001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 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 * <p>
029 * Detects empty statements (standalone ';').
030 * Empty statements often introduce bugs
031 * that are hard to spot, such as in
032 * </p>
033 * <pre>
034 * if (someCondition);
035 *   doConditionalStuff();
036 * doUnconditionalStuff();
037 * </pre>
038 * <p>
039 * An example of how to configure the check is:
040 * </p>
041 * <pre>
042 * &lt;module name="EmptyStatement"/&gt;
043 * </pre>
044 * @author Rick Giles
045 */
046@StatelessCheck
047public class EmptyStatementCheck extends AbstractCheck {
048
049    /**
050     * A key is pointing to the warning message text in "messages.properties"
051     * file.
052     */
053    public static final String MSG_KEY = "empty.statement";
054
055    @Override
056    public int[] getDefaultTokens() {
057        return getRequiredTokens();
058    }
059
060    @Override
061    public int[] getAcceptableTokens() {
062        return getRequiredTokens();
063    }
064
065    @Override
066    public int[] getRequiredTokens() {
067        return new int[] {TokenTypes.EMPTY_STAT};
068    }
069
070    @Override
071    public void visitToken(DetailAST ast) {
072        log(ast.getLineNo(), ast.getColumnNo(), MSG_KEY);
073    }
074}