001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2021 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 com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.DetailNode;
024import com.puppycrawl.tools.checkstyle.api.JavadocTokenTypes;
025import com.puppycrawl.tools.checkstyle.utils.JavadocUtil;
026
027/**
028 * <p>
029 * Checks that there is at least one whitespace after the leading asterisk.
030 * Although spaces after asterisks are optional in the Javadoc comments, their absence
031 * makes the documentation difficult to read. It is the de facto standard to put at least
032 * one whitespace after the leading asterisk.
033 * </p>
034 * <ul>
035 * <li>
036 * Property {@code violateExecutionOnNonTightHtml} - Control when to print violations
037 * if the Javadoc being examined by this check violates the tight html rules defined at
038 * <a href="https://checkstyle.org/writingjavadocchecks.html#Tight-HTML_rules">Tight-HTML Rules</a>.
039 * Type is {@code boolean}.
040 * Default value is {@code false}.
041 * </li>
042 * </ul>
043 * <p>
044 * To configure the default check:
045 * </p>
046 * <pre>
047 * &lt;module name="JavadocMissingWhitespaceAfterAsterisk"/&gt;
048 * </pre>
049 * <p>
050 * Code Example:
051 * </p>
052 * <pre>
053 * &#47;** This is valid single-line Javadoc. *&#47;
054 * class TestClass {
055 *   &#47;**
056 *     *This is invalid Javadoc.
057 *     *&#47;
058 *   int invalidJavaDoc;
059 *   &#47;**
060 *     * This is valid Javadoc.
061 *     *&#47;
062 *   void validJavaDocMethod() {
063 *   }
064 *   &#47;**This is invalid single-line Javadoc. *&#47;
065 *   void invalidSingleLineJavaDocMethod() {
066 *   }
067 *   &#47;** This is valid single-line Javadoc. *&#47;
068 *   void validSingleLineJavaDocMethod() {
069 *   }
070 * }
071 * </pre>
072 * <p>
073 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
074 * </p>
075 * <p>
076 * Violation Message Keys:
077 * </p>
078 * <ul>
079 * <li>
080 * {@code javadoc.missed.html.close}
081 * </li>
082 * <li>
083 * {@code javadoc.missing.whitespace}
084 * </li>
085 * <li>
086 * {@code javadoc.parse.rule.error}
087 * </li>
088 * <li>
089 * {@code javadoc.wrong.singleton.html.tag}
090 * </li>
091 * </ul>
092 *
093 * @since 8.32
094 */
095@StatelessCheck
096public class JavadocMissingWhitespaceAfterAsteriskCheck extends AbstractJavadocCheck {
097
098    /**
099     * A key is pointing to the warning message text in "messages.properties" file.
100     */
101    public static final String MSG_KEY = "javadoc.missing.whitespace";
102
103    @Override
104    public int[] getDefaultJavadocTokens() {
105        return new int[] {
106            JavadocTokenTypes.JAVADOC,
107            JavadocTokenTypes.LEADING_ASTERISK,
108        };
109    }
110
111    @Override
112    public int[] getRequiredJavadocTokens() {
113        return getAcceptableJavadocTokens();
114    }
115
116    @Override
117    public void visitJavadocToken(DetailNode detailNode) {
118        final DetailNode textNode;
119
120        if (detailNode.getType() == JavadocTokenTypes.JAVADOC) {
121            textNode = JavadocUtil.getFirstChild(detailNode);
122        }
123        else {
124            textNode = JavadocUtil.getNextSibling(detailNode);
125        }
126
127        if (textNode != null && textNode.getType() != JavadocTokenTypes.EOF) {
128            final String text = textNode.getText();
129            final int lastAsteriskPosition = getLastLeadingAsteriskPosition(text);
130
131            if (!isLast(lastAsteriskPosition, text)
132                    && !Character.isWhitespace(text.charAt(lastAsteriskPosition + 1))) {
133                log(textNode.getLineNumber(), textNode.getColumnNumber(), MSG_KEY);
134            }
135        }
136    }
137
138    /**
139     * Checks if the character position is the last one of the string.
140     *
141     * @param position the position of the character
142     * @param text String literal.
143     * @return true if the character position is the last one of the string.
144     *
145     */
146    private static boolean isLast(int position, String text) {
147        return position == text.length() - 1;
148    }
149
150    /**
151     * Finds the position of the last leading asterisk in the string.
152     * If {@code text} contains no leading asterisk, -1 will be returned.
153     *
154     * @param text String literal.
155     * @return the index of the last leading asterisk.
156     *
157     */
158    private static int getLastLeadingAsteriskPosition(String text) {
159        int index = -1;
160
161        for (int i = 0; i < text.length(); i++) {
162            if (text.charAt(i) != '*') {
163                break;
164            }
165            index++;
166        }
167
168        return index;
169    }
170
171}