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; 026 027/** 028 * <div> 029 * Check that the {@code default} is after all the cases in a {@code switch} statement. 030 * </div> 031 * 032 * <p> 033 * Rationale: Java allows {@code default} anywhere within the 034 * {@code switch} statement. But it is more readable if it comes after the last {@code case}. 035 * </p> 036 * <ul> 037 * <li> 038 * Property {@code skipIfLastAndSharedWithCase} - Control whether to allow {@code default} 039 * along with {@code case} if they are not last. 040 * Type is {@code boolean}. 041 * Default value is {@code false}. 042 * </li> 043 * </ul> 044 * 045 * <p> 046 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 047 * </p> 048 * 049 * <p> 050 * Violation Message Keys: 051 * </p> 052 * <ul> 053 * <li> 054 * {@code default.comes.last} 055 * </li> 056 * <li> 057 * {@code default.comes.last.in.casegroup} 058 * </li> 059 * </ul> 060 * 061 * @since 3.4 062 */ 063@StatelessCheck 064public class DefaultComesLastCheck extends AbstractCheck { 065 066 /** 067 * A key is pointing to the warning message text in "messages.properties" 068 * file. 069 */ 070 public static final String MSG_KEY = "default.comes.last"; 071 072 /** 073 * A key is pointing to the warning message text in "messages.properties" 074 * file. 075 */ 076 public static final String MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE = 077 "default.comes.last.in.casegroup"; 078 079 /** Control whether to allow {@code default} along with {@code case} if they are not last. */ 080 private boolean skipIfLastAndSharedWithCase; 081 082 @Override 083 public int[] getAcceptableTokens() { 084 return getRequiredTokens(); 085 } 086 087 @Override 088 public int[] getDefaultTokens() { 089 return getRequiredTokens(); 090 } 091 092 @Override 093 public int[] getRequiredTokens() { 094 return new int[] { 095 TokenTypes.LITERAL_DEFAULT, 096 }; 097 } 098 099 /** 100 * Setter to control whether to allow {@code default} along with 101 * {@code case} if they are not last. 102 * 103 * @param newValue whether to ignore checking. 104 * @since 7.7 105 */ 106 public void setSkipIfLastAndSharedWithCase(boolean newValue) { 107 skipIfLastAndSharedWithCase = newValue; 108 } 109 110 @Override 111 public void visitToken(DetailAST ast) { 112 final DetailAST defaultGroupAST = ast.getParent(); 113 114 // Switch rules are not subject to fall through. 115 final boolean isSwitchRule = defaultGroupAST.getType() == TokenTypes.SWITCH_RULE; 116 117 if (skipIfLastAndSharedWithCase && !isSwitchRule) { 118 if (isNextSiblingOf(ast, TokenTypes.LITERAL_CASE)) { 119 log(ast, MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE); 120 } 121 else if (ast.getPreviousSibling() == null 122 && isNextSiblingOf(defaultGroupAST, 123 TokenTypes.CASE_GROUP)) { 124 log(ast, MSG_KEY); 125 } 126 } 127 else if (isNextSiblingOf(defaultGroupAST, 128 TokenTypes.CASE_GROUP) 129 || isNextSiblingOf(defaultGroupAST, 130 TokenTypes.SWITCH_RULE)) { 131 log(ast, MSG_KEY); 132 } 133 } 134 135 /** 136 * Return true only if passed tokenType in argument is found or returns false. 137 * 138 * @param ast root node. 139 * @param tokenType tokentype to be processed. 140 * @return true if desired token is found or else false. 141 */ 142 private static boolean isNextSiblingOf(DetailAST ast, int tokenType) { 143 return ast.getNextSibling() != null && ast.getNextSibling().getType() == tokenType; 144 } 145 146}