JavadocParagraphCheck.java
////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code for adherence to a set of rules.
// Copyright (C) 2001-2021 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 com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.DetailNode;
import com.puppycrawl.tools.checkstyle.api.JavadocTokenTypes;
import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
import com.puppycrawl.tools.checkstyle.utils.JavadocUtil;
/**
* <p>
* Checks the Javadoc paragraph.
* </p>
* <p>
* Checks that:
* </p>
* <ul>
* <li>There is one blank line between each of two paragraphs.</li>
* <li>Each paragraph but the first has <p> immediately
* before the first word, with no space after.</li>
* </ul>
* <ul>
* <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>
* <li>
* Property {@code allowNewlineParagraph} - Control whether the <p> tag
* should be placed immediately before the first word.
* Type is {@code boolean}.
* Default value is {@code true}.
* </li>
* </ul>
* <p>
* To configure the default check:
* </p>
* <pre>
* <module name="JavadocParagraph"/>
* </pre>
* <p>
* By default, the check will report a violation if there is a new line
* or whitespace after the <p> tag:
* </p>
* <pre>
* /**
* * No tag (ok).
* *
* * <p>Tag immediately before the text (ok).
* * <p>No blank line before the tag (violation).
* *
* * <p>
* * New line after tag (violation).
* *
* * <p> Whitespace after tag (violation).
* *
* */
* public class TestClass {
* }
* </pre>
* <p>
* To allow newlines and spaces immediately after the <p> tag:
* </p>
* <pre>
* <module name="JavadocParagraph">
* <property name="allowNewlineParagraph" value="false"/>
* </module>
* </pre>
* <p>
* In case of {@code allowNewlineParagraph} set to {@code false}
* the following example will not have any violations:
* </p>
* <pre>
* /**
* * No tag (ok).
* *
* * <p>Tag immediately before the text (ok).
* * <p>No blank line before the tag (violation).
* *
* * <p>
* * New line after tag (ok).
* *
* * <p> Whitespace after tag (ok).
* *
* */
* public class TestClass {
* }
* </pre>
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
* </p>
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code javadoc.missed.html.close}
* </li>
* <li>
* {@code javadoc.paragraph.line.before}
* </li>
* <li>
* {@code javadoc.paragraph.misplaced.tag}
* </li>
* <li>
* {@code javadoc.paragraph.redundant.paragraph}
* </li>
* <li>
* {@code javadoc.paragraph.tag.after}
* </li>
* <li>
* {@code javadoc.parse.rule.error}
* </li>
* <li>
* {@code javadoc.wrong.singleton.html.tag}
* </li>
* </ul>
*
* @since 6.0
*/
@StatelessCheck
public class JavadocParagraphCheck extends AbstractJavadocCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_TAG_AFTER = "javadoc.paragraph.tag.after";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_LINE_BEFORE = "javadoc.paragraph.line.before";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_REDUNDANT_PARAGRAPH = "javadoc.paragraph.redundant.paragraph";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_MISPLACED_TAG = "javadoc.paragraph.misplaced.tag";
/**
* Control whether the <p> tag should be placed immediately before the first word.
*/
private boolean allowNewlineParagraph = true;
/**
* Setter to control whether the <p> tag should be placed
* immediately before the first word.
*
* @param value value to set.
*/
public void setAllowNewlineParagraph(boolean value) {
allowNewlineParagraph = value;
}
@Override
public int[] getDefaultJavadocTokens() {
return new int[] {
JavadocTokenTypes.NEWLINE,
JavadocTokenTypes.HTML_ELEMENT,
};
}
@Override
public int[] getRequiredJavadocTokens() {
return getAcceptableJavadocTokens();
}
@Override
public void visitJavadocToken(DetailNode ast) {
if (ast.getType() == JavadocTokenTypes.NEWLINE && isEmptyLine(ast)) {
checkEmptyLine(ast);
}
else if (ast.getType() == JavadocTokenTypes.HTML_ELEMENT
&& JavadocUtil.getFirstChild(ast).getType() == JavadocTokenTypes.P_TAG_START) {
checkParagraphTag(ast);
}
}
/**
* Determines whether or not the next line after empty line has paragraph tag in the beginning.
*
* @param newline NEWLINE node.
*/
private void checkEmptyLine(DetailNode newline) {
final DetailNode nearestToken = getNearestNode(newline);
if (nearestToken.getType() == JavadocTokenTypes.TEXT
&& !CommonUtil.isBlank(nearestToken.getText())) {
log(newline.getLineNumber(), MSG_TAG_AFTER);
}
}
/**
* Determines whether or not the line with paragraph tag has previous empty line.
*
* @param tag html tag.
*/
private void checkParagraphTag(DetailNode tag) {
final DetailNode newLine = getNearestEmptyLine(tag);
if (isFirstParagraph(tag)) {
log(tag.getLineNumber(), MSG_REDUNDANT_PARAGRAPH);
}
else if (newLine == null || tag.getLineNumber() - newLine.getLineNumber() != 1) {
log(tag.getLineNumber(), MSG_LINE_BEFORE);
}
if (allowNewlineParagraph && isImmediatelyFollowedByText(tag)) {
log(tag.getLineNumber(), MSG_MISPLACED_TAG);
}
}
/**
* Returns nearest node.
*
* @param node DetailNode node.
* @return nearest node.
*/
private static DetailNode getNearestNode(DetailNode node) {
DetailNode tag = JavadocUtil.getNextSibling(node);
while (tag.getType() == JavadocTokenTypes.LEADING_ASTERISK
|| tag.getType() == JavadocTokenTypes.NEWLINE) {
tag = JavadocUtil.getNextSibling(tag);
}
return tag;
}
/**
* Determines whether or not the line is empty line.
*
* @param newLine NEWLINE node.
* @return true, if line is empty line.
*/
private static boolean isEmptyLine(DetailNode newLine) {
boolean result = false;
DetailNode previousSibling = JavadocUtil.getPreviousSibling(newLine);
if (previousSibling != null
&& previousSibling.getParent().getType() == JavadocTokenTypes.JAVADOC) {
if (previousSibling.getType() == JavadocTokenTypes.TEXT
&& CommonUtil.isBlank(previousSibling.getText())) {
previousSibling = JavadocUtil.getPreviousSibling(previousSibling);
}
result = previousSibling != null
&& previousSibling.getType() == JavadocTokenTypes.LEADING_ASTERISK;
}
return result;
}
/**
* Determines whether or not the line with paragraph tag is first line in javadoc.
*
* @param paragraphTag paragraph tag.
* @return true, if line with paragraph tag is first line in javadoc.
*/
private static boolean isFirstParagraph(DetailNode paragraphTag) {
boolean result = true;
DetailNode previousNode = JavadocUtil.getPreviousSibling(paragraphTag);
while (previousNode != null) {
if (previousNode.getType() == JavadocTokenTypes.TEXT
&& !CommonUtil.isBlank(previousNode.getText())
|| previousNode.getType() != JavadocTokenTypes.LEADING_ASTERISK
&& previousNode.getType() != JavadocTokenTypes.NEWLINE
&& previousNode.getType() != JavadocTokenTypes.TEXT) {
result = false;
break;
}
previousNode = JavadocUtil.getPreviousSibling(previousNode);
}
return result;
}
/**
* Finds and returns nearest empty line in javadoc.
*
* @param node DetailNode node.
* @return Some nearest empty line in javadoc.
*/
private static DetailNode getNearestEmptyLine(DetailNode node) {
DetailNode newLine = JavadocUtil.getPreviousSibling(node);
while (newLine != null) {
final DetailNode previousSibling = JavadocUtil.getPreviousSibling(newLine);
if (newLine.getType() == JavadocTokenTypes.NEWLINE && isEmptyLine(newLine)) {
break;
}
newLine = previousSibling;
}
return newLine;
}
/**
* Tests whether the paragraph tag is immediately followed by the text.
*
* @param tag html tag.
* @return true, if the paragraph tag is immediately followed by the text.
*/
private static boolean isImmediatelyFollowedByText(DetailNode tag) {
final DetailNode nextSibling = JavadocUtil.getNextSibling(tag);
return nextSibling.getType() == JavadocTokenTypes.NEWLINE
|| nextSibling.getType() == JavadocTokenTypes.EOF
|| CommonUtil.startsWithChar(nextSibling.getText(), ' ');
}
}