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;
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 * Checks that long constants are defined with an upper ell. That is {@code 'L'}
30 * and not {@code 'l'}. This is in accordance with the Java Language Specification,
31 * <a href="https://docs.oracle.com/javase/specs/jls/se11/html/jls-3.html#jls-3.10.1">
32 * Section 3.10.1</a>.
33 * </div>
34 *
35 * <p>
36 * Rationale: The lower-case ell {@code 'l'} looks a lot like {@code 1}.
37 * </p>
38 *
39 * <p>
40 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
41 * </p>
42 *
43 * <p>
44 * Violation Message Keys:
45 * </p>
46 * <ul>
47 * <li>
48 * {@code upperEll}
49 * </li>
50 * </ul>
51 *
52 * @since 3.0
53 */
54 @StatelessCheck
55 public class UpperEllCheck extends AbstractCheck {
56
57 /**
58 * A key is pointing to the warning message text in "messages.properties"
59 * file.
60 */
61 public static final String MSG_KEY = "upperEll";
62
63 @Override
64 public int[] getDefaultTokens() {
65 return getRequiredTokens();
66 }
67
68 @Override
69 public int[] getAcceptableTokens() {
70 return getRequiredTokens();
71 }
72
73 @Override
74 public int[] getRequiredTokens() {
75 return new int[] {TokenTypes.NUM_LONG};
76 }
77
78 @Override
79 public void visitToken(DetailAST ast) {
80 if (ast.getText().endsWith("l")) {
81 log(ast, MSG_KEY);
82 }
83 }
84
85 }