001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2024 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; 026import com.puppycrawl.tools.checkstyle.utils.TokenUtil; 027 028/** 029 * <div> 030 * Checks for over-complicated boolean expressions. Currently, it finds code like 031 * {@code if (b == true)}, {@code b || true}, {@code !false}, 032 * {@code boolean a = q > 12 ? true : false}, 033 * etc. 034 * </div> 035 * 036 * <p> 037 * Rationale: Complex boolean logic makes code hard to understand and maintain. 038 * </p> 039 * 040 * <p> 041 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 042 * </p> 043 * 044 * <p> 045 * Violation Message Keys: 046 * </p> 047 * <ul> 048 * <li> 049 * {@code simplify.expression} 050 * </li> 051 * </ul> 052 * 053 * @since 3.0 054 */ 055@StatelessCheck 056public class SimplifyBooleanExpressionCheck 057 extends AbstractCheck { 058 059 /** 060 * A key is pointing to the warning message text in "messages.properties" 061 * file. 062 */ 063 public static final String MSG_KEY = "simplify.expression"; 064 065 @Override 066 public int[] getDefaultTokens() { 067 return getRequiredTokens(); 068 } 069 070 @Override 071 public int[] getAcceptableTokens() { 072 return getRequiredTokens(); 073 } 074 075 @Override 076 public int[] getRequiredTokens() { 077 return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE}; 078 } 079 080 @Override 081 public void visitToken(DetailAST ast) { 082 final DetailAST parent = ast.getParent(); 083 switch (parent.getType()) { 084 case TokenTypes.NOT_EQUAL: 085 case TokenTypes.EQUAL: 086 case TokenTypes.LNOT: 087 case TokenTypes.LOR: 088 case TokenTypes.LAND: 089 log(parent, MSG_KEY); 090 break; 091 case TokenTypes.QUESTION: 092 final DetailAST nextSibling = ast.getNextSibling(); 093 if (TokenUtil.isBooleanLiteralType(parent.getFirstChild().getType()) 094 || nextSibling != null && nextSibling.getNextSibling() != null 095 && TokenUtil.isBooleanLiteralType( 096 nextSibling.getNextSibling().getType())) { 097 log(parent, MSG_KEY); 098 } 099 break; 100 default: 101 break; 102 } 103 } 104 105}