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 * <p> 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 * </p> 035 * <p> 036 * Rationale: Complex boolean logic makes code hard to understand and maintain. 037 * </p> 038 * <p> 039 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 040 * </p> 041 * <p> 042 * Violation Message Keys: 043 * </p> 044 * <ul> 045 * <li> 046 * {@code simplify.expression} 047 * </li> 048 * </ul> 049 * 050 * @since 3.0 051 */ 052@StatelessCheck 053public class SimplifyBooleanExpressionCheck 054 extends AbstractCheck { 055 056 /** 057 * A key is pointing to the warning message text in "messages.properties" 058 * file. 059 */ 060 public static final String MSG_KEY = "simplify.expression"; 061 062 @Override 063 public int[] getDefaultTokens() { 064 return getRequiredTokens(); 065 } 066 067 @Override 068 public int[] getAcceptableTokens() { 069 return getRequiredTokens(); 070 } 071 072 @Override 073 public int[] getRequiredTokens() { 074 return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE}; 075 } 076 077 @Override 078 public void visitToken(DetailAST ast) { 079 final DetailAST parent = ast.getParent(); 080 switch (parent.getType()) { 081 case TokenTypes.NOT_EQUAL: 082 case TokenTypes.EQUAL: 083 case TokenTypes.LNOT: 084 case TokenTypes.LOR: 085 case TokenTypes.LAND: 086 log(parent, MSG_KEY); 087 break; 088 case TokenTypes.QUESTION: 089 final DetailAST nextSibling = ast.getNextSibling(); 090 if (TokenUtil.isBooleanLiteralType(parent.getFirstChild().getType()) 091 || nextSibling != null && nextSibling.getNextSibling() != null 092 && TokenUtil.isBooleanLiteralType( 093 nextSibling.getNextSibling().getType())) { 094 log(parent, MSG_KEY); 095 } 096 break; 097 default: 098 break; 099 } 100 } 101 102}