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.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;
026
027/**
028 * <div>
029 * Checks if unnecessary semicolon is in enum definitions.
030 * Semicolon is not needed if enum body contains only enum constants.
031 * </div>
032 *
033 * @since 8.22
034 */
035@StatelessCheck
036public final class UnnecessarySemicolonInEnumerationCheck extends AbstractCheck {
037
038    /**
039     * A key is pointing to the warning message text in "messages.properties"
040     * file.
041     */
042    public static final String MSG_SEMI = "unnecessary.semicolon";
043
044    @Override
045    public int[] getDefaultTokens() {
046        return getRequiredTokens();
047    }
048
049    @Override
050    public int[] getAcceptableTokens() {
051        return getRequiredTokens();
052    }
053
054    @Override
055    public int[] getRequiredTokens() {
056        return new int[] {
057            TokenTypes.ENUM_DEF,
058        };
059    }
060
061    @Override
062    public void visitToken(DetailAST ast) {
063        final DetailAST enumBlock = ast.findFirstToken(TokenTypes.OBJBLOCK);
064        final boolean hasMembers = hasMembersAfterConstants(enumBlock);
065        DetailAST sibling = enumBlock.getFirstChild();
066        while (sibling != null) {
067            if (sibling.getType() == TokenTypes.SEMI
068                    && (!hasMembers || isPrecededBySemi(sibling))) {
069                log(sibling, MSG_SEMI);
070            }
071            sibling = sibling.getNextSibling();
072        }
073    }
074
075    /**
076     * Checks if enum body contains any member (method, constructor, field, etc.)
077     * in addition to enum constants and semicolons.
078     *
079     * @param enumBlock the enum body to check
080     * @return true if enum body has members, false if it only has constants and semicolons.
081     */
082    private static boolean hasMembersAfterConstants(DetailAST enumBlock) {
083        boolean result = false;
084        DetailAST sibling = enumBlock.getFirstChild();
085        while (sibling != null) {
086            final int type = sibling.getType();
087            if (type != TokenTypes.LCURLY
088                    && type != TokenTypes.RCURLY
089                    && type != TokenTypes.ENUM_CONSTANT_DEF
090                    && type != TokenTypes.SEMI
091                    && type != TokenTypes.COMMA) {
092                result = true;
093                break;
094            }
095            sibling = sibling.getNextSibling();
096        }
097        return result;
098    }
099
100    /**
101     * Checks if semicolon is immediately preceded by another semicolon,
102     * making it a redundant duplicate.
103     *
104     * @param ast semicolon to check
105     * @return true if previous sibling is also a semicolon, false otherwise.
106     */
107    private static boolean isPrecededBySemi(DetailAST ast) {
108        final DetailAST prev = ast.getPreviousSibling();
109        return prev.getType() == TokenTypes.SEMI;
110    }
111}