com.puppycrawl.tools.checkstyle.checks.coding.NoEnumTrailingCommaCheck Maven / Gradle / Ivy

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///////////////////////////////////////////////////////////////////////////////////////////////
// checkstyle: Checks Java source code and other text files for adherence to a set of rules.
// Copyright (C) 2001-2024 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.coding;

import com.puppycrawl.tools.checkstyle.StatelessCheck;
import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
import com.puppycrawl.tools.checkstyle.api.DetailAST;
import com.puppycrawl.tools.checkstyle.api.TokenTypes;
import com.puppycrawl.tools.checkstyle.utils.TokenUtil;

/**
 * 
 *  Checks that enum definition does not contain a trailing comma.
 *  Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
 *  them in other locations. To unify the coding style, the use of trailing commas should
 *  be prohibited.
 * 
 *  * enum Foo1 {
 *   FOO,
 *   BAR;
 * }
 * 
 * 
 *  The check demands that there should not be any comma after last constant in
 *  enum definition.
 * 
 *  * enum Foo1 {
 *   FOO,
 *   BAR, //violation
 * }
 * 
 * 
 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
 * 
 * 
 * Violation Message Keys:
 * 
 * 
 * 
 * {@code no.enum.trailing.comma}
 * 
 * 
 *
 * @since 8.29
 */
@StatelessCheck
public class NoEnumTrailingCommaCheck extends AbstractCheck {

    /**
     * A key is pointing to the warning message text in "messages.properties"
     * file.
     */
    public static final String MSG_KEY = "no.enum.trailing.comma";

    @Override
    public int[] getDefaultTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getAcceptableTokens() {
        return getRequiredTokens();
    }

    @Override
    public int[] getRequiredTokens() {
        return new int[] {TokenTypes.ENUM_DEF};
    }

    @Override
    public void visitToken(DetailAST detailAST) {
        final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK);
        TokenUtil.findFirstTokenByPredicate(enumBlock,
            node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY))
            .map(DetailAST::getPreviousSibling)
            .filter(token -> token.getType() == TokenTypes.COMMA)
            .ifPresent(comma -> log(comma, MSG_KEY));
    }
}