001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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.annotation;
021
022import java.util.regex.Matcher;
023import java.util.regex.Pattern;
024
025import com.puppycrawl.tools.checkstyle.StatelessCheck;
026import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
027import com.puppycrawl.tools.checkstyle.api.DetailAST;
028import com.puppycrawl.tools.checkstyle.api.TokenTypes;
029import com.puppycrawl.tools.checkstyle.utils.AnnotationUtility;
030import com.puppycrawl.tools.checkstyle.utils.CommonUtils;
031
032/**
033 * <p>
034 * This check allows you to specify what warnings that
035 * {@link SuppressWarnings SuppressWarnings} is not
036 * allowed to suppress.  You can also specify a list
037 * of TokenTypes that the configured warning(s) cannot
038 * be suppressed on.
039 * </p>
040 *
041 * <p>
042 * The {@link #setFormat warnings} property is a
043 * regex pattern.  Any warning being suppressed matching
044 * this pattern will be flagged.
045 * </p>
046 *
047 * <p>
048 * By default, any warning specified will be disallowed on
049 * all legal TokenTypes unless otherwise specified via
050 * the
051 * {@link AbstractCheck#setTokens(String[]) tokens}
052 * property.
053 *
054 * Also, by default warnings that are empty strings or all
055 * whitespace (regex: ^$|^\s+$) are flagged.  By specifying,
056 * the format property these defaults no longer apply.
057 * </p>
058 *
059 * <p>Limitations:  This check does not consider conditionals
060 * inside the SuppressWarnings annotation. <br>
061 * For example:
062 * {@code @SuppressWarnings((false) ? (true) ? "unchecked" : "foo" : "unused")}.
063 * According to the above example, the "unused" warning is being suppressed
064 * not the "unchecked" or "foo" warnings.  All of these warnings will be
065 * considered and matched against regardless of what the conditional
066 * evaluates to.
067 * <br>
068 * The check also does not support code like {@code @SuppressWarnings("un" + "used")},
069 * {@code @SuppressWarnings((String) "unused")} or
070 * {@code @SuppressWarnings({('u' + (char)'n') + (""+("used" + (String)"")),})}.
071 * </p>
072 *
073 * <p>This check can be configured so that the "unchecked"
074 * and "unused" warnings cannot be suppressed on
075 * anything but variable and parameter declarations.
076 * See below of an example.
077 * </p>
078 *
079 * <pre>
080 * &lt;module name=&quot;SuppressWarnings&quot;&gt;
081 *    &lt;property name=&quot;format&quot;
082 *        value=&quot;^unchecked$|^unused$&quot;/&gt;
083 *    &lt;property name=&quot;tokens&quot;
084 *        value=&quot;
085 *        CLASS_DEF,INTERFACE_DEF,ENUM_DEF,
086 *        ANNOTATION_DEF,ANNOTATION_FIELD_DEF,
087 *        ENUM_CONSTANT_DEF,METHOD_DEF,CTOR_DEF
088 *        &quot;/&gt;
089 * &lt;/module&gt;
090 * </pre>
091 * @author Travis Schneeberger
092 */
093@StatelessCheck
094public class SuppressWarningsCheck extends AbstractCheck {
095    /**
096     * A key is pointing to the warning message text in "messages.properties"
097     * file.
098     */
099    public static final String MSG_KEY_SUPPRESSED_WARNING_NOT_ALLOWED =
100        "suppressed.warning.not.allowed";
101
102    /** {@link SuppressWarnings SuppressWarnings} annotation name. */
103    private static final String SUPPRESS_WARNINGS = "SuppressWarnings";
104
105    /**
106     * Fully-qualified {@link SuppressWarnings SuppressWarnings}
107     * annotation name.
108     */
109    private static final String FQ_SUPPRESS_WARNINGS =
110        "java.lang." + SUPPRESS_WARNINGS;
111
112    /** The regexp to match against. */
113    private Pattern format = Pattern.compile("^$|^\\s+$");
114
115    /**
116     * Set the format for the specified regular expression.
117     * @param pattern the new pattern
118     */
119    public final void setFormat(Pattern pattern) {
120        format = pattern;
121    }
122
123    @Override
124    public final int[] getDefaultTokens() {
125        return getAcceptableTokens();
126    }
127
128    @Override
129    public final int[] getAcceptableTokens() {
130        return new int[] {
131            TokenTypes.CLASS_DEF,
132            TokenTypes.INTERFACE_DEF,
133            TokenTypes.ENUM_DEF,
134            TokenTypes.ANNOTATION_DEF,
135            TokenTypes.ANNOTATION_FIELD_DEF,
136            TokenTypes.ENUM_CONSTANT_DEF,
137            TokenTypes.PARAMETER_DEF,
138            TokenTypes.VARIABLE_DEF,
139            TokenTypes.METHOD_DEF,
140            TokenTypes.CTOR_DEF,
141        };
142    }
143
144    @Override
145    public int[] getRequiredTokens() {
146        return CommonUtils.EMPTY_INT_ARRAY;
147    }
148
149    @Override
150    public void visitToken(final DetailAST ast) {
151        final DetailAST annotation = getSuppressWarnings(ast);
152
153        if (annotation != null) {
154            final DetailAST warningHolder =
155                findWarningsHolder(annotation);
156
157            final DetailAST token =
158                    warningHolder.findFirstToken(TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR);
159            DetailAST warning;
160
161            if (token == null) {
162                warning = warningHolder.findFirstToken(TokenTypes.EXPR);
163            }
164            else {
165                // case like '@SuppressWarnings(value = UNUSED)'
166                warning = token.findFirstToken(TokenTypes.EXPR);
167            }
168
169            //rare case with empty array ex: @SuppressWarnings({})
170            if (warning == null) {
171                //check to see if empty warnings are forbidden -- are by default
172                logMatch(warningHolder.getLineNo(),
173                    warningHolder.getColumnNo(), "");
174            }
175            else {
176                while (warning != null) {
177                    if (warning.getType() == TokenTypes.EXPR) {
178                        final DetailAST fChild = warning.getFirstChild();
179                        switch (fChild.getType()) {
180                            //typical case
181                            case TokenTypes.STRING_LITERAL:
182                                final String warningText =
183                                    removeQuotes(warning.getFirstChild().getText());
184                                logMatch(warning.getLineNo(),
185                                        warning.getColumnNo(), warningText);
186                                break;
187                            // conditional case
188                            // ex:
189                            // @SuppressWarnings((false) ? (true) ? "unchecked" : "foo" : "unused")
190                            case TokenTypes.QUESTION:
191                                walkConditional(fChild);
192                                break;
193                            // param in constant case
194                            // ex: public static final String UNCHECKED = "unchecked";
195                            // @SuppressWarnings(UNCHECKED)
196                            // or
197                            // @SuppressWarnings(SomeClass.UNCHECKED)
198                            case TokenTypes.IDENT:
199                            case TokenTypes.DOT:
200                                break;
201                            default:
202                                // Known limitation: cases like @SuppressWarnings("un" + "used") or
203                                // @SuppressWarnings((String) "unused") are not properly supported,
204                                // but they should not cause exceptions.
205                        }
206                    }
207                    warning = warning.getNextSibling();
208                }
209            }
210        }
211    }
212
213    /**
214     * Gets the {@link SuppressWarnings SuppressWarnings} annotation
215     * that is annotating the AST.  If the annotation does not exist
216     * this method will return {@code null}.
217     *
218     * @param ast the AST
219     * @return the {@link SuppressWarnings SuppressWarnings} annotation
220     */
221    private static DetailAST getSuppressWarnings(DetailAST ast) {
222        DetailAST annotation = AnnotationUtility.getAnnotation(ast, SUPPRESS_WARNINGS);
223
224        if (annotation == null) {
225            annotation = AnnotationUtility.getAnnotation(ast, FQ_SUPPRESS_WARNINGS);
226        }
227        return annotation;
228    }
229
230    /**
231     * This method looks for a warning that matches a configured expression.
232     * If found it logs a violation at the given line and column number.
233     *
234     * @param lineNo the line number
235     * @param colNum the column number
236     * @param warningText the warning.
237     */
238    private void logMatch(final int lineNo,
239        final int colNum, final String warningText) {
240        final Matcher matcher = format.matcher(warningText);
241        if (matcher.matches()) {
242            log(lineNo, colNum,
243                    MSG_KEY_SUPPRESSED_WARNING_NOT_ALLOWED, warningText);
244        }
245    }
246
247    /**
248     * Find the parent (holder) of the of the warnings (Expr).
249     *
250     * @param annotation the annotation
251     * @return a Token representing the expr.
252     */
253    private static DetailAST findWarningsHolder(final DetailAST annotation) {
254        final DetailAST annValuePair =
255            annotation.findFirstToken(TokenTypes.ANNOTATION_MEMBER_VALUE_PAIR);
256        final DetailAST annArrayInit;
257
258        if (annValuePair == null) {
259            annArrayInit =
260                    annotation.findFirstToken(TokenTypes.ANNOTATION_ARRAY_INIT);
261        }
262        else {
263            annArrayInit =
264                    annValuePair.findFirstToken(TokenTypes.ANNOTATION_ARRAY_INIT);
265        }
266
267        DetailAST warningsHolder = annotation;
268        if (annArrayInit != null) {
269            warningsHolder = annArrayInit;
270        }
271
272        return warningsHolder;
273    }
274
275    /**
276     * Strips a single double quote from the front and back of a string.
277     *
278     * <p>For example:
279     * <br/>
280     * Input String = "unchecked"
281     * <br/>
282     * Output String = unchecked
283     *
284     * @param warning the warning string
285     * @return the string without two quotes
286     */
287    private static String removeQuotes(final String warning) {
288        return warning.substring(1, warning.length() - 1);
289    }
290
291    /**
292     * Recursively walks a conditional expression checking the left
293     * and right sides, checking for matches and
294     * logging violations.
295     *
296     * @param cond a Conditional type
297     * {@link TokenTypes#QUESTION QUESTION}
298     */
299    private void walkConditional(final DetailAST cond) {
300        if (cond.getType() == TokenTypes.QUESTION) {
301            walkConditional(getCondLeft(cond));
302            walkConditional(getCondRight(cond));
303        }
304        else {
305            final String warningText =
306                    removeQuotes(cond.getText());
307            logMatch(cond.getLineNo(), cond.getColumnNo(), warningText);
308        }
309    }
310
311    /**
312     * Retrieves the left side of a conditional.
313     *
314     * @param cond cond a conditional type
315     * {@link TokenTypes#QUESTION QUESTION}
316     * @return either the value
317     *     or another conditional
318     */
319    private static DetailAST getCondLeft(final DetailAST cond) {
320        final DetailAST colon = cond.findFirstToken(TokenTypes.COLON);
321        return colon.getPreviousSibling();
322    }
323
324    /**
325     * Retrieves the right side of a conditional.
326     *
327     * @param cond a conditional type
328     * {@link TokenTypes#QUESTION QUESTION}
329     * @return either the value
330     *     or another conditional
331     */
332    private static DetailAST getCondRight(final DetailAST cond) {
333        final DetailAST colon = cond.findFirstToken(TokenTypes.COLON);
334        return colon.getNextSibling();
335    }
336}