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.coding;
021
022import com.puppycrawl.tools.checkstyle.StatelessCheck;
023import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
024import com.puppycrawl.tools.checkstyle.api.DetailAST;
025import com.puppycrawl.tools.checkstyle.api.TokenTypes;
026import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
027
028/**
029 * <p>
030 *  Checks that enum definition does not contain a trailing comma.
031 *  Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
032 *  them in other locations. To unify the coding style, the use of trailing commas should
033 *  be prohibited.
034 * </p>
035 * <pre>
036 * enum Foo1 {
037 *   FOO,
038 *   BAR;
039 * }
040 * </pre>
041 * <p>
042 *  The check demands that there should not be any comma after last constant in
043 *  enum definition.
044 * </p>
045 * <pre>
046 * enum Foo1 {
047 *   FOO,
048 *   BAR, //violation
049 * }
050 * </pre>
051 * <p>
052 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
053 * </p>
054 * <p>
055 * Violation Message Keys:
056 * </p>
057 * <ul>
058 * <li>
059 * {@code no.enum.trailing.comma}
060 * </li>
061 * </ul>
062 *
063 * @since 8.29
064 */
065@StatelessCheck
066public class NoEnumTrailingCommaCheck 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 = "no.enum.trailing.comma";
073
074    @Override
075    public int[] getDefaultTokens() {
076        return getRequiredTokens();
077    }
078
079    @Override
080    public int[] getAcceptableTokens() {
081        return getRequiredTokens();
082    }
083
084    @Override
085    public int[] getRequiredTokens() {
086        return new int[] {TokenTypes.ENUM_DEF};
087    }
088
089    @Override
090    public void visitToken(DetailAST detailAST) {
091        final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK);
092        TokenUtil.findFirstTokenByPredicate(enumBlock,
093            node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY))
094            .map(DetailAST::getPreviousSibling)
095            .filter(token -> token.getType() == TokenTypes.COMMA)
096            .ifPresent(comma -> log(comma, MSG_KEY));
097    }
098}