001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2018 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 * Checks for overly complicated boolean expressions. Currently finds code like
030 * {@code if (b == true)}, {@code b || true}, {@code !false},
031 * etc.
032 * </p>
033 * <p>
034 * Rationale: Complex boolean logic makes code hard to understand and maintain.
035 * </p>
036 * <p>
037 * An example of how to configure the check is:
038 * </p>
039 * <pre>
040 * &lt;module name="SimplifyBooleanExpression"/&gt;
041 * </pre>
042 */
043@StatelessCheck
044public class SimplifyBooleanExpressionCheck
045        extends AbstractCheck {
046
047    /**
048     * A key is pointing to the warning message text in "messages.properties"
049     * file.
050     */
051    public static final String MSG_KEY = "simplify.expression";
052
053    @Override
054    public int[] getDefaultTokens() {
055        return getRequiredTokens();
056    }
057
058    @Override
059    public int[] getAcceptableTokens() {
060        return getRequiredTokens();
061    }
062
063    @Override
064    public int[] getRequiredTokens() {
065        return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE};
066    }
067
068    @Override
069    public void visitToken(DetailAST ast) {
070        final DetailAST parent = ast.getParent();
071        switch (parent.getType()) {
072            case TokenTypes.NOT_EQUAL:
073            case TokenTypes.EQUAL:
074            case TokenTypes.LNOT:
075            case TokenTypes.LOR:
076            case TokenTypes.LAND:
077                log(parent, MSG_KEY);
078                break;
079            default:
080                break;
081        }
082    }
083
084}