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
30 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
31 import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
32
33 /**
34 * <div>
35 * Checks the placement of right curly braces (<code>'}'</code>) for code blocks. This check
36 * supports if-else, try-catch-finally blocks, switch statements, switch cases, while-loops,
37 * for-loops, method definitions, class definitions, constructor definitions,
38 * instance, static initialization blocks, annotation definitions and enum definitions.
39 * For right curly brace of expression blocks of arrays, lambdas and class instances
40 * please follow issue
41 * <a href="https://github.com/checkstyle/checkstyle/issues/5945">#5945</a>.
42 * For right curly brace of enum constant please follow issue
43 * <a href="https://github.com/checkstyle/checkstyle/issues/7519">#7519</a>.
44 * </div>
45 *
46 * <ul>
47 * <li>
48 * Property {@code option} - Specify the policy on placement of a right curly brace
49 * (<code>'}'</code>).
50 * Type is {@code com.puppycrawl.tools.checkstyle.checks.blocks.RightCurlyOption}.
51 * Default value is {@code same}.
52 * </li>
53 * <li>
54 * Property {@code tokens} - tokens to check
55 * Type is {@code java.lang.String[]}.
56 * Validation type is {@code tokenSet}.
57 * Default value is:
58 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_TRY">
59 * LITERAL_TRY</a>,
60 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_CATCH">
61 * LITERAL_CATCH</a>,
62 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_FINALLY">
63 * LITERAL_FINALLY</a>,
64 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_IF">
65 * LITERAL_IF</a>,
66 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_ELSE">
67 * LITERAL_ELSE</a>.
68 * </li>
69 * </ul>
70 *
71 * <p>
72 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
73 * </p>
74 *
75 * <p>
76 * Violation Message Keys:
77 * </p>
78 * <ul>
79 * <li>
80 * {@code line.alone}
81 * </li>
82 * <li>
83 * {@code line.break.before}
84 * </li>
85 * <li>
86 * {@code line.same}
87 * </li>
88 * </ul>
89 *
90 * @since 3.0
91 */
92 @StatelessCheck
93 public class RightCurlyCheck extends AbstractCheck {
94
95 /**
96 * A key is pointing to the warning message text in "messages.properties"
97 * file.
98 */
99 public static final String MSG_KEY_LINE_BREAK_BEFORE = "line.break.before";
100
101 /**
102 * A key is pointing to the warning message text in "messages.properties"
103 * file.
104 */
105 public static final String MSG_KEY_LINE_ALONE = "line.alone";
106
107 /**
108 * A key is pointing to the warning message text in "messages.properties"
109 * file.
110 */
111 public static final String MSG_KEY_LINE_SAME = "line.same";
112
113 /**
114 * Specify the policy on placement of a right curly brace (<code>'}'</code>).
115 */
116 private RightCurlyOption option = RightCurlyOption.SAME;
117
118 /**
119 * Setter to specify the policy on placement of a right curly brace (<code>'}'</code>).
120 *
121 * @param optionStr string to decode option from
122 * @throws IllegalArgumentException if unable to decode
123 * @since 3.0
124 */
125 public void setOption(String optionStr) {
126 option = RightCurlyOption.valueOf(optionStr.trim().toUpperCase(Locale.ENGLISH));
127 }
128
129 @Override
130 public int[] getDefaultTokens() {
131 return new int[] {
132 TokenTypes.LITERAL_TRY,
133 TokenTypes.LITERAL_CATCH,
134 TokenTypes.LITERAL_FINALLY,
135 TokenTypes.LITERAL_IF,
136 TokenTypes.LITERAL_ELSE,
137 };
138 }
139
140 @Override
141 public int[] getAcceptableTokens() {
142 return new int[] {
143 TokenTypes.LITERAL_TRY,
144 TokenTypes.LITERAL_CATCH,
145 TokenTypes.LITERAL_FINALLY,
146 TokenTypes.LITERAL_IF,
147 TokenTypes.LITERAL_ELSE,
148 TokenTypes.CLASS_DEF,
149 TokenTypes.METHOD_DEF,
150 TokenTypes.CTOR_DEF,
151 TokenTypes.LITERAL_FOR,
152 TokenTypes.LITERAL_WHILE,
153 TokenTypes.LITERAL_DO,
154 TokenTypes.STATIC_INIT,
155 TokenTypes.INSTANCE_INIT,
156 TokenTypes.ANNOTATION_DEF,
157 TokenTypes.ENUM_DEF,
158 TokenTypes.INTERFACE_DEF,
159 TokenTypes.RECORD_DEF,
160 TokenTypes.COMPACT_CTOR_DEF,
161 TokenTypes.LITERAL_SWITCH,
162 TokenTypes.LITERAL_CASE,
163 };
164 }
165
166 @Override
167 public int[] getRequiredTokens() {
168 return CommonUtil.EMPTY_INT_ARRAY;
169 }
170
171 @Override
172 public void visitToken(DetailAST ast) {
173 final Details details = Details.getDetails(ast);
174 final DetailAST rcurly = details.rcurly;
175
176 if (rcurly != null) {
177 final String violation = validate(details);
178 if (!violation.isEmpty()) {
179 log(rcurly, violation, "}", rcurly.getColumnNo() + 1);
180 }
181 }
182 }
183
184 /**
185 * Does general validation.
186 *
187 * @param details for validation.
188 * @return violation message or empty string
189 * if there was no violation during validation.
190 */
191 private String validate(Details details) {
192 String violation = "";
193 if (shouldHaveLineBreakBefore(option, details)) {
194 violation = MSG_KEY_LINE_BREAK_BEFORE;
195 }
196 else if (shouldBeOnSameLine(option, details)) {
197 violation = MSG_KEY_LINE_SAME;
198 }
199 else if (shouldBeAloneOnLine(option, details, getLine(details.rcurly.getLineNo() - 1))) {
200 violation = MSG_KEY_LINE_ALONE;
201 }
202 return violation;
203 }
204
205 /**
206 * Checks whether a right curly should have a line break before.
207 *
208 * @param bracePolicy option for placing the right curly brace.
209 * @param details details for validation.
210 * @return true if a right curly should have a line break before.
211 */
212 private static boolean shouldHaveLineBreakBefore(RightCurlyOption bracePolicy,
213 Details details) {
214 return bracePolicy == RightCurlyOption.SAME
215 && !hasLineBreakBefore(details.rcurly)
216 && !TokenUtil.areOnSameLine(details.lcurly, details.rcurly);
217 }
218
219 /**
220 * Checks that a right curly should be on the same line as the next statement.
221 *
222 * @param bracePolicy option for placing the right curly brace
223 * @param details Details for validation
224 * @return true if a right curly should be alone on a line.
225 */
226 private static boolean shouldBeOnSameLine(RightCurlyOption bracePolicy, Details details) {
227 return bracePolicy == RightCurlyOption.SAME
228 && !details.shouldCheckLastRcurly
229 && !TokenUtil.areOnSameLine(details.rcurly, details.nextToken);
230 }
231
232 /**
233 * Checks that a right curly should be alone on a line.
234 *
235 * @param bracePolicy option for placing the right curly brace
236 * @param details Details for validation
237 * @param targetSrcLine A string with contents of rcurly's line
238 * @return true if a right curly should be alone on a line.
239 */
240 private static boolean shouldBeAloneOnLine(RightCurlyOption bracePolicy,
241 Details details,
242 String targetSrcLine) {
243 return bracePolicy == RightCurlyOption.ALONE
244 && shouldBeAloneOnLineWithAloneOption(details, targetSrcLine)
245 || (bracePolicy == RightCurlyOption.ALONE_OR_SINGLELINE
246 || details.shouldCheckLastRcurly)
247 && shouldBeAloneOnLineWithNotAloneOption(details, targetSrcLine);
248 }
249
250 /**
251 * Whether right curly should be alone on line when ALONE option is used.
252 *
253 * @param details details for validation.
254 * @param targetSrcLine A string with contents of rcurly's line
255 * @return true, if right curly should be alone on line when ALONE option is used.
256 */
257 private static boolean shouldBeAloneOnLineWithAloneOption(Details details,
258 String targetSrcLine) {
259 return !isAloneOnLine(details, targetSrcLine);
260 }
261
262 /**
263 * Whether right curly should be alone on line when ALONE_OR_SINGLELINE or SAME option is used.
264 *
265 * @param details details for validation.
266 * @param targetSrcLine A string with contents of rcurly's line
267 * @return true, if right curly should be alone on line
268 * when ALONE_OR_SINGLELINE or SAME option is used.
269 */
270 private static boolean shouldBeAloneOnLineWithNotAloneOption(Details details,
271 String targetSrcLine) {
272 return shouldBeAloneOnLineWithAloneOption(details, targetSrcLine)
273 && !isBlockAloneOnSingleLine(details);
274 }
275
276 /**
277 * Checks whether right curly is alone on a line.
278 *
279 * @param details for validation.
280 * @param targetSrcLine A string with contents of rcurly's line
281 * @return true if right curly is alone on a line.
282 */
283 private static boolean isAloneOnLine(Details details, String targetSrcLine) {
284 final DetailAST rcurly = details.rcurly;
285 final DetailAST nextToken = details.nextToken;
286 return (nextToken == null || !TokenUtil.areOnSameLine(rcurly, nextToken)
287 || skipDoubleBraceInstInit(details))
288 && CommonUtil.hasWhitespaceBefore(details.rcurly.getColumnNo(),
289 targetSrcLine);
290 }
291
292 /**
293 * This method determines if the double brace initialization should be skipped over by the
294 * check. Double brace initializations are treated differently. The corresponding inner
295 * rcurly is treated as if it was alone on line even when it may be followed by another
296 * rcurly and a semi, raising no violations.
297 * <i>Please do note though that the line should not contain anything other than the following
298 * right curly and the semi following it or else violations will be raised.</i>
299 * Only the kind of double brace initializations shown in the following example code will be
300 * skipped over:<br>
301 * <pre>
302 * {@code Map<String, String> map = new LinkedHashMap<>() {{
303 * put("alpha", "man");
304 * }}; // no violation}
305 * </pre>
306 *
307 * @param details {@link Details} object containing the details relevant to the rcurly
308 * @return if the double brace initialization rcurly should be skipped over by the check
309 */
310 private static boolean skipDoubleBraceInstInit(Details details) {
311 boolean skipDoubleBraceInstInit = false;
312 final DetailAST tokenAfterNextToken = Details.getNextToken(details.nextToken);
313 if (tokenAfterNextToken != null) {
314 final DetailAST rcurly = details.rcurly;
315 skipDoubleBraceInstInit = rcurly.getParent().getParent()
316 .getType() == TokenTypes.INSTANCE_INIT
317 && details.nextToken.getType() == TokenTypes.RCURLY
318 && !TokenUtil.areOnSameLine(rcurly, Details.getNextToken(tokenAfterNextToken));
319 }
320 return skipDoubleBraceInstInit;
321 }
322
323 /**
324 * Checks whether block has a single-line format and is alone on a line.
325 *
326 * @param details for validation.
327 * @return true if block has single-line format and is alone on a line.
328 */
329 private static boolean isBlockAloneOnSingleLine(Details details) {
330 DetailAST nextToken = details.nextToken;
331
332 while (nextToken != null && nextToken.getType() == TokenTypes.LITERAL_ELSE) {
333 nextToken = Details.getNextToken(nextToken);
334 }
335
336 // sibling tokens should be allowed on a single line
337 final int[] tokensWithBlockSibling = {
338 TokenTypes.DO_WHILE,
339 TokenTypes.LITERAL_FINALLY,
340 TokenTypes.LITERAL_CATCH,
341 };
342
343 if (TokenUtil.isOfType(nextToken, tokensWithBlockSibling)) {
344 final DetailAST parent = nextToken.getParent();
345 nextToken = Details.getNextToken(parent);
346 }
347
348 return TokenUtil.areOnSameLine(details.lcurly, details.rcurly)
349 && (nextToken == null || !TokenUtil.areOnSameLine(details.rcurly, nextToken)
350 || isRightcurlyFollowedBySemicolon(details));
351 }
352
353 /**
354 * Checks whether the right curly is followed by a semicolon.
355 *
356 * @param details details for validation.
357 * @return true if the right curly is followed by a semicolon.
358 */
359 private static boolean isRightcurlyFollowedBySemicolon(Details details) {
360 return details.nextToken.getType() == TokenTypes.SEMI;
361 }
362
363 /**
364 * Checks if right curly has line break before.
365 *
366 * @param rightCurly right curly token.
367 * @return true, if right curly has line break before.
368 */
369 private static boolean hasLineBreakBefore(DetailAST rightCurly) {
370 DetailAST previousToken = rightCurly.getPreviousSibling();
371 if (previousToken == null) {
372 previousToken = rightCurly.getParent();
373 }
374 return !TokenUtil.areOnSameLine(rightCurly, previousToken);
375 }
376
377 /**
378 * Structure that contains all details for validation.
379 */
380 private static final class Details {
381
382 /**
383 * Token types that identify tokens that will never have SLIST in their AST.
384 */
385 private static final int[] TOKENS_WITH_NO_CHILD_SLIST = {
386 TokenTypes.CLASS_DEF,
387 TokenTypes.ENUM_DEF,
388 TokenTypes.ANNOTATION_DEF,
389 TokenTypes.INTERFACE_DEF,
390 TokenTypes.RECORD_DEF,
391 };
392
393 /** Right curly. */
394 private final DetailAST rcurly;
395 /** Left curly. */
396 private final DetailAST lcurly;
397 /** Next token. */
398 private final DetailAST nextToken;
399 /** Should check last right curly. */
400 private final boolean shouldCheckLastRcurly;
401
402 /**
403 * Constructor.
404 *
405 * @param lcurly the lcurly of the token whose details are being collected
406 * @param rcurly the rcurly of the token whose details are being collected
407 * @param nextToken the token after the token whose details are being collected
408 * @param shouldCheckLastRcurly boolean value to determine if to check last rcurly
409 */
410 private Details(DetailAST lcurly, DetailAST rcurly,
411 DetailAST nextToken, boolean shouldCheckLastRcurly) {
412 this.lcurly = lcurly;
413 this.rcurly = rcurly;
414 this.nextToken = nextToken;
415 this.shouldCheckLastRcurly = shouldCheckLastRcurly;
416 }
417
418 /**
419 * Collects validation Details.
420 *
421 * @param ast a {@code DetailAST} value
422 * @return object containing all details to make a validation
423 */
424 private static Details getDetails(DetailAST ast) {
425 return switch (ast.getType()) {
426 case TokenTypes.LITERAL_TRY, TokenTypes.LITERAL_CATCH -> getDetailsForTryCatch(ast);
427 case TokenTypes.LITERAL_IF -> getDetailsForIf(ast);
428 case TokenTypes.LITERAL_DO -> getDetailsForDoLoops(ast);
429 case TokenTypes.LITERAL_SWITCH -> getDetailsForSwitch(ast);
430 case TokenTypes.LITERAL_CASE -> getDetailsForCase(ast);
431 default -> getDetailsForOthers(ast);
432 };
433 }
434
435 /**
436 * Collects details about switch statements and expressions.
437 *
438 * @param switchNode switch statement or expression to gather details about
439 * @return new Details about given switch statement or expression
440 */
441 private static Details getDetailsForSwitch(DetailAST switchNode) {
442 final DetailAST lcurly = switchNode.findFirstToken(TokenTypes.LCURLY);
443 final DetailAST rcurly;
444 DetailAST nextToken = null;
445 // skipping switch expression as check only handles statements
446 if (isSwitchExpression(switchNode)) {
447 rcurly = null;
448 }
449 else {
450 rcurly = switchNode.getLastChild();
451 nextToken = getNextToken(switchNode);
452 }
453 return new Details(lcurly, rcurly, nextToken, true);
454 }
455
456 /**
457 * Collects details about case statements.
458 *
459 * @param caseNode case statement to gather details about
460 * @return new Details about given case statement
461 */
462 private static Details getDetailsForCase(DetailAST caseNode) {
463 final DetailAST caseParent = caseNode.getParent();
464 final int parentType = caseParent.getType();
465 final Optional<DetailAST> lcurly;
466 final DetailAST statementList;
467
468 if (parentType == TokenTypes.SWITCH_RULE) {
469 statementList = caseParent.findFirstToken(TokenTypes.SLIST);
470 lcurly = Optional.ofNullable(statementList);
471 }
472 else {
473 statementList = caseNode.getNextSibling();
474 lcurly = Optional.ofNullable(statementList)
475 .map(DetailAST::getFirstChild)
476 .filter(node -> node.getType() == TokenTypes.SLIST);
477 }
478 final DetailAST rcurly = lcurly.map(DetailAST::getLastChild)
479 .filter(child -> !isSwitchExpression(caseParent))
480 .orElse(null);
481 final Optional<DetailAST> nextToken =
482 Optional.ofNullable(lcurly.map(DetailAST::getNextSibling)
483 .orElseGet(() -> getNextToken(caseParent)));
484
485 return new Details(lcurly.orElse(null), rcurly, nextToken.orElse(null), true);
486 }
487
488 /**
489 * Check whether switch is expression or not.
490 *
491 * @param switchNode switch statement or expression to provide detail
492 * @return true if it is a switch expression
493 */
494 private static boolean isSwitchExpression(DetailAST switchNode) {
495 DetailAST currentNode = switchNode;
496 boolean ans = false;
497
498 while (currentNode != null) {
499 if (currentNode.getType() == TokenTypes.EXPR) {
500 ans = true;
501 }
502 currentNode = currentNode.getParent();
503 }
504 return ans;
505 }
506
507 /**
508 * Collects validation details for LITERAL_TRY, and LITERAL_CATCH.
509 *
510 * @param ast a {@code DetailAST} value
511 * @return object containing all details to make a validation
512 */
513 private static Details getDetailsForTryCatch(DetailAST ast) {
514 final DetailAST lcurly;
515 DetailAST nextToken;
516 final int tokenType = ast.getType();
517 if (tokenType == TokenTypes.LITERAL_TRY) {
518 if (ast.getFirstChild().getType() == TokenTypes.RESOURCE_SPECIFICATION) {
519 lcurly = ast.getFirstChild().getNextSibling();
520 }
521 else {
522 lcurly = ast.getFirstChild();
523 }
524 nextToken = lcurly.getNextSibling();
525 }
526 else {
527 nextToken = ast.getNextSibling();
528 lcurly = ast.getLastChild();
529 }
530
531 final boolean shouldCheckLastRcurly;
532 if (nextToken == null) {
533 shouldCheckLastRcurly = true;
534 nextToken = getNextToken(ast);
535 }
536 else {
537 shouldCheckLastRcurly = false;
538 }
539
540 final DetailAST rcurly = lcurly.getLastChild();
541 return new Details(lcurly, rcurly, nextToken, shouldCheckLastRcurly);
542 }
543
544 /**
545 * Collects validation details for LITERAL_IF.
546 *
547 * @param ast a {@code DetailAST} value
548 * @return object containing all details to make a validation
549 */
550 private static Details getDetailsForIf(DetailAST ast) {
551 final boolean shouldCheckLastRcurly;
552 final DetailAST lcurly;
553 DetailAST nextToken = ast.findFirstToken(TokenTypes.LITERAL_ELSE);
554
555 if (nextToken == null) {
556 shouldCheckLastRcurly = true;
557 nextToken = getNextToken(ast);
558 lcurly = ast.getLastChild();
559 }
560 else {
561 shouldCheckLastRcurly = false;
562 lcurly = nextToken.getPreviousSibling();
563 }
564
565 DetailAST rcurly = null;
566 if (lcurly.getType() == TokenTypes.SLIST) {
567 rcurly = lcurly.getLastChild();
568 }
569 return new Details(lcurly, rcurly, nextToken, shouldCheckLastRcurly);
570 }
571
572 /**
573 * Collects validation details for CLASS_DEF, RECORD_DEF, METHOD DEF, CTOR_DEF, STATIC_INIT,
574 * INSTANCE_INIT, ANNOTATION_DEF, ENUM_DEF, and COMPACT_CTOR_DEF.
575 *
576 * @param ast a {@code DetailAST} value
577 * @return an object containing all details to make a validation
578 */
579 private static Details getDetailsForOthers(DetailAST ast) {
580 DetailAST rcurly = null;
581 final DetailAST lcurly;
582 final int tokenType = ast.getType();
583 if (isTokenWithNoChildSlist(tokenType)) {
584 final DetailAST child = ast.getLastChild();
585 lcurly = child;
586 rcurly = child.getLastChild();
587 }
588 else {
589 lcurly = ast.findFirstToken(TokenTypes.SLIST);
590 if (lcurly != null) {
591 // SLIST could be absent if method is abstract
592 rcurly = lcurly.getLastChild();
593 }
594 }
595 return new Details(lcurly, rcurly, getNextToken(ast), true);
596 }
597
598 /**
599 * Tests whether the provided tokenType will never have a SLIST as child in its AST.
600 * Like CLASS_DEF, ANNOTATION_DEF etc.
601 *
602 * @param tokenType the tokenType to test against.
603 * @return weather provided tokenType is definition token.
604 */
605 private static boolean isTokenWithNoChildSlist(int tokenType) {
606 return Arrays.stream(TOKENS_WITH_NO_CHILD_SLIST).anyMatch(token -> token == tokenType);
607 }
608
609 /**
610 * Collects validation details for LITERAL_DO loops' tokens.
611 *
612 * @param ast a {@code DetailAST} value
613 * @return an object containing all details to make a validation
614 */
615 private static Details getDetailsForDoLoops(DetailAST ast) {
616 final DetailAST lcurly = ast.findFirstToken(TokenTypes.SLIST);
617 final DetailAST nextToken = ast.findFirstToken(TokenTypes.DO_WHILE);
618 DetailAST rcurly = null;
619 if (lcurly != null) {
620 rcurly = lcurly.getLastChild();
621 }
622 return new Details(lcurly, rcurly, nextToken, false);
623 }
624
625 /**
626 * Finds next token after the given one.
627 *
628 * @param ast the given node.
629 * @return the token which represents next lexical item.
630 */
631 private static DetailAST getNextToken(DetailAST ast) {
632 DetailAST next = null;
633 DetailAST parent = ast;
634 while (next == null && parent != null) {
635 next = parent.getNextSibling();
636 parent = parent.getParent();
637 }
638 return next;
639 }
640 }
641 }