JavadocBlockTagLocationCheck.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2022 the original author or authors.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
///////////////////////////////////////////////////////////////////////////////////////////////
package com.puppycrawl.tools.checkstyle.checks.javadoc;
import java.util.Arrays;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.stream.Collectors;
import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.DetailNode;
import com.puppycrawl.tools.checkstyle.api.JavadocTokenTypes;
/**
* <p>
* Checks that a
* <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
* javadoc block tag</a> appears only at the beginning of a line, ignoring
* leading asterisks and white space. A block tag is a token that starts with
* {@code @} symbol and is preceded by a whitespace. This check ignores block
* tags in comments and inside inline tags {@code } and {@literal }.
* </p>
* <p>
* Rationale: according to
* <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
* the specification</a> all javadoc block tags should be placed at the beginning
* of a line. Tags that are not placed at the beginning are treated as plain text.
* To recognize intentional tag placement to text area it is better to escape the
* {@code @} symbol, and all non-escaped tags should be located at the beginning
* of the line. See NOTE section for details on how to escape.
* </p>
* <p>
* To place a tag explicitly as text, escape the {@code @} symbol with HTML entity
* &#64; or place it inside {@code {@code }}, for example:
* </p>
* <pre>
* /**
* * &#64;serial literal in {@code @serial} Javadoc tag.
* */
* </pre>
* <ul>
* <li>
* Property {@code tags} - Specify the javadoc tags to process.
* Type is {@code java.lang.String[]}.
* Default value is {@code author, deprecated, exception, hidden, param, provides,
* return, see, serial, serialData, serialField, since, throws, uses, version}.
* </li>
* <li>
* Property {@code violateExecutionOnNonTightHtml} - Control when to print violations
* if the Javadoc being examined by this check violates the tight html rules defined at
* <a href="https://checkstyle.org/writingjavadocchecks.html#Tight-HTML_rules">Tight-HTML Rules</a>.
* Type is {@code boolean}.
* Default value is {@code false}.
* </li>
* </ul>
* <p>
* To configure the default check:
* </p>
* <pre>
* <module name="JavadocBlockTagLocation"/>
* </pre>
* <p>
* Example:
* </p>
* <pre>
* /**
* * Escaped tag &#64;version (OK)
* * Plain text with {@code @see} (OK)
* * A @custom tag (OK)
* * <!-- @see commented out (OK) -->
* * email@author (OK)
* * (@param in parentheses) (OK)
* * '@param in single quotes' (OK)
* * @since 1.0 (OK)
* * text @return (violation)
* * * @param (violation)
* +* @serial (violation)
* * @see first (OK) @see second (violation)
* */
* public int field;
* </pre>
* <p>
* To configure the check to verify tags from
* <a href="https://openjdk.java.net/jeps/8068562">JEP 8068562</a> only:
* </p>
* <pre>
* <module name="JavadocBlockTagLocation">
* <property name="tags" value="apiNote, implSpec, implNote"/>
* </module>
* </pre>
* <p>
* To configure the check to verify all default tags and some custom tags in addition:
* </p>
* <pre>
* <module name="JavadocBlockTagLocation">
* <!-- default tags -->
* <property name="tags" value="author, deprecated, exception, hidden"/>
* <property name="tags" value="param, provides, return, see, serial"/>
* <property name="tags" value="serialData, serialField, since, throws"/>
* <property name="tags" value="uses, version"/>
* <!-- additional tags used in the project -->
* <property name="tags" value="noinspection"/>
* </module>
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code javadoc.blockTagLocation}
* </li>
* <li>
* {@code javadoc.missed.html.close}
* </li>
* <li>
* {@code javadoc.parse.rule.error}
* </li>
* <li>
* {@code javadoc.wrong.singleton.html.tag}
* </li>
* </ul>
*
* @since 8.24
*/
@StatelessCheck
public class JavadocBlockTagLocationCheck extends AbstractJavadocCheck {
/**
* A key is pointing to the warning message text in "messages.properties" file.
*/
public static final String MSG_BLOCK_TAG_LOCATION = "javadoc.blockTagLocation";
/**
* This regexp is used to extract the javadoc tags.
*/
private static final Pattern JAVADOC_BLOCK_TAG_PATTERN = Pattern.compile("\\s@(\\w+)");
/**
* Block tags from Java 11
* <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html">
* Documentation Comment Specification</a>.
*/
private static final String[] DEFAULT_TAGS = {
"author",
"deprecated",
"exception",
"hidden",
"param",
"provides",
"return",
"see",
"serial",
"serialData",
"serialField",
"since",
"throws",
"uses",
"version",
};
/**
* Specify the javadoc tags to process.
*/
private Set<String> tags;
/**
* Creates a new {@code JavadocBlockTagLocationCheck} instance with default settings.
*/
public JavadocBlockTagLocationCheck() {
setTags(DEFAULT_TAGS);
}
/**
* Setter to specify the javadoc tags to process.
*
* @param values user's values.
*/
public final void setTags(String... values) {
tags = Arrays.stream(values).collect(Collectors.toSet());
}
/**
* The javadoc tokens that this check must be registered for. According to
* <a href="https://docs.oracle.com/en/java/javase/11/docs/specs/doc-comment-spec.html#block-tags">
* the specs</a> each block tag must appear at the beginning of a line, otherwise
* it will be interpreted as a plain text. This check looks for a block tag
* in the javadoc text, thus it needs the {@code TEXT} tokens.
*
* @return the javadoc token set this must be registered for.
* @see JavadocTokenTypes
*/
@Override
public int[] getRequiredJavadocTokens() {
return new int[] {
JavadocTokenTypes.TEXT,
};
}
@Override
public int[] getAcceptableJavadocTokens() {
return getRequiredJavadocTokens();
}
@Override
public int[] getDefaultJavadocTokens() {
return getRequiredJavadocTokens();
}
@Override
public void visitJavadocToken(DetailNode ast) {
if (!isCommentOrInlineTag(ast.getParent())) {
final Matcher tagMatcher = JAVADOC_BLOCK_TAG_PATTERN.matcher(ast.getText());
while (tagMatcher.find()) {
final String tagName = tagMatcher.group(1);
if (tags.contains(tagName)) {
log(ast.getLineNumber(), MSG_BLOCK_TAG_LOCATION, tagName);
}
}
}
}
/**
* Checks if the node can contain an unescaped block tag without violation.
*
* @param node to check
* @return {@code true} if node is {@code @code}, {@code @literal} or HTML comment.
*/
private static boolean isCommentOrInlineTag(DetailNode node) {
return node.getType() == JavadocTokenTypes.JAVADOC_INLINE_TAG
|| node.getType() == JavadocTokenTypes.HTML_COMMENT;
}
}