Source code

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.javadoc;
021
022import java.util.Locale;
023
024import com.puppycrawl.tools.checkstyle.StatelessCheck;
025import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
026import com.puppycrawl.tools.checkstyle.api.DetailAST;
027import com.puppycrawl.tools.checkstyle.api.TokenTypes;
028import com.puppycrawl.tools.checkstyle.utils.JavadocUtil;
029import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
030
031/**
032 * <div>
033 * Checks that the Javadoc content begins from the same position
034 * for all Javadoc comments in the project. Any leading asterisks and spaces
035 * are not counted as the beginning of the content and are therefore ignored.
036 * </div>
037 *
038 * <p>
039 * It is possible to enforce two different styles:
040 * </p>
041 * <ul>
042 * <li>
043 * {@code first_line} - Javadoc content starts from the first line:
044 * <pre>
045 * &#47;** Summary text.
046 *   * More details.
047 *   *&#47;
048 * public void method();
049 * </pre>
050 * </li>
051 * <li>
052 * {@code second_line} - Javadoc content starts from the second line:
053 * <pre>
054 * &#47;**
055 *   * Summary text.
056 *   * More details.
057 *   *&#47;
058 * public void method();
059 * </pre>
060 * </li>
061 * </ul>
062 *
063 * <p>
064 * This check does not validate the Javadoc summary itself nor its presence.
065 * The check will not report any violations for missing or malformed javadoc summary.
066 * To validate the Javadoc summary use
067 * <a href="https://checkstyle.org/checks/javadoc/summaryjavadoc.html#SummaryJavadoc">
068 * SummaryJavadoc</a> check.
069 * </p>
070 *
071 * <p>
072 * The <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html">
073 * Documentation Comment Specification</a> permits leading asterisks on the first line.
074 * For these Javadoc comments:
075 * </p>
076 * <pre>
077 * &#47;***
078 *   * Some text.
079 *   *&#47;
080 * &#47;************
081 *   * Some text.
082 *   *&#47;
083 * &#47;**           **
084 *   * Some text.
085 *   *&#47;
086 * </pre>
087 *
088 * <p>
089 * The documentation generated will be just "Some text." without any asterisks.
090 * Since these asterisks will not appear in the generated documentation,
091 * they should not be considered as the beginning of the Javadoc content.
092 * In such cases, the check assumes that the Javadoc content begins on the second line.
093 * </p>
094 * <ul>
095 * <li>
096 * Property {@code location} - Specify the policy on placement of the Javadoc content.
097 * Type is {@code com.puppycrawl.tools.checkstyle.checks.javadoc.JavadocContentLocationOption}.
098 * Default value is {@code second_line}.
099 * </li>
100 * </ul>
101 *
102 * <p>
103 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
104 * </p>
105 *
106 * <p>
107 * Violation Message Keys:
108 * </p>
109 * <ul>
110 * <li>
111 * {@code javadoc.content.first.line}
112 * </li>
113 * <li>
114 * {@code javadoc.content.second.line}
115 * </li>
116 * </ul>
117 *
118 * @since 8.27
119 */
120@StatelessCheck
121public class JavadocContentLocationCheck extends AbstractCheck {
122
123    /**
124     * A key is pointing to the warning message text in "messages.properties" file.
125     */
126    public static final String MSG_JAVADOC_CONTENT_FIRST_LINE = "javadoc.content.first.line";
127
128    /**
129     * A key is pointing to the warning message text in "messages.properties" file.
130     */
131    public static final String MSG_JAVADOC_CONTENT_SECOND_LINE = "javadoc.content.second.line";
132
133    /**
134     * Specify the policy on placement of the Javadoc content.
135     */
136    private JavadocContentLocationOption location = JavadocContentLocationOption.SECOND_LINE;
137
138    @Override
139    public int[] getRequiredTokens() {
140        return new int[] {
141            TokenTypes.BLOCK_COMMENT_BEGIN,
142        };
143    }
144
145    @Override
146    public int[] getAcceptableTokens() {
147        return getRequiredTokens();
148    }
149
150    @Override
151    public int[] getDefaultTokens() {
152        return getRequiredTokens();
153    }
154
155    @Override
156    public boolean isCommentNodesRequired() {
157        return true;
158    }
159
160    /**
161     * Setter to specify the policy on placement of the Javadoc content.
162     *
163     * @param value string to decode location from
164     * @throws IllegalArgumentException if unable to decode
165     * @since 8.27
166     */
167    public void setLocation(String value) {
168        location = JavadocContentLocationOption.valueOf(value.trim().toUpperCase(Locale.ENGLISH));
169    }
170
171    @Override
172    public void visitToken(DetailAST ast) {
173        if (isMultilineComment(ast) && JavadocUtil.isJavadocComment(ast)) {
174            final String commentContent = JavadocUtil.getJavadocCommentContent(ast);
175            final int indexOfFirstNonBlankLine = findIndexOfFirstNonBlankLine(commentContent);
176            if (indexOfFirstNonBlankLine >= 0) {
177                if (location == JavadocContentLocationOption.FIRST_LINE
178                        && indexOfFirstNonBlankLine != 0) {
179                    log(ast, MSG_JAVADOC_CONTENT_FIRST_LINE);
180                }
181                else if (location == JavadocContentLocationOption.SECOND_LINE
182                        && indexOfFirstNonBlankLine != 1) {
183                    log(ast, MSG_JAVADOC_CONTENT_SECOND_LINE);
184                }
185            }
186        }
187    }
188
189    /**
190     * Checks if a DetailAST of type {@code TokenTypes.BLOCK_COMMENT_BEGIN} span
191     * more than one line. The node always has at least one child of the type
192     * {@code TokenTypes.BLOCK_COMMENT_END}.
193     *
194     * @param node node to check
195     * @return {@code true} for multi-line comment nodes
196     */
197    private static boolean isMultilineComment(DetailAST node) {
198        return !TokenUtil.areOnSameLine(node, node.getLastChild());
199    }
200
201    /**
202     * Returns the index of the first non-blank line.
203     * All lines consists only of asterisks and whitespaces are treated as blank.
204     *
205     * @param commentContent Javadoc content to process
206     * @return the index of the first non-blank line or {@code -1} if all lines are blank
207     */
208    private static int findIndexOfFirstNonBlankLine(String commentContent) {
209        int lineNo = 0;
210        boolean noContent = true;
211        for (int i = 0; i < commentContent.length(); ++i) {
212            final char character = commentContent.charAt(i);
213            if (character == '\n') {
214                ++lineNo;
215            }
216            else if (character != '*' && !Character.isWhitespace(character)) {
217                noContent = false;
218                break;
219            }
220        }
221        if (noContent) {
222            lineNo = -1;
223        }
224        return lineNo;
225    }
226
227}