001///////////////////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
003// Copyright (C) 2001-2024 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 * <p>
032 * Checks that package names conform to a specified pattern.
033 * </p>
034 * <p>
035 * The default value of {@code format} for module {@code PackageName} has been chosen to match
036 * the requirements in the
037 * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.5.3">
038 * Java Language specification</a>
039 * and the Sun coding conventions. However, both underscores and uppercase letters are rather
040 * uncommon, so most configurations should probably assign value
041 * {@code ^[a-z]+(\.[a-z][a-z0-9]*)*$} to {@code format} for module {@code PackageName}.
042 * </p>
043 * <ul>
044 * <li>
045 * Property {@code format} - Control the pattern to match valid identifiers.
046 * Type is {@code java.util.regex.Pattern}.
047 * Default value is {@code "^[a-z]+(\.[a-zA-Z_]\w*)*$"}.
048 * </li>
049 * </ul>
050 * <p>
051 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
052 * </p>
053 * <p>
054 * Violation Message Keys:
055 * </p>
056 * <ul>
057 * <li>
058 * {@code name.invalidPattern}
059 * </li>
060 * </ul>
061 *
062 * @since 3.0
063 */
064@StatelessCheck
065public class PackageNameCheck
066    extends AbstractCheck {
067
068    /**
069     * A key is pointing to the warning message text in "messages.properties"
070     * file.
071     */
072    public static final String MSG_KEY = "name.invalidPattern";
073
074    /** Control the pattern to match valid identifiers. */
075    // Uppercase letters seem rather uncommon, but they're allowed in
076    // https://docs.oracle.com/javase/specs/
077    //  second_edition/html/packages.doc.html#40169
078    private Pattern format = Pattern.compile("^[a-z]+(\\.[a-zA-Z_]\\w*)*$");
079
080    /**
081     * Setter to control the pattern to match valid identifiers.
082     *
083     * @param pattern the new pattern
084     * @since 3.0
085     */
086    public void setFormat(Pattern pattern) {
087        format = pattern;
088    }
089
090    @Override
091    public int[] getDefaultTokens() {
092        return getRequiredTokens();
093    }
094
095    @Override
096    public int[] getAcceptableTokens() {
097        return getRequiredTokens();
098    }
099
100    @Override
101    public int[] getRequiredTokens() {
102        return new int[] {TokenTypes.PACKAGE_DEF};
103    }
104
105    @Override
106    public void visitToken(DetailAST ast) {
107        final DetailAST nameAST = ast.getLastChild().getPreviousSibling();
108        final FullIdent full = FullIdent.createFullIdent(nameAST);
109        if (!format.matcher(full.getText()).find()) {
110            log(full.getDetailAst(),
111                MSG_KEY,
112                full.getText(),
113                format.pattern());
114        }
115    }
116
117}