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 import com.puppycrawl.tools.checkstyle.utils.TokenUtil;
27
28 /**
29 * <p>
30 * Checks that enum definition does not contain a trailing comma.
31 * Rationale: JLS allows trailing commas in arrays and enumerations, but does not allow
32 * them in other locations. To unify the coding style, the use of trailing commas should
33 * be prohibited.
34 * </p>
35 * <pre>
36 * enum Foo1 {
37 * FOO,
38 * BAR;
39 * }
40 * </pre>
41 * <p>
42 * The check demands that there should not be any comma after last constant in
43 * enum definition.
44 * </p>
45 * <pre>
46 * enum Foo1 {
47 * FOO,
48 * BAR, //violation
49 * }
50 * </pre>
51 * <p>
52 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
53 * </p>
54 * <p>
55 * Violation Message Keys:
56 * </p>
57 * <ul>
58 * <li>
59 * {@code no.enum.trailing.comma}
60 * </li>
61 * </ul>
62 *
63 * @since 8.29
64 */
65 @StatelessCheck
66 public class NoEnumTrailingCommaCheck extends AbstractCheck {
67
68 /**
69 * A key is pointing to the warning message text in "messages.properties"
70 * file.
71 */
72 public static final String MSG_KEY = "no.enum.trailing.comma";
73
74 @Override
75 public int[] getDefaultTokens() {
76 return getRequiredTokens();
77 }
78
79 @Override
80 public int[] getAcceptableTokens() {
81 return getRequiredTokens();
82 }
83
84 @Override
85 public int[] getRequiredTokens() {
86 return new int[] {TokenTypes.ENUM_DEF};
87 }
88
89 @Override
90 public void visitToken(DetailAST detailAST) {
91 final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK);
92 TokenUtil.findFirstTokenByPredicate(enumBlock,
93 node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY))
94 .map(DetailAST::getPreviousSibling)
95 .filter(token -> token.getType() == TokenTypes.COMMA)
96 .ifPresent(comma -> log(comma, MSG_KEY));
97 }
98 }