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 * <div>
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 * </div>
35 * <pre>
36 * enum Foo1 {
37 * FOO,
38 * BAR;
39 * }
40 * </pre>
41 *
42 * <p>
43 * The check demands that there should not be any comma after last constant in
44 * enum definition.
45 * </p>
46 * <pre>
47 * enum Foo1 {
48 * FOO,
49 * BAR, //violation
50 * }
51 * </pre>
52 *
53 * <p>
54 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
55 * </p>
56 *
57 * <p>
58 * Violation Message Keys:
59 * </p>
60 * <ul>
61 * <li>
62 * {@code no.enum.trailing.comma}
63 * </li>
64 * </ul>
65 *
66 * @since 8.29
67 */
68 @StatelessCheck
69 public class NoEnumTrailingCommaCheck extends AbstractCheck {
70
71 /**
72 * A key is pointing to the warning message text in "messages.properties"
73 * file.
74 */
75 public static final String MSG_KEY = "no.enum.trailing.comma";
76
77 @Override
78 public int[] getDefaultTokens() {
79 return getRequiredTokens();
80 }
81
82 @Override
83 public int[] getAcceptableTokens() {
84 return getRequiredTokens();
85 }
86
87 @Override
88 public int[] getRequiredTokens() {
89 return new int[] {TokenTypes.ENUM_DEF};
90 }
91
92 @Override
93 public void visitToken(DetailAST detailAST) {
94 final DetailAST enumBlock = detailAST.findFirstToken(TokenTypes.OBJBLOCK);
95 TokenUtil.findFirstTokenByPredicate(enumBlock,
96 node -> TokenUtil.isOfType(node, TokenTypes.SEMI, TokenTypes.RCURLY))
97 .map(DetailAST::getPreviousSibling)
98 .filter(token -> token.getType() == TokenTypes.COMMA)
99 .ifPresent(comma -> log(comma, MSG_KEY));
100 }
101 }