001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2026 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.naming;
021
022import java.util.regex.Pattern;
023
024import com.puppycrawl.tools.checkstyle.StatelessCheck;
025import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
026import com.puppycrawl.tools.checkstyle.api.DetailAST;
027import com.puppycrawl.tools.checkstyle.api.FullIdent;
028import com.puppycrawl.tools.checkstyle.api.TokenTypes;
029
030/**
031 * <div>
032 * Checks that package names conform to a specified pattern.
033 * </div>
034 *
035 * <p>
036 * The default value of {@code format} for module {@code PackageName} has been chosen to match
037 * the requirements in the
038 * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.5.3">
039 * Java Language specification</a>
040 * and the Sun coding conventions. However, both underscores and uppercase letters are rather
041 * uncommon, so most configurations should probably assign value
042 * {@code ^[a-z]+(\.[a-z][a-z0-9]*)*$} to {@code format} for module {@code PackageName}.
043 * </p>
044 *
045 * @since 3.0
046 */
047@StatelessCheck
048public class PackageNameCheck extends AbstractCheck {
049
050    /**
051     * A key is pointing to the warning message text in "messages.properties" file.
052     */
053    public static final String MSG_KEY = "name.invalidPattern";
054
055    /** Control the pattern to match valid identifiers. */
056    // Uppercase letters seem rather uncommon, but they're allowed in
057    // https://docs.oracle.com/javase/specs/
058    //  second_edition/html/packages.doc.html#40169
059    private Pattern format = Pattern.compile("^[a-z]+(\\.[a-zA-Z_]\\w*)*$");
060
061    /**
062     * Creates a new {@code PackageNameCheck} instance.
063     */
064    public PackageNameCheck() {
065        // no code by default
066    }
067
068    /**
069     * Setter to control the pattern to match valid identifiers.
070     *
071     * @param pattern the new pattern
072     * @since 3.0
073     */
074    public void setFormat(Pattern pattern) {
075        format = pattern;
076    }
077
078    @Override
079    public int[] getDefaultTokens() {
080        return getRequiredTokens();
081    }
082
083    @Override
084    public int[] getAcceptableTokens() {
085        return getRequiredTokens();
086    }
087
088    @Override
089    public int[] getRequiredTokens() {
090        return new int[] {TokenTypes.PACKAGE_DEF};
091    }
092
093    @Override
094    public void visitToken(DetailAST ast) {
095        final DetailAST nameAST = ast.getLastChild().getPreviousSibling();
096        final FullIdent full = FullIdent.createFullIdent(nameAST);
097        if (!format.matcher(full.getText()).find()) {
098            log(full.getDetailAst(),
099                MSG_KEY,
100                full.getText(),
101                format.pattern());
102        }
103    }
104
105}