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