1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2026 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.coding;
21
22 import java.util.AbstractMap.SimpleEntry;
23 import java.util.ArrayList;
24 import java.util.List;
25 import java.util.Map.Entry;
26 import java.util.Optional;
27 import java.util.Set;
28 import java.util.regex.Matcher;
29 import java.util.regex.Pattern;
30
31 import com.puppycrawl.tools.checkstyle.StatelessCheck;
32 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
33 import com.puppycrawl.tools.checkstyle.api.DetailAST;
34 import com.puppycrawl.tools.checkstyle.api.FullIdent;
35 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
36 import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
37
38 /**
39 * <div>
40 * Checks the distance between declaration of variable and its first usage.
41 * Note: Any additional variables declared or initialized between the declaration and
42 * the first usage of the said variable are not counted when calculating the distance.
43 * </div>
44 *
45 * @since 5.8
46 */
47 @StatelessCheck
48 public class VariableDeclarationUsageDistanceCheck extends AbstractCheck {
49
50 /**
51 * Warning message key.
52 */
53 public static final String MSG_KEY = "variable.declaration.usage.distance";
54
55 /**
56 * Warning message key.
57 */
58 public static final String MSG_KEY_EXT = "variable.declaration.usage.distance.extend";
59
60 /**
61 * Default value of distance between declaration of variable and its first
62 * usage.
63 */
64 private static final int DEFAULT_DISTANCE = 3;
65
66 /** Tokens that should be ignored when calculating usage distance. */
67 private static final Set<Integer> ZERO_DISTANCE_TOKENS = Set.of(
68 TokenTypes.VARIABLE_DEF,
69 TokenTypes.TYPE,
70 TokenTypes.MODIFIERS,
71 TokenTypes.RESOURCE,
72 TokenTypes.EXTENDS_CLAUSE,
73 TokenTypes.IMPLEMENTS_CLAUSE,
74 TokenTypes.TYPE_PARAMETERS,
75 TokenTypes.PARAMETERS,
76 TokenTypes.LITERAL_THROWS
77 );
78
79 /**
80 * Specify the maximum distance between a variable's declaration and its first usage.
81 * Value should be greater than 0.
82 */
83 private int allowedDistance = DEFAULT_DISTANCE;
84
85 /**
86 * Define RegExp to ignore distance calculation for variables listed in
87 * this pattern.
88 */
89 private Pattern ignoreVariablePattern = Pattern.compile("");
90
91 /**
92 * Allow to calculate the distance between a variable's declaration and its first usage
93 * across different scopes.
94 */
95 private boolean validateBetweenScopes;
96
97 /** Allow to ignore variables with a 'final' modifier. */
98 private boolean ignoreFinal = true;
99
100 /**
101 * Setter to specify the maximum distance between a variable's declaration and its first usage.
102 * Value should be greater than 0.
103 *
104 * @param allowedDistance
105 * Allowed distance between declaration of variable and its first
106 * usage.
107 * @since 5.8
108 */
109 public void setAllowedDistance(int allowedDistance) {
110 this.allowedDistance = allowedDistance;
111 }
112
113 /**
114 * Setter to define RegExp to ignore distance calculation for variables listed in this pattern.
115 *
116 * @param pattern a pattern.
117 * @since 5.8
118 */
119 public void setIgnoreVariablePattern(Pattern pattern) {
120 ignoreVariablePattern = pattern;
121 }
122
123 /**
124 * Setter to allow to calculate the distance between a variable's declaration
125 * and its first usage across different scopes.
126 *
127 * @param validateBetweenScopes
128 * Defines if allow to calculate distance between declaration of
129 * variable and its first usage in different scopes or not.
130 * @since 5.8
131 */
132 public void setValidateBetweenScopes(boolean validateBetweenScopes) {
133 this.validateBetweenScopes = validateBetweenScopes;
134 }
135
136 /**
137 * Setter to allow to ignore variables with a 'final' modifier.
138 *
139 * @param ignoreFinal
140 * Defines if ignore variables with 'final' modifier or not.
141 * @since 5.8
142 */
143 public void setIgnoreFinal(boolean ignoreFinal) {
144 this.ignoreFinal = ignoreFinal;
145 }
146
147 @Override
148 public int[] getDefaultTokens() {
149 return getRequiredTokens();
150 }
151
152 @Override
153 public int[] getAcceptableTokens() {
154 return getRequiredTokens();
155 }
156
157 @Override
158 public int[] getRequiredTokens() {
159 return new int[] {TokenTypes.VARIABLE_DEF};
160 }
161
162 @Override
163 public void visitToken(DetailAST ast) {
164 final int parentType = ast.getParent().getType();
165 final DetailAST modifiers = ast.getFirstChild();
166
167 if (parentType != TokenTypes.OBJBLOCK
168 && (!ignoreFinal || modifiers.findFirstToken(TokenTypes.FINAL) == null)) {
169 final DetailAST variable = ast.findFirstToken(TokenTypes.IDENT);
170
171 if (!isVariableMatchesIgnorePattern(variable.getText())) {
172 final DetailAST semicolonAst = ast.getNextSibling();
173 final Entry<DetailAST, Integer> entry;
174 if (validateBetweenScopes) {
175 entry = calculateDistanceBetweenScopes(semicolonAst, variable);
176 }
177 else {
178 entry = calculateDistanceInSingleScope(semicolonAst, variable);
179 }
180 final DetailAST variableUsageAst = entry.getKey();
181 final int dist = entry.getValue();
182 if (dist > allowedDistance
183 && !isInitializationSequence(variableUsageAst, variable.getText())) {
184 if (ignoreFinal) {
185 log(ast, MSG_KEY_EXT, variable.getText(), dist, allowedDistance);
186 }
187 else {
188 log(ast, MSG_KEY, variable.getText(), dist, allowedDistance);
189 }
190 }
191 }
192 }
193 }
194
195 /**
196 * Get name of instance whose method is called.
197 *
198 * @param methodCallAst
199 * DetailAST of METHOD_CALL.
200 * @return name of instance.
201 */
202 private static String getInstanceName(DetailAST methodCallAst) {
203 final String methodCallName =
204 FullIdent.createFullIdentBelow(methodCallAst).getText();
205 final int lastDotIndex = methodCallName.lastIndexOf('.');
206 String instanceName = "";
207 if (lastDotIndex != -1) {
208 instanceName = methodCallName.substring(0, lastDotIndex);
209 }
210 return instanceName;
211 }
212
213 /**
214 * Processes statements until usage of variable to detect sequence of
215 * initialization methods.
216 *
217 * @param variableUsageAst
218 * DetailAST of expression that uses variable named variableName.
219 * @param variableName
220 * name of considered variable.
221 * @return true if statements between declaration and usage of variable are
222 * initialization methods.
223 */
224 private static boolean isInitializationSequence(
225 DetailAST variableUsageAst, String variableName) {
226 boolean result = true;
227 boolean isUsedVariableDeclarationFound = false;
228 DetailAST currentSiblingAst = variableUsageAst;
229 String initInstanceName = "";
230
231 while (result && !isUsedVariableDeclarationFound && currentSiblingAst != null) {
232 if (currentSiblingAst.getType() == TokenTypes.EXPR
233 && currentSiblingAst.getFirstChild().getType() == TokenTypes.METHOD_CALL) {
234 final DetailAST methodCallAst = currentSiblingAst.getFirstChild();
235 final String instanceName = getInstanceName(methodCallAst);
236 if (instanceName.isEmpty()) {
237 result = false;
238 }
239 else if (!instanceName.equals(initInstanceName)) {
240 if (initInstanceName.isEmpty()) {
241 initInstanceName = instanceName;
242 }
243 else {
244 result = false;
245 }
246 }
247
248 }
249 else if (currentSiblingAst.getType() == TokenTypes.VARIABLE_DEF) {
250 final String currentVariableName =
251 currentSiblingAst.findFirstToken(TokenTypes.IDENT).getText();
252 isUsedVariableDeclarationFound = variableName.equals(currentVariableName);
253 }
254 else {
255 result = currentSiblingAst.getType() == TokenTypes.SEMI;
256 }
257 currentSiblingAst = currentSiblingAst.getPreviousSibling();
258 }
259 return result;
260 }
261
262 /**
263 * Calculates distance between declaration of variable and its first usage
264 * in single scope.
265 *
266 * @param semicolonAst
267 * Regular node of Ast which is checked for content of checking
268 * variable.
269 * @param variableIdentAst
270 * Variable which distance is calculated for.
271 * @return entry which contains expression with variable usage and distance.
272 * If variable usage is not found, then the expression node is null,
273 * although the distance can be greater than zero.
274 */
275 private static Entry<DetailAST, Integer> calculateDistanceInSingleScope(
276 DetailAST semicolonAst, DetailAST variableIdentAst) {
277 int dist = 0;
278 boolean firstUsageFound = false;
279 DetailAST currentAst = semicolonAst;
280 DetailAST variableUsageAst = null;
281
282 while (!firstUsageFound && currentAst != null) {
283 if (currentAst.getFirstChild() != null) {
284 if (isChild(currentAst, variableIdentAst)) {
285 dist = getDistToVariableUsageInChildNode(currentAst, dist);
286 variableUsageAst = currentAst;
287 firstUsageFound = true;
288 }
289 else if (currentAst.getType() != TokenTypes.VARIABLE_DEF) {
290 dist++;
291 }
292 }
293 currentAst = currentAst.getNextSibling();
294 }
295
296 return new SimpleEntry<>(variableUsageAst, dist);
297 }
298
299 /**
300 * Returns the distance to variable usage for in the child node.
301 *
302 * @param childNode child node.
303 * @param currentDistToVarUsage current distance to the variable usage.
304 * @return the distance to variable usage for in the child node.
305 */
306 private static int getDistToVariableUsageInChildNode(DetailAST childNode,
307 int currentDistToVarUsage) {
308 return switch (childNode.getType()) {
309 case TokenTypes.SLIST -> 0;
310 case TokenTypes.LITERAL_FOR,
311 TokenTypes.LITERAL_WHILE,
312 TokenTypes.LITERAL_DO,
313 TokenTypes.LITERAL_IF -> currentDistToVarUsage + 1;
314 default -> {
315 if (childNode.findFirstToken(TokenTypes.SLIST) == null) {
316 yield currentDistToVarUsage + 1;
317 }
318 yield 0;
319 }
320 };
321 }
322
323 /**
324 * Calculates distance between declaration of variable and its first usage
325 * in multiple scopes.
326 *
327 * @param ast
328 * Regular node of Ast which is checked for content of checking
329 * variable.
330 * @param variable
331 * Variable which distance is calculated for.
332 * @return entry which contains expression with variable usage and distance.
333 */
334 private static Entry<DetailAST, Integer> calculateDistanceBetweenScopes(
335 DetailAST ast, DetailAST variable) {
336 int dist = 0;
337 DetailAST currentScopeAst = ast;
338 DetailAST variableUsageAst = null;
339 while (currentScopeAst != null) {
340 final Entry<List<DetailAST>, Integer> searchResult =
341 searchVariableUsageExpressions(variable, currentScopeAst);
342
343 currentScopeAst = null;
344
345 final List<DetailAST> variableUsageExpressions = searchResult.getKey();
346 dist += searchResult.getValue();
347
348 // If variable usage exists in a single scope, then look into
349 // this scope and count distance until variable usage.
350 if (variableUsageExpressions.size() == 1) {
351 final DetailAST blockWithVariableUsage = variableUsageExpressions.getFirst();
352 currentScopeAst = switch (blockWithVariableUsage.getType()) {
353 case TokenTypes.VARIABLE_DEF, TokenTypes.EXPR -> {
354 dist++;
355 yield null;
356 }
357 case TokenTypes.LITERAL_FOR, TokenTypes.LITERAL_WHILE, TokenTypes.LITERAL_DO ->
358 getFirstNodeInsideForWhileDoWhileBlocks(blockWithVariableUsage, variable);
359 case TokenTypes.LITERAL_IF ->
360 getFirstNodeInsideIfBlock(blockWithVariableUsage, variable);
361 case TokenTypes.LITERAL_SWITCH ->
362 getFirstNodeInsideSwitchBlock(blockWithVariableUsage, variable);
363 case TokenTypes.LITERAL_TRY ->
364 getFirstNodeInsideTryCatchFinallyBlocks(blockWithVariableUsage, variable);
365 default -> blockWithVariableUsage.getFirstChild();
366 };
367 variableUsageAst = blockWithVariableUsage;
368 }
369
370 // If there's no any variable usage, then distance = 0.
371 else if (variableUsageExpressions.isEmpty()) {
372 variableUsageAst = null;
373 }
374 // If variable usage exists in different scopes, then distance =
375 // distance until variable first usage.
376 else {
377 dist++;
378 variableUsageAst = variableUsageExpressions.getFirst();
379 }
380 }
381 return new SimpleEntry<>(variableUsageAst, dist);
382 }
383
384 /**
385 * Searches variable usages starting from specified statement.
386 *
387 * @param variableAst Variable that is used.
388 * @param statementAst DetailAST to start searching from.
389 * @return entry which contains list with found expressions that use the variable
390 * and distance from specified statement to first found expression.
391 */
392 private static Entry<List<DetailAST>, Integer>
393 searchVariableUsageExpressions(final DetailAST variableAst, final DetailAST statementAst) {
394 final List<DetailAST> variableUsageExpressions = new ArrayList<>();
395 int distance = 0;
396 DetailAST currentStatementAst = statementAst;
397 while (currentStatementAst != null) {
398 if (currentStatementAst.getFirstChild() != null) {
399 if (isChild(currentStatementAst, variableAst)) {
400 variableUsageExpressions.add(currentStatementAst);
401 }
402 // If expression hasn't been met yet, then distance + 1.
403 else if (variableUsageExpressions.isEmpty()
404 && !isZeroDistanceToken(currentStatementAst.getType())) {
405 distance++;
406 }
407 }
408 currentStatementAst = currentStatementAst.getNextSibling();
409 }
410 return new SimpleEntry<>(variableUsageExpressions, distance);
411 }
412
413 /**
414 * Gets first Ast node inside FOR, WHILE or DO-WHILE blocks if variable
415 * usage is met only inside the block (not in its declaration!).
416 *
417 * @param block
418 * Ast node represents FOR, WHILE or DO-WHILE block.
419 * @param variable
420 * Variable which is checked for content in block.
421 * @return If variable usage is met only inside the block
422 * (not in its declaration!) then return the first Ast node
423 * of this block, otherwise - null.
424 */
425 private static DetailAST getFirstNodeInsideForWhileDoWhileBlocks(
426 DetailAST block, DetailAST variable) {
427 DetailAST firstNodeInsideBlock = null;
428
429 if (!isVariableInOperatorExpr(block, variable)) {
430 final DetailAST currentNode;
431
432 // Find currentNode for DO-WHILE block.
433 if (block.getType() == TokenTypes.LITERAL_DO) {
434 currentNode = block.getFirstChild();
435 }
436 // Find currentNode for FOR or WHILE block.
437 else {
438 // Looking for RPAREN ( ')' ) token to mark the end of operator
439 // expression.
440 currentNode = block.findFirstToken(TokenTypes.RPAREN).getNextSibling();
441 }
442
443 final int currentNodeType = currentNode.getType();
444
445 if (currentNodeType != TokenTypes.EXPR) {
446 firstNodeInsideBlock = currentNode;
447 }
448 }
449
450 return firstNodeInsideBlock;
451 }
452
453 /**
454 * Gets first Ast node inside IF block if variable usage is met
455 * only inside the block (not in its declaration!).
456 *
457 * @param block
458 * Ast node represents IF block.
459 * @param variable
460 * Variable which is checked for content in block.
461 * @return If variable usage is met only inside the block
462 * (not in its declaration!) then return the first Ast node
463 * of this block, otherwise - null.
464 */
465 private static DetailAST getFirstNodeInsideIfBlock(
466 DetailAST block, DetailAST variable) {
467 DetailAST firstNodeInsideBlock = null;
468
469 if (!isVariableInOperatorExpr(block, variable)) {
470 final Optional<DetailAST> slistToken = TokenUtil
471 .findFirstTokenByPredicate(block, token -> token.getType() == TokenTypes.SLIST);
472 final DetailAST lastNode = block.getLastChild();
473 DetailAST previousNode = lastNode.getPreviousSibling();
474
475 if (slistToken.isEmpty()
476 && lastNode.getType() == TokenTypes.LITERAL_ELSE) {
477
478 // Is if statement without '{}' and has a following else branch,
479 // then change previousNode to the if statement body.
480 previousNode = previousNode.getPreviousSibling();
481 }
482
483 final List<DetailAST> variableUsageExpressions = new ArrayList<>();
484 if (isChild(previousNode, variable)) {
485 variableUsageExpressions.add(previousNode);
486 }
487
488 if (isChild(lastNode, variable)) {
489 variableUsageExpressions.add(lastNode);
490 }
491
492 // If variable usage exists in several related blocks, then
493 // firstNodeInsideBlock = null, otherwise if variable usage exists
494 // only inside one block, then get node from
495 // variableUsageExpressions.
496 if (variableUsageExpressions.size() == 1) {
497 firstNodeInsideBlock = variableUsageExpressions.getFirst();
498 }
499 }
500
501 return firstNodeInsideBlock;
502 }
503
504 /**
505 * Gets first Ast node inside SWITCH block if variable usage is met
506 * only inside the block (not in its declaration!).
507 *
508 * @param block
509 * Ast node represents SWITCH block.
510 * @param variable
511 * Variable which is checked for content in block.
512 * @return If variable usage is met only inside the block
513 * (not in its declaration!) then return the first Ast node
514 * of this block, otherwise - null.
515 */
516 private static DetailAST getFirstNodeInsideSwitchBlock(
517 DetailAST block, DetailAST variable) {
518 final List<DetailAST> variableUsageExpressions =
519 getVariableUsageExpressionsInsideSwitchBlock(block, variable);
520
521 // If variable usage exists in several related blocks, then
522 // firstNodeInsideBlock = null, otherwise if variable usage exists
523 // only inside one block, then get node from
524 // variableUsageExpressions.
525 DetailAST firstNodeInsideBlock = null;
526 if (variableUsageExpressions.size() == 1) {
527 firstNodeInsideBlock = variableUsageExpressions.getFirst();
528 }
529
530 return firstNodeInsideBlock;
531 }
532
533 /**
534 * Helper method for getFirstNodeInsideSwitchBlock to return all variable
535 * usage expressions inside a given switch block.
536 *
537 * @param block the switch block to check.
538 * @param variable variable which is checked for in switch block.
539 * @return List of usages or empty list if none are found.
540 */
541 private static List<DetailAST> getVariableUsageExpressionsInsideSwitchBlock(DetailAST block,
542 DetailAST variable) {
543 final Optional<DetailAST> firstToken = TokenUtil.findFirstTokenByPredicate(block, child -> {
544 return child.getType() == TokenTypes.SWITCH_RULE
545 || child.getType() == TokenTypes.CASE_GROUP;
546 });
547
548 final List<DetailAST> variableUsageExpressions = new ArrayList<>();
549
550 firstToken.ifPresent(token -> {
551 TokenUtil.forEachChild(block, token.getType(), child -> {
552 final DetailAST lastNodeInCaseGroup = child.getLastChild();
553 if (isChild(lastNodeInCaseGroup, variable)) {
554 variableUsageExpressions.add(lastNodeInCaseGroup);
555 }
556 });
557 });
558
559 return variableUsageExpressions;
560 }
561
562 /**
563 * Gets first Ast node inside TRY-CATCH-FINALLY blocks if variable usage is
564 * met only inside the block (not in its declaration!).
565 *
566 * @param block
567 * Ast node represents TRY-CATCH-FINALLY block.
568 * @param variable
569 * Variable which is checked for content in block.
570 * @return If variable usage is met only inside the block
571 * (not in its declaration!) then return the first Ast node
572 * of this block, otherwise - null.
573 */
574 private static DetailAST getFirstNodeInsideTryCatchFinallyBlocks(
575 DetailAST block, DetailAST variable) {
576 DetailAST currentNode = block.getFirstChild();
577 final List<DetailAST> variableUsageExpressions =
578 new ArrayList<>();
579
580 // Checking variable usage inside TRY block.
581 if (isChild(currentNode, variable)) {
582 variableUsageExpressions.add(currentNode);
583 }
584
585 // Switch on CATCH block.
586 currentNode = currentNode.getNextSibling();
587
588 // Checking variable usage inside all CATCH blocks.
589 while (currentNode != null
590 && currentNode.getType() == TokenTypes.LITERAL_CATCH) {
591 final DetailAST catchBlock = currentNode.getLastChild();
592
593 if (isChild(catchBlock, variable)) {
594 variableUsageExpressions.add(catchBlock);
595 }
596 currentNode = currentNode.getNextSibling();
597 }
598
599 // Checking variable usage inside FINALLY block.
600 if (currentNode != null) {
601 final DetailAST finalBlock = currentNode.getLastChild();
602
603 if (isChild(finalBlock, variable)) {
604 variableUsageExpressions.add(finalBlock);
605 }
606 }
607
608 DetailAST variableUsageNode = null;
609
610 // If variable usage exists in several related blocks, then
611 // firstNodeInsideBlock = null, otherwise if variable usage exists
612 // only inside one block, then get node from
613 // variableUsageExpressions.
614 if (variableUsageExpressions.size() == 1) {
615 variableUsageNode = variableUsageExpressions.getFirst().getFirstChild();
616 }
617
618 return variableUsageNode;
619 }
620
621 /**
622 * Checks if variable is in operator declaration. For instance:
623 * <pre>
624 * boolean b = true;
625 * if (b) {...}
626 * </pre>
627 * Variable 'b' is in declaration of operator IF.
628 *
629 * @param operator
630 * Ast node which represents operator.
631 * @param variable
632 * Variable which is checked for content in operator.
633 * @return true if operator contains variable in its declaration, otherwise
634 * - false.
635 */
636 private static boolean isVariableInOperatorExpr(
637 DetailAST operator, DetailAST variable) {
638 boolean isVarInOperatorDeclaration = false;
639
640 DetailAST ast = operator.findFirstToken(TokenTypes.LPAREN);
641
642 // Look if variable is in operator expression
643 while (ast.getType() != TokenTypes.RPAREN) {
644 if (isChild(ast, variable)) {
645 isVarInOperatorDeclaration = true;
646 break;
647 }
648 ast = ast.getNextSibling();
649 }
650
651 return isVarInOperatorDeclaration;
652 }
653
654 /**
655 * Checks if Ast node contains given element.
656 *
657 * @param parent
658 * Node of AST.
659 * @param ast
660 * Ast element which is checked for content in Ast node.
661 * @return true if Ast element was found in Ast node, otherwise - false.
662 */
663 private static boolean isChild(DetailAST parent, DetailAST ast) {
664 boolean isChild = false;
665 DetailAST curNode = parent.getFirstChild();
666
667 while (curNode != null) {
668 if (curNode.getType() == ast.getType() && curNode.getText().equals(ast.getText())) {
669 isChild = true;
670 break;
671 }
672
673 DetailAST toVisit = curNode.getFirstChild();
674 while (toVisit == null) {
675 toVisit = curNode.getNextSibling();
676 curNode = curNode.getParent();
677
678 if (curNode == parent) {
679 break;
680 }
681 }
682
683 curNode = toVisit;
684 }
685
686 return isChild;
687 }
688
689 /**
690 * Checks if entrance variable is contained in ignored pattern.
691 *
692 * @param variable
693 * Variable which is checked for content in ignored pattern.
694 * @return true if variable was found, otherwise - false.
695 */
696 private boolean isVariableMatchesIgnorePattern(String variable) {
697 final Matcher matcher = ignoreVariablePattern.matcher(variable);
698 return matcher.matches();
699 }
700
701 /**
702 * Check if the token should be ignored for distance counting.
703 * For example,
704 * <pre>
705 * try (final AutoCloseable t = new java.io.StringReader(a);) {
706 * }
707 * </pre>
708 * final is a zero-distance token and should be ignored for distance counting.
709 * <pre>
710 * class Table implements Comparator<Integer>{
711 * }
712 * </pre>
713 * An inner class may be defined. Both tokens implements and extends
714 * are zero-distance tokens.
715 * <pre>
716 * public int method(Object b){
717 * }
718 * </pre>
719 * public is a modifier and zero-distance token. int is a type and
720 * zero-distance token.
721 *
722 * @param type
723 * Token type of the ast node.
724 * @return true if it should be ignored for distance counting, otherwise false.
725 */
726 private static boolean isZeroDistanceToken(int type) {
727 return ZERO_DISTANCE_TOKENS.contains(type);
728 }
729
730 }