1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2024 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.whitespace;
21
22 import java.util.Optional;
23
24 import com.puppycrawl.tools.checkstyle.StatelessCheck;
25 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
26 import com.puppycrawl.tools.checkstyle.api.DetailAST;
27 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
28 import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
29
30 /**
31 * <p>
32 * Checks that there is no whitespace after a token.
33 * More specifically, it checks that it is not followed by whitespace,
34 * or (if linebreaks are allowed) all characters on the line after are
35 * whitespace. To forbid linebreaks after a token, set property
36 * {@code allowLineBreaks} to {@code false}.
37 * </p>
38 * <p>
39 * The check processes
40 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
41 * ARRAY_DECLARATOR</a> and
42 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
43 * INDEX_OP</a> tokens specially from other tokens. Actually it is checked that
44 * there is no whitespace before these tokens, not after them. Space after the
45 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ANNOTATIONS">
46 * ANNOTATIONS</a> before
47 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
48 * ARRAY_DECLARATOR</a> and
49 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
50 * INDEX_OP</a> will be ignored.
51 * </p>
52 * <p>
53 * If the annotation is between the type and the array, like {@code char @NotNull [] param},
54 * the check will skip validation for spaces.
55 * </p>
56 * <p>
57 * Note: This check processes the
58 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LITERAL_SYNCHRONIZED">
59 * LITERAL_SYNCHRONIZED</a> token only when it appears as a part of a
60 * <a href="https://docs.oracle.com/javase/specs/jls/se19/html/jls-14.html#jls-14.19">
61 * synchronized statement</a>, i.e. {@code synchronized(this) {}}.
62 * </p>
63 * <ul>
64 * <li>
65 * Property {@code allowLineBreaks} - Control whether whitespace is allowed
66 * if the token is at a linebreak.
67 * Type is {@code boolean}.
68 * Default value is {@code true}.
69 * </li>
70 * <li>
71 * Property {@code tokens} - tokens to check
72 * Type is {@code java.lang.String[]}.
73 * Validation type is {@code tokenSet}.
74 * Default value is:
75 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_INIT">
76 * ARRAY_INIT</a>,
77 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#AT">
78 * AT</a>,
79 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INC">
80 * INC</a>,
81 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#DEC">
82 * DEC</a>,
83 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#UNARY_MINUS">
84 * UNARY_MINUS</a>,
85 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#UNARY_PLUS">
86 * UNARY_PLUS</a>,
87 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#BNOT">
88 * BNOT</a>,
89 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#LNOT">
90 * LNOT</a>,
91 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#DOT">
92 * DOT</a>,
93 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#ARRAY_DECLARATOR">
94 * ARRAY_DECLARATOR</a>,
95 * <a href="https://checkstyle.org/apidocs/com/puppycrawl/tools/checkstyle/api/TokenTypes.html#INDEX_OP">
96 * INDEX_OP</a>.
97 * </li>
98 * </ul>
99 * <p>
100 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
101 * </p>
102 * <p>
103 * Violation Message Keys:
104 * </p>
105 * <ul>
106 * <li>
107 * {@code ws.followed}
108 * </li>
109 * </ul>
110 *
111 * @since 3.0
112 */
113 @StatelessCheck
114 public class NoWhitespaceAfterCheck extends AbstractCheck {
115
116 /**
117 * A key is pointing to the warning message text in "messages.properties"
118 * file.
119 */
120 public static final String MSG_KEY = "ws.followed";
121
122 /** Control whether whitespace is allowed if the token is at a linebreak. */
123 private boolean allowLineBreaks = true;
124
125 @Override
126 public int[] getDefaultTokens() {
127 return new int[] {
128 TokenTypes.ARRAY_INIT,
129 TokenTypes.AT,
130 TokenTypes.INC,
131 TokenTypes.DEC,
132 TokenTypes.UNARY_MINUS,
133 TokenTypes.UNARY_PLUS,
134 TokenTypes.BNOT,
135 TokenTypes.LNOT,
136 TokenTypes.DOT,
137 TokenTypes.ARRAY_DECLARATOR,
138 TokenTypes.INDEX_OP,
139 };
140 }
141
142 @Override
143 public int[] getAcceptableTokens() {
144 return new int[] {
145 TokenTypes.ARRAY_INIT,
146 TokenTypes.AT,
147 TokenTypes.INC,
148 TokenTypes.DEC,
149 TokenTypes.UNARY_MINUS,
150 TokenTypes.UNARY_PLUS,
151 TokenTypes.BNOT,
152 TokenTypes.LNOT,
153 TokenTypes.DOT,
154 TokenTypes.TYPECAST,
155 TokenTypes.ARRAY_DECLARATOR,
156 TokenTypes.INDEX_OP,
157 TokenTypes.LITERAL_SYNCHRONIZED,
158 TokenTypes.METHOD_REF,
159 };
160 }
161
162 @Override
163 public int[] getRequiredTokens() {
164 return CommonUtil.EMPTY_INT_ARRAY;
165 }
166
167 /**
168 * Setter to control whether whitespace is allowed if the token is at a linebreak.
169 *
170 * @param allowLineBreaks whether whitespace should be
171 * flagged at linebreaks.
172 * @since 3.0
173 */
174 public void setAllowLineBreaks(boolean allowLineBreaks) {
175 this.allowLineBreaks = allowLineBreaks;
176 }
177
178 @Override
179 public void visitToken(DetailAST ast) {
180 if (shouldCheckWhitespaceAfter(ast)) {
181 final DetailAST whitespaceFollowedAst = getWhitespaceFollowedNode(ast);
182 final int whitespaceColumnNo = getPositionAfter(whitespaceFollowedAst);
183 final int whitespaceLineNo = whitespaceFollowedAst.getLineNo();
184
185 if (hasTrailingWhitespace(ast, whitespaceColumnNo, whitespaceLineNo)) {
186 log(ast, MSG_KEY, whitespaceFollowedAst.getText());
187 }
188 }
189 }
190
191 /**
192 * For a visited ast node returns node that should be checked
193 * for not being followed by whitespace.
194 *
195 * @param ast
196 * , visited node.
197 * @return node before ast.
198 */
199 private static DetailAST getWhitespaceFollowedNode(DetailAST ast) {
200 final DetailAST whitespaceFollowedAst;
201 switch (ast.getType()) {
202 case TokenTypes.TYPECAST:
203 whitespaceFollowedAst = ast.findFirstToken(TokenTypes.RPAREN);
204 break;
205 case TokenTypes.ARRAY_DECLARATOR:
206 whitespaceFollowedAst = getArrayDeclaratorPreviousElement(ast);
207 break;
208 case TokenTypes.INDEX_OP:
209 whitespaceFollowedAst = getIndexOpPreviousElement(ast);
210 break;
211 default:
212 whitespaceFollowedAst = ast;
213 }
214 return whitespaceFollowedAst;
215 }
216
217 /**
218 * Returns whether whitespace after a visited node should be checked. For example, whitespace
219 * is not allowed between a type and an array declarator (returns true), except when there is
220 * an annotation in between the type and array declarator (returns false).
221 *
222 * @param ast the visited node
223 * @return true if whitespace after ast should be checked
224 */
225 private static boolean shouldCheckWhitespaceAfter(DetailAST ast) {
226 final DetailAST previousSibling = ast.getPreviousSibling();
227 final boolean isSynchronizedMethod = ast.getType() == TokenTypes.LITERAL_SYNCHRONIZED
228 && ast.getFirstChild() == null;
229 return !isSynchronizedMethod
230 && (previousSibling == null || previousSibling.getType() != TokenTypes.ANNOTATIONS);
231 }
232
233 /**
234 * Gets position after token (place of possible redundant whitespace).
235 *
236 * @param ast Node representing token.
237 * @return position after token.
238 */
239 private static int getPositionAfter(DetailAST ast) {
240 final int after;
241 // If target of possible redundant whitespace is in method definition.
242 if (ast.getType() == TokenTypes.IDENT
243 && ast.getNextSibling() != null
244 && ast.getNextSibling().getType() == TokenTypes.LPAREN) {
245 final DetailAST methodDef = ast.getParent();
246 final DetailAST endOfParams = methodDef.findFirstToken(TokenTypes.RPAREN);
247 after = endOfParams.getColumnNo() + 1;
248 }
249 else {
250 after = ast.getColumnNo() + ast.getText().length();
251 }
252 return after;
253 }
254
255 /**
256 * Checks if there is unwanted whitespace after the visited node.
257 *
258 * @param ast
259 * , visited node.
260 * @param whitespaceColumnNo
261 * , column number of a possible whitespace.
262 * @param whitespaceLineNo
263 * , line number of a possible whitespace.
264 * @return true if whitespace found.
265 */
266 private boolean hasTrailingWhitespace(DetailAST ast,
267 int whitespaceColumnNo, int whitespaceLineNo) {
268 final boolean result;
269 final int astLineNo = ast.getLineNo();
270 final int[] line = getLineCodePoints(astLineNo - 1);
271 if (astLineNo == whitespaceLineNo && whitespaceColumnNo < line.length) {
272 result = CommonUtil.isCodePointWhitespace(line, whitespaceColumnNo);
273 }
274 else {
275 result = !allowLineBreaks;
276 }
277 return result;
278 }
279
280 /**
281 * Returns proper argument for getPositionAfter method, it is a token after
282 * {@link TokenTypes#ARRAY_DECLARATOR ARRAY_DECLARATOR}, in can be {@link TokenTypes#RBRACK
283 * RBRACK}, {@link TokenTypes#IDENT IDENT} or an array type definition (literal).
284 *
285 * @param ast
286 * , {@link TokenTypes#ARRAY_DECLARATOR ARRAY_DECLARATOR} node.
287 * @return previous node by text order.
288 * @throws IllegalStateException if an unexpected token type is encountered.
289 */
290 private static DetailAST getArrayDeclaratorPreviousElement(DetailAST ast) {
291 final DetailAST previousElement;
292
293 if (ast.getPreviousSibling() != null
294 && ast.getPreviousSibling().getType() == TokenTypes.ARRAY_DECLARATOR) {
295 // Covers higher dimension array declarations and initializations
296 previousElement = getPreviousElementOfMultiDimArray(ast);
297 }
298 else {
299 // first array index, is preceded with identifier or type
300 final DetailAST parent = ast.getParent();
301 switch (parent.getType()) {
302 // generics
303 case TokenTypes.TYPE_UPPER_BOUNDS:
304 case TokenTypes.TYPE_LOWER_BOUNDS:
305 previousElement = ast.getPreviousSibling();
306 break;
307 case TokenTypes.LITERAL_NEW:
308 case TokenTypes.TYPE_ARGUMENT:
309 case TokenTypes.DOT:
310 previousElement = getTypeLastNode(ast);
311 break;
312 // mundane array declaration, can be either java style or C style
313 case TokenTypes.TYPE:
314 previousElement = getPreviousNodeWithParentOfTypeAst(ast, parent);
315 break;
316 // java 8 method reference
317 case TokenTypes.METHOD_REF:
318 final DetailAST ident = getIdentLastToken(ast);
319 if (ident == null) {
320 // i.e. int[]::new
321 previousElement = ast.getParent().getFirstChild();
322 }
323 else {
324 previousElement = ident;
325 }
326 break;
327 default:
328 throw new IllegalStateException("unexpected ast syntax " + parent);
329 }
330 }
331 return previousElement;
332 }
333
334 /**
335 * Gets the previous element of a second or higher dimension of an
336 * array declaration or initialization.
337 *
338 * @param leftBracket the token to get previous element of
339 * @return the previous element
340 */
341 private static DetailAST getPreviousElementOfMultiDimArray(DetailAST leftBracket) {
342 final DetailAST previousRightBracket = leftBracket.getPreviousSibling().getLastChild();
343
344 DetailAST ident = null;
345 // This will get us past the type ident, to the actual identifier
346 DetailAST parent = leftBracket.getParent().getParent();
347 while (ident == null) {
348 ident = parent.findFirstToken(TokenTypes.IDENT);
349 parent = parent.getParent();
350 }
351
352 final DetailAST previousElement;
353 if (ident.getColumnNo() > previousRightBracket.getColumnNo()
354 && ident.getColumnNo() < leftBracket.getColumnNo()) {
355 // C style and Java style ' int[] arr []' in same construct
356 previousElement = ident;
357 }
358 else {
359 // 'int[][] arr' or 'int arr[][]'
360 previousElement = previousRightBracket;
361 }
362 return previousElement;
363 }
364
365 /**
366 * Gets previous node for {@link TokenTypes#INDEX_OP INDEX_OP} token
367 * for usage in getPositionAfter method, it is a simplified copy of
368 * getArrayDeclaratorPreviousElement method.
369 *
370 * @param ast
371 * , {@link TokenTypes#INDEX_OP INDEX_OP} node.
372 * @return previous node by text order.
373 */
374 private static DetailAST getIndexOpPreviousElement(DetailAST ast) {
375 final DetailAST result;
376 final DetailAST firstChild = ast.getFirstChild();
377 if (firstChild.getType() == TokenTypes.INDEX_OP) {
378 // second or higher array index
379 result = firstChild.findFirstToken(TokenTypes.RBRACK);
380 }
381 else if (firstChild.getType() == TokenTypes.IDENT) {
382 result = firstChild;
383 }
384 else {
385 final DetailAST ident = getIdentLastToken(ast);
386 if (ident == null) {
387 final DetailAST rparen = ast.findFirstToken(TokenTypes.RPAREN);
388 // construction like new int[]{1}[0]
389 if (rparen == null) {
390 final DetailAST lastChild = firstChild.getLastChild();
391 result = lastChild.findFirstToken(TokenTypes.RCURLY);
392 }
393 // construction like ((byte[]) pixels)[0]
394 else {
395 result = rparen;
396 }
397 }
398 else {
399 result = ident;
400 }
401 }
402 return result;
403 }
404
405 /**
406 * Searches parameter node for a type node.
407 * Returns it or its last node if it has an extended structure.
408 *
409 * @param ast
410 * , subject node.
411 * @return type node.
412 */
413 private static DetailAST getTypeLastNode(DetailAST ast) {
414 final DetailAST typeLastNode;
415 final DetailAST parent = ast.getParent();
416 final boolean isPrecededByTypeArgs =
417 parent.findFirstToken(TokenTypes.TYPE_ARGUMENTS) != null;
418 final Optional<DetailAST> objectArrayType = Optional.ofNullable(getIdentLastToken(ast));
419
420 if (isPrecededByTypeArgs) {
421 typeLastNode = parent.findFirstToken(TokenTypes.TYPE_ARGUMENTS)
422 .findFirstToken(TokenTypes.GENERIC_END);
423 }
424 else if (objectArrayType.isPresent()) {
425 typeLastNode = objectArrayType.orElseThrow();
426 }
427 else {
428 typeLastNode = parent.getFirstChild();
429 }
430
431 return typeLastNode;
432 }
433
434 /**
435 * Finds previous node by text order for an array declarator,
436 * which parent type is {@link TokenTypes#TYPE TYPE}.
437 *
438 * @param ast
439 * , array declarator node.
440 * @param parent
441 * , its parent node.
442 * @return previous node by text order.
443 */
444 private static DetailAST getPreviousNodeWithParentOfTypeAst(DetailAST ast, DetailAST parent) {
445 final DetailAST previousElement;
446 final DetailAST ident = getIdentLastToken(parent.getParent());
447 final DetailAST lastTypeNode = getTypeLastNode(ast);
448 // sometimes there are ident-less sentences
449 // i.e. "(Object[]) null", but in casual case should be
450 // checked whether ident or lastTypeNode has preceding position
451 // determining if it is java style or C style
452
453 if (ident == null || ident.getLineNo() > ast.getLineNo()) {
454 previousElement = lastTypeNode;
455 }
456 else if (ident.getLineNo() < ast.getLineNo()) {
457 previousElement = ident;
458 }
459 // ident and lastTypeNode lay on one line
460 else {
461 final int instanceOfSize = 13;
462 // +2 because ast has `[]` after the ident
463 if (ident.getColumnNo() >= ast.getColumnNo() + 2
464 // +13 because ident (at most 1 character) is followed by
465 // ' instanceof ' (12 characters)
466 || lastTypeNode.getColumnNo() >= ident.getColumnNo() + instanceOfSize) {
467 previousElement = lastTypeNode;
468 }
469 else {
470 previousElement = ident;
471 }
472 }
473 return previousElement;
474 }
475
476 /**
477 * Gets leftmost token of identifier.
478 *
479 * @param ast
480 * , token possibly possessing an identifier.
481 * @return leftmost token of identifier.
482 */
483 private static DetailAST getIdentLastToken(DetailAST ast) {
484 final DetailAST result;
485 final Optional<DetailAST> dot = getPrecedingDot(ast);
486 // method call case
487 if (dot.isEmpty() || ast.getFirstChild().getType() == TokenTypes.METHOD_CALL) {
488 final DetailAST methodCall = ast.findFirstToken(TokenTypes.METHOD_CALL);
489 if (methodCall == null) {
490 result = ast.findFirstToken(TokenTypes.IDENT);
491 }
492 else {
493 result = methodCall.findFirstToken(TokenTypes.RPAREN);
494 }
495 }
496 // qualified name case
497 else {
498 result = dot.orElseThrow().getFirstChild().getNextSibling();
499 }
500 return result;
501 }
502
503 /**
504 * Gets the dot preceding a class member array index operation or class
505 * reference.
506 *
507 * @param leftBracket the ast we are checking
508 * @return dot preceding the left bracket
509 */
510 private static Optional<DetailAST> getPrecedingDot(DetailAST leftBracket) {
511 final DetailAST referencedMemberDot = leftBracket.findFirstToken(TokenTypes.DOT);
512 final Optional<DetailAST> result = Optional.ofNullable(referencedMemberDot);
513 return result.or(() -> getReferencedClassDot(leftBracket));
514 }
515
516 /**
517 * Gets the dot preceding a class reference.
518 *
519 * @param leftBracket the ast we are checking
520 * @return dot preceding the left bracket
521 */
522 private static Optional<DetailAST> getReferencedClassDot(DetailAST leftBracket) {
523 final DetailAST parent = leftBracket.getParent();
524 Optional<DetailAST> classDot = Optional.empty();
525 if (parent.getType() != TokenTypes.ASSIGN) {
526 classDot = Optional.ofNullable(parent.findFirstToken(TokenTypes.DOT));
527 }
528 return classDot;
529 }
530 }