1 ///////////////////////////////////////////////////////////////////////////////////////////////
2 // checkstyle: Checks Java source code and other text files for adherence to a set of rules.
3 // Copyright (C) 2001-2025 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.naming;
21
22 import java.util.regex.Pattern;
23
24 import com.puppycrawl.tools.checkstyle.StatelessCheck;
25 import com.puppycrawl.tools.checkstyle.api.AbstractCheck;
26 import com.puppycrawl.tools.checkstyle.api.DetailAST;
27 import com.puppycrawl.tools.checkstyle.api.FullIdent;
28 import com.puppycrawl.tools.checkstyle.api.TokenTypes;
29
30 /**
31 * <div>
32 * Checks that package names conform to a specified pattern.
33 * </div>
34 *
35 * <p>
36 * The default value of {@code format} for module {@code PackageName} has been chosen to match
37 * the requirements in the
38 * <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-6.html#jls-6.5.3">
39 * Java Language specification</a>
40 * and the Sun coding conventions. However, both underscores and uppercase letters are rather
41 * uncommon, so most configurations should probably assign value
42 * {@code ^[a-z]+(\.[a-z][a-z0-9]*)*$} to {@code format} for module {@code PackageName}.
43 * </p>
44 * <ul>
45 * <li>
46 * Property {@code format} - Control the pattern to match valid identifiers.
47 * Type is {@code java.util.regex.Pattern}.
48 * Default value is {@code "^[a-z]+(\.[a-zA-Z_]\w*)*$"}.
49 * </li>
50 * </ul>
51 *
52 * <p>
53 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
54 * </p>
55 *
56 * <p>
57 * Violation Message Keys:
58 * </p>
59 * <ul>
60 * <li>
61 * {@code name.invalidPattern}
62 * </li>
63 * </ul>
64 *
65 * @since 3.0
66 */
67 @StatelessCheck
68 public class PackageNameCheck
69 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 = "name.invalidPattern";
76
77 /** Control the pattern to match valid identifiers. */
78 // Uppercase letters seem rather uncommon, but they're allowed in
79 // https://docs.oracle.com/javase/specs/
80 // second_edition/html/packages.doc.html#40169
81 private Pattern format = Pattern.compile("^[a-z]+(\\.[a-zA-Z_]\\w*)*$");
82
83 /**
84 * Setter to control the pattern to match valid identifiers.
85 *
86 * @param pattern the new pattern
87 * @since 3.0
88 */
89 public void setFormat(Pattern pattern) {
90 format = pattern;
91 }
92
93 @Override
94 public int[] getDefaultTokens() {
95 return getRequiredTokens();
96 }
97
98 @Override
99 public int[] getAcceptableTokens() {
100 return getRequiredTokens();
101 }
102
103 @Override
104 public int[] getRequiredTokens() {
105 return new int[] {TokenTypes.PACKAGE_DEF};
106 }
107
108 @Override
109 public void visitToken(DetailAST ast) {
110 final DetailAST nameAST = ast.getLastChild().getPreviousSibling();
111 final FullIdent full = FullIdent.createFullIdent(nameAST);
112 if (!format.matcher(full.getText()).find()) {
113 log(full.getDetailAst(),
114 MSG_KEY,
115 full.getText(),
116 format.pattern());
117 }
118 }
119
120 }