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 for over-complicated boolean expressions. Currently, it finds code like
31 * {@code if (b == true)}, {@code b || true}, {@code !false},
32 * {@code boolean a = q > 12 ? true : false},
33 * etc.
34 * </div>
35 *
36 * <p>
37 * Rationale: Complex boolean logic makes code hard to understand and maintain.
38 * </p>
39 *
40 * <p>
41 * Parent is {@code com.puppycrawl.tools.checkstyle.TreeWalker}
42 * </p>
43 *
44 * <p>
45 * Violation Message Keys:
46 * </p>
47 * <ul>
48 * <li>
49 * {@code simplify.expression}
50 * </li>
51 * </ul>
52 *
53 * @since 3.0
54 */
55 @StatelessCheck
56 public class SimplifyBooleanExpressionCheck
57 extends AbstractCheck {
58
59 /**
60 * A key is pointing to the warning message text in "messages.properties"
61 * file.
62 */
63 public static final String MSG_KEY = "simplify.expression";
64
65 @Override
66 public int[] getDefaultTokens() {
67 return getRequiredTokens();
68 }
69
70 @Override
71 public int[] getAcceptableTokens() {
72 return getRequiredTokens();
73 }
74
75 @Override
76 public int[] getRequiredTokens() {
77 return new int[] {TokenTypes.LITERAL_TRUE, TokenTypes.LITERAL_FALSE};
78 }
79
80 @Override
81 public void visitToken(DetailAST ast) {
82 final DetailAST parent = ast.getParent();
83 switch (parent.getType()) {
84 case TokenTypes.NOT_EQUAL:
85 case TokenTypes.EQUAL:
86 case TokenTypes.LNOT:
87 case TokenTypes.LOR:
88 case TokenTypes.LAND:
89 log(parent, MSG_KEY);
90 break;
91 case TokenTypes.QUESTION:
92 final DetailAST nextSibling = ast.getNextSibling();
93 if (TokenUtil.isBooleanLiteralType(parent.getFirstChild().getType())
94 || nextSibling != null && nextSibling.getNextSibling() != null
95 && TokenUtil.isBooleanLiteralType(
96 nextSibling.getNextSibling().getType())) {
97 log(parent, MSG_KEY);
98 }
99 break;
100 default:
101 break;
102 }
103 }
104
105 }