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 * <div>
29 * Check that the {@code default} is after all the cases in a {@code switch} statement.
30 * </div>
31 *
32 * <p>
33 * Rationale: Java allows {@code default} anywhere within the
34 * {@code switch} statement. But it is more readable if it comes after the last {@code case}.
35 * </p>
36 * <ul>
37 * <li>
38 * Property {@code skipIfLastAndSharedWithCase} - Control whether to allow {@code default}
39 * along with {@code case} if they are not last.
40 * Type is {@code boolean}.
41 * Default value is {@code false}.
42 * </li>
43 * </ul>
44 *
45 * <p>
46 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
47 * </p>
48 *
49 * <p>
50 * Violation Message Keys:
51 * </p>
52 * <ul>
53 * <li>
54 * {@code default.comes.last}
55 * </li>
56 * <li>
57 * {@code default.comes.last.in.casegroup}
58 * </li>
59 * </ul>
60 *
61 * @since 3.4
62 */
63 @StatelessCheck
64 public class DefaultComesLastCheck extends AbstractCheck {
65
66 /**
67 * A key is pointing to the warning message text in "messages.properties"
68 * file.
69 */
70 public static final String MSG_KEY = "default.comes.last";
71
72 /**
73 * A key is pointing to the warning message text in "messages.properties"
74 * file.
75 */
76 public static final String MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE =
77 "default.comes.last.in.casegroup";
78
79 /** Control whether to allow {@code default} along with {@code case} if they are not last. */
80 private boolean skipIfLastAndSharedWithCase;
81
82 @Override
83 public int[] getAcceptableTokens() {
84 return getRequiredTokens();
85 }
86
87 @Override
88 public int[] getDefaultTokens() {
89 return getRequiredTokens();
90 }
91
92 @Override
93 public int[] getRequiredTokens() {
94 return new int[] {
95 TokenTypes.LITERAL_DEFAULT,
96 };
97 }
98
99 /**
100 * Setter to control whether to allow {@code default} along with
101 * {@code case} if they are not last.
102 *
103 * @param newValue whether to ignore checking.
104 * @since 7.7
105 */
106 public void setSkipIfLastAndSharedWithCase(boolean newValue) {
107 skipIfLastAndSharedWithCase = newValue;
108 }
109
110 @Override
111 public void visitToken(DetailAST ast) {
112 final DetailAST defaultGroupAST = ast.getParent();
113
114 // Switch rules are not subject to fall through.
115 final boolean isSwitchRule = defaultGroupAST.getType() == TokenTypes.SWITCH_RULE;
116
117 if (skipIfLastAndSharedWithCase && !isSwitchRule) {
118 if (isNextSiblingOf(ast, TokenTypes.LITERAL_CASE)) {
119 log(ast, MSG_KEY_SKIP_IF_LAST_AND_SHARED_WITH_CASE);
120 }
121 else if (ast.getPreviousSibling() == null
122 && isNextSiblingOf(defaultGroupAST,
123 TokenTypes.CASE_GROUP)) {
124 log(ast, MSG_KEY);
125 }
126 }
127 else if (isNextSiblingOf(defaultGroupAST,
128 TokenTypes.CASE_GROUP)
129 || isNextSiblingOf(defaultGroupAST,
130 TokenTypes.SWITCH_RULE)) {
131 log(ast, MSG_KEY);
132 }
133 }
134
135 /**
136 * Return true only if passed tokenType in argument is found or returns false.
137 *
138 * @param ast root node.
139 * @param tokenType tokentype to be processed.
140 * @return true if desired token is found or else false.
141 */
142 private static boolean isNextSiblingOf(DetailAST ast, int tokenType) {
143 return ast.getNextSibling() != null && ast.getNextSibling().getType() == tokenType;
144 }
145
146 }