RegexpHeaderCheck.java
///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2025 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.header;
import java.io.File;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.List;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;
import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.FileText;
import com.puppycrawl.tools.checkstyle.utils.CommonUtil;
import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
/**
* <div>
* Checks the header of a source file against a header that contains a
* <a href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/util/regex/Pattern.html">
* pattern</a> for each line of the source header.
* </div>
* <ul>
* <li>
* Property {@code charset} - Specify the character encoding to use when reading the headerFile.
* Type is {@code java.lang.String}.
* Default value is {@code the charset property of the parent
* <a href="https://checkstyle.org/config.html#Checker">Checker</a> module}.
* </li>
* <li>
* Property {@code fileExtensions} - Specify the file extensions of the files to process.
* Type is {@code java.lang.String[]}.
* Default value is {@code ""}.
* </li>
* <li>
* Property {@code header} - Define the required header specified inline.
* Individual header lines must be separated by the string {@code "\n"}
* (even on platforms with a different line separator).
* For header lines containing {@code "\n\n"} checkstyle will
* forcefully expect an empty line to exist. See examples below.
* Regular expressions must not span multiple lines.
* Type is {@code java.lang.String}.
* Default value is {@code null}.
* </li>
* <li>
* Property {@code headerFile} - Specify the name of the file containing the required header.
* Type is {@code java.net.URI}.
* Default value is {@code null}.
* </li>
* <li>
* Property {@code multiLines} - Specify the line numbers to repeat (zero or more times).
* Type is {@code int[]}.
* Default value is {@code ""}.
* </li>
* </ul>
*
* <p>
* Parent is {@code com.puppycrawl.tools.checkstyle.Checker}
* </p>
*
* <p>
* Violation Message Keys:
* </p>
* <ul>
* <li>
* {@code header.mismatch}
* </li>
* <li>
* {@code header.missing}
* </li>
* </ul>
*
* @since 3.2
*/
@StatelessCheck
public class RegexpHeaderCheck extends AbstractHeaderCheck {
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_HEADER_MISSING = "header.missing";
/**
* A key is pointing to the warning message text in "messages.properties"
* file.
*/
public static final String MSG_HEADER_MISMATCH = "header.mismatch";
/** Regex pattern for a blank line. **/
private static final String EMPTY_LINE_PATTERN = "^$";
/** Compiled regex pattern for a blank line. **/
private static final Pattern BLANK_LINE = Pattern.compile(EMPTY_LINE_PATTERN);
/** The compiled regular expressions. */
private final List<Pattern> headerRegexps = new ArrayList<>();
/** Specify the line numbers to repeat (zero or more times). */
private BitSet multiLines = new BitSet();
/**
* Setter to specify the line numbers to repeat (zero or more times).
*
* @param list line numbers to repeat in header.
* @since 3.4
*/
public void setMultiLines(int... list) {
multiLines = TokenUtil.asBitSet(list);
}
@Override
protected void processFiltered(File file, FileText fileText) {
final int headerSize = getHeaderLines().size();
final int fileSize = fileText.size();
if (headerSize - multiLines.cardinality() > fileSize) {
log(1, MSG_HEADER_MISSING);
}
else {
int headerLineNo = 0;
int index;
for (index = 0; headerLineNo < headerSize && index < fileSize; index++) {
final String line = fileText.get(index);
boolean isMatch = isMatch(line, headerLineNo);
while (!isMatch && isMultiLine(headerLineNo)) {
headerLineNo++;
isMatch = headerLineNo == headerSize
|| isMatch(line, headerLineNo);
}
if (!isMatch) {
log(index + 1, MSG_HEADER_MISMATCH, getHeaderLine(headerLineNo));
break;
}
if (!isMultiLine(headerLineNo)) {
headerLineNo++;
}
}
if (index == fileSize) {
// if file finished, but we have at least one non-multi-line
// header isn't completed
logFirstSinglelineLine(headerLineNo, headerSize);
}
}
}
/**
* Returns the line from the header. Where the line is blank return the regexp pattern
* for a blank line.
*
* @param headerLineNo header line number to return
* @return the line from the header
*/
private String getHeaderLine(int headerLineNo) {
String line = getHeaderLines().get(headerLineNo);
if (line.isEmpty()) {
line = EMPTY_LINE_PATTERN;
}
return line;
}
/**
* Logs warning if any non-multiline lines left in header regexp.
*
* @param startHeaderLine header line number to start from
* @param headerSize whole header size
*/
private void logFirstSinglelineLine(int startHeaderLine, int headerSize) {
for (int lineNum = startHeaderLine; lineNum < headerSize; lineNum++) {
if (!isMultiLine(lineNum)) {
log(1, MSG_HEADER_MISSING);
break;
}
}
}
/**
* Checks if a code line matches the required header line.
*
* @param line the code line
* @param headerLineNo the header line number.
* @return true if and only if the line matches the required header line.
*/
private boolean isMatch(String line, int headerLineNo) {
return headerRegexps.get(headerLineNo).matcher(line).find();
}
/**
* Returns true if line is multiline header lines or false.
*
* @param lineNo a line number
* @return if {@code lineNo} is one of the repeat header lines.
*/
private boolean isMultiLine(int lineNo) {
return multiLines.get(lineNo + 1);
}
@Override
protected void postProcessHeaderLines() {
final List<String> headerLines = getHeaderLines();
for (String line : headerLines) {
try {
if (line.isEmpty()) {
headerRegexps.add(BLANK_LINE);
}
else {
headerRegexps.add(Pattern.compile(line));
}
}
catch (final PatternSyntaxException exc) {
throw new IllegalArgumentException("line "
+ (headerRegexps.size() + 1)
+ " in header specification"
+ " is not a regular expression", exc);
}
}
}
/**
* Setter to define the required header specified inline.
* Individual header lines must be separated by the string {@code "\n"}
* (even on platforms with a different line separator).
* For header lines containing {@code "\n\n"} checkstyle will forcefully
* expect an empty line to exist. See examples below.
* Regular expressions must not span multiple lines.
*
* @param header the header value to validate and set (in that order)
* @since 5.0
*/
@Override
public void setHeader(String header) {
if (!CommonUtil.isBlank(header)) {
if (!CommonUtil.isPatternValid(header)) {
throw new IllegalArgumentException("Unable to parse format: " + header);
}
super.setHeader(header);
}
}
}