001/////////////////////////////////////////////////////////////////////////////////////////////// 002// checkstyle: Checks Java source code and other text files for adherence to a set of rules. 003// Copyright (C) 2001-2022 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 that enum definition does not contain a trailing comma. 031 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow 032 * them in other locations. To unify the coding style, the use of trailing commas should 033 * be prohibited. 034 * </p> 035 * <pre> 036 * enum Foo1 { 037 * FOO, 038 * BAR; 039 * } 040 * </pre> 041 * <p> 042 * The check demands that there should not be any comma after last constant in 043 * enum definition. 044 * </p> 045 * <pre> 046 * enum Foo1 { 047 * FOO, 048 * BAR, //violation 049 * } 050 * </pre> 051 * <p> 052 * To configure the check: 053 * </p> 054 * <pre> 055 * <module name="NoEnumTrailingComma"/> 056 * </pre> 057 * <p> 058 * Which results in the following violations: 059 * </p> 060 * <pre> 061 * enum Foo1 { 062 * FOO, 063 * BAR; //OK 064 * } 065 * enum Foo2 { 066 * FOO, 067 * BAR //OK 068 * } 069 * enum Foo3 { 070 * FOO, 071 * BAR, //violation 072 * } 073 * enum Foo4 { 074 * FOO, 075 * BAR, // violation 076 * ; 077 * } 078 * enum Foo5 { 079 * FOO, 080 * BAR,; // violation 081 * } 082 * enum Foo6 { FOO, BAR,; } // violation 083 * enum Foo7 { FOO, BAR, } // violation 084 * enum Foo8 { 085 * FOO, 086 * BAR // OK 087 * ; 088 * } 089 * enum Foo9 { FOO, BAR; } // OK 090 * enum Foo10 { FOO, BAR } // OK 091 * </pre> 092 * <p> 093 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker} 094 * </p> 095 * <p> 096 * Violation Message Keys: 097 * </p> 098 * <ul> 099 * <li> 100 * {@code no.enum.trailing.comma} 101 * </li> 102 * </ul> 103 * 104 * @since 8.29 105 */ 106@StatelessCheck 107public class NoEnumTrailingCommaCheck extends AbstractCheck { 108 109 /** 110 * A key is pointing to the warning message text in "messages.properties" 111 * file. 112 */ 113 public static final String MSG_KEY = "no.enum.trailing.comma"; 114 115 @Override 116 public int[] getDefaultTokens() { 117 return getRequiredTokens(); 118 } 119 120 @Override 121 public int[] getAcceptableTokens() { 122 return getRequiredTokens(); 123 } 124 125 @Override 126 public int[] getRequiredTokens() { 127 return new int[] {TokenTypes.ENUM_DEF}; 128 } 129 130 @Override 131 public void visitToken(DetailAST detailAST) { 132 final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK); 133 TokenUtil.findFirstTokenByPredicate(enumBlock, 134 node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY)) 135 .map(DetailAST::getPreviousSibling) 136 .filter(token -> token.getType() == TokenTypes.COMMA) 137 .ifPresent(comma -> log(comma, MSG_KEY)); 138 } 139}