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