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 java.util.Arrays;
023import java.util.Set;
024import java.util.regex.Matcher;
025import java.util.regex.Pattern;
026import java.util.stream.Collectors;
027
028import com.puppycrawl.tools.checkstyle.StatelessCheck;
029import com.puppycrawl.tools.checkstyle.api.DetailNode;
030import com.puppycrawl.tools.checkstyle.api.JavadocTokenTypes;
031
032/**
033 * <p>
034 * Checks that a
035 * <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
036 * javadoc block tag</a> appears only at the beginning of a line, ignoring
037 * leading asterisks and white space. A block tag is a token that starts with
038 * {@code @} symbol and is preceded by a whitespace. This check ignores block
039 * tags in comments and inside inline tags {&#64;code } and {&#64;literal }.
040 * </p>
041 * <p>
042 * Rationale: according to
043 * <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
044 * the specification</a> all javadoc block tags should be placed at the beginning
045 * of a line. Tags that are not placed at the beginning are treated as plain text.
046 * To recognize intentional tag placement to text area it is better to escape the
047 * {@code @} symbol, and all non-escaped tags should be located at the beginning
048 * of the line. See NOTE section for details on how to escape.
049 * </p>
050 * <p>
051 * To place a tag explicitly as text, escape the {@code @} symbol with HTML entity
052 * &amp;#64; or place it inside {@code {@code }}, for example:
053 * </p>
054 * <pre>
055 * &#47;**
056 *  * &amp;#64;serial literal in {&#64;code &#64;serial} Javadoc tag.
057 *  *&#47;
058 * </pre>
059 * <ul>
060 * <li>
061 * Property {@code tags} - Specify the javadoc tags to process.
062 * Type is {@code java.lang.String[]}.
063 * Default value is {@code author, deprecated, exception, hidden, param, provides,
064 * return, see, serial, serialData, serialField, since, throws, uses, version}.
065 * </li>
066 * <li>
067 * Property {@code violateExecutionOnNonTightHtml} - Control when to print violations
068 * if the Javadoc being examined by this check violates the tight html rules defined at
069 * <a href="https://checkstyle.org/writingjavadocchecks.html#Tight-HTML_rules">Tight-HTML Rules</a>.
070 * Type is {@code boolean}.
071 * Default value is {@code false}.
072 * </li>
073 * </ul>
074 * <p>
075 * To configure the default check:
076 * </p>
077 * <pre>
078 * &lt;module name="JavadocBlockTagLocation"/&gt;
079 * </pre>
080 * <p>
081 * Example:
082 * </p>
083 * <pre>
084 * &#47;**
085 *  * Escaped tag &amp;#64;version (OK)
086 *  * Plain text with {&#64;code &#64;see} (OK)
087 *  * A @custom tag (OK)
088 *  * <!-- @see commented out (OK) -->
089 *  * email@author (OK)
090 *  * (@param in parentheses) (OK)
091 *  * '@param in single quotes' (OK)
092 *  * &#64;since 1.0 (OK)
093 *  * text &#64;return (violation)
094 *  * * &#64;param (violation)
095 * +* &#64;serial (violation)
096 *  * &#64;see first (OK) &#64;see second (violation)
097 *  *&#47;
098 * public int field;
099 * </pre>
100 * <p>
101 * To configure the check to verify tags from
102 * <a href="https://openjdk.java.net/jeps/8068562">JEP 8068562</a> only:
103 * </p>
104 * <pre>
105 * &lt;module name="JavadocBlockTagLocation"&gt;
106 *   &lt;property name="tags" value="apiNote, implSpec, implNote"/&gt;
107 * &lt;/module&gt;
108 * </pre>
109 * <p>
110 * To configure the check to verify all default tags and some custom tags in addition:
111 * </p>
112 * <pre>
113 * &lt;module name="JavadocBlockTagLocation"&gt;
114 *   &lt;!-- default tags --&gt;
115 *   &lt;property name="tags" value="author, deprecated, exception, hidden"/&gt;
116 *   &lt;property name="tags" value="param, provides, return, see, serial"/&gt;
117 *   &lt;property name="tags" value="serialData, serialField, since, throws"/&gt;
118 *   &lt;property name="tags" value="uses, version"/&gt;
119 *   &lt;!-- additional tags used in the project --&gt;
120 *   &lt;property name="tags" value="noinspection"/&gt;
121 * &lt;/module&gt;
122 * </pre>
123 * <p>
124 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
125 * </p>
126 * <p>
127 * Violation Message Keys:
128 * </p>
129 * <ul>
130 * <li>
131 * {@code javadoc.blockTagLocation}
132 * </li>
133 * <li>
134 * {@code javadoc.missed.html.close}
135 * </li>
136 * <li>
137 * {@code javadoc.parse.rule.error}
138 * </li>
139 * <li>
140 * {@code javadoc.wrong.singleton.html.tag}
141 * </li>
142 * </ul>
143 *
144 * @since 8.24
145 */
146@StatelessCheck
147public class JavadocBlockTagLocationCheck extends AbstractJavadocCheck {
148
149    /**
150     * A key is pointing to the warning message text in "messages.properties" file.
151     */
152    public static final String MSG_BLOCK_TAG_LOCATION = "javadoc.blockTagLocation";
153
154    /**
155     * This regexp is used to extract the javadoc tags.
156     */
157    private static final Pattern JAVADOC_BLOCK_TAG_PATTERN = Pattern.compile("\\s@(\\w+)");
158
159    /**
160     * Block tags from Java 11
161     * <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html">
162     * Documentation Comment Specification</a>.
163     */
164    private static final String[] DEFAULT_TAGS = {
165        "author",
166        "deprecated",
167        "exception",
168        "hidden",
169        "param",
170        "provides",
171        "return",
172        "see",
173        "serial",
174        "serialData",
175        "serialField",
176        "since",
177        "throws",
178        "uses",
179        "version",
180    };
181
182    /**
183     * Specify the javadoc tags to process.
184     */
185    private Set<String> tags;
186
187    /**
188     * Creates a new {@code JavadocBlockTagLocationCheck} instance with default settings.
189     */
190    public JavadocBlockTagLocationCheck() {
191        setTags(DEFAULT_TAGS);
192    }
193
194    /**
195     * Setter to specify the javadoc tags to process.
196     *
197     * @param values user's values.
198     */
199    public final void setTags(String... values) {
200        tags = Arrays.stream(values).collect(Collectors.toSet());
201    }
202
203    /**
204     * The javadoc tokens that this check must be registered for. According to
205     * <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
206     * the specs</a> each block tag must appear at the beginning of a line, otherwise
207     * it will be interpreted as a plain text. This check looks for a block tag
208     * in the javadoc text, thus it needs the {@code TEXT} tokens.
209     *
210     * @return the javadoc token set this must be registered for.
211     * @see JavadocTokenTypes
212     */
213    @Override
214    public int[] getRequiredJavadocTokens() {
215        return new int[] {
216            JavadocTokenTypes.TEXT,
217        };
218    }
219
220    @Override
221    public int[] getAcceptableJavadocTokens() {
222        return getRequiredJavadocTokens();
223    }
224
225    @Override
226    public int[] getDefaultJavadocTokens() {
227        return getRequiredJavadocTokens();
228    }
229
230    @Override
231    public void visitJavadocToken(DetailNode ast) {
232        if (!isCommentOrInlineTag(ast.getParent())) {
233            final Matcher tagMatcher = JAVADOC_BLOCK_TAG_PATTERN.matcher(ast.getText());
234            while (tagMatcher.find()) {
235                final String tagName = tagMatcher.group(1);
236                if (tags.contains(tagName)) {
237                    log(ast.getLineNumber(), MSG_BLOCK_TAG_LOCATION, tagName);
238                }
239            }
240        }
241    }
242
243    /**
244     * Checks if the node can contain an unescaped block tag without violation.
245     *
246     * @param node to check
247     * @return {@code true} if node is {@code @code}, {@code @literal} or HTML comment.
248     */
249    private static boolean isCommentOrInlineTag(DetailNode node) {
250        return node.getType() == JavadocTokenTypes.JAVADOC_INLINE_TAG
251                || node.getType() == JavadocTokenTypes.HTML_COMMENT;
252    }
253
254}