1 /////////////////////////////////////////////////////////////////////////////////////////////// 2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules. 3 // Copyright (C) 2001-2024 the original author or authors. 4 // 5 // This library is free software; you can redistribute it and/or 6 // modify it under the terms of the GNU Lesser General Public 7 // License as published by the Free Software Foundation; either 8 // version 2.1 of the License, or (at your option) any later version. 9 // 10 // This library is distributed in the hope that it will be useful, 11 // but WITHOUT ANY WARRANTY; without even the implied warranty of 12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 // Lesser General Public License for more details. 14 // 15 // You should have received a copy of the GNU Lesser General Public 16 // License along with this library; if not, write to the Free Software 17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 18 /////////////////////////////////////////////////////////////////////////////////////////////// 19 20 package com.puppycrawl.tools.checkstyle.checks.coding; 21 22 import com.puppycrawl.tools.checkstyle.StatelessCheck; 23 import com.puppycrawl.tools.checkstyle.api.AbstractCheck; 24 import com.puppycrawl.tools.checkstyle.api.DetailAST; 25 import com.puppycrawl.tools.checkstyle.api.TokenTypes; 26 27 /** 28 * <p> 29 * Check that the {@code default} is after all the cases in a {@code switch} statement. 30 * </p> 31 * <p> 32 * Rationale: Java allows {@code default} anywhere within the 33 * {@code switch} statement. But it is more readable if it comes after the last {@code case}. 34 * </p> 35 * <ul> 36 * <li> 37 * Property {@code skipIfLastAndSharedWithCase} - Control whether to allow {@code default} 38 * along with {@code case} if they are not last. 39 * Type is {@code boolean}. 40 * Default value is {@code false}. 41 * </li> 42 * </ul> 43 * <p> 44 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 45 * </p> 46 * <p> 47 * Violation Message Keys: 48 * </p> 49 * <ul> 50 * <li> 51 * {@code default.comes.last} 52 * </li> 53 * <li> 54 * {@code default.comes.last.in.casegroup} 55 * </li> 56 * </ul> 57 * 58 * @since 3.4 59 */ 60 @StatelessCheck 61 public class DefaultComesLastCheck extends AbstractCheck { 62 63 /** 64 * A key is pointing to the warning message text in "messages.properties" 65 * file. 66 */ 67 public static final String MSG_KEY = "default.comes.last"; 68 69 /** 70 * A key is pointing to the warning message text in "messages.properties" 71 * file. 72 */ 73 public static final String MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE = 74 "default.comes.last.in.casegroup"; 75 76 /** Control whether to allow {@code default} along with {@code case} if they are not last. */ 77 private boolean skipIfLastAndSharedWithCase; 78 79 @Override 80 public int[] getAcceptableTokens() { 81 return getRequiredTokens(); 82 } 83 84 @Override 85 public int[] getDefaultTokens() { 86 return getRequiredTokens(); 87 } 88 89 @Override 90 public int[] getRequiredTokens() { 91 return new int[] { 92 TokenTypes.LITERAL_DEFAULT, 93 }; 94 } 95 96 /** 97 * Setter to control whether to allow {@code default} along with 98 * {@code case} if they are not last. 99 * 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 }