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1   /*
2    * Copyright (c) 2011-2024 Qulice.com
3    *
4    * All rights reserved.
5    *
6    * Redistribution and use in source and binary forms, with or without
7    * modification, are permitted provided that the following conditions
8    * are met: 1) Redistributions of source code must retain the above
9    * copyright notice, this list of conditions and the following
10   * disclaimer. 2) Redistributions in binary form must reproduce the above
11   * copyright notice, this list of conditions and the following
12   * disclaimer in the documentation and/or other materials provided
13   * with the distribution. 3) Neither the name of the Qulice.com nor
14   * the names of its contributors may be used to endorse or promote
15   * products derived from this software without specific prior written
16   * permission.
17   *
18   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT
20   * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
21   * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
22   * THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
23   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
24   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
27   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
29   * OF THE POSSIBILITY OF SUCH DAMAGE.
30   */
31  package com.qulice.checkstyle;
32  
33  import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
34  import com.puppycrawl.tools.checkstyle.api.DetailAST;
35  import com.puppycrawl.tools.checkstyle.api.TokenTypes;
36  
37  /**
38   * Check for empty line at the beginning and at the end of Javadoc.
39   *
40   * <p>You can't have empty line at the beginning or at the end of Javadoc.
41   *
42   * <p>The following red lines in class Javadoc will be reported as violations.
43   * <pre>
44   * &#47;**
45   *  <span style="color:red" >*</span>
46   *  * This is my class.
47   *  <span style="color:red" >*</span>
48   *  *&#47;
49   * public final class Foo {
50   *     // ...
51   * </pre>
52   *
53   * @since 0.17
54   */
55  public final class JavadocEmptyLineCheck extends AbstractCheck {
56  
57      @Override
58      public int[] getDefaultTokens() {
59          return new int[] {
60              TokenTypes.PACKAGE_DEF,
61              TokenTypes.CLASS_DEF,
62              TokenTypes.INTERFACE_DEF,
63              TokenTypes.ANNOTATION_DEF,
64              TokenTypes.ANNOTATION_FIELD_DEF,
65              TokenTypes.ENUM_DEF,
66              TokenTypes.ENUM_CONSTANT_DEF,
67              TokenTypes.VARIABLE_DEF,
68              TokenTypes.CTOR_DEF,
69              TokenTypes.METHOD_DEF,
70          };
71      }
72  
73      @Override
74      public int[] getAcceptableTokens() {
75          return this.getDefaultTokens();
76      }
77  
78      @Override
79      public int[] getRequiredTokens() {
80          return this.getDefaultTokens();
81      }
82  
83      @Override
84      public void visitToken(final DetailAST ast) {
85          final String[] lines = this.getLines();
86          final int current = ast.getLineNo();
87          final int start =
88              JavadocEmptyLineCheck.findCommentStart(lines, current) + 1;
89          if (JavadocEmptyLineCheck.isNodeHavingJavadoc(ast, start)) {
90              if (JavadocEmptyLineCheck.isJavadocLineEmpty(lines[start])) {
91                  this.log(start + 1, "Empty Javadoc line at the beginning");
92              }
93              final int end =
94                  JavadocEmptyLineCheck.findCommentEnd(lines, current) - 1;
95              if (JavadocEmptyLineCheck.isJavadocLineEmpty(lines[end])) {
96                  this.log(end + 1, "Empty Javadoc line at the end");
97              }
98          }
99      }
100 
101     /**
102      * Check if Javadoc line is empty.
103      * @param line Javadoc line
104      * @return True when Javadoc line is empty
105      */
106     private static boolean isJavadocLineEmpty(final String line) {
107         return "*".equals(line.trim());
108     }
109 
110     /**
111      * Check if node has Javadoc.
112      * @param node Node to be checked for Javadoc.
113      * @param start Line number where comment starts.
114      * @return True when node has Javadoc
115      */
116     private static boolean isNodeHavingJavadoc(final DetailAST node,
117         final int start) {
118         return start > getLineNoOfPreviousNode(node);
119     }
120 
121     /**
122      * Returns line number of previous node.
123      * @param node Current node.
124      * @return Line number of previous node
125      */
126     private static int getLineNoOfPreviousNode(final DetailAST node) {
127         int start = 0;
128         final DetailAST previous = node.getPreviousSibling();
129         if (previous != null) {
130             start = previous.getLineNo();
131         }
132         return start;
133     }
134 
135     /**
136      * Find Javadoc starting comment.
137      * @param lines List of lines to check.
138      * @param start Start searching from this line number.
139      * @return Line number with found starting comment or -1 otherwise.
140      */
141     private static int findCommentStart(final String[] lines, final int start) {
142         return JavadocEmptyLineCheck.findTrimmedTextUp(lines, start, "/**");
143     }
144 
145     /**
146      * Find Javadoc ending comment.
147      * @param lines Array of lines to check.
148      * @param start Start searching from this line number.
149      * @return Line number with found ending comment, or -1 if it wasn't found.
150      */
151     private static int findCommentEnd(final String[] lines, final int start) {
152         return JavadocEmptyLineCheck.findTrimmedTextUp(lines, start, "*/");
153     }
154 
155     /**
156      * Find a text in lines, by going up.
157      * @param lines Array of lines to check.
158      * @param start Start searching from this line number.
159      * @param text Text to find.
160      * @return Line number with found text, or -1 if it wasn't found.
161      */
162     private static int findTrimmedTextUp(final String[] lines,
163         final int start, final String text) {
164         int found = -1;
165         for (int pos = start - 1; pos >= 0; pos -= 1) {
166             if (lines[pos].trim().equals(text)) {
167                 found = pos;
168                 break;
169             }
170         }
171         return found;
172     }
173 }