001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2020 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 * Default value is {@code false}.
040 * </li>
041 * </ul>
042 * <p>
043 * To configure the default check:
044 * </p>
045 * <pre>
046 * &lt;module name="JavadocMissingWhitespaceAfterAsterisk"/&gt;
047 * </pre>
048 * <p>
049 * Code Example:
050 * </p>
051 * <pre>
052 * &#47;** This is valid single-line Javadoc. *&#47;
053 * class TestClass {
054 *   &#47;**
055 *     *This is invalid Javadoc.
056 *     *&#47;
057 *   int invalidJavaDoc;
058 *   &#47;**
059 *     * This is valid Javadoc.
060 *     *&#47;
061 *   void validJavaDocMethod() {
062 *   }
063 *   &#47;**This is invalid single-line Javadoc. *&#47;
064 *   void invalidSingleLineJavaDocMethod() {
065 *   }
066 *   &#47;** This is valid single-line Javadoc. *&#47;
067 *   void validSingleLineJavaDocMethod() {
068 *   }
069 * }
070 * </pre>
071 *
072 * @since 8.32
073 */
074@StatelessCheck
075public class JavadocMissingWhitespaceAfterAsteriskCheck extends AbstractJavadocCheck {
076
077    /**
078     * A key is pointing to the warning message text in "messages.properties" file.
079     */
080    public static final String MSG_KEY = "javadoc.missing.whitespace";
081
082    @Override
083    public int[] getDefaultJavadocTokens() {
084        return new int[] {
085            JavadocTokenTypes.JAVADOC,
086            JavadocTokenTypes.LEADING_ASTERISK,
087        };
088    }
089
090    @Override
091    public int[] getRequiredJavadocTokens() {
092        return getAcceptableJavadocTokens();
093    }
094
095    @Override
096    public void visitJavadocToken(DetailNode detailNode) {
097        final DetailNode textNode;
098
099        if (detailNode.getType() == JavadocTokenTypes.JAVADOC) {
100            textNode = JavadocUtil.getFirstChild(detailNode);
101        }
102        else {
103            textNode = JavadocUtil.getNextSibling(detailNode);
104        }
105
106        if (textNode != null && textNode.getType() != JavadocTokenTypes.EOF) {
107            final String text = textNode.getText();
108            final int lastAsteriskPosition = getLastLeadingAsteriskPosition(text);
109
110            if (!isLast(lastAsteriskPosition, text)
111                    && !Character.isWhitespace(text.charAt(lastAsteriskPosition + 1))) {
112                log(textNode.getLineNumber(), textNode.getColumnNumber(), MSG_KEY);
113            }
114        }
115    }
116
117    /**
118     * Checks if the character position is the last one of the string.
119     *
120     * @param position the position of the character
121     * @param text String literal.
122     * @return true if the character position is the last one of the string.
123     *
124     */
125    private static boolean isLast(int position, String text) {
126        return position == text.length() - 1;
127    }
128
129    /**
130     * Finds the position of the last leading asterisk in the string.
131     * If {@code text} contains no leading asterisk, -1 will be returned.
132     *
133     * @param text String literal.
134     * @return the index of the last leading asterisk.
135     *
136     */
137    private static int getLastLeadingAsteriskPosition(String text) {
138        int index = -1;
139
140        for (int i = 0; i < text.length(); i++) {
141            if (text.charAt(i) != '*') {
142                break;
143            }
144            index++;
145        }
146
147        return index;
148    }
149
150}