001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2014  Oliver Burn
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////////////////////////////////////////////////////////////////////////////////
019package com.puppycrawl.tools.checkstyle.checks.coding;
020
021import com.puppycrawl.tools.checkstyle.api.Check;
022import com.puppycrawl.tools.checkstyle.api.TokenTypes;
023import com.puppycrawl.tools.checkstyle.api.DetailAST;
024
025/**
026 * <p>
027 * Checks for overly complicated boolean expressions. Currently finds code like
028 * <code>if (b == true)</code>, <code>b || true</code>, <code>!false</code>,
029 * etc.
030 * </p>
031 * <p>
032 * Rationale: Complex boolean logic makes code hard to understand and maintain.
033 * </p>
034 * <p>
035 * An example of how to configure the check is:
036 * </p>
037 * <pre>
038 * &lt;module name="SimplifyBooleanExpression"/&gt;
039 * </pre>
040 * @author lkuehne
041 */
042public class SimplifyBooleanExpressionCheck
043        extends Check
044{
045    @Override
046    public int[] getDefaultTokens()
047    {
048        return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE};
049    }
050
051    @Override
052    public int[] getAcceptableTokens()
053    {
054        // Return empty list to prevent user changing tokens in the
055        // configuration.
056        return new int[] {};
057    }
058
059    @Override
060    public int[] getRequiredTokens()
061    {
062        return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE};
063    }
064
065    @Override
066    public void visitToken(DetailAST ast)
067    {
068        final DetailAST parent = ast.getParent();
069        switch (parent.getType()) {
070            case TokenTypes.NOT_EQUAL:
071            case TokenTypes.EQUAL:
072            case TokenTypes.LNOT:
073            case TokenTypes.LOR:
074            case TokenTypes.LAND:
075                log(parent.getLineNo(), parent.getColumnNo(),
076                    "simplify.expression");
077                break;
078            default:
079                break;
080        }
081    }
082}