Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
TrailingCommentCheck |
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1 | //////////////////////////////////////////////////////////////////////////////// | |
2 | // checkstyle: Checks Java source code for adherence to a set of rules. | |
3 | // Copyright (C) 2001-2014 Oliver Burn | |
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 | package com.puppycrawl.tools.checkstyle.checks; | |
20 | ||
21 | import com.google.common.collect.Sets; | |
22 | import com.puppycrawl.tools.checkstyle.api.DetailAST; | |
23 | import com.puppycrawl.tools.checkstyle.api.TextBlock; | |
24 | import com.puppycrawl.tools.checkstyle.api.Utils; | |
25 | import java.util.List; | |
26 | import java.util.Map; | |
27 | import java.util.Set; | |
28 | import java.util.regex.Pattern; | |
29 | import java.util.regex.PatternSyntaxException; | |
30 | import org.apache.commons.beanutils.ConversionException; | |
31 | ||
32 | /** | |
33 | * <p> | |
34 | * The check to ensure that requires that comments be the only thing on a line. | |
35 | * For the case of // comments that means that the only thing that should | |
36 | * precede it is whitespace. | |
37 | * It doesn't check comments if they do not end line, i.e. it accept | |
38 | * the following: | |
39 | * <code>Thread.sleep( 10 <some comment here> );</code> | |
40 | * Format property is intended to deal with the "} // while" example. | |
41 | * </p> | |
42 | * <p> | |
43 | * Rationale: Steve McConnel in "Code Complete" suggests that endline | |
44 | * comments are a bad practice. An end line comment would | |
45 | * be one that is on the same line as actual code. For example: | |
46 | * <pre> | |
47 | * a = b + c; // Some insightful comment | |
48 | * d = e / f; // Another comment for this line | |
49 | * </pre> | |
50 | * Quoting "Code Complete" for the justification: | |
51 | * <ul> | |
52 | * <li> | |
53 | * "The comments have to be aligned so that they do not | |
54 | * interfere with the visual structure of the code. If you don't | |
55 | * align them neatly, they'll make your listing look like it's been | |
56 | * through a washing machine." | |
57 | * </li> | |
58 | * <li> | |
59 | * "Endline comments tend to be hard to format...It takes time | |
60 | * to align them. Such time is not spent learning more about | |
61 | * the code; it's dedicated solely to the tedious task of | |
62 | * pressing the spacebar or tab key." | |
63 | * </li> | |
64 | * <li> | |
65 | * "Endline comments are also hard to maintain. If the code on | |
66 | * any line containing an endline comment grows, it bumps the | |
67 | * comment farther out, and all the other endline comments will | |
68 | * have to bumped out to match. Styles that are hard to | |
69 | * maintain aren't maintained...." | |
70 | * </li> | |
71 | * <li> | |
72 | * "Endline comments also tend to be cryptic. The right side of | |
73 | * the line doesn't offer much room and the desire to keep the | |
74 | * comment on one line means the comment must be short. | |
75 | * Work then goes into making the line as short as possible | |
76 | * instead of as clear as possible. The comment usually ends | |
77 | * up as cryptic as possible...." | |
78 | * </li> | |
79 | * <li> | |
80 | * "A systemic problem with endline comments is that it's hard | |
81 | * to write a meaningful comment for one line of code. Most | |
82 | * endline comments just repeat the line of code, which hurts | |
83 | * more than it helps." | |
84 | * </li> | |
85 | * </ul> | |
86 | * His comments on being hard to maintain when the size of | |
87 | * the line changes are even more important in the age of | |
88 | * automated refactorings. | |
89 | * </p> | |
90 | * <p> | |
91 | * To configure the check so it enforces only comment on a line: | |
92 | * <pre> | |
93 | * <module name="TrailingComment"> | |
94 | * <property name="format" value="^\\s*$"/> | |
95 | * </module> | |
96 | * </pre> | |
97 | * </p> | |
98 | * @author o_sukhodolsky | |
99 | */ | |
100 | public class TrailingCommentCheck extends AbstractFormatCheck | |
101 | { | |
102 | /** default format for allowed blank line. */ | |
103 | private static final String DEFAULT_FORMAT = "^[\\s\\}\\);]*$"; | |
104 | ||
105 | /** pattern for legal trailing comment. */ | |
106 | private Pattern mLegalComment; | |
107 | ||
108 | /** | |
109 | * Sets patter for legal trailing comments. | |
110 | * @param aFormat format to set. | |
111 | * @throws ConversionException unable to parse a given format. | |
112 | */ | |
113 | public void setLegalComment(final String aFormat) | |
114 | throws ConversionException | |
115 | { | |
116 | try { | |
117 | 1 | mLegalComment = Utils.getPattern(aFormat); |
118 | } | |
119 | 0 | catch (final PatternSyntaxException e) { |
120 | 0 | throw new ConversionException("unable to parse " + aFormat, e); |
121 | 1 | } |
122 | 1 | } |
123 | /** | |
124 | * Creates new instance of the check. | |
125 | * @throws ConversionException unable to parse DEFAULT_FORMAT. | |
126 | */ | |
127 | public TrailingCommentCheck() throws ConversionException | |
128 | { | |
129 | 2 | super(DEFAULT_FORMAT); |
130 | 2 | } |
131 | ||
132 | @Override | |
133 | public int[] getDefaultTokens() | |
134 | { | |
135 | 2 | return new int[0]; |
136 | } | |
137 | ||
138 | @Override | |
139 | public void visitToken(DetailAST aAST) | |
140 | { | |
141 | 0 | throw new IllegalStateException("visitToken() shouldn't be called."); |
142 | } | |
143 | ||
144 | @Override | |
145 | public void beginTree(DetailAST aRootAST) | |
146 | { | |
147 | 2 | final Pattern blankLinePattern = getRegexp(); |
148 | 2 | final Map<Integer, TextBlock> cppComments = getFileContents() |
149 | .getCppComments(); | |
150 | 2 | final Map<Integer, List<TextBlock>> cComments = getFileContents() |
151 | .getCComments(); | |
152 | 2 | final Set<Integer> lines = Sets.newHashSet(); |
153 | 2 | lines.addAll(cppComments.keySet()); |
154 | 2 | lines.addAll(cComments.keySet()); |
155 | ||
156 | 2 | for (Integer lineNo : lines) { |
157 | 30 | final String line = getLines()[lineNo.intValue() - 1]; |
158 | 30 | String lineBefore = ""; |
159 | 30 | TextBlock comment = null; |
160 | 30 | if (cppComments.containsKey(lineNo)) { |
161 | 10 | comment = cppComments.get(lineNo); |
162 | 10 | lineBefore = line.substring(0, comment.getStartColNo()); |
163 | } | |
164 | 20 | else if (cComments.containsKey(lineNo)) { |
165 | 20 | final List<TextBlock> commentList = cComments.get(lineNo); |
166 | 20 | comment = commentList.get(commentList.size() - 1); |
167 | 20 | lineBefore = line.substring(0, comment.getStartColNo()); |
168 | 20 | if (comment.getText().length == 1) { |
169 | 14 | final String lineAfter = |
170 | line.substring(comment.getEndColNo() + 1).trim(); | |
171 | 14 | if (!"".equals(lineAfter)) { |
172 | // do not check comment which doesn't end line | |
173 | 6 | continue; |
174 | } | |
175 | } | |
176 | } | |
177 | 24 | if ((comment != null) |
178 | && !blankLinePattern.matcher(lineBefore).find() | |
179 | && !isLegalComment(comment)) | |
180 | { | |
181 | 11 | log(lineNo.intValue(), "trailing.comments"); |
182 | } | |
183 | 24 | } |
184 | 2 | } |
185 | ||
186 | /** | |
187 | * Checks if given comment is legal (single-line and matches to the | |
188 | * pattern). | |
189 | * @param aComment comment to check. | |
190 | * @return true if the comment if legal. | |
191 | */ | |
192 | private boolean isLegalComment(final TextBlock aComment) | |
193 | { | |
194 | 12 | if (mLegalComment == null) { |
195 | 6 | return false; |
196 | } | |
197 | // multi-line comment can not be legal | |
198 | 6 | if (aComment.getStartLineNo() != aComment.getEndLineNo()) { |
199 | 1 | return false; |
200 | } | |
201 | 5 | String commentText = aComment.getText()[0]; |
202 | // remove chars which start comment | |
203 | 5 | commentText = commentText.substring(2); |
204 | // if this is a C-style comment we need to remove its end | |
205 | 5 | if (commentText.endsWith("*/")) { |
206 | 2 | commentText = commentText.substring(0, commentText.length() - 2); |
207 | } | |
208 | 5 | commentText = commentText.trim(); |
209 | 5 | return mLegalComment.matcher(commentText).find(); |
210 | } | |
211 | } |