001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018///////////////////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks;
021
022import java.util.Collections;
023import java.util.HashMap;
024import java.util.LinkedList;
025import java.util.List;
026import java.util.Locale;
027import java.util.Map;
028import java.util.Optional;
029import java.util.regex.Pattern;
030
031import com.puppycrawl.tools.checkstyle.StatelessCheck;
032import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
033import com.puppycrawl.tools.checkstyle.api.AuditEvent;
034import com.puppycrawl.tools.checkstyle.api.DetailAST;
035import com.puppycrawl.tools.checkstyle.api.TokenTypes;
036
037/**
038 * <div>
039 * Maintains a set of check suppressions from {@code @SuppressWarnings} annotations.
040 * It allows to prevent Checkstyle from reporting violations from parts of code that were
041 * annotated with {@code @SuppressWarnings} and using name of the check to be excluded.
042 * It is possible to suppress all the checkstyle warnings with the argument {@code "all"}.
043 * You can also use a {@code checkstyle:} prefix to prevent compiler
044 * from processing these annotations.
045 * You can also define aliases for check names that need to be suppressed.
046 * </div>
047 *
048 * <ul>
049 * <li>
050 * Property {@code aliasList} - Specify aliases for check names that can be used in code
051 * within {@code SuppressWarnings} in a format of comma separated attribute=value entries.
052 * The attribute is the fully qualified name of the Check and value is its alias.
053 * Type is {@code java.lang.String[]}.
054 * Default value is {@code ""}.
055 * </li>
056 * </ul>
057 *
058 * <p>
059 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
060 * </p>
061 *
062 * @since 5.7
063 */
064@StatelessCheck
065public class SuppressWarningsHolder
066    extends AbstractCheck {
067
068    /**
069     * Optional prefix for warning suppressions that are only intended to be
070     * recognized by checkstyle. For instance, to suppress {@code
071     * FallThroughCheck} only in checkstyle (and not in javac), use the
072     * suppression {@code "checkstyle:fallthrough"} or {@code "checkstyle:FallThrough"}.
073     * To suppress the warning in both tools, just use {@code "fallthrough"}.
074     */
075    private static final String CHECKSTYLE_PREFIX = "checkstyle:";
076
077    /** Java.lang namespace prefix, which is stripped from SuppressWarnings. */
078    private static final String JAVA_LANG_PREFIX = "java.lang.";
079
080    /** Suffix to be removed from subclasses of Check. */
081    private static final String CHECK_SUFFIX = "check";
082
083    /** Special warning id for matching all the warnings. */
084    private static final String ALL_WARNING_MATCHING_ID = "all";
085
086    /** A map from check source names to suppression aliases. */
087    private static final Map<String, String> CHECK_ALIAS_MAP = new HashMap<>();
088
089    /**
090     * A thread-local holder for the list of suppression entries for the last
091     * file parsed.
092     */
093    private static final ThreadLocal<List<Entry>> ENTRIES =
094            ThreadLocal.withInitial(LinkedList::new);
095
096    /**
097     * Compiled pattern used to match whitespace in text block content.
098     */
099    private static final Pattern WHITESPACE = Pattern.compile("\\s+");
100
101    /**
102     * Compiled pattern used to match preceding newline in text block content.
103     */
104    private static final Pattern NEWLINE = Pattern.compile("\\n");
105
106    /**
107     * Returns the default alias for the source name of a check, which is the
108     * source name in lower case with any dotted prefix or "Check"/"check"
109     * suffix removed.
110     *
111     * @param sourceName the source name of the check (generally the class
112     *        name)
113     * @return the default alias for the given check
114     */
115    public static String getDefaultAlias(String sourceName) {
116        int endIndex = sourceName.length();
117        final String sourceNameLower = sourceName.toLowerCase(Locale.ENGLISH);
118        if (sourceNameLower.endsWith(CHECK_SUFFIX)) {
119            endIndex -= CHECK_SUFFIX.length();
120        }
121        final int startIndex = sourceNameLower.lastIndexOf('.') + 1;
122        return sourceNameLower.substring(startIndex, endIndex);
123    }
124
125    /**
126     * Returns the alias for the source name of a check. If an alias has been
127     * explicitly registered via {@link #setAliasList(String...)}, that
128     * alias is returned; otherwise, the default alias is used.
129     *
130     * @param sourceName the source name of the check (generally the class
131     *        name)
132     * @return the current alias for the given check
133     */
134    public static String getAlias(String sourceName) {
135        String checkAlias = CHECK_ALIAS_MAP.get(sourceName);
136        if (checkAlias == null) {
137            checkAlias = getDefaultAlias(sourceName);
138        }
139        return checkAlias;
140    }
141
142    /**
143     * Registers an alias for the source name of a check.
144     *
145     * @param sourceName the source name of the check (generally the class
146     *        name)
147     * @param checkAlias the alias used in {@link SuppressWarnings} annotations
148     */
149    private static void registerAlias(String sourceName, String checkAlias) {
150        CHECK_ALIAS_MAP.put(sourceName, checkAlias);
151    }
152
153    /**
154     * Setter to specify aliases for check names that can be used in code
155     * within {@code SuppressWarnings} in a format of comma separated attribute=value entries.
156     * The attribute is the fully qualified name of the Check and value is its alias.
157     *
158     * @param aliasList comma-separated alias assignments
159     * @throws IllegalArgumentException when alias item does not have '='
160     * @since 5.7
161     */
162    public void setAliasList(String... aliasList) {
163        for (String sourceAlias : aliasList) {
164            final int index = sourceAlias.indexOf('=');
165            if (index > 0) {
166                registerAlias(sourceAlias.substring(0, index), sourceAlias
167                    .substring(index + 1));
168            }
169            else if (!sourceAlias.isEmpty()) {
170                throw new IllegalArgumentException(
171                    "'=' expected in alias list item: " + sourceAlias);
172            }
173        }
174    }
175
176    /**
177     * Checks for a suppression of a check with the given source name and
178     * location in the last file processed.
179     *
180     * @param event audit event.
181     * @return whether the check with the given name is suppressed at the given
182     *         source location
183     */
184    public static boolean isSuppressed(AuditEvent event) {
185        final List<Entry> entries = ENTRIES.get();
186        final String sourceName = event.getSourceName();
187        final String checkAlias = getAlias(sourceName);
188        final int line = event.getLine();
189        final int column = event.getColumn();
190        boolean suppressed = false;
191        for (Entry entry : entries) {
192            final boolean afterStart = isSuppressedAfterEventStart(line, column, entry);
193            final boolean beforeEnd = isSuppressedBeforeEventEnd(line, column, entry);
194            final String checkName = entry.getCheckName();
195            final boolean nameMatches =
196                ALL_WARNING_MATCHING_ID.equals(checkName)
197                    || checkName.equalsIgnoreCase(checkAlias)
198                    || getDefaultAlias(checkName).equalsIgnoreCase(checkAlias);
199            if (afterStart && beforeEnd
200                    && (nameMatches || checkName.equals(event.getModuleId()))) {
201                suppressed = true;
202                break;
203            }
204        }
205        return suppressed;
206    }
207
208    /**
209     * Checks whether suppression entry position is after the audit event occurrence position
210     * in the source file.
211     *
212     * @param line the line number in the source file where the event occurred.
213     * @param column the column number in the source file where the event occurred.
214     * @param entry suppression entry.
215     * @return true if suppression entry position is after the audit event occurrence position
216     *         in the source file.
217     */
218    private static boolean isSuppressedAfterEventStart(int line, int column, Entry entry) {
219        return entry.getFirstLine() < line
220            || entry.getFirstLine() == line
221            && (column == 0 || entry.getFirstColumn() <= column);
222    }
223
224    /**
225     * Checks whether suppression entry position is before the audit event occurrence position
226     * in the source file.
227     *
228     * @param line the line number in the source file where the event occurred.
229     * @param column the column number in the source file where the event occurred.
230     * @param entry suppression entry.
231     * @return true if suppression entry position is before the audit event occurrence position
232     *         in the source file.
233     */
234    private static boolean isSuppressedBeforeEventEnd(int line, int column, Entry entry) {
235        return entry.getLastLine() > line
236            || entry.getLastLine() == line && entry
237                .getLastColumn() >= column;
238    }
239
240    @Override
241    public int[] getDefaultTokens() {
242        return getRequiredTokens();
243    }
244
245    @Override
246    public int[] getAcceptableTokens() {
247        return getRequiredTokens();
248    }
249
250    @Override
251    public int[] getRequiredTokens() {
252        return new int[] {TokenTypes.ANNOTATION};
253    }
254
255    @Override
256    public void beginTree(DetailAST rootAST) {
257        ENTRIES.get().clear();
258    }
259
260    @Override
261    public void visitToken(DetailAST ast) {
262        // check whether annotation is SuppressWarnings
263        // expected children: AT ( IDENT | DOT ) LPAREN <values> RPAREN
264        String identifier = getIdentifier(getNthChild(ast, 1));
265        if (identifier.startsWith(JAVA_LANG_PREFIX)) {
266            identifier = identifier.substring(JAVA_LANG_PREFIX.length());
267        }
268        if ("SuppressWarnings".equals(identifier)) {
269            getAnnotationTarget(ast).ifPresent(targetAST -> {
270                addSuppressions(getAllAnnotationValues(ast), targetAST);
271            });
272        }
273    }
274
275    /**
276     * Method to populate list of suppression entries.
277     *
278     * @param values
279     *            - list of check names
280     * @param targetAST
281     *            - annotation target
282     */
283    private static void addSuppressions(List<String> values, DetailAST targetAST) {
284        // get text range of target
285        final int firstLine = targetAST.getLineNo();
286        final int firstColumn = targetAST.getColumnNo();
287        final DetailAST nextAST = targetAST.getNextSibling();
288        final int lastLine;
289        final int lastColumn;
290        if (nextAST == null) {
291            lastLine = Integer.MAX_VALUE;
292            lastColumn = Integer.MAX_VALUE;
293        }
294        else {
295            lastLine = nextAST.getLineNo();
296            lastColumn = nextAST.getColumnNo();
297        }
298
299        final List<Entry> entries = ENTRIES.get();
300        for (String value : values) {
301            // strip off the checkstyle-only prefix if present
302            final String checkName = removeCheckstylePrefixIfExists(value);
303            entries.add(new Entry(checkName, firstLine, firstColumn,
304                    lastLine, lastColumn));
305        }
306    }
307
308    /**
309     * Method removes checkstyle prefix (checkstyle:) from check name if exists.
310     *
311     * @param checkName
312     *            - name of the check
313     * @return check name without prefix
314     */
315    private static String removeCheckstylePrefixIfExists(String checkName) {
316        String result = checkName;
317        if (checkName.startsWith(CHECKSTYLE_PREFIX)) {
318            result = checkName.substring(CHECKSTYLE_PREFIX.length());
319        }
320        return result;
321    }
322
323    /**
324     * Get all annotation values.
325     *
326     * @param ast annotation token
327     * @return list values
328     * @throws IllegalArgumentException if there is an unknown annotation value type.
329     */
330    private static List<String> getAllAnnotationValues(DetailAST ast) {
331        // get values of annotation
332        List<String> values = Collections.emptyList();
333        final DetailAST lparenAST = ast.findFirstToken(TokenTypes.LPAREN);
334        if (lparenAST != null) {
335            final DetailAST nextAST = lparenAST.getNextSibling();
336            final int nextType = nextAST.getType();
337            switch (nextType) {
338                case TokenTypes.EXPR:
339                case TokenTypes.ANNOTATION_ARRAY_INIT:
340                    values = getAnnotationValues(nextAST);
341                    break;
342
343                case TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR:
344                    // expected children: IDENT ASSIGN ( EXPR |
345                    // ANNOTATION_ARRAY_INIT )
346                    values = getAnnotationValues(getNthChild(nextAST, 2));
347                    break;
348
349                case TokenTypes.RPAREN:
350                    // no value present (not valid Java)
351                    break;
352
353                default:
354                    // unknown annotation value type (new syntax?)
355                    throw new IllegalArgumentException("Unexpected AST: " + nextAST);
356            }
357        }
358        return values;
359    }
360
361    /**
362     * Get target of annotation.
363     *
364     * @param ast the AST node to get the child of
365     * @return get target of annotation
366     * @throws IllegalArgumentException if there is an unexpected container type.
367     */
368    private static Optional<DetailAST> getAnnotationTarget(DetailAST ast) {
369        final Optional<DetailAST> result;
370        final DetailAST parentAST = ast.getParent();
371        switch (parentAST.getType()) {
372            case TokenTypes.MODIFIERS:
373            case TokenTypes.ANNOTATIONS:
374            case TokenTypes.ANNOTATION:
375            case TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR:
376                result = Optional.of(parentAST.getParent());
377                break;
378            case TokenTypes.LITERAL_DEFAULT:
379                result = Optional.empty();
380                break;
381            case TokenTypes.ANNOTATION_ARRAY_INIT:
382                result = getAnnotationTarget(parentAST);
383                break;
384            default:
385                // unexpected container type
386                throw new IllegalArgumentException("Unexpected container AST: " + parentAST);
387        }
388        return result;
389    }
390
391    /**
392     * Returns the n'th child of an AST node.
393     *
394     * @param ast the AST node to get the child of
395     * @param index the index of the child to get
396     * @return the n'th child of the given AST node, or {@code null} if none
397     */
398    private static DetailAST getNthChild(DetailAST ast, int index) {
399        DetailAST child = ast.getFirstChild();
400        for (int i = 0; i < index && child != null; ++i) {
401            child = child.getNextSibling();
402        }
403        return child;
404    }
405
406    /**
407     * Returns the Java identifier represented by an AST.
408     *
409     * @param ast an AST node for an IDENT or DOT
410     * @return the Java identifier represented by the given AST subtree
411     * @throws IllegalArgumentException if the AST is invalid
412     */
413    private static String getIdentifier(DetailAST ast) {
414        if (ast == null) {
415            throw new IllegalArgumentException("Identifier AST expected, but get null.");
416        }
417        final String identifier;
418        if (ast.getType() == TokenTypes.IDENT) {
419            identifier = ast.getText();
420        }
421        else {
422            identifier = getIdentifier(ast.getFirstChild()) + "."
423                + getIdentifier(ast.getLastChild());
424        }
425        return identifier;
426    }
427
428    /**
429     * Returns the literal string expression represented by an AST.
430     *
431     * @param ast an AST node for an EXPR
432     * @return the Java string represented by the given AST expression
433     *         or empty string if expression is too complex
434     * @throws IllegalArgumentException if the AST is invalid
435     */
436    private static String getStringExpr(DetailAST ast) {
437        final DetailAST firstChild = ast.getFirstChild();
438        String expr = "";
439
440        switch (firstChild.getType()) {
441            case TokenTypes.STRING_LITERAL:
442                // NOTE: escaped characters are not unescaped
443                final String quotedText = firstChild.getText();
444                expr = quotedText.substring(1, quotedText.length() - 1);
445                break;
446            case TokenTypes.IDENT:
447                expr = firstChild.getText();
448                break;
449            case TokenTypes.DOT:
450                expr = firstChild.getLastChild().getText();
451                break;
452            case TokenTypes.TEXT_BLOCK_LITERAL_BEGIN:
453                final String textBlockContent = firstChild.getFirstChild().getText();
454                expr = getContentWithoutPrecedingWhitespace(textBlockContent);
455                break;
456            default:
457                // annotations with complex expressions cannot suppress warnings
458        }
459        return expr;
460    }
461
462    /**
463     * Returns the annotation values represented by an AST.
464     *
465     * @param ast an AST node for an EXPR or ANNOTATION_ARRAY_INIT
466     * @return the list of Java string represented by the given AST for an
467     *         expression or annotation array initializer
468     * @throws IllegalArgumentException if the AST is invalid
469     */
470    private static List<String> getAnnotationValues(DetailAST ast) {
471        final List<String> annotationValues;
472        switch (ast.getType()) {
473            case TokenTypes.EXPR:
474                annotationValues = Collections.singletonList(getStringExpr(ast));
475                break;
476            case TokenTypes.ANNOTATION_ARRAY_INIT:
477                annotationValues = findAllExpressionsInChildren(ast);
478                break;
479            default:
480                throw new IllegalArgumentException(
481                        "Expression or annotation array initializer AST expected: " + ast);
482        }
483        return annotationValues;
484    }
485
486    /**
487     * Method looks at children and returns list of expressions in strings.
488     *
489     * @param parent ast, that contains children
490     * @return list of expressions in strings
491     */
492    private static List<String> findAllExpressionsInChildren(DetailAST parent) {
493        final List<String> valueList = new LinkedList<>();
494        DetailAST childAST = parent.getFirstChild();
495        while (childAST != null) {
496            if (childAST.getType() == TokenTypes.EXPR) {
497                valueList.add(getStringExpr(childAST));
498            }
499            childAST = childAST.getNextSibling();
500        }
501        return valueList;
502    }
503
504    /**
505     * Remove preceding newline and whitespace from the content of a text block.
506     *
507     * @param textBlockContent the actual text in a text block.
508     * @return content of text block with preceding whitespace and newline removed.
509     */
510    private static String getContentWithoutPrecedingWhitespace(String textBlockContent) {
511        final String contentWithNoPrecedingNewline =
512            NEWLINE.matcher(textBlockContent).replaceAll("");
513        return WHITESPACE.matcher(contentWithNoPrecedingNewline).replaceAll("");
514    }
515
516    @Override
517    public void destroy() {
518        super.destroy();
519        ENTRIES.remove();
520    }
521
522    /** Records a particular suppression for a region of a file. */
523    private static final class Entry {
524
525        /** The source name of the suppressed check. */
526        private final String checkName;
527        /** The suppression region for the check - first line. */
528        private final int firstLine;
529        /** The suppression region for the check - first column. */
530        private final int firstColumn;
531        /** The suppression region for the check - last line. */
532        private final int lastLine;
533        /** The suppression region for the check - last column. */
534        private final int lastColumn;
535
536        /**
537         * Constructs a new suppression region entry.
538         *
539         * @param checkName the source name of the suppressed check
540         * @param firstLine the first line of the suppression region
541         * @param firstColumn the first column of the suppression region
542         * @param lastLine the last line of the suppression region
543         * @param lastColumn the last column of the suppression region
544         */
545        private Entry(String checkName, int firstLine, int firstColumn,
546            int lastLine, int lastColumn) {
547            this.checkName = checkName;
548            this.firstLine = firstLine;
549            this.firstColumn = firstColumn;
550            this.lastLine = lastLine;
551            this.lastColumn = lastColumn;
552        }
553
554        /**
555         * Gets the source name of the suppressed check.
556         *
557         * @return the source name of the suppressed check
558         */
559        public String getCheckName() {
560            return checkName;
561        }
562
563        /**
564         * Gets the first line of the suppression region.
565         *
566         * @return the first line of the suppression region
567         */
568        public int getFirstLine() {
569            return firstLine;
570        }
571
572        /**
573         * Gets the first column of the suppression region.
574         *
575         * @return the first column of the suppression region
576         */
577        public int getFirstColumn() {
578            return firstColumn;
579        }
580
581        /**
582         * Gets the last line of the suppression region.
583         *
584         * @return the last line of the suppression region
585         */
586        public int getLastLine() {
587            return lastLine;
588        }
589
590        /**
591         * Gets the last column of the suppression region.
592         *
593         * @return the last column of the suppression region
594         */
595        public int getLastColumn() {
596            return lastColumn;
597        }
598
599    }
600
601}