SingleLineCommentCheck.java
/*
* Copyright (c) 2011-2025 Yegor Bugayenko
*
* All rights reserved.
*
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package com.qulice.checkstyle;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* C++ style inline comment is not allowed.
* Use //-style comment instead.
* @since 0.18
*/
public final class SingleLineCommentCheck extends AbstractCheck {
/**
* Pattern for check.
* It is not final as it is initialized from the configuration.
*/
private Pattern format = Pattern.compile("^$");
/**
* The message to report for a match.
* It is not final as it is initialized from the configuration.
*/
private String message = "";
/**
* Comment line.
* It is not final because the visitToken method is called many times
* during the class under test and the field is reinitialized with a new object.
*/
@SuppressWarnings("PMD.AvoidStringBufferField")
private StringBuilder line;
/**
* When inside a block comment, holds begin line number.
*/
private int begin;
@Override
public boolean isCommentNodesRequired() {
return true;
}
@Override
public int[] getDefaultTokens() {
return new int[]{
TokenTypes.BLOCK_COMMENT_BEGIN,
TokenTypes.COMMENT_CONTENT,
TokenTypes.BLOCK_COMMENT_END,
};
}
@Override
public int[] getAcceptableTokens() {
return this.getDefaultTokens();
}
@Override
public int[] getRequiredTokens() {
return this.getDefaultTokens();
}
@Override
public void visitToken(final DetailAST ast) {
if (ast.getType() == TokenTypes.BLOCK_COMMENT_BEGIN) {
this.line = new StringBuilder(ast.getText());
this.begin = ast.getLineNo();
} else if (ast.getType() == TokenTypes.COMMENT_CONTENT) {
this.line.append(ast.getText());
} else {
this.line.append(ast.getText());
final Matcher matcher = this.format.matcher(this.line.toString());
if (matcher.matches() && this.singleLineCStyleComment(ast)) {
this.log(ast, this.message);
}
}
}
/**
* The method is called from checkstyle to configure this class.
* The parameter is set from the checks.xml file
* <module name="com.qulice.checkstyle.SingleLineCommentCheck"/> and
* <property name="format" value=" this regexp "/> property
*
* @param fmt Validatig regexp.
*/
public void setFormat(final String fmt) {
this.format = Pattern.compile(fmt);
}
/**
* The method is called from checkstyle to configure this class.
* The parameter is set from the checks.xml file
* <module name="com.qulice.checkstyle.SingleLineCommentCheck"/> and
* <property name="message" value="This kind of comment is not allowed."/>
* property
*
* @param msg Error message.
*/
public void setMessage(final String msg) {
this.message = msg;
}
/**
* Checks for the end of a comment line.
* @param ast Checkstyle's AST nodes.
* @return True if this is the end of the comment
* and the starting line number is equal to the ending line number.
*/
private boolean singleLineCStyleComment(final DetailAST ast) {
return ast.getType() == TokenTypes.BLOCK_COMMENT_END && this.begin == ast.getLineNo();
}
}