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 }